Figure 1

Effects of MP470 or the MP470-Erlotinib combination on prostate cancer cell proliferation and apoptosis. (a). LNCaP, DU145 and PC-3 cells were exposed to varying concentrations of MP470 for 4 days. Cell viability was assessed by MTS analysis. Points are the means of triplicate determinations ± SD. The IC₅₀ for LNCaP and PC-3 is ~4 μM and 8 μM, respectively. Chemical structure of MP470 was shown at bottom. (b). LNCaP cells were exposed to varying concentrations of Erlotinib (Tarceva), MP470 or Erlotinib (10 μM) plus MP470 (varied concentrations) for 4 days. Cell viability was assessed by MTS analysis. IC₅₀ was calculated with CalcuSyn software and the graph was shown. (c). LNCaP cells were treated with the indicated doses of Erlotinib or MP470 alone or in combination for 48 hr, and apoptosis was detected as morphologic change by fluorescent microscopy. Values are the means of three independent experiments ± SD. Control cells were treated with DMSO vehicle. (d). LNCaP cells were treated with DMSO (control), 10 μM of Erlotinib or MP470 or in combination for 48 h. Flow cytometric analysis of apoptotic fraction based on propidium iodide (Y-axis) and annexin V staining (X-axis) showed up to 28% and 46% of apoptosis was induced by MP470 alone and in combination with Erlotinib, respectively. (e). LNCaP cells were treated with the indicated doses of Erlotinib or MP470 or IM alone or the combinations for 48 hr, and PARP cleavage was determined by immunoblotting with anti-PARP antibody. β-actin was used as a loading control. MP470 or MP470-Erlotinib but not Erlotinib or IM or Erlotinib-IM combination was shown to cause PARP cleavage in LNCaP cells.