Tagged: Breast Cancer

Targeting Stem Cell-like Traits: How miR-10b Inhibition Treats Metastatic Breast Cancer

“Our results demonstrate that inhibition of miR-10b using MN-anti-miR10b decreases the stemness of breast cancer cells, supporting dedifferentiation as a mechanism through which the nanodrug may function as a therapy.”

While there have been significant improvements in breast cancer detection and treatment, the outlook for metastatic breast cancer remains bleak, with only a 30% five-year survival rate. This is largely due to existing therapies’ inability to effectively target the unique characteristics of metastatic cells. One key factor in metastasis is miR-10b, a small noncoding RNA known to influence cancer cell invasion, migration, viability, and proliferation.

In their paper, researchers Alan Halim, Nasreen Al-Qadi, Elizabeth Kenyon, Kayla N. Conner, Sujan Kumar Mondal, Zdravka Medarova, and Anna Moore from Michigan State University’s Precision Health Program, College of Human Medicine, and College of Veterinary Medicine, and Transcode Therapeutics Inc. in Newton, Massachusetts, shared findings showing that inhibiting miR-10b impairs breast cancer cell stemness. Their research paper, entitled, “Inhibition of miR-10b treats metastatic breast cancer by targeting stem cell-like properties” was published in Volume 15 of Oncotarget on August 26, 2024.

THE STUDY

In this study, researchers investigated the effects of repeated MN-anti-miR10b treatments on local and distant metastases. They observed over 93% inhibition of miR-10b in cryosectioned samples and noted reduced miR-10b expression in lymph node and lung metastases after weekly dosing. RNA sequencing revealed upregulation of genes, including ATP6V0D2, EPHB2, KLF4, KLF7, NCOR2, TMEM268, and VDR, associated with developmental processes. Functional enrichment analysis highlighted biological processes such as cell differentiation and tissue development in these upregulated genes.

The researchers also explored the link between miR-10b expression and stem-like properties in cancer cells. Elevated miR-10b levels were found in stem-like breast cancer cells. MN-anti-miR10b reduced stemness-related traits in MDA-MB-231 and MCF-7 cells, as shown by reduced aldehyde dehydrogenase activity and smaller spheroids in tumorsphere assays. These results suggest that inhibiting miR-10b effectively targets stem-like properties in metastatic breast cancer, offering potential therapeutic benefits.

DISCUSSION

Inhibition of miR-10b has been shown to be an effective treatment strategy for metastatic breast cancer. The nanodrug MN-anti-miR10b was found to significantly downregulate miR-10b expression in cancer cells, leading to decreased cell migration, invasion, proliferation, and viability. The researchers investigated the time course of miR-10b inhibition and confirmed that the nanodrug effectively reduced miR-10b expression in both regional and distant metastases. RNA sequencing analysis revealed that the inhibition of miR-10b by MN-anti-miR10b upregulated genes associated with developmental processes, indicating an effect on the stem cell-like properties of cancer cells.

The study also demonstrated a correlation between miR-10b expression and stemness in cancer cells. Cells with increased stemness, identified by the CD44+/CD24- surface marker phenotype, showed higher miR-10b expression. Treatment with MN-anti-miR10b resulted in decreased stemness-associated properties, as observed through the Aldefluor assay and tumorsphere formation assays. These findings suggest that MN-anti-miR10b has a differentiation effect on cancer cells and targets dedifferentiated, stem cell-like cancer cells. The upregulation of genes associated with developmental processes by MN-anti-miR10b further supports the notion that cancer cells overexpressing miR-10b are in a less-developed, more stem cell-like state.

Overall, the study provides valuable insights into the therapeutic effects of miR-10b inhibition using MN-anti-miR10b in metastatic breast cancer. The findings suggest that targeting miR-10b and stem cell-like properties in cancer cells could be a promising approach for the treatment of various types of metastatic carcinoma.

IN CONCLUSION

Despite the progress made in breast cancer detection and treatment, the prognosis for metastatic breast cancer remains poor. A significant factor contributing to metastasis is miR-10b, a small RNA molecule involved in cancer cell invasion and migration. The researchers have developed a nanodrug called MN-anti-miR10b that delivers antisense oligomers to inhibit miR-10b in cancer cells.

In mouse models of metastatic triple-negative breast cancer, MN-anti-miR10b has shown promising results. It prevents the development of metastases and can eliminate existing metastases when combined with chemotherapy, even after treatment cessation. Recent studies have also linked miR-10b to the acquisition of stem cell-like properties in cancer cells, including chemotherapy resistance.

In this study, the researchers provide transcriptional evidence that inhibiting miR-10b with MN-anti-miR10b activates developmental processes in cancer cells. They also demonstrate that stem-like cancer cells have higher expression of miR-10b. Importantly, treatment of breast cancer cells with MN-anti-miR10b reduces their stemness, indicating that the nanodrug can effectively target and impair the stem-like properties of breast cancer cells.

These findings highlight the potential of MN-anti-miR10b as a treatment option for breast cancer subtypes characterized by stem-like properties. By inhibiting miR-10b, the nanodrug could disrupt the stemness of cancer cells and may offer a new approach to improve the outcomes for metastatic breast cancer patients.

Click here to read the full research paper in Oncotarget.

Oncotarget is an open-access, peer-reviewed journal that has published primarily oncology-focused research papers since 2010. These papers are available to readers (at no cost and free of subscription barriers) in a continuous publishing format at Oncotarget.com

Oncotarget is indexed and archived by PubMed/Medline, PubMed Central, Scopus, EMBASE, META (Chan Zuckerberg Initiative) (2018-2022), and Dimensions (Digital Science).

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Harnessing the Power of Nanobodies: Inhibiting Metastasis of 4T1-12B Breast Tumor Cells

In this study, researchers show that treatment of 4T1-12B mouse breast cancer cells with this nanobody inhibits V-ATPase-dependent acidification of the media and invasion of these cells in vitro.

Researchers recently developed a nanobody directed against an extracellular epitope of the mouse V-ATPase c subunit. Zhen Li, Mohammed A. Alshagawi, Rebecca A. Oot, Mariam K. Alamoudi, Kevin Su, Wenhui Li, Michael P. Collins, Stephan Wilkens, and Michael Forgac from Tufts University School of MedicineTufts UniversityDana Farber Cancer Institute, Harvard Medical SchoolUniversity of Minnesota School of MedicinePrince Sattam Bin Abdulaziz UniversityKorro BioSUNY Upstate Medical University; and Foghorn Therapeutics, suggest that plasma membrane V-ATPases represent a novel therapeutic target to limit breast cancer metastasis. The vacuolar H+-ATPase (V-ATPase) is an ATP-dependent proton pump that functions to control the pH of intracellular compartments as well as to transport protons across the plasma membrane of various cell types, including cancer cells.

