Rosiglitazone Potentializing The Growth Inhibition And Apoptosis Induction Of Human Colon Cancer Cells By Fluorouracil

Objective The aim of our work was to investigate the potential effects ofrosiglitazone(ROZ) on the proliferation inhibition and apoptosis induction of human colon cancer(HT-29) cells by fluorouracil (5-Fu) and its mechanism.Methods Human colon cancer (HT-29) cells were cultured in vitro. HT-29 cellsline were treated with various concentration of Roz or 5-Fu or both, the cell proliferation was evaluated by MTT assay. Trypan blue exclusion method was used to test the influence of growth in HT-29 cells. The apoptosis of HT-29 cells was determined by AO/EB fluorescence stain and PI staining flow cytometry . The expression of PPARγ, NF-κ B,Bcl-2, Bax protein were analyzed by Western blot.Results 5-Fu inhibited proliferation of HT-29 cells and its IC₅₀ to HT-29 cells is8.05 μ g/ml, so did Rosiglitazone whose IC₅₀ to HT-29 cells is 140.7 μ mol/L. Rosiglitazone significantly increased inhibitory proliferation effect of 5-Fu to HT-29 cells at 1.0μ mol/L. Trypan blue exclusion showed that rosiglitazone and 5- Fu were able to inhibit growth of HT-29 cells accompanied with increasing of concentration and time. 1.0, 10.0μ mol/L rosiglitazone had no cytotoxic to HT-29 cells. But Rosiglitazone at 1.0μ mol/L significantly increased inhibition growth effect of 5-Fu to HT-29, prolonging HT-29 cell multiple time from 50.7h to 900h,which consistent with growth curve. AO/EB fluorescence stain and PI staining flow cytometry data showed the apoptosis of HT-29 cells induced by 5-Fu and rosiglitazone in a concentration dependent manner. Apoptosis rate of HT-29 cells treated with rosiglitazone at 1.0μmol/L for 72h was 1.44ï¼…and treated with 5-Fu at 12.0μg/ml was 23.14ï¼…, while rosiglitazone (1.0μmol/L) significantly promoted apoptosis induction of HT-29 cells by 5-Fu(12.0μg/ml) to 48.41ï¼…. Western blot results showed that HT-29 cells treated with ROZ reduced NF-κB, Bcl-2 proteins expression and increased Bax proteins expression via activating PPARγprotein, in a concentration dependent manner(P＜0.05).Conclusion (1) Rosiglitazone at no cytotoxic concentration(1.0μmol/L) enhances the inhibition of proliferation and growth of human colon cancer cells by fluorouracil. (2) Rosiglitazone at no cytotoxic concentration (1.0μmol/L) promotes the apoptosis induction of human colon cancer cells by 5-Fu. (3) The chemosenitization of rosiglitazone to 5-Fu might be associated with downregnlation expression of NF-κB, Bcl-2 protein and upregulation expression of Bax protein via activating of PPARγ.