Abstract 1927: Myc-induced suppression of the RNA-binding protein ZAR2 in breast cancer cells

Abstract

Abstract Our objective is to verify the hypothesis that c-Myc-regulated oncomiR miR-130a-5p suppresses the level of the RNA-binding tumor suppressor protein ZAR2 in the cMyc-high aggressive breast cancer cells. We experimentally validated the binding of miR130a-5p miRISC to ZAR2 mRNA in vivo and inhibition of the translation of this mRNA by this binding. We used three commercially available c-Myc-high ZAR2-low breast cancer cell lines BT549, MDA-MB-453 and MDA-MB-231 and two c-Myc-low ZAR2-high breast cancer cells MCF7 and HCC38 for our studies. We cloned the full length 3′-UTR (179 bp) of human ZAR2 mRNA immediately downstream of the firefly luciferase open reading frame sequence contained in the reporter plasmid. We also have created different mutants of the 3’-UTR, each having mutation in each of the putative miR130a-5p binding sites. We transiently transfected the recombinant plasmid and miR130a-5p miRNA mimic into breast cancer cells and assessed luciferase activity or fluorescence 24-48 hours after transfection. We also have transfected just the reporter construct into breast cancer cells which express the endogenous miR130a-5p miRNAs, along with vectors which express mutant versions of the miRNA binding sites. In this experimental system the wild-type reporters had less activity than their respective mutants. To evaluate the functional importance of miR130a-5p miRNA/ZAR2 mRNA pair, we transiently over-expressed a miR130a-5p miRNA mimic in the cMyc-low breast cancer breast cancer cells and subsequently analyzed the level of ZAR2 protein levels. Our data showed that ZAR2 protein levels are decreased by the mimic increasing the in vitro invasiveness of these cells. Our results thus reveal a novel mechanism for the induction of aggressiveness by cMyc in the breast cancer cells. This research is supported in part by DOD-CDMRP IDEA Expansion Grant# BC103645 and NIH/NCI grant 1R21CA181920-01 to GC and NIH grant 1U54RR026140 TO SM Citation Format: Smita Misra, Gautam Chaudhuri. Myc-induced suppression of the RNA-binding protein ZAR2 in breast cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1927.