Panoxadiol saponin enhances apoptotic effect of cisplatin on DU145 prostatic cancer cells

The research is to approach the effect of low dose of cisplatin combined with panoxadiol saponin (PDS) on DU145 prostatic cancer cells proliferation and apoptosis in vitro and hope that PDS could enhance the apoptotic effect and decrease the toxicity of cisplatin. Cell viability was examined by Methylthiazolyl tetrazolium (MTT) assay. The techniques of acridine orange staining and flow cytometry were used to analyze apoptotic cycle and calculate the apoptotic rates. The expressions of c-Myc, cyclinD1, cdk4, P53, caspase3 and Bcl-2 mRNA in DU145 cells were semi-quantitatively detected by using RT-PCR. The apoptosis in DU145 was detected by TUNEL staining. We found that DU145 cells were exposed to 100mg/L PDS combined with 0.2μmol.L-1DDP: (1) Cell viability inhibitory rate was increased from 16.35% to 47.13% after treated for 48 hours, (2)Acridine orange staining found that the cells launched orange fluorescent, (3)Flow cytometry results showed that the cell apoptotic rates were elevated from 5.53 % to 19.39%, which showed similar effect with 2.0μmol.L-1DDP(21.05%) (4)The expressions of c-Myc, cyclinD1, cdk4, Bcl-2 mRNA in 0.2μ, mol.L-1DDP combined with 100mg/L PDS group were significantly lower than those in control group but similar to those of 2μ, mol.L-1DDP group. The expression of P53 and Caspase3 mRNA in 0.2μmol.L-1DDP combined with 100mg/L PDS group were significantly higher than those in control group but similar to those of 2μmol.L-1DDP group, (5)TUNEL staining found the apoptotic cells were negative in control group; but in 2μmol.L-1DDP group, the cells were less but relatively more apoptotic cells, in 0.2μmol.L-1DDP+100mg.L-1PDS group, less cells but more apoptotic cells compared with controlled but similar with that in 2μmol.L-1DDP group. In short, PDS could enhance the apoptotic effect of DDP on DU145 prostatic cancer cells greatly.