On August 14, 2024, their research paper was published in Oncotarget’s Volume 15, entitled, A nanobody against the V-ATPase c subunit inhibits metastasis of 4T1-12B breast tumor cells to lung in mice.”

The Research

Breast cancer is one of the most diagnosed cancers, accounting for almost one-third (30%) of all new diagnoses in women in 2022. At the time of diagnosis, 20–30% of patients with early-stage breast cancer will go on to develop metastatic breast cancer. 6–10% of all patients with breast cancer have stage IV disease at time of diagnosis. It has been shown that V-ATPase plays an important role in promoting the invasiveness of many cancer cell types, including breast cancer cells. 

This study demonstrated that inhibiting cell surface V-ATPases can effectively block tumor cell invasion. The findings indicate that anti-V-ATPase antibodies targeting an extracellular region of the V-ATPase can suppress activity on the surface of cancer cells, as well as inhibit both in vitro invasion and in vivo metastasis in a mouse model. This represents a promising advancement toward developing a new therapy to limit breast cancer metastasis.

Results

A camelid nanobody against the N-terminus of the mouse V-ATPase c subunit was prepared using phage display. The nanobody was dimerized through disulfide bonding to create a bivalent molecule. The purified nanobody was detected using Coomassie blue staining and Western blotting. The apparent molecular weight of the dimer on SDS-PAGE was around 45 kDa, slightly faster than the predicted weight of 56.8 kDa. The nanobody was tested for its ability to inhibit V-ATPase-dependent acidification in mouse 4T1-12B cells. The nanobody treatment resulted in a similar increase in extracellular pH as treatment with concanamycin, a known V-ATPase inhibitor. 

Combining both the nanobody and concanamycin did not significantly enhance the effect. The nanobody effectively inhibited V-ATPase-dependent extracellular acidification without affecting cell viability. The anti-V-ATPase nanobody was tested for its ability to inhibit in vitro invasion of 4T1-12B cells. Treatment with the nanobody significantly inhibited invasion, like its inhibition of extracellular acidification. The nanobody effectively inhibits both extracellular acidification and in vitro invasion of 4T1-12B cells with similar affinity. 

The administration of the anti-V-ATPase nanobody was tested to determine its effect on tumor growth and metastasis in mice. Different amounts of the nanobody were administered to mice without any adverse effects. The effect of nanobody administration on in vivo metastasis was then tested using 4T1-12B cells implanted in the mammary fat pad. However, no significant difference in tumor volumes was observed between the control and nanobody-treated groups at the end of the study. Treatment with the anti-V-ATPase nanobody resulted in a significant reduction in lung metastasis but had no effect on tumor growth or leg metastases. No significant metastasis was observed in other organs. In contrast, treatment with the anti-GFP nanobody did not reduce lung metastases.

Discussion

The researchers’ previous results demonstrated that selective inhibition of cell surface V-ATPases using an antibody or bafilomycin showed potential in inhibiting invasion of breast cancer cells. However, the use of antibodies against the native c subunit proved challenging due to its conservation and limited exposure. To overcome this, a nanobody against a native epitope of the c subunit was developed through in vitro screening. This nanobody successfully inhibited cell surface V-ATPase activity in mouse 4T1-12B breast cancer cells and showed a correlation between inhibition of invasion and extracellular acidification. In mice, the nanobody treatment significantly reduced lung metastases, but had no effect on tumor growth or leg metastasis. 

The study suggests that different mechanisms may be involved in tumor cell invasion in different tissues. The potential side effects of inhibiting cell surface V-ATPases were also discussed, highlighting the limited presence of these pumps in certain cells and the potential benefits of inhibiting osteoclast function for breast cancer metastasis to bone. 

Overall, the findings support the use of inhibitory nanobodies against cell surface V-ATPases as a potential therapeutic approach to inhibit breast cancer metastasis.

“These results provide support for the use of an inhibitory antibody directed against an extracellular epitope of the V-ATPase as a potential anti-metastatic therapeutic to inhibit breast cancer metastasis.”

Click here to read the full research paper in Oncotarget.

Oncotarget is an open-access, peer-reviewed journal that has published primarily oncology-focused research papers since 2010. These papers are available to readers (at no cost and free of subscription barriers) in a continuous publishing format at Oncotarget.com

Oncotarget is indexed and archived by PubMed/Medline, PubMed Central, Scopus, EMBASE, META (Chan Zuckerberg Initiative) (2018-2022), and Dimensions (Digital Science).

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Impact of Dual Immunotherapies Before Surgery in HR+/HER2-negative Breast Cancer

In this new study, researchers assessed the feasibility of treating HR+/HER2-negative breast cancer patients with the immunotherapies durvalumab and tremelimumab before standard neoadjuvant chemotherapy and surgery.

Breast cancer immunotherapy has shown promise, but its clinical efficacy remains limited, especially for hormone receptor positive (HR+)/HER2-negative breast cancer. While immune checkpoint inhibitors combined with chemotherapy have benefitted some early-stage and metastatic triple-negative breast cancer patients, HR+/HER2-negative cases have seen fewer improvements.

Recent neoadjuvant trials indicate that early-stage HR+/HER2-negative breast cancers might respond better to immunotherapy strategies that amplify tumor-infiltrating lymphocytes (TILs) through dual PD-(L)1/CTLA-4 checkpoint inhibition before surgery and chemotherapy. This approach could enhance the immune response in the tumor microenvironment and improve outcomes for this challenging breast cancer subtype.

The Study

Increased TILs are associated with improved neoadjuvant chemotherapy (NACT) responses across breast cancer subtypes. Recently, researchers Haven R. Garber, Sreyashi Basu, Sonali Jindal, Zhong He, Khoi Chu, Akshara Singareeka Raghavendra, Clinton Yam, Lumarie Santiago, Beatriz E. Adrada, Padmanee Sharma, Elizabeth A. Mittendorf, and Jennifer K. Litton from the University of Texas MD Anderson Cancer Center, Brigham and Women’s Hospital, Dana-Farber Brigham Cancer Center, and Harvard Medical School hypothesized that amplifying TILs via dual checkpoint blockade would enhance the response to subsequent NACT in breast tumors. 

Their new study aimed to assess the feasibility of enrolling untreated patients with stage II or III HR+/HER2-negative breast cancer for upfront treatment with combined PD-L1/CTLA-4 checkpoint inhibition before standard NACT and surgery. The research paper, published in Oncotarget’s Volume 15 on March 19, 2024, was entitled, “Durvalumab and tremelimumab before surgery in patients with hormone receptor positive, HER2-negative stage II–III breast cancer.”

“This feasibility study was conducted to begin testing the hypothesis that dual checkpoint blockade would increase TIL and enhance the response to subsequent NACT in patients with stage II or III HR+/HER2-negative breast cancer.”

