EXPRESSION PATTERN OF miR-125b-2, -155, -221, AND -320a IS ASSOCIATED WITH RESPONSE OF BREAST CANCER PATIENTS TO TAMOXIFEN.

Abstract

Hormonal therapy is one of themain methods of comprehensive treatment of patients with locally advanced breast cancer(BC). Despite theintensive search for molecules associated with theaggressiveness of thetumor process, currently there are no reliable markers predicting response to neoadjuvant hormonal therapy(NHT). To investigate thecorrelation between miR-125b-2, -155, -221, -320a expression in tumor tissue and HER2/neu status and response to tamoxifen treatment in BC patients. Expression levels of miR-125b-2, -155, -221, and -320a were analyzed in biopsy samples of 50BC patients using a real-time polymerase chain reaction. We found that levels of miR-125b-2, -155, -221, and -320a were 1.72, 1.65, 1.85, and 2.89times higher in BC biopsy samples expressing estrogen/progesterone receptors and HER2/neu compared with HER2/neu-negative luminal tumors. Patients with a luminal BC showing higher levels of miR-125b-2and miR-320a expression before therapy demonstrated better response to NHT with tamoxifen. A strong correlation was calculated for miR-221expression and response to NHT(r = 0.61). Thehigh levels of miR-125b-2, -155, -221, and -320a in tumor tissue are associated with theHER2/neu-positive status of luminal BC subtypes. Tumor samples of patients showing thelow response to NHT with tamoxifen are characterized by lower expression of miR-125b-2and -320a. Hence, miR-125b-2and -320a could be considered as putative predictive biomarkers associated with tamoxifen sensitivity of hormone-dependent BC.