MiR-150-5p Overexpression in Triple-Negative Breast Cancer Contributes to the In Vitro Aggressiveness of This Breast Cancer Subtype

SIMPLE SUMMARY: Triple-negative breast cancer (TNBC) is a clinically aggressive type of breast cancer. MicroRNAs (miRNAs) are small molecules that regulate the expression of genes involved in tumor cell signaling. The miR-150-5p is frequently deregulated in cancer, with expression and mode of action varying according to the cancer type. In this study, we investigated the expression levels of miR-150-5p in TNBC, its association with clinical and pathological features of patients, and its role in modulating TNBC cell proliferation, migration, and drug resistance. Our results suggest that miR-150-5p is highly expressed in TNBC and that miR-150-5p expression levels are associated with tumor grade, patient survival, and ethnicity. Our findings also indicate that miR-150-5p contributes to the aggressive phenotypes of TNBC cells in vitro. ABSTRACT: MiR-150-5p is frequently deregulated in cancer, with expression and mode of action varying according to the tumor type. Here, we investigated the expression levels and role of miR-150-5p in the aggressive breast cancer subtype triple-negative breast cancer (TNBC). MiR-150-5p expression levels were analyzed in tissue samples from 113 patients with invasive breast cancer (56 TNBC and 57 non-TNBC) and 41 adjacent non-tumor tissues (ANT). Overexpression of miR-150-5p was observed in tumor tissues compared with ANT tissues and in TNBC compared with non-TNBC tissues. MiR-150-5p expression levels were significantly associated with high tumor grades and the Caucasian ethnicity. Interestingly, high miR-150-5p levels were associated with prolonged overall survival. Manipulation of miR-150-5p expression in TNBC cells modulated cell proliferation, clonogenicity, migration, and drug resistance. Manipulation of miR-150-5p expression also resulted in altered expression of its mRNA targets, including epithelial-to-mesenchymal transition markers, MYB, and members of the SRC pathway. These findings suggest that miR-150-5p is overexpressed in TNBC and contributes to the aggressiveness of TNBC cells in vitro.