ASSOCIATION OF MICRORNA EXPRESSION WITH EARLY STAGE OF BREAST CANCER METASTASIS

Abstract

A serious complication of breast cancer is metastasis of tumor cells. The initiation of this process takes place in the nearby lymphatic vessels. To date, the molecular mechanisms of metastasis are not well understood and further research is required. In this regard, the level of miRNA expression can provide information both on the mechanisms of metastasis development and also be a source of markers for the prognosis of metastatic breast cancer. In the present work, according to the literature, we selected four microRNAs (miR-34a, miR-145, miR-125b and miR-222), potentially capable of being associated with metastasis, to study their association with metastasis to lymph nodes at an early stage. The measurement of the expression of four selected miRNAs on 40 paired samples (tumor-norm) was performed using real-time PCR. Frequencies of miR-34a, miR-145, miR-125b, and miR-222 relative to normal tissue were determined for reduced or increased miR-mRNA expression. For a more detailed study of the association of miRNA expression with lymph node metastasis, miR-125b and miR-222 were selected. An association of expression of these two miRNAs was found with the onset of metastasis to the lymph nodes: with the same level of confidence, differences (p = 0.01). Both miRNAs (miR-125b and miR-222) are involved in the metastasis of breast cancer, apparently by influencing the epithelial-mesenchymal transition. They can potentially act as prognostic biomarkers to assess the likelihood of early lymph node metastases in breast cancer.