Abstract: Objective: To detect the changes of the proliferation,cell cycle and apotopsis of liver cancer HepG₂ cells after treated with Xiaoaiping(XAP) combined with X-raysradiation,and to clarify their anti-tumor mechanisms. Methods: The human liver cancer HepG₂ cells at logarithmic phase were selected,and divided into control,XAP,2 Gy radiation and XAP + 2 Gy radiation groups.The HepG₂ cells were treated with 75 mg·L^-1 final concentration of XAP,and they were irradiated with 2 Gy X-rays 12 h later.The cell proliferation activity was detected with CCK8 kits,the cell cycle and apoptotic rates were measured by FCM with PI single staining and Annexin Ⅴ-FITC double staining,and the caspase-3 protein expression was measured by Western blotting method. Results: After the cells were treated with XAP,the proliferation activities in XAP,2 Gy radiation and XAP+2 Gy radiation groups were significantly decreased compared with control group at 12,24 and 48 h (P<0.05 or P<0.01); the percentages of cells at S and G₂/M phases in XAP,2 Gy radiation and XAP + 2 Gy radiatin groups were significantly increased compared with control group (P<0.05 or P<0.01); the apoptotic rates were significantly increased compared with control group (P<0.05 or P<0.01),especially in XAP + 2 Gy radiation group.The Western blotting results showed that caspase-3 was cleaved into 17 000 and 19 000 fragments,and its expression was also increased compared with control group. Conclusion: XAP combined with X-rays radiation could inhibit the proliferation,and induce the G₂/M arrest and the apoptosis of liver cancer HepG₂ cells; the combination of them shows a synergistic anti-tumor effect.

Key words: Xiaoaiping, X-rays, liver neoplasms, cell proliferation, apoptosis