Experiment Study Of A New Radiosensitizer-tirapazamine On Radiosensitive Effect In Mouse Model Of Lewis Lung Cancer

Objective: To compare the efficacy of radiosensitization of tirapazamine (produced by pharmacal college of Sichuan university) in combination of radiotherapy with CMNa (another radiosensitizer) plus radiotherapy and radiotherapy alone.Methods: In this experiment, Lewis lung tumor model was established in C57 mice. Then tumor-bearing mice were treated by tirapazamine combined with radiotherapy(experimental group), CMNa plus radiotherapy and radiotherapy alone(control groups). Measures including tumor Vt/Vo ratio , tumor volume inhibitory ratio , tumor weights and immunohistochemical technique were used to evaluate the treatment effects of three different means of therapy.Results: The results show that tirapazamine combined with radiotherapy can apparently suppress tumor growth. Significant differences were obversed in tumor WV6 ratio , tumor volume inhibitory ratio and tumor weights between experimental group and two control groups. Significant differences were alsofound when VEGF and Bcl-2 expresses in tumor cells were tested by immunohistochemical technique between experimental group and two control groups. The results suggest that tirapazamine can improve the radiosensitivity of tumor hypoxia cells and reversal radioresistance of tumor.Conclusion: Tirapazamine produced by pharmacal college of Sichuan university combined with radiotherapy can apparently improve tumor hypoxia cells radiosensitivity and increase the efficacy of radiotherapy without additional side-effect of radiotherapy. The experiments definitely, prove that tirapazamine is a new type of radiosensitizer.