Breast cancer is the most common tumor type in women, and the main cause of death in these patients is tumor progression and the development of metastases. An improvement in disease-free time has been documented with the widespread use of early screening and diagnosis, as well as adjuvant systemic therapies. Knowledge of prognostic and / or predictive factors is extremely important in identifying which patients have an increased risk of recurrence and in selecting which systemic therapy is most appropriate for a specific patient. Therefore, the identification of tumor markers that can predict tumor behavior is in the particular interest to the scientific community. 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 microRNAs, miR-152 has received special interest in the study of angiogenesis and tumor metastasis. Recent studies show that, in breast cancer cell lines and tumor fragments, the high expression of miR-152 inhibits the expression of IGF-1R through its binding to the 3'-UTR region, leading to the blockade of HIF- 1± and VEGF and, consequently, angiogenesis. In this context, the objective of this study is to evaluate the expression of miR-152 as a marker for the diagnosis and prognosis of women with breast cancer from mammary (normal and tumor) fragments. For this study, 15 tumor fragments of women with breast cancer and 5 mammary fragments of women without tumor and without a history of cancer in the family will be collected. Next, RNA extraction, cDNA synthesis and real-time PCR will be performed. In the validation stage of this study, the expression of miRNA target proteins (IGF-1R, HIF-1a and VEGF) will be analyzed by immunohistochemistry.
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