Exp Mol Med.  2010 Jun;42(6):428-436. 10.3858/emm.2010.42.6.044.

Slug suppression induces apoptosis via Puma transactivation in rheumatoid arthritis fibroblast-like synoviocytes treated with hydrogen peroxide

• Cha HS
• Bae EK
• Ahn JK
• Lee J
• Ahn KS
• Koh EM

• KMID: 1078358
• DOI: http://doi.org/10.3858/emm.2010.42.6.044

Abstract

Inadequate apoptosis contributes to synovial hyperplasia in rheumatoid arthritis (RA). Recent study shows that low expression of Puma might be partially responsible for the decreased apoptosis of fibroblast-like synoviocytes (FLS). Slug, a highly conserved zinc finger transcriptional repressor, is known to antagonize apoptosis of hematopoietic progenitor cells by repressing Puma transactivation. In this study, we examined the expression and function of Slug in RA FLS. Slug mRNA expression was measured in the synovial tissue (ST) and FLS obtained from RA and osteoarthritis patients. Slug and Puma mRNA expression in FLS by apoptotic stimuli were measured by real-time PCR analysis. FLS were transfected with control siRNA or Slug siRNA. Apoptosis was quantified by trypan blue exclusion, DNA fragmentation and caspase-3 assay. RA ST expressed higher level of Slug mRNA compared with osteoarthritis ST. Slug was significantly induced by hydrogen peroxide (H2O2) but not by exogenous p53 in RA FLS. Puma induction by H2O2 stimulation was significantly higher in Slug siRNA-transfected FLS compared with control siRNA-transfected FLS. After H2O2 stimulation, viable cell number was significantly lower in Slug siRNA-transfected FLS compared with control siRNA-transfected FLS. Apoptosis enhancing effect of Slug siRNA was further confirmed by ELISA that detects cytoplasmic histone-associated DNA fragments and caspase-3 assay. These data demonstrate that Slug is overexpressed in RA ST and that suppression of Slug gene facilitates apoptosis of FLS by increasing Puma transactivation. Slug may therefore represent a potential therapeutic target in RA.

Keyword

apoptosis; Puma; rheumatoid arthritis; snail family transcription factors; synovial membrane

MeSH Terms

Apoptosis/*drug effects/genetics
Apoptosis Regulatory Proteins/*genetics/metabolism
Arthritis, Rheumatoid/genetics/metabolism/*pathology
Cells, Cultured
Drug Evaluation, Preclinical
Fibroblasts/drug effects/metabolism/pathology
Humans
Hydrogen Peroxide/*pharmacology
Proto-Oncogene Proteins/*genetics/metabolism
RNA, Small Interfering/*pharmacology
Synovial Membrane/cytology/drug effects/metabolism/*pathology
Transcription Factors/*antagonists & inhibitors/genetics
Transcriptional Activation/drug effects
Transfection