Objective      To determine the cytotoxic effect of gamma knife assisted with different copy numbers of CArG/5HRE+ herpessimplex virus-thymidine kinase (HSV-TK) system on C6 glioma cells.       Methods      Intracranial C6 glioma model was established in Wister rats. The recombinant plasmids with different copy numbers of CArG/5HRE an

d suicide gene HSV-TK were artificially constructed. These different recombinant plasmids were transfected into C6 glioma rats with GCV injected abdominally afterward. After Gamma knife

tumor tissue of rats was collected

and then the killing effect of the tumor was decided by conventional pathology

tumor cell apoptosis and the expression of HSV-TK gene.       Results      The destruction and apoptosis of tumor cells were observed in all group

and more obvious in the groups containing CArG/HRE promoter (

P

0.05)

especially in 9CArG/5HRE group (

P

0.05). The mRNA and protein expression of HSV-TK was increased significantly in groups containing CArG/HRE promoter (

P

0.05)

especially in 9CArG/5HRE group (

P

0.05).       Conclusion      Under stereotactic radiosurgery (SRS) treatment

CArG/HRE double promoter significantly promotes the expression of target gene HSV-TK

and enhances the killing effect to C6 glioma cells. The effect of 9CArG/5HRE double promoter is identified as the most significant.