Abstract: Objective To investigate the influence of Valproic acid(VPA) on cell cycle of Kasumi-1 cells. Methods Kasumi-1 cell line model transplanted subcutaneously in nude mice were established and divided into control group and VPA group, to observe and record the growth of nude mice and their transplanted tumors and calculate volume and inhibition rate.Kasumi-1 cell of each group cell cycle changes were analyzed by flow cytometry.P21WAF1/CIPand pRB were detected by immunohistochemistry and Western blot. Results ①VPA obviously inhibited the growth of tumor, animals treaed with VPA showed a statistically significant decrease in tumor volume and weight compared with controls with 57.25% growth inhibition. ?VPA blocked cell in G0/G1 phase were detected by flow cytometry. ?The P21WAF1/CIP protein significantly increased with VPA group. pRB protein significantly decrease with VPA group. Conclusion We conclude that administration of VPA inhibit the growth of Kasumi-1 cell line tumor VPA can arrest Kasumi-l cell in Go/G1 phase through the regulation of P21WAF1/CIP and pRB.

Key words: Leukemia , Valproic acid, Cell cycle, xenograft tumor, pRB