Patient Screening, Recruitment, & Assessment

The study aimed to accrue 16 patients to evaluate the feasibility of enrolling patients with clinical stage II or III HR+/HER2-negative breast cancer onto a trial evaluating investigational immunotherapy agents before standard NACT. Patient tumor samples were collected to assess immunologic and molecular responses to combination checkpoint blockade.

Eligible patients had to have HR+/HER2-negative breast cancer, defined as estrogen receptor (ER) and/or progesterone receptor (PR) expression >10% by immunohistochemistry (IHC), and HER2-negative defined as 0/1+ by IHC or if 2+, negative by fluorescence in situ hybridization. Other inclusion criteria included an ECOG performance status of 0 or 1, planned NACT, and adequate blood counts and organ function.

Patients were excluded if they had received prior PD-1, PD-L1, or CTLA-4 inhibitors or any prior treatment for the primary breast cancer. Other exclusions included current or prior use of immunosuppressive medications within 28 days, active or previous autoimmune disease within 2 years, inflammatory bowel disease, or receipt of a live attenuated vaccination within 30 days before study entry or treatment.

Durvalumab was administered at 1500 mg IV, and tremelimumab at 75 mg IV for 2 cycles on days 1 and 28. Patients then proceeded to standard NACT followed by breast surgery. Baseline breast ultrasounds were performed within 21 days before the first immunotherapy cycle and again between 1 and 7 days after the second cycle. Research biopsies were collected at baseline and after 2 cycles of immunotherapy.

Results & Discussion

The trial’s target accrual of 16 patients was not met, as it was stopped early after three of the first eight enrolled patients experienced immunotherapy-related toxicity or suspected disease progression, indicating that this strategy is not clinically feasible.

Among the eight patients who did receive the study-specified combination immunotherapy, seven had pre- and post-immunotherapy ultrasounds performed, showing mixed responses. Three experienced an increase in tumor volume, three a decrease, and one showed stable disease. The impact of combination immunotherapy on TILs was also mixed. Though limited by the number of patients with available serial biopsies, there did not appear to be a significant increase in the immune response within the tumor microenvironment (TME).

The Phase II NIMBUS trial also assessed dual checkpoint blockade in breast cancer, though in a population of metastatic breast cancer patients with tumors harboring a high tumor mutation burden (TMB ≥9 mutations per megabase). Of the 30 patients enrolled, 20 had ER+/HER2-negative breast cancer. The overall response rate (ORR) was 16.7%, with four durable responses lasting at least 15 months. Three of the five responders had a TMB ≥14 mutations per megabase. The ORR among patients with TMB <14 mutations per megabase was 6.7%. Three patients (10%) experienced grade 3 immune toxicity.

The TAPUR basket trial similarly included patients with TMB-high metastatic breast cancer but utilized single-agent anti-PD-1 checkpoint blockade (pembrolizumab) rather than combination immunotherapy. Half of the 28 enrolled patients had ER+ breast cancer, and the majority had received multiple prior lines of systemic therapy. The ORR was 21% with a median progression-free survival (PFS) of 10.6 weeks. Five patients (17.9%) experienced one or more grade 3 adverse events possibly attributed to pembrolizumab, and six patients discontinued treatment due to side effects.

In summary, while a minority of patients with ER+ metastatic breast cancer may benefit from anti-PD-(L)1/anti-CTLA-4 checkpoint blockade, the majority risk exposure to immune-related adverse events without additional benefit.

Conclusion & Future Directions

The present study did not demonstrate a clear benefit for dual checkpoint blockade administered prior to NACT in patients with stage II or III HR+/HER2-negative breast cancer. Only one out of eight patients (12.5%) achieved a pathologic complete response (pCR) at the time of breast surgery after immune therapy and NACT. Two patients experienced grade 3 immunotherapy-related toxicity.

While the KEYNOTE-756 and CheckMate 7FL trials have demonstrated improved pCR rates with the addition of single-agent anti-PD-1 checkpoint blockade to NACT for patients with high-risk HR+/HER2-negative, stage II/III breast cancer, the risk/benefit calculus of adding immunotherapy for this subtype is different from metastatic triple-negative breast cancer (TNBC) or even stage II/III TNBC, where the risks of morbidity and mortality from disease are higher.

Hopefully, biomarkers such as PD-L1 expression and tumor mutation burden (TMB) will guide the use of single or dual-agent immunotherapy towards those patients most likely to benefit, sparing others from significant toxicity. Notably, immune-mediated adverse events of grade 3 or higher were reported in 12.9% of breast cancer patients receiving pembrolizumab in the KEYNOTE-522 trial and in 38% of patients receiving dual ipilimumab/nivolumab in a trial of patients with metastatic melanoma.

For immunotherapy to play a meaningful role in HR+/HER2-negative early breast cancer, a breast cancer subtype where most patients are cured with standard therapy, it will need to significantly increase the fraction of cured patients without disproportionately causing serious and/or long-term immune toxicity. Future research should focus on identifying predictive biomarkers and optimizing combination strategies to enhance the efficacy of immunotherapy in this challenging breast cancer subtype.

Click here to read the full research paper in Oncotarget.

Oncotarget is an open-access, peer-reviewed journal that has published primarily oncology-focused research papers since 2010. These papers are available to readers (at no cost and free of subscription barriers) in a continuous publishing format at Oncotarget.com

Oncotarget is indexed and archived by PubMed/Medline, PubMed Central, Scopus, EMBASE, META (Chan Zuckerberg Initiative) (2018-2022), and Dimensions (Digital Science).

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Identifying Biomarkers for Predicting Paclitaxel Response

In this research perspective, researchers discuss causal and correlative approaches to identify potential biomarkers for predicting paclitaxel response.

Cancer therapy has come a long way from its one-size-fits-all beginning to the awakening era of personalized medicine. This change has been largely driven by the discovery of biomarkers. Biomarkers can help refine patient selection for specific therapies. A blend of causal and correlative approaches is needed to elucidate the full potential of biomarkers in cancer research. This fusion of methodologies allows for a comprehensive exploration of biomarker efficacy, leading to more accurate predictions of drug response.

In a new paper, researchers Alberto Moscona-Nissan, Karl J. Habashy, Victor A. Arrieta, Adam M. Sonabend, and Crismita Dmello from the Universidad Panamericana School of Medicine, Northwestern University and Universidad Nacional Autónoma de México discuss causal and correlative approaches to identify potential biomarkers for predicting response to paclitaxel — a commonly used chemotherapeutic agent. On February 8, 2024, their research perspective was published in Oncotarget’s Volume 15, entitled, “Combining causal and correlative approaches to discover biomarkers of response to paclitaxel.”

“[…] studying the combination of non-overlapping biomarkers’ expression, in addition to clinical and sociodemographic data could generate predictive models for paclitaxel susceptibility.”

