Background and purpose: Quinonoids can change the cell cycle distribution of tumor cells

and effect the radiosensitizing. This study aimed to investigate the radiosensitization effects

cell cycle and apoptosis of cryptotanshinone on H22 hepatoma-bearing mice. Methods: The mouse hepatoma H22 model was established

then divided into blank control group

irradiation alone group

high dose of cryptotanshinone group

cryptotanshinone (low

medium and high) + IR groups. After irradiated

observed the growth of tumor’s conditions

record epigenetic tumor irradiation time

calculated the delay time of tumor growth and enhancement factor (EF). After 22 days

mice were killed

stripped tumor

and calculated the inhibition rate. The cell cycle distribution and

apoptosis were measured by flow cytometry. Results: Cryptotanshinone (low

medium and high) groups inhibited the tumor growth better than the blank group

and had the significant radiosensitizing effect. The enhancement factor was 1.22

1.43

2.19

respectively. Cells were treated with cryptotanshinone which had significant effects on cell cycle

and induced apoptosis

which indicated significant G

2

/M phase arrest and a decrease in S phase. Conclusion: Cryptotanshinone inhibited the tumor growth and had the radiosensitizing effects on H22 hepatoma-bearing mice. One of the mechanism may be that it might make significant G

2

/M phase arrest and S phase decreased

and induced apoptosis. So cells were more sensitive to radiation.