Cilostazol ameliorates diabetic nephropathy by inhibiting highglucose- induced apoptosis.

Diabetic nephropathy (DN) is a hyperglycemia-induced progressive development of renal insufficiency. Excessive glucose can increase mitochondrial reactive oxygen species (ROS) and induce cell damage, causing mitochondrial dysfunction. Our previous study indicated that cilostazol (CTZ) can reduce ROS levels and decelerate DN progression in streptozotocin (STZ)-induced type 1 diabetes. This study investigated the potential mechanisms of CTZ in rats with DN and in high glucose-treated mesangial cells. Male Sprague-Dawley rats were fed 5 mg/kg/day of CTZ after developing STZ-induced diabetes mellitus. Electron microscopy revealed that CTZ reduced the thickness of the glomerular basement membrane and improved mitochondrial morphology in mesangial cells of diabetic kidney. CTZ treatment reduced excessive kidney mitochondrial DNA copy numbers induced by hyperglycemia and interacted with the intrinsic pathway for regulating cell apoptosis as an antiapoptotic mechanism. In high-glucose-treated mesangial cells, CTZ reduced ROS production, altered the apoptotic status, and down-regulated transforming growth factor beta (TGF-ß) and nuclear factor kappa light chain enhancer of activated B cells (NF-κB). Base on the results of our previous and current studies, CTZ deceleration of hyperglycemia-induced DN is attributable to ROS reduction and thereby maintenance of the mitochondrial function and reduction in TGF-ß and NF-κB levels.

Gallic acid induces G2/M phase cell cycle arrest via regulating 14-3-3ß release from Cdc25C and Chk2 activation in human bladder transitional carcinoma cells.

SCOPE: Cell cycle regulation is a critical issue in cancer treatment. Previously, gallic acid (GA) has been reported to possess anticancer ability. Here, we have evaluated the molecular mechanism of GA on cell cycle modulation in a human bladder transitional carcinoma cell line (TSGH-8301 cell). METHODS AND RESULTS: Using flow cytometer analysis, exposure of the cells to 40 µM GA resulted in a statistically significant increase in G2/M phase cells, which was accompanied by a decrease in G0/G1 phase cells. GA-treated cells resulted in significant growth inhibition in a dose-dependent manner accompanied by a decrease in cyclin-dependent kinases (Cdk1), Cyclin B1, and Cdc25C, but significant increases in p-cdc2 (Tyr-15) and Cip1/p21 by western blotting. Additional mechanistic studies showed that GA induces phosphorylation of Cdc25C at Ser-216. This mechanism leads to its translocation from the nucleus to the cytoplasm resulting in an increased binding with 14-3-3ß. When treated with GA, phosphorylated Cdc25C can be activated by ataxia telangiectasia-mutated checkpoint kinase 2 (Chk2). This might be a DNA damage response as indicated by Ser-139 phosphorylation of histine H2A.X. Furthermore, treatment of the cells with a Chk2 inhibitor significantly attenuated GA-induced G2/M phase arrest. CONCLUSION: These results indicate that GA can induce cell cycle arrest at G2/M phase via Chk2-mediated phosphorylation of Cdc25C in a bladder transitional carcinoma cell line.