Combining Causal and Correlative Approaches

Paclitaxel is a mainstay of treatment for various cancers, including breast, pancreatic, ovarian, and non-small cell lung carcinomas. However, the benefit derived from paclitaxel treatment varies across patients, and a significant proportion does not receive therapeutic benefit and experiences unnecessary toxicity. The variability in response to paclitaxel underscores the need for predictive biomarkers. Predictive biomarkers of response to paclitaxel can lead to improved treatment efficacy, less unnecessary toxicity, and potentially better health outcomes.

In a recent study, researchers used a whole-genome CRISPR/Cas9 knockout to identify genes that influence paclitaxel susceptibility in gliomas. They identified 51 genes that have implications in pathways such as NFkB, toll-like receptor, and MAPK signaling, transcriptional misregulation, and apoptosis. The team also identified the signal sequence receptor 3 (SSR3) gene as a predictive biomarker for paclitaxel susceptibility.

The SSR3 gene encodes the gamma subunit of the signal sequence receptor (SSR) complex, a glycosylated membrane receptor located at the endoplasmic reticulum (ER). This complex is involved in protein translocation across the ER membrane. In the study, it was found that higher SSR3 expression correlated with increased paclitaxel susceptibility in cancer cell lines. SSR3 knockout cells showed decreased susceptibility to paclitaxel, while cells overexpressing SSR3 had increased susceptibility.

The study also revealed a link between SSR3 and the unfolded protein response (UPR) pathway, which reduces the amount of unfolded proteins in the cell under stressful conditions. A positive correlation was found between SSR3 expression and IRE1a levels in glioma PDX cells. IRE1a is a serine/threonine kinase that is involved in the UPR pathway and has been implicated in various disorders.

Conclusions & Future Directions

A significant challenge in the treatment of glioblastoma is the blood-brain barrier which limits the efficacy of paclitaxel. However, innovative strategies like convection-enhanced delivery, biodegradable wafers, peptide-drug conjugates, and low-intensity pulsed ultrasound administered with microbubbles are being developed to overcome this barrier.

The researchers also wrote in their research perspective that, after identifying a potential predictive biomarker in a training cohort of patients, it is vital to validate the finding in an independent cohort. The correlation between patients’ overall survival and SSR3 expression is currently being studied in a phase 2 trial at Northwestern University. Based on the outcomes of these validations, the predictive models can be further refined by incorporating other non-overlapping histologic and molecular biomarkers along with patient demographics. The discovery of predictive biomarkers for paclitaxel response, such as SSR3, promises to significantly impact cancer treatment. 

“Precision and personalized medicine can lead to a transition from a stochastic treatment response into predictable scenarios. Further identification of predictive biomarkers, validation, and study of combinations as predictive models is critical to generate a greater impact that can be translated to the bedside of patients.”

Click here to read the full research paper in Oncotarget.

Oncotarget is an open-access, peer-reviewed journal that has published primarily oncology-focused research papers since 2010. These papers are available to readers (at no cost and free of subscription barriers) in a continuous publishing format at Oncotarget.com

Oncotarget is indexed and archived by PubMed/Medline, PubMed Central, Scopus, EMBASE, META (Chan Zuckerberg Initiative) (2018-2022), and Dimensions (Digital Science).

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Antitumor Effects of Sacituzumab Govitecan Plus Platinum-Based Chemotherapy

In this study, researchers investigated the antitumor effects of Sacituzumab govitecan in combination with platinum-based chemotherapy.

The relentless search for effective cancer therapies has led to numerous breakthroughs in drug discovery and development. Advancements have emerged in recent years through the promising avenue of combination therapy, where two or more drugs are used synergistically to enhance their collective therapeutic effect. This strategy has shown significant potential in overcoming drug resistance, reducing side effects, and improving patient survival rates.

In a new study, researchers Thomas M. Cardillo, Maria B. Zalath, Roberto Arrojo, Robert M. Sharkey, Serengulam V. Govindan, Chien-Hsing Chang, and David M. Goldenberg from Gilead Sciences and the Center for Molecular Medicine and Immunology demonstrated the significant antitumor effects of Sacituzumab govitecan, an anti-Trop-2-SN-38 antibody-drug conjugate, in combination with platinum-based chemotherapy. On February 22, 2024, their research paper was published in Oncotarget, entitled, “Sacituzumab govitecan plus platinum-based chemotherapy mediates significant antitumor effects in triple-negative breast, urinary bladder, and small-cell lung carcinomas.”

Sacituzumab Govitecan & Platinum-Based Chemotherapy

Sacituzumab govitecan is an innovative drug that has gained prominence in recent years due to its unique mechanism of action and remarkable antitumor effects. It is an antibody-drug conjugate composed of an anti-Trop-2-directed antibody linked with the topoisomerase I inhibitory drug, SN-38, via a proprietary hydrolysable linker. Trop-2 is a transmembrane glycoprotein that is highly expressed in various solid tumors, making it an attractive target for cancer therapy. SN-38, the active metabolite of the chemotherapy drug irinotecan, is a potent topoisomerase I inhibitor that triggers DNA damage and apoptosis in cancer cells.

Platinum-based chemotherapy, primarily cisplatin and carboplatin, is a cornerstone of cancer treatment. These drugs work by interfering with DNA replication in cancer cells, leading to cell death. However, their use is often limited by drug resistance and toxic side effects.

“Using multiple drugs to treat cancer may allow for direct activity against multiple targets simultaneously or may indirectly affect the same target through different mechanisms of action [16].”

The Study

The combination of Sacituzumab govitecan and platinum-based chemotherapy has the potential to overcome these limitations. In the current study, the researchers found this combination to produce significant antitumor effects in various cancer models, including triple-negative breast, urinary bladder, and small-cell lung carcinomas. They found that the combination treatment resulted in additive growth inhibitory effects in vitro. The combination led to significant down-regulation of anti-apoptotic proteins and up-regulation of pro-apoptotic proteins, suggesting a shift towards pro-apoptotic signaling.

The in vivo efficacy of the combination therapy was further confirmed in mice bearing human tumor xenografts. The combination of Sacituzumab govitecan and carboplatin or cisplatin resulted in significant tumor regressions in all tested models. Importantly, the combination therapy was well tolerated by the animals, indicating a favorable safety profile.

Conclusions

The findings from this study represent a significant leap forward in the field of chemotherapy combination therapy drug discovery. The team provided strong evidence to support the clinical investigation of Sacituzumab govitecan in combination with platinum-based chemotherapy for the treatment of various solid tumors. Future studies should investigate the optimal dosing and sequencing of this combination therapy to maximize its efficacy and minimize potential toxicities. Additionally, the exploration of potential biomarkers could help identify patients who are most likely to benefit from this combination therapy.

In summary, the combination of Sacituzumab govitecan (SG) and platinum-based chemotherapy holds great promise as a potent antitumor therapy. It represents a novel approach that could potentially revolutionize the treatment of various solid tumors and improve patient outcomes.

