[Radiation induced apoptosis and X linked inhibitor of apoptosis expression in Hep-2 cells]

To investigate the expression of X-linked inhibitor of apoptosis protein (XIAP) and the apoptosis rate in cultured Hep-2 cells, and discuss their relationship.

Cultured Hep-2 cells were irradiated with 2, 4, 8 Gy gamma ray. Living inhibitor rate detected with MTT, apoptosis rate and fluorescence index number of XIAP in mRNA level by RT-PCR and in protein level by flow cytometry (FCM) were measured at 12th, 24th, 48th hours after radiation respectively.

After irradiation, the volume of adherent cells increased and the number of suspended cells increased accordingly. 48 hours after irradiation with 2, 4, 8 Gy, the living inhibitor rate of Hep2 cells were 3.24%, 8.29%, 13.53%, and apoptosis rate was 3.27%, 5.33%, 8.22%. The fluorescence index number of XIAP protein measured by FCM was 1.23, 1.46, 1.58 respectively. With the dosage of 4 Gy, at the 12th, 24th, 48th hours of irradiation, the apoptosis rate was 3.19%, 3.22%, 5.31%. The living inhibitor rate was direct correlation with apoptosis rate in radiated Hep-2 cells. The expression of XIAP increased quickly at the 24th hours after radiation but the apoptosis rate did not increased in the course. XIAP was no more increase at the 48th hours, while the apoptosis rate was significantly higher. Which indicated that Them two were negative correlation.

gamma-ray can inhibit the growth of Hep-2 cells. The irradiation dosage was direct correlation with living inhibitor rate. Apoptosis is the main death method of Hep-2 cells after irradiation. The over expression of XIAP maybe one reason which caused the delayed apoptosis after radiation.