Dichloroacetate Combined With Cisplatin Inducing Apoptosis Of Colorectal Carcinoma Cell HCT116 And Mechanisms

Objective: To explore the effects of DCA combined with cisplatin on the apoptosis of colorectal carcinoma cells HCT116, and the possible mechanisms.Methods: The inhibition of DCA and cisplatin alone or combined use on human colorectal carcinoma cell line HCT116 was assayed by(3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di- phenytetrazoliumromide)MTT. The morphological change of the apoptosis cells was probed by Hoechst 33342 staining. The mitochondrial membrane potential(??m) changes were measured by molecular probe Rodanmine123 and checked under fluorescent microscope. The activity of Caspase-3 was evaluated by spectrophotometry. Real-Time PCR analysis was used to detect the relative expression of bcl-2 gene. The activation of Bcl-2, Caspase-3 and Cytochrome c in HCT116 cells was analyzed by Western Blot.Results: MTT assay showed that both DCA and cisplatin alone could inhibit the growth of HCT116, as well as showed an obvious time and dose dependent effects. Compared with single drug treatment, an apparent synergistic effect were observed after treatment with 10mmol/L DCA combined with 20?g/ml cisplatin(CDI=0.434±0.021) for 48 hrs. The nuclear morphology changes such as chromatin condensation and fragmentation, and the mitochondrial transmembrane potential decrease in DCA+cisplatin group were compared with the monotherapy group, with a markedly different between two groups: the monotherapy group and the DCA+cisplatin group. DCA combined with cisplatin treatment for 24 hrs could lead the activity of Caspase-3 increased significantly, compared with the monotherapy group(P<0.01), and the control group(P<0.01). The results of Real-Time PCR analysis showed that DCA combined with cisplatin treatment with 12 hrs could decrease the expression of bcl-2 gene, compared with the monotherapy group(P<0.05). DCA combined with cisplatin treatment for 48 hrs could decrease the activation of Bcl-2, increase the activation of Caspase-3, and a marked Cytochrome c release.Conclusion: DCA could inhibit the proliferation and induce the apoptosis of HCT116 cells in a time and dose dependent manner. The combination use of DCA and cisplatin has a synergistic effect on the death of HCT116. This may be due to a combined protocol lowering the mitochondrial transmembrane potential, suppressing the expression of Bcl-2 and increasing the activation of Caspase-3, and increase the releasing of Cytochrome c, et al.