Association of ETV5 gene with estrogen receptor (ER) in breast cancer

Breast cancer poses a significant threat to women's health worldwide and is recognized as one of the most prevalent cancer types. One in eight women is at risk of developing this disease at some point in their lives. Breast cancer ranks as the second leading cause of cancer-related mortality in women, following lung cancer. However, early diagnosis and intervention can substantially improve treatment outcomes. This study focuses on the E26 transformation-specific (ETS) transcription factor family, which plays a crucial role in the molecular pathogenesis of breast cancer. These factors are involved in fundamental biological processes such as cell growth, differentiation, and development, exerting significant effects on cancer initiation and progression. Among the ETS factors, the ETV5 gene plays a particularly important role in cell growth and differentiation. Alterations in ETV5 expression levels in various cancer types, including breast cancer, may provide valuable insights into disease progression and prognosis. This study investigates whether ETV5 gene expression differs between estrogen receptor (ER) positive (ER (+)) and triple-negative breast cancer (TNBC) tissues. ETV5 expression levels were measured using Real Time Polymerase Chain Reaction (Real Time PCR) in invasive ductal breast carcinoma tissues preserved at the Department of Medical Pathology, Istanbul University-Cerrahpaşa. The results revealed a significant reduction in ETV5 expression in breast cancer tissues compared to normal breast tissues. Interestingly, ETV5 expression was found to be lower in ER+ breast cancer tissues than in TNBC tissues. These findings suggest that the ETV5 gene may function as a tumor suppressor rather than an oncogene in ER(+) breast cancer, but not in TNBC. That is, the presence of ER may be reducing the ETV5 expression. This may suggest that ETV5, a transcription factor, may be associated with genes encoding the receptor. The decrease in ETV5 expression may be influenced by various factors, such as transcriptional regulation, the effects of the tumor microenvironment, the molecular characteristics of cancer cells, and post-transcriptional processes. Keywords: ER positive, triple negative, breast cancer, ductal carcinoma