“Importantly, these data demonstrate significantly greater antitumor effects of SG plus carboplatin or cisplatin in tumor-bearing mice than monotherapies, and that they were well tolerated by the animals. Based on these results, SG plus platinum-based chemotherapeutics merit clinical investigation.”

Click here to read the full research paper in Oncotarget.

Oncotarget is an open-access, peer-reviewed journal that has published primarily oncology-focused research papers since 2010. These papers are available to readers (at no cost and free of subscription barriers) in a continuous publishing format at Oncotarget.com

Oncotarget is indexed and archived by PubMed/Medline, PubMed Central, Scopus, EMBASE, META (Chan Zuckerberg Initiative) (2018-2022), and Dimensions (Digital Science).

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How Osteopontin Stimulates Mitochondrial Biogenesis and Cancer Metastasis

In this new study, researchers investigated the role of Osteopontin splice variants in cancer metastasis.

Mitochondrial biogenesis, the process of increasing the size and number of mitochondria within cells, plays a crucial role in cancer metastasis. Metastasizing cells exhibit a unique metabolism that differs from the well-known Warburg effect observed in primary tumors. While primary tumors primarily rely on glycolysis for energy production, metastatic cells rely on oxidative phosphorylation and ATP generation for short-term energy needs. However, over longer time frames, mitochondrial biogenesis becomes a prominent feature in the success of metastasis.

In a new study, researchers Gulimirerouzi Fnu and Georg F. Weber from the University of Cincinnati’s James L. Winkle College of Pharmacy investigate the connection between short-term oxidative metabolism and long-term mitochondrial biogenesis in cancer metastasis. They hypothesized that Osteopontin splice variants, specifically Osteopontin-c, stimulate an increase in mitochondrial size through the activation of specific signaling mechanisms. On December 1, 2023, their new research paper was published in Oncotarget, entitled, “Osteopontin induces mitochondrial biogenesis in deadherent cancer cells.”

“Over longer time frames, mitochondrial biogenesis becomes a pronounced feature and aids metastatic success. It has not been known whether or how these two phenomena are connected. We hypothesized that Osteopontin splice variants, which synergize to increase ATP levels in deadherent cells, also increase the mitochondrial mass via the same signaling mechanisms.”

The Role of Osteopontin Variants in Mitochondrial Biogenesis

Deadhesion, the process of detaching cancer cells from the extracellular matrix, is known to induce metabolic reprogramming and promote cancer cell survival in circulation. Osteopontin (OPN), a cytokine produced by cancer cells, has been implicated in tumor progression and the development of metastases. It mediates tumor cell survival and expansion under deadherent conditions, making it an ideal candidate for studying the mechanisms behind mitochondrial biogenesis. The authors of the research paper focused on two Osteopontin splice variants, Osteopontin-a and Osteopontin-c, and their effects on mitochondrial biogenesis.

Through their experiments with breast tumor cells, the authors found that both Osteopontin-a and Osteopontin-c contribute to mitochondrial biogenesis in deadherent cells. However, Osteopontin-c was more effective in stimulating an increase in mitochondrial size compared to Osteopontin-a. The authors also observed that the autocrine effects of Osteopontin variants are critical for the survival and anchorage-independence of disseminating malignant cells.

The Role of CD44v and SLC7A11 in Osteopontin Signaling

To further elucidate the mechanism behind Osteopontin-induced mitochondrial biogenesis, the authors investigated the receptors involved in Osteopontin signaling. They focused on CD44, a cell surface receptor known to interact with Osteopontin, and its variant CD44v. The authors found that Osteopontin-induced mitochondrial biogenesis is mediated via the binding of Osteopontin to CD44v.

Additionally, the authors discovered that the chloride-dependent cystine-glutamate transporter SLC7A11 plays a crucial role in Osteopontin signaling. The upregulation and co-ligation of SLC7A11, along with CD44v, leads to the activation of PGC-1, a known inducer of mitochondrial biogenesis. Surprisingly, the authors found that peroxide, an important intermediate in this signaling cascade, acts upstream of PGC-1 and is likely produced as a consequence of SLC7A11 recruitment and activation.

In Vivo Implications and Therapeutic Targets

To validate the relevance of their findings in clinical settings, the authors analyzed gene expression profiles in breast cancer metastases and metastases from other types of cancers. They identified the master regulator of mitochondrial biogenesis, PPARG, as well as its downstream effectors NRF1 and BACH1, to be upregulated in various metastases. These findings suggest that the Osteopontin-induced activation of PGC-1 and subsequent mitochondrial biogenesis may play a crucial role in cancer metastasis.

The authors also conducted in vivo experiments using mouse models. They observed that suppression of the biogenesis-inducing mechanisms led to a reduction in disseminated tumor mass. These findings not only confirm the functional connection between short-term oxidative metabolism and long-term mitochondrial biogenesis in cancer metastasis but also provide potential mechanisms and targets for treating cancer metastasis.

Conclusion

This study provides valuable insights into the role of Osteopontin splice variants in regulating mitochondrial biogenesis in metastatic cancer cells. The researchers demonstrated that Osteopontin-c stimulates an increase in mitochondrial size through the activation of specific signaling mechanisms involving CD44v and SLC7A11. These findings have significant implications for understanding the metabolic adaptations of metastatic cancer cells and suggest potential targets for therapeutic interventions. Further research is needed to fully elucidate the intricate signaling pathways involved in Osteopontin-induced mitochondrial biogenesis and to explore the clinical applications of these findings in cancer treatment.

“This study confirms a functional connection between the short-term oxidative metabolism and the longer-term mitochondrial biogenesis in cancer metastasis – both are induced by Osteopontin-c. The results imply possible mechanisms and targets for treating cancer metastasis.”

Click here to read the full research paper in Oncotarget.

Oncotarget is an open-access, peer-reviewed journal that has published primarily oncology-focused research papers since 2010. These papers are available to readers (at no cost and free of subscription barriers) in a continuous publishing format at Oncotarget.com. Oncotarget is indexed/archived on MEDLINE / PMC / PubMed.

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Genetic Insights into Early Breast Cancer in Kazakhstan

In this new study, researchers aimed to determine the genetic predisposition to early breast cancer in women from Kazakhstan.

Genetic Insights into Early Breast Cancer in Kazakhstan

Breast cancer (BC) is one of the most common and deadly cancers worldwide, affecting millions of women every year. However, not all women share the same risk of developing breast cancer. There are many factors that influence this disease, including age, lifestyle, family history, and genetic makeup.

One of the most important aspects of breast cancer research is to identify the genetic factors that predispose some women to develop breast cancer at an early age, especially in different ethnic groups that may have unique genetic variants. This can help to improve the prevention, diagnosis and treatment of breast cancer, as well as to reduce the health disparities among different populations.

