Additive effect of metastamiR-193b and breast cancer metastasis suppressor 1 as an anti-metastatic strategy.

Abstract

It has been reported that enhancing the cellular levels of miR-193b as well as breast cancer-metastasis-suppressor-1 (BRMS1) protein is associated with diminished metastatic characteristics in breast cancer. In view of these facts, as a new therapeutic intervention, we employed a restoration-based strategy using both miR-193b-3p mimic and optimized BRMS1 in the context of a chimeric construct. miR-193b-3p and BRMS1 genes were cloned and the resulting plasmids were transfected into the MDA-MB231, MCF-7 and MCF-10A cell lines. microRNA expression levels were assessed by rea time PCR using LNA-primer and protein expression was confirmed by western blot method. Then, apoptosis, MTT, colony formation and invasion assays were carried out. The expression levels of miR-146a, miR-146b and miR-373 were up-regulated, while the miR-520c, miR-335 and miR-10b were down-regulated following the exogenous BRMS1 expression. The exogenous over-expression of BRMS1 was associated with higher amounts of endogenous miR-193b-3p expression and enabled more efficient targeting of the 3'UTR of uPA. Although, miR-193b-3p and BRMS1 are individually capable of suppressing breast cancer cell growth, migration and invasion abilities, their cistronic expression was capable of enhancing the ability to repress the breast cancer cells invasion. Our results collectively indicated the existence of an additive anti-metastatic effect between miR-193b-3p and BRMS1. Moreover, it has been hypothesized that the exogenous expression of a protein can effect endogenous expression of non-relevant microRNA. Our findings provide new grounds for miR-restoration therapy applications as an amenable anti-metastatic strategy.