miR-186, miR-216b, miR-337-3p, and miR-760 cooperatively induce cellular senescence by targeting α subunit of protein kinase CKII in human colorectal cancer cells

We previously demonstrated that downregulation of protein kinase CKII induces cellular senescence in human colon cancer HCT116 cells. To investigate the role of microRNAs (miRNAs) in CKII downregulation during senescence, we employed computational algorithms. Four miRNAs (miR-186, miR-216b, miR-337-3p. and miR-760) were predicted to be miRNAs against CKII alpha mRNA. Mimics of all four miRNAs jointly downregulated CKII alpha expression in HCT116 cells. Reporter analysis and RT-PCR have suggested that these four miRNAs may stimulate degradation of CKII alpha mRNA by targeting its 3' untranslated regions (UTRs). The four miRNA mimics increased senescent-associated beta-galactosidase (SA-beta-gal) staining, p53 and p21(Cip1/WAF1) expression, and reactive oxygen species (ROS) production. In contrast, concomitant knockdown of the four miRNAs by antisense inhibitors increased the CKII alpha protein level and suppressed CKII inhibition-mediated senescence. Finally, CKII alpha overexpression antagonized senescence induced by the four miRNA mimics. Therefore, the present results show that miR-186, miR-216b, miR-337-3p, and miR-760 cooperatively promote cellular senescence through the p53-p21(Cip1/WAF1) pathway by CKII downregulation-mediated ROS production in HCT116 cells. (C) 2012 Elsevier Inc. All rights reserved.