Chk1 gene scijencing potentiates human hepatoma Huh7 cells to curcumin-induced apoptosis / 中国癌症杂志

ABSTRACT

Background and purpose: Checkpoint kinase 1 and 2 have been proposed to be potential therapeutic targets to sensitize cancers to radio- or chemo-therapeutics. However, little is known about whether Chk1/2 is also a suitable target for sensitizing cancers to curcumin. In the present study, we investigated effects of Chk1/2 siRNA on curcumin-induced apopotosis in hepatoma cell line Huh7 and evaluated the effectiveness of Chkl/2as a therapeutic target to potentiate human hepatoma to curcumin. Methods: Effect of curcumin on the cell cycle checkpoint-associated proteins was detected by Westem blot. The knockdown efficacy of Chk1/2 siRNA was measured by RT-PCR and Westem blot. Effect of Chk1/2 siRNA on curcumin-induced apoptosis in Huh7 cells was evaluated by DAPI staining. Effect of Chk1/2 siRNA on cell cycle distribution in curcumin-treated Huh7 cells was analyzed by flow cytometry. Results: Curcumin significantly inhibited phosphorylation of cell cycle checkpoint-associtaed proteins Chk1(S317), Cdc25C(S216) and Cdk1(Y15). Chk1 siRNA decreased Chk1 mRNA and protein by 95% and 92% and Chk2 siRNA decreased Chk2 mRNA and protein by 60% and 55% respectively as compared with negative control siRNA (P<0.01). Inhibition of Chk1, but not Chk2, increased apoptotic rate from (21.3±1.8)% to (29.5±2.6)% (P<0.05). Neither Chk1 nor Cbk2 siRNA had any impact on cell cycle distribution in Huh7 cells induced by curcumin. Conclusion: Chk1 siRNA sensitized Huh7 cells to curcumin-induced apoptosis, suggesting that Chk1 is a potential therapeutic target to sensitize human hepatoma to curcumin.