Non-coding RNAs as Mediators of Tamoxifen Resistance in Breast Cancers.

A large proportion of breast cancer patients are estrogen receptor positive. They generally benefit from tamoxifen, the drug that targets estrogen receptor signaling. However, de novo and acquired resistance against tamoxifen is well known. A number of signaling pathways and de-regulated factors have been evaluated to better understand the mechanism(s) of tamoxifen resistance. For past several years, non-coding RNAs have also gained attention as the putative regulators and determinants of tamoxifen resistance. A number of reports have documented evidence from in vitro and/or in vivo studies, as well as from evaluation of clinical samples, to showcase the power of non-coding RNAs as mediators of tamoxifen resistance and the predictors of disease relapse. This article puts into perspective the available information on microRNAs and the long non-coding RNAs regarding their ability to tweak resistance vs. sensitivity to tamoxifen.