Breast cancer is the most prevalent neoplasm and mortality in women worldwide, and in 2018 it was estimated the occurrence of 57,960 new cases in Brazil. Current diagnostic methods are mainly limited to invasive procedures, and even after diagnosis, prognostic determination may not be conclusive, as patients may gain resistance to treatment, favoring tumor growth, invasion, and metastasis. Thus, diagnostic and prognostic markers can be used to determine tumor characteristics, identifying patients who will benefit from specific treatments. MicroRNAs (miRNAs or miRs) are small non-coding mRNA molecules that play a key role in gene regulation. Expression of miRNAs is closely associated with tumor development, invasion, angiogenesis and metastasis of various types of cancer, including breast cancer. Among the microRNAs, in breast cancer, oncomiR-210 stands out. Recent studies show that overexpression of this miRNA in breast cancer is associated with increased aggressiveness and shorter disease-free time. According to the literature, miR-210 inhibits the expression of the VHL gene and, consequently, increases the expression of pro-angiogenic factors such as HIF-1± and VEGF, thereby allowing the growth of new blood vessels to supply tumor growth. Based on this context, the purpose of this study is to validate miR-210 as a marker for the diagnosis and prognosis of women with breast cancer from mammary (normal and tumor) samples. OncomiR-210 has been studied in our group of a total of 15 tumor fragments were collected from women with breast cancer and 5 mammary fragments from women with no tumor and no history of cancer in the family, followed by extraction of RNA, cDNA synthesis and real-time PCR In the validation step, the protein expression of the miRNA target proteins (VHL, HIF-1±, and VEGF) will be analyzed by immunohistochemistry.
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