Low expression of miR-195 is associated with cell proliferation, glycolysis and poor survival in estrogen receptor (ER)-positive but not in triple negative breast cancer.

MiR-195 is a tumor suppressive microRNA in breast cancer. Its clinical relevance remains debatable as it has only been studied via in vitro experiments or small cohort studies. We analyzed a total of 2,038 patients in the TCGA and METABRIC cohorts to assess whether low miR-195 expressing tumors are associated with aggressive cancer characteristics and poor prognostic outcomes. The median cutoff of miR-195 expression was used to split the groups into miR-195 high and low groups. Low miR-19 expressing tumors demonstrated high cell proliferating features by enriching the gene sets associated with cell proliferation, MKI67 expression and pathological grade. One-third of the top target miR-195 genes were related to cell proliferation. Low miR-195 expressing tumors were associated with both pro-cancerous and anti-cancerous immune cells. Low miR-195 expressing tumors were associated with enhanced glycolysis and poor survival in ER-positive tumors, but not other subtypes of breast cancer. In conclusion, low expression of miR-195 in ER-positive breast cancer was associated with enhanced cancer cell proliferation, glycolysis, and worse overall survival.