Effects of CG-5 on the expression of HuR-targeted signaling proteins and HuR protein stability.
A, validation of the role of HuR in mediating the suppressive effect of CG-5 on various tumor-promoting signaling proteins encoded by HuR-targeted mRNAs, including cyclin B1, cyclin E1, MMP9, Snail, and VEGF in LNCaP cells. Ectopic expression of full-length HuR protected cells from CG-5-mediated suppression of these proteins. B, cycloheximide chase assays of the effect of CG-5 on the half-life of HuR protein in LNCaP cells. Cells were treated with 5 μm CG-5 for 12 h, followed by exposure to 100 μg/ml cycloheximide for the indicated time intervals. C, protective effect of proteasome inhibitor MG132 on CG-5-mediated HuR degradation. LNCaP cells were treated with CG-5 at the indicated concentration, alone or in combination with 10 μm MG132, for 24 h.