In a new study, researchers Gulnur Zhunussova, Nazgul Omarbayeva, Dilyara Kaidarova, Saltanat Abdikerim, Natalya Mit, Ilya Kisselev, Kanagat Yergali, Aigul Zhunussova, Tatyana Goncharova, Aliya Abdrakhmanova, and Leyla Djansugurova from the Institute of Genetics and Physiology, Kazakh Institute of Oncology and Radiology, Al-Farabi Kazakh National University, and Asfendiyarov Kazakh National Medical University aimed to determine the genetic predisposition to early breast cancer in women from Kazakhstan — a population that has not been well studied before. On October 4, 2023, their research paper was published in Oncotarget, entitled, “Determination of genetic predisposition to early breast cancer in women of Kazakh ethnicity.”

“Our study may reveal previously uncharacterized population-specific variants that may increase the risk of BC in the Kazakh population.”

The Study

The researchers enrolled 224 unrelated Kazakh women diagnosed with early onset breast cancer. All patients were treated at the Kazakh Institute of Oncology and Radiology from August 2017 to October 2019. Cohort characteristics reported that the median age of the women was 34.6 years old (ranging between 19 and 40 years), 15.6% were diagnosed under the age of 30 and 13.8% had breast cancer within their family history. The researchers utilized next-generation sequencing (NGS) to perform a comprehensive analysis of germline mutations and gene expression profiles using the MiSeq platform. They used a targeted panel of 94 cancer-associated genes, including a vast number of genes implicated in hereditary cancer syndromes and overall breast cancer predisposition.

“To our knowledge, this is the first study using NGS technology to study the genetic predisposition to early-onset BC women from Kazakhstan and assess their impact on the patients’ clinical outcomes.”

The NGS-based multigene panel testing allowed the researchers to identify recurrent, possible founder and novel PVs in Kazakh women with early-onset BC that were undetected in earlier studies. Among 57 patients (25.4%), 38 unique pathogenic variants (PVs) were identified in 13 different cancer-predisposing genes. Notably, 12 of the 38 PVs were recurrent, including specific variants in BRCA1 and BRCA2 genes, which may represent founder mutations in this population. BRCA1 carriers had a significantly higher likelihood of developing triple-negative breast cancer and having a family history of breast cancer compared to non-carriers. Six of the 38 variants were novel.

“We demonstrated the remarkable efficacy of an NGS-based panel to identify rare germline variants in early onset BC patients. These findings could contribute to the development of population-specific multigene panels for more rapid and cost-effective testing.”

Conclusions

The study provides valuable insights into the genetic predisposition of early breast cancer in women of Kazakh ethnicity. It also highlights the value of next generation sequencing technology and the importance of studying different ethnic groups to understand the diversity and complexity of breast cancer genetics. The authors suggest that broadening the scope of genetic testing for hereditary breast cancer from only BRCA genes to testing multiple genes at once could lead to better results. However, further studies are needed to validate the clinical utility of the panels used in this study. Nonetheless, these findings may aid in developing personalized risk assessment and management strategies for Kazakh women with early-onset breast cancer, as well as to inform future clinical trials and treatments.

“With this in mind, we will focus in the future on segregation analyses of family members and functional analyses to evaluate the inheritance pattern and pathogenicity of the identified recurrent and novel BC variants. Retrospective analyses of their possible association with progression-free, metastasis-free, and overall survival are also an exciting direction for future research. No less interesting would be the study of these variants regarding the chemosensitivity and efficacy of specific targeted therapies for their carriers.”

Click here to read the full research paper in Oncotarget.

Oncotarget is an open-access, peer-reviewed journal that has published primarily oncology-focused research papers since 2010. These papers are available to readers (at no cost and free of subscription barriers) in a continuous publishing format at Oncotarget.com. Oncotarget is indexed/archived on MEDLINE / PMC / PubMed.

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New Study Reveals Genetic Risk Factors for Cancer in Saudi Arabia

In a new study, researchers found that 38.4% of a cohort in Saudi Arabia carried pathogenic variants linked to hereditary cancer risk.

New Study Reveals Genetic Risk Factors for Cancer in Saudi Arabia

Familial cancer is a fearsome reality for millions of people worldwide. While some cases of familial cancer syndrome (FCS) may be influenced by shared environmental or lifestyle factors within a family, others are solely due to genetic mutations passed down through generations. This problem is especially prevalent in Saudi Arabia—where rates of familial cancer are among the highest in the world.

“Cancer increased in the Kingdom of Saudi Arabia by 136% between 1999 and 2015 [4].”

Approximately 20% of all Saudi Arabian cancer patients have a family history of cancer. This population is likely to carry mutant alleles, presenting an opportunity for further exploration and research. By studying these individuals and their genetic profiles, scientists and healthcare professionals can gain valuable insights into the genetic factors contributing to familial cancer in the Saudi Arabian population. This knowledge can help improve risk assessment, develop targeted prevention strategies, and potentially lead to more effective treatments for familial cancer cases. 

In a new study, researchers Musa AlHarbi, Nahla Ali Mobark, Wael Abdel Rahman AlJabarat, Hadeel ElBardis, Ebtehal AlSolme, Abdullah Bany Hamdan, Ali H. AlFakeeh, Fatimah AlMushawah, Fawz AlHarthi, Abdullah A. AlSharm, Ali Abdullah O. Balbaid, Naji AlJohani, Alicia Y. Zhou, Heather A. Robinson, Saleh A. Alqahtani, and Malak Abedalthagafi from King Fahad Medical City, Color Health Inc., University of Manchester, Johns Hopkins University, King Faisal Specialist Hospital and Research Center, and Emory University Hospital conducted a next-generation sequencing (NGS) assessment for hereditary cancer risk in a Saudi Arabian population. Their research paper was published in Oncotarget on June 12, 2023, entitled, “Investigating the prevalence of pathogenic variants in Saudi Arabian patients with familial cancer using a multigene next generation sequencing panel.”

The Study

The researchers used a 30-gene, targeted NGS panel to screen 310 subjects, including 57 non-cancer patients, 110 index patients with cancer and 143 of their relatives, 16 of whom also had cancer. (“Index patients” refers to individuals who are the first in a family to be diagnosed with a particular disease or condition of interest.) The NGS panel covered genes related to breast, ovarian, colorectal, endometrial, gastric, pancreatic, prostate, thyroid, renal, and skin cancers, as well as familiar adenomatous polyposis (FAP) and Lynch syndrome.

“This kit has been previously trialed as a means of capturing potential PVs [pathogenic variants] at a population level in Nigeria and the Caribbean, and in identifying rare variants in cancer patients who have tested negative for common cancer variants [3538].”

