title: Proteasome inhibitor inhibits proliferation and induces apoptosis in renal interstitial fibroblasts.
abstract: BACKGROUND
  The ubiquitin proteasome pathway plays a pivotal role in controlling cell proliferation, apoptosis and differentiation in a variety of normal and tumor cells. This study aimed to investigate the role of a proteasome inhibitor on proliferation, apoptosis and related proteins in renal interstitial fibroblasts (NRK-49F).
  
  
  METHODS
  NRK-49F cells were induced using transforming growth factor-β1 (TGF-β1) and pretreated with the proteasome inhibitor MG-132. Cell proliferation was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The cell cycle and apoptosis were analyzed using flow cytometry. Apoptosis was also analyzed using a DNA ladder. The protein expression of p53, p27, p21, caspase-3, Bcl-2 and Bax was examined using western blots.
  
  
  RESULTS
  The results showed that TGF-β1 (5 ng/ml) can stimulate the proliferation of NRK-49F cells.MG-132 (0.25-5 μM) inhibited TGF-β1-induced proliferation in a dose-dependent manner through G1-arrest; TGF-β1 alone did not induce apoptosis (3.8 ± 0.4% vs. 4.7 ± 1.6%). However, pretreatment with MG-132 significantly induced apoptosis in TGF-b1-stimulated NRK-49F cells in a dose-dependent manner. A typical DNA ladder was also confirmed in these two groups. Western blot analysis showed that MG-132 activated p53, p21, caspase-3 and Bax, and inhibited Bcl-2 in a dose-dependent manner, while p27 expression remained unchanged.
  
  
  CONCLUSIONS
  A proteasome inhibitor inhibited proliferation and induced apoptosis in renal interstitial fibroblasts stimulated by TGF-β1. The mechanism may relate to the p53, p21, caspase-3, Bcl-2 and Bax pathways. Our results suggest that a proteasome inhibitor could be a new strategy to treat renal interstitial fibrosis.
authors.affiliation: Department of Nephrology, Ruijin Hospital, Shanghai Jiao Tong University, Shanghai, 200025, P.R. China. wweiming@medmail.com.cn.
authors.forename: Bingbing
authors.initials: B
authors.lastname: Zhu
authors.forename: Yuanmeng
authors.initials: Y
authors.lastname: Jin
authors.forename: Lin
authors.initials: L
authors.lastname: Han
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Fang
authors.initials: F
authors.lastname: Zhong
authors.forename: Weiming
authors.initials: W
authors.lastname: Wang
authors.forename: Nan
authors.initials: N
authors.lastname: Chen
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D005355:Fibrosis; D007668:Kidney / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D007976:Leupeptins / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D061988:Proteasome Inhibitors / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: C494828:Bax protein, rat; C493958:Cdkn1a protein, rat; C493962:Cdkn1b protein, rat; D050759:Cyclin-Dependent Kinase Inhibitor p21; D007976:Leupeptins; D061988:Proteasome Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D053773:Transforming Growth Factor beta1; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D050760:Cyclin-Dependent Kinase Inhibitor p27; C505410:Casp3 protein, rat; D053148:Caspase 3; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde