Triptolide Inhibits PCa Cells Proliferation cells were treated with indicated doses of Triptolide for 24 h before qRT-PCR analysis using respective specific primers. (F) Triptolide inhibited PSA protein level in LNCaP cells. LNCaP cells were treated with Triptolide or Celastrol for 24 h or 48 h. Aliquots of medium and cell lysis from the treated cells were collected and the total PSA level was measured by CLIA. doi:10.1371/journal.pone.0037693.g005 Figure 6. Triptolide down-regulated c-Jun expression in PCa cells. (A) Triptolide decreased c-Jun mRNA level in LNCaP and PC-3 cells in a dose-dependent manner. Cells were treated with indicated dose of Triptolide for 24 h before RNA extraction and qRT-PCR using the specific primers for c-Jun and b-actin. (B) Triptolide decreased c-Jun mRNA level in LNCaP and PC-3 cells in a time-dependent manner. Cells were treated with 0.1 mM Triptolide for indicated time before RNA extraction and qRT-PCR. (C) and (D) Triptolide decreased c-Jun protein level in LNCaP (C) and PC-3 (D) cells in a dose-dependent manner. Cells were treated with indicated dose of Triptolide or Celastrol for 24 h before Western blot analysis. a-tubulin was used as a loading control. (E) Triptolide decreased c-Jun protein level in LNCaP cells in a time-dependent manner. LNCaP cells were treated with 0.1 mM Triptolide for indicated time before Western blot analysis. a-tubulin was used as a loading control. (F) Triptolide inhibited c-Jun target genes expression in LNCaP cells. LNCaP cells were treated with indicated concentration of Triptolide for 24 h before qRT-PCR analysis of c-Jun target genes using respective specific primers. doi:10.1371/journal.pone.0037693.g006 PLoS ONE | www.plosone.org 10 May 2012 | Volume 7 | Issue 5 | e37693