Estrogen repression of microRNA as a potential cause of cancer

•miRNAs are involved in estrogen signaling and metabolism.•miRNAs are involved in all cancer hallmarks.•miRNAs show reduced expression levels in tumors and cancer cell lines.•Global repression of miRNA after estrogen exposure, contributes to cell growth and proliferation and possibly cause to cancerous transformation.

MicroRNAs (miRNAs) are endogenous small molecules that regulate gene expression and have been implicated in the pathogenesis of many human diseases, including cancer.This review describes the results that show a global repression in miRNA expression in various tumors and cancer cell lines. Intriguingly, recent discoveries have shown a widespread downregulation of miRNA after exposure to the steroid hormone estrogen. The integration of the results suggests that estrogen-dependent repression of miRNA is a potential cause of cancer.