The role and function of SOX11 in DNA damage in triple-negative breast cancer
Lee, Tian Yu
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Breast cancer is a complex heterogenous disease that consists of several different subtypes displaying distinct behaviors and responses to different treatments. It is the second leading cause of cancer death among women, and is the most commonly diagnosed cancer in women. Although recent developments have helped shed light into this disease, there is still much to investigate. One particular subtype of breast cancer, known as triple-negative breast cancer, remains the most aggressive, as this tumor type is of high histological grade and preferentially affects women with BRCA1 mutations and women who are younger than 40 years of age. Unlike other subtypes with better prognoses, triple-negative breast cancer still has no targeted therapy, and chemotherapy remains the primary systemic treatment. Recently, there has been an increase of interest in the SOXC family of high mobility group transcription factors and their roles in tumor development. Studies have revealed some of the effects that SOXC genes may have on various tumor types. However, further studies are still needed to elucidate the roles, functions, regulations, and mechanisms of these transcription factors. This study aims to focus on one particular gene in the SOXC family known as sex determining region Y-box 11. Recent studies have shown that sex determining region Y-box 11, also known as SOX11, is one of the factors required for maintaining the basal-like breast cancer phenotype and is also critical in regulating growth, migration, invasion, and expression of signature basal-like breast cancer genes. Emerging evidence also reveals that this transcription factor may have an impact on homologous recombination repair when DNA damage occurs, in triple-negative breast cancer. Using SOX11 overexpression and knockout cell models combined with basic science laboratory techniques and omics, the next generation of laboratory tools, this study seeks to explore the role and function of SOX11 in DNA damage in triple-negative breast cancer. The results of this study have confirmed the recent findings of the role of SOX11 in cell proliferation and growth in triple-negative breast cancer. It has also revealed that overexpression of SOX11 in triple-negative breast cancer cell lines leads to an increase in DNA damage, loss of BRCA1 function, and dysregulation in the cell cycle. High expression of SOX11 is also associated with worse prognostic outcomes in triple-negative breast cancer patients. Because overexpression of SOX11 resulted in a loss of BRCA1 function, there may be a potential role for SOX11 in inducing the BRCAness phenotype commonly seen in basal-like breast cancers. The results of this study strongly suggest that SOX11 is involved in defective DNA damage repair pathways. Further studies need to be conducted in order to evaluate SOX11 as an inducer of the BRCAness phenotype, which occurs when there is a homologous recombination repair defect and no germline BRCA1 mutation present. Because of this, SOX11 may also have the potential to act as a functional biomarker for therapies targeting DNA damage, as recent developments in identifying therapies that could potentially target homologous recombination repair defects have been promising.
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