ABSTRACT
Objective To study the synergistic effect of endostatin (YH-16) and irradiation on human non-small cell lung cancer (NSCLC) cell line A549 and the expression level of vascular endothefial growth factor. Methods ① A549 cells were exposed to various concentrations of endostatin for different time. The optimal concentration giving ≤20% inhibition concentration (IC20) by MTT assay was selected. ② The cells were divided into 4 groups:control group,chemotherapy alone,radiotherapy alone,and radio-chemotherapy group. All groups were exposed in distinct treatment,the cells survival fraction and the plating efficiency of the four groups provided to select the optimal radiotherapy dosage. ③ The radio-chemotherapy group had been exposed to endostatin for 48 hours,followed by irradiation at 48 hours with various doses:0,2,4,6,8 Gy. After 14 days,the cell clonogenic survival curves and the SER were evaluated. ④ Detect the different groups' VEGF value by ELISA kit. Results Incubating cells in 200 mg/L endostatin culture medium the value of SER radiated by linear accelerator in 2 Gy after 48 h were 1.61 and 1.04. And endostatin with proper dosage and radio-exposure time could decrease the VEGF level. Conlusion It is suggested that endostatin enhances the radiosensitivity of NSCLC A549 cell line in vitro (SER=1.61,1.04). The enhancement depends on the time of exposure drug. The optimal radiation time should be 48 hour after exposure.