The novel role of miRNAs for tamoxifen resistance in human breast cancer.

The selective estrogen receptor modulator tamoxifen is the most commonly used treatment for patients with ER-positive breast cancer. However, tumor cells often develop resistance to tamoxifen therapy, which is a major obstacle limiting the success of breast cancer treatment. miRNAs, as oncogenic or tumor suppressor genes, regulate the expression and function of their related target genes to affect the biological behaviors of cancer cells, including cancer initiation, progression, metastasis, and therapeutic resistance. In detail, many miRNAs associated with breast cancer tamoxifen resistance have been identified, which offer new targets for breast cancer therapy. Here, we review the miRNAs involved in regulation of tamoxifen resistance in human breast cancer and the mechanism of how the modulation of miRNAs may regulate the sensitivity of breast cancer cells to tamoxifen. We also discuss the future prospects of studies about miRNAs in regulation of tamoxifen resistance and miRNA-based therapeutics for tamoxifen resistance breast cancer patients.