Triptolide Inhibits PCa Cells Proliferation Figure 2. Triptolide and Celastrol induce apoptosis in PCa cells in vitro. (A) and (B) Fluorescence microscopy observation of Triptolide- and Celastrol- induced apoptosis in LNCaP (A) and PC-3 (B) cells. After treatment with 1 mM Celastrol or Triptolide for 24 h, LNCaP and PC-3 cells were incubated with AV-FITC (green) and PI (red). Representative bright field and fluorescent images are shown. (C) Flow cytometric detection of apoptosis in LNCaP and PC-3 cells treated as above. Percentage of intact cells (AV2/PI2), early apoptotic cells (AV+/PI2), late apoptotic/necrotic cells (AV+/PI+) and necrotic cells (AV2/PI+) are presented. (D) and (E) Western blot analysis of caspase-3 protein in Triptolide- or Celastrol-treated LNCaP (D) and PC- 3 (E) cells. Cells were treated with indicated concentrations of Triptolide or Celastrol for 24 h and subjected to analysis. Uncleaved caspase-3 and PLoS ONE | www.plosone.org 5 May 2012 | Volume 7 | Issue 5 | e37693