Effects of proteasome inhibitor on proliferation, apoptosis and related proteins in renal interstitial fibroblasts / 中华肾脏病杂志

ABSTRACT

ObjectiveTo investigate the role of MG-132, a specific dipeptide proteasome inhibitor, on the proliferation, apoptosis and the related proteins in renal interstitial fibroblasts. MethodsRenal interstitial fibroblasts (NRK-49F) were induced by transforming growth factor β1 (TGF-β1, 5 μg/L) and pro-treated with MG-132 (0～5 μmol/L). The cell proliferation was measured with MTT method. Cell cycle and apoptosis were analyzed by flow cytometry. The apoptosis was also analyzed by Annexin V/PI staining and DNA ladder. Expression of p53, p27, p21, caspase-3, Bcl-2 and Bax protein was examined by Western blot. ResultsTGF-β1 (5 μg/L) could stimulate the proliferation of NRK-49F. MG-132 (0.25～5 μmol/L) could inhibit TGF-β1-induced proliferation in a dose-dependent manner through G1-arrest. TGF-β1 alone could not induce apoptosis (3.880%±0.365% vs 4.723%±1.582%). But pretreatment of MG-132 (0.1～2.5 μmol/L) could significantly induce apoptosis of TGF-β1-stimulated NRK-49F in a dose-dependent manner. Typical DNA ladder was also confirmed in these two groups in the DNA fragments analysis after being incubated with 2.5 μmol/L MG-132 with or without 5 μg/L TGF-β1. Western blot showed that MG-132 could activate the cell-cycle and apoptosis-related proteins such as p53, p21, caspase-3, Bax and inhibit Bcl-2 in a dose-dependent manner, while expression of p27 remained unchanged. ConclusionsProteasome inhibitor MG-132 can inhibit proliferation and induce the cell apoptosis in renal interstitial fibroblasts stimulated by TGF-β1. The mechanism may be associated to the mediation of p53, p21, caspase-3, Bcl-2 and bax pathways. Protoasome inhibitor may be a new strategy to treat renal interstitial fibrosis.