ABSTRACT
OBJECTIVE: To investigate the mechanism of inhibition and radiosensitization effects of combining treatment with tanshinone I and(irradiation) IR on mice bearing Lewis lung carcinoma(LLC). METHODS: The models of LLC in C57BL/6 mice were established via subcutaneous injection of mouse LLC cells, and divided into model control group, radiation alone group, Tan I (40 mg · kg-1) group, 5-Fu + IR group, Tan I (10, 20, 40 mg · kg-1) + IR groups. After irradiated, the relative volume of tumor was observed, the delay time of tumor growth and enhancement factor (EF) was calculated. After stripped, the inhibition rate was calculated. Cell apoptosis index( AI) was in vestigated by TUNEL staining. The protein expressions of Bcl-2 and Bax were detected by Western blot. RESULTS The different concentrations of Tan I (low, medium and high) + IR groups inhibited the tumor growth significantly, and the inhibition rate was 27.14%, 38.46%, 59.78%, respectively, which were significant difference as compared with IR group (P < 0.01). And also had the significant radiosensitizing effect, the enhancement factor was 1.09, 1.76, 2.03, respectively. The AI was 51.3% in Tan I (H) + IR group, which was significant difference as compared with IR group(P < 0.05). The expression of Bcl-2 protein was decreased, and Bax proteins was increased by combining treatment with Tan I and IR. CONCLUSION Combining treatment with Tan I and IR inhibited the tumor growth and had radiosensitizing effects in mice bearing LLC. One of the mechanism may be that it might induce apoptosis by regulated the expression of Bcl-2/Bax protein, so cells were more sensitive to radiation.