The results showed that 119 subjects (38.4% of the cohort) carried pathogenic or likely pathogenic variants (PVs) affecting genes associated with hereditary cancer risk. (TP53, ATM, CHEK2, CDH1, CDKN2A, BRCA1, BRCA2, PALB2, BRIP1, RAD51D, APC, MLH1, MSH2, MSH6, PMS2, PTEN, NBN/NBS1, and MUTYH were identified as genes with pathogenic or likely pathogenic variants.) Among 126 patients and relatives with a history of cancer, 49 subjects (38.9%) carried pathogenic or likely pathogenic variants. Two specific variants (APC c.3920T>A and TP53 c.868C>T) were significantly associated with the occurrence of colorectal cancer/Lynch syndrome and multiple colon polyposis. Diverse variants in BRCA2, many of which were previously unreported as pathogenic, were found at a higher frequency in individuals with a history of cancer compared to the general patient population. Overall, these subjects had more genetic variants associated with familial cancers compared to other populations.

Conclusion

“In conclusion, this study is one of the first to report the prevalence of inherited cancer genetic variants in a cohort from the Arab world. Our study gives critical first insights into the genetic variants associated with overall cancer risk in this specific population, and specific forms including CRC/Lynch syndrome and breast cancer.”

The researchers concluded that their study was the first to use a comprehensive NGS panel for FCS risk assessment in Saudi Arabia and that it provided valuable insights into the genetic landscape of cancer in this population. They also acknowledged some limitations of their study, such as the small sample size, the lack of clinical data for some subjects and the possibility of false negatives due to technical or analytical issues. Overall, this study highlighted the importance of genetic testing and counseling for FCS in Saudi Arabia, where consanguineous marriages are common and may increase the risk of inheriting cancer-associated alleles from both parents. These findings also suggested that knowing the genetic profile of patients and their families could help tailor preventive strategies and treatments according to their specific risks.

“Whilst a larger population level study is still needed, we demonstrate that multigene NGS panel testing may serve as non-invasive diagnostic and cost-effective tool to predict familial cancer risk at the pre-clinical stage, allowing targeted screening and enabling early intervention.”

Click here to read the full research paper in Oncotarget.

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Oncotarget is an open-access, peer-reviewed journal that has published primarily oncology-focused research papers since 2010. These papers are available to readers (at no cost and free of subscription barriers) in a continuous publishing format at Oncotarget.com. Oncotarget is indexed/archived on MEDLINE / PMC / PubMed.

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Reaching the Brain Through the Groin: A Novel Approach to Brain Cancer

In a new editorial, researchers discuss opening the blood-brain barrier and a promising new strategy for the treatment of brain cancer.

Figure 1: A transfemoral path to BBB opening.
Figure 1: A transfemoral path to BBB opening.

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Just a small number of molecules, including alcohol and caffeine, are able to cross the blood-brain barrier (BBB). The BBB is a highly selective semipermeable membrane that separates circulating blood from extracellular fluid in the brain. It plays a critical role in protecting the brain from harmful substances in the blood while also maintaining a stable and consistent environment for neuronal function. Without the BBB, humans would be at the mercy of any harmful toxin, pathogen and unwanted substance that could cross from the bloodstream into the brain.

This protective function also makes it difficult to deliver therapeutic agents to the brain, as the majority of drugs and other molecules are unable to cross the BBB. This is particularly problematic for the treatment of brain-localized diseases, including brain cancers and neurological disorders, which require high concentrations of drugs to effectively target sites in the brain. In a new editorial paper, researchers Thomas C. Chen, Weijun Wang and Axel H. Schönthal from the University of Southern California‘s Keck School of Medicine discuss a series of preclinical studies that introduced the novel concept of intraarterial (IA) injection of NEO100—a promising strategy aimed at temporarily and safely opening the BBB up for therapeutic treatment. Their editorial was published in Oncotarget’s Volume 14 on May 4, 2023, entitled, “From the groin to the brain: a transfemoral path to blood-brain barrier opening.”

“It is believed that procedures to open the BBB in a controlled and safe fashion might provide tremendous advantages by allowing optimal brain entry of any and all circulating therapeutics.”

Opening the BBB

The authors first describe previously used methods of opening the BBB for therapeutic intervention, including intracarotid injection of hyperosmolar mannitol and MRI-guided pFUS with intravascular microbubbles. Unfortunately, these methods have yielded issues with safety and efficacy. Fortunately, Chen, Wang, Schönthal, and their co-authors came up with a new idea for opening the BBB safely. 

In a 2021 study, the researchers discovered that NEO100 enables the delivery of BBB-impermeable therapeutics to the brain. NEO100 is a type of perillyl alcohol—a natural chemical found in citrus fruit peels—that has been studied for its potential to treat cancer. Wang et al. aimed to see if injecting NEO100 into an artery would open the BBB safely and temporarily. This could help other drugs that are normally unable to pass through the BBB, such as methotrexate and therapeutic antibodies, to enter the brain. Previously, NEO100 had been administered through the nose to treat cancer, but this study focused on its ability to open the BBB.

The researchers injected NEO100 into the left ventricle of the heart and then injected a dye called Evans blue into the mice’s veins. Normally, this dye cannot penetrate the brain, but when the BBB is weakened or opened up, it can get through and turn the brain blue. And that’s exactly what happened—the mice’s brains turned blue after the injections. Interestingly, when they tried using another substance called mannitol, it did not have the same effect on the BBB. The team performed additional studies and found that NEO100 seemed to affect the connections between cells in the barrier.

In further experiments, the researchers used methotrexate and special markers that usually do not enter the brain. They gave these drugs and markers to mice and found that NEO100 made it easier for the drugs and markers to enter the brain. This effect lasted between two and four hours before the BBB reverted to normal functioning. The researchers also tested administering NEO100 by injecting it into the mouse’s veins, but this was not effective. 

The main question the researchers wanted to answer was if opening the BBB using IA NEO100 could help treat brain tumors. To answer this question, they conducted experiments using mice that had tumor cells implanted in their brains. In one study, they used breast cancer cells that were engineered to have the protein HER2 and treated them with trastuzumab. In another study, they used models of brain cancer called melanoma and glioblastoma and treated them with drugs that help the immune system fight cancer. These studies have found a way to improve drug delivery for CNS diseases, but there are limitations that need further investigation.

Transfemoral IA catheterization

As noted in this editorial, the preclinical models above used one injection of NEO100 with a therapeutic agent, but it’s unclear if this will work as well in humans. Tumors in humans are more complex than in rodents, so multiple interventions might be needed. It is also important to determine the best way to perform the injection(s) in humans. The researchers suggest using a catheter inserted through the femoral artery near the groin and guided by fluoroscopy to safely inject NEO100 into the cranial arteries.

“Transfemoral IA catherization (Figure 1) is a low-risk procedure that is routinely performed by endovascular neurosurgeons in the context of cerebral angiograms, aneurysm coiling, tumor embolization, and thrombectomies [18]. It is considered ‘the gold standard technique for catheter-based neuro-interventions’ [19]. However, it has never been used as a means to access tumor-feeding cranial arteries for purposes of BBB opening.”

