Lovastatin inhibits mesangial cell proliferation via p27Kip1

Mesangial cell proliferation is a key feature of glomerulonephritis. The hydroxymethylglutaryl-coenzyme A reductase inhibitor lovastatin is known to inhibit cell cycle progression. To determine the inhibitory mechanisms of mesangial cell proliferation by lovastatin, the cyclin-dependent kinase (CDK) activity, and expression of CDK inhibitor (p27Kip1, p21Cip1, and p16INK4) mRNA and protein were measured. Lovastatin inhibited phosphorylation of retinoblastoma protein and mesangial cell proliferation dose dependently. Lovastatin increased the p27Kip1 protein level but produced no changes in the abundance of the p27Kip1 mRNA level both in the presence and absence of mitogens. Treatment with lovastatin revealed the increment of both CDK2- and CDK4-bound-p27Kip1. The experiment using antisense oligonucleotide against p27Kip1 showed significant amelioration of lovastatin-induced cell cycle arrest. Lovastatin reduced both platelet-derived growth factor-stimulated CDK2 and CDK4 kinase activities. In conclusion, lovastatin inhibited mesangial proliferation via translational upregulation or impairment of p27Kip1 protein degradation. Lovastatin serves as a potential therapeutic approach to mesangial proliferative disease.