miR-21 coordinates tumor growth and modulates KRIT1 levels.
Bottom Line: Here, we show that expression of miR-21 in primary tumors anticorrelates with KRIT1/CCM1, an interacting partner of the Ras-like GTPase Rap1, involved in Cerebral Cavernous Malformations (CCM).We present evidences that miR-21 silences KRIT1 by targeting its mRNA 3'UTR and that this interaction is involved in tumor growth control.In fact, miR-21 over-expression or KRIT1 knock-down promote anchorage independent tumor cell growth compared to controls, whereas the opposite is observed when anti-miR-21 or KRIT1 overexpression are employed.
Affiliation: Molecular Biotechnology Center, University of Torino, Torino, Italy.Show MeSH
Related in: MedlinePlus
Mentions: Bioinformatics analysis revealed that KRIT1 3′UTR contained two putative miR-21 binding sites for miR-21 (Fig. 3A). To examine whether miR-21 binds at its putative binding site, 293T or MC-1 or HeLa cells were transiently transfected with a Luciferase reporter vector containing a 973 bps portion (including both sites) of the 3′UTR for KRIT1 in miR-21 overexpression (pre-miR-21 or pWPT-miR-21) or silencing (anti-miR-21) conditions and luciferase activity measured and compared to the negative controls (pre- or anti-controls; pWPT-ctrl). As shown in Fig. 3B, luciferase activity was significantly reduced in presence of miR-21 overexpression in 293T and MC-1 cells. Conversely, it was increased following miR-21 silencing in HeLa cells. As a positive control, a miR-21-sensor construct, containing 3 perfect bindings for miR-21, was used for each experiment. Results were normalized on Renilla activity.
Affiliation: Molecular Biotechnology Center, University of Torino, Torino, Italy.