Objective      To study the effect of bortezomib (BTZ) on radiosensitivity of U87 glioma and distribution of cell cycle.       Methods      A nude mouse U87 glioma model was established. The nude mice were randomly divided into control group

irradiation group

BTZ group

and irradiation + BTZ group. After treatment with 8MeV-β irradiation

mice in irradiation +BTZ group were treated with BTZ by intraperitoneal injection. U87 glioma tissue was isolated and weighed. U87 glioma-inhibiting rat

e was calculated. Distribution of cell cycle

tumor growth delay (TGD) time

and sensitizing enhancement ratio (SER) were detected. The average survival time of nude mice in different groups was compared.       Results      The U87 glioma-inhibiting rate was significantly higher and the TGD time was significantly longer in irradiation +BTZ group than in irradiation group (46.5%vs31.5%

59 dvs38 d，P0.01). The sensitivity of radiotherapy was increased 1.44-fold when irradiation was combined with BTZ treatment. The proportion of tumor cells at the G

0

/G

1

phase was significantly lower than that of those at the G

2

/M phase after irradiation and BTZ treatment than before irradiation and BTZ treatment (79.9%vs66.0％

3.2％vs16.4％

P0.05). The survival time of nude mice was longer after irradiation and BTZ treatment.       Conclusion      BTZ can significantly up-regulate the radiosensitivity of U87 glioma

effectively reverse the irradiation-induced retardation of tumor cells at the G

0

/G

1

phase

increase the proportion of tumor cells at the G

2

/M phase

and prolong the survival time of tumor-bearing mice.