Transfemoral IA catheterization is a medical procedure that involves inserting a catheter through a blood vessel in the leg and guiding it to the brain to perform various treatments. It is a safe and common technique, already used by doctors who specialize in treating brain conditions. However, it has never been used to open the BBB in order to access the blood vessels. Using NEO100 with this procedure could be a new and innovative way to treat aggressive brain tumors. If necessary, the procedure could even be repeated multiple times due to its safe and simplistic nature. The researchers believe that using this new method to open the BBB could be just as successful in treating brain tumors as current treatments are for tumors in other parts of the body. This could potentially lead to better outcomes for patients with brain tumors, such as improved survival rates and fewer side effects.

Conclusions

The blood-brain barrier (BBB) is a protective barrier that prevents harmful substances from entering the brain. However, this barrier also makes it difficult to deliver therapeutic agents to the brain. In a new study, researchers have proposed a novel method of intraarterial injection of NEO100 to temporarily and safely open the BBB. This method has been shown to enable the delivery of BBB-impermeable therapeutics to the brain. The authors of this editorial have suggested using transfemoral IA catheterization to perform this intervention. The method requires further investigation and development.

“The authors envision that clinical implementation of this new BBB-opening method might achieve a similarly high rate of success in the treatment of brain-localized malignancies as do current treatments for peripherally distributed tumors; as a result, reduced morbidity and increased patient survival is expected.”

Click here to read the full editorial in Oncotarget.

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Oncotarget is an open-access, peer-reviewed journal that has published primarily oncology-focused research papers since 2010. These papers are available to readers (at no cost and free of subscription barriers) in a continuous publishing format at Oncotarget.com. Oncotarget is indexed/archived on MEDLINE / PMC / PubMed.

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Defining the Complexity of EGFR Endocytosis in Cancer

In a new editorial perspective, researchers delve into the complex mechanisms underlying EGFR endocytosis and its potential as a therapeutic target.

Figure 1: SNX3 protein downregulation in breast tumors.
Figure 1: SNX3 protein downregulation in breast tumors.

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EGFR (epidermal growth factor receptor) is a crucial protein that plays a significant role in various biological processes such as cell growth, proliferation, differentiation, and survival. Dysregulation of EGFR signaling has been implicated in the development and progression of numerous human cancers, including lung, breast and colon cancer. Therefore, EGFR has emerged as an attractive target for cancer therapy, and several drugs that target EGFR are in clinical use or under investigation.

In recent years, endocytosis, the process by which cells internalize molecules and transport them into intracellular compartments, has emerged as a critical modulator of EGFR signaling. Endocytosis of EGFR not only regulates the duration and intensity of EGFR signaling but also modulates the signaling output. Dysregulation of EGFR endocytosis has been implicated in the development of drug resistance to EGFR-targeted therapies, highlighting the importance of understanding the mechanisms that regulate EGFR endocytosis.

In a new editorial perspective, researchers Aysegul Sapmaz and Ayse Elif Erson-Bensan from Middle East Technical University provide an overview of the recent advances in our understanding of EGFR endocytosis and its role in EGFR signaling and cancer. The authors highlight the importance of the dynamic interplay between EGFR endocytosis and downstream signaling pathways and discuss how aberrant EGFR endocytosis contributes to drug resistance to EGFR-targeted therapies. On April 10, 2023, their editorial perspective was published in Oncotarget’s Volume 14, entitled, “EGFR endocytosis: more than meets the eye.”

“Here we review the role of the EGF-SNX3-EGFR axis in breast cancers with an extended discussion on deregulated EGFR endocytosis in cancer.”

EGFR Endocytosis

In a recent 2022 study, Sapmaz, Erson-Bensan and their team made significant contributions to understanding the role of deregulated endocytosis in cancer by describing the tumor suppressor role of Sorting Nexin 3 (SNX3) in triple-negative breast cancers (TNBCs). SNX3 is a protein-coding gene belonging to a family of proteins called sorting nexins, which are involved in sorting and trafficking of cellular membrane proteins and lipids. At the conclusion of their study, the researchers found that SNX3 is a critical player in TNBCs through the EGF-SNX3-EGFR axis.

“SNX3, an endosomal trafficking protein, is an emerging tumor suppressor in breast cancers as a target of the EGFactivated EGFR pathways and a modulator of EGFR protein levels.”

In the current editorial perspective by Sapmaz and Erson-Bensan, they discuss overexpression of EGFR and its activating mutations linked to various cancer phenotypes, including stemness, metastasis and drug resistance. Endocytosis and the internalization of EGFR play a crucial role in regulating its activity, which is dependent on post-translational modifications and regulated by various proteins, including ubiquitin. Deregulation of these players in endocytic processes has significant implications for EGFR activity in cancers. The ubiquitination status of EGFR and other proteins in the endocytic pathway is functionally essential and is balanced by E3 ubiquitin ligases and deubiquitinating enzymes (DUBs). Targeting these enzymes to alter ubiquitination dynamics could offer future perspectives in manipulating EGFR endocytosis and signaling in cancers.

The researchers discuss the non-canonical functions of endocytosis and endocytosis-related proteins, such as their involvement in nucleocytoplasmic shuttling and transcriptional activity. Several endocytic proteins have been found to interact with nuclear proteins and modulate gene transcription. Examples include EPS15, EPN1 and RNF11, which can shuttle between the cytoplasm and nucleus and have been shown to positively regulate transcription. Other endocytic proteins and adaptors have also been found to shuttle between the cytoplasm and nucleus with functions in endocytosis and gene expression. The authors emphasize the need for a better understanding of both the canonical and non-canonical functions of endocytic processes for normal physiology and diseases, including cancer and other pathologies.

“A better understanding of these backstage mechanisms will allow a more comprehensive understanding of receptor fate and activity.”

Conclusions

In conclusion, EGFR and its regulation through endocytosis have emerged as critical players in cancer development and progression. Dysregulation of EGFR endocytosis has been implicated in drug resistance to EGFR-targeted therapies, highlighting the importance of understanding the mechanisms that regulate this process. Recent advances in our understanding of EGFR endocytosis and its role in cancer have revealed the critical interplay between EGFR signaling and downstream pathways. The research by Sapmaz and Erson-Bensan sheds light on the tumor suppressor role of SNX3 in TNBCs and highlights the need for a better understanding of the canonical and non-canonical functions of endocytic processes in normal physiology and diseases, including cancer. Future research focusing on manipulating EGFR endocytosis and signaling could offer new perspectives on cancer therapy.

“Finally, before we can consider key endocytosis regulators as therapeutic targets, these candidate proteins must also be evaluated within the context of potential feedback mechanisms to modulate the biosynthesis and repopulation of receptors in cancer cells.”

Click here to read the full editorial perspective in Oncotarget.

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Oncotarget is an open-access, peer-reviewed journal that has published primarily oncology-focused research papers since 2010. These papers are available to readers (at no cost and free of subscription barriers) in a continuous publishing format at Oncotarget.com. Oncotarget is indexed/archived on MEDLINE / PMC / PubMed.

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