Abstract:

Objective To study the effects of low-dose radiation (LDR) combined with adriamycin(ADM) on the growth of transplantation tumor cells, hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF) expressions in transplantation tumor tissue of breast cancer-bearing nude mice, and to clarify the mechanism of enhancing anti-tumor effect of LDR combined with ADM. Methods Twenty-four breast cancer-bearing nude mice were divided into sham irradiation group(0 mGy), LDR group(75 mGy), ADM group and LDR-6h-ADM group (administed with ADM 6 h after LDR).The tumor weight was measured, the inhibitory rate of tumor was calculated, the morphology of tumor tissue was observed by light microscope, and the HIF-1α and VEGF expressions were detected with immunohistochemistry method. Results Compared with sham irradiation group, the mean tumor weights of the mice in other groups were decreased apparently(P<0.05). The mean tumor weight of the mice in LDR-6h-ADM group was the lowest, but had no significant differences when compared with LDR group and ADM group (P>0.05).The inhibitory rate of tumor of the mice in LDR-6h-ADM group was significantly higher than those in ADM group and LDR group (P<0.05).The pathological results showed that the cancer cells could be seen in each group, necrosis of cancer cells could be seen in LDR-6h-ADM group, the cancer tissue's interstitial was loose, and its extent of necrosis in cancer cells was significant compared with ADM and LDR groups.Compared with sham irradiation group, the mean gray values of HTF-1α and VEGF expressions in tumor tissue of mice were increased apparently in other groups (P<0.05). Conclusion LDR combined with ADM can enhance the body's anti-tumor effect, and the effect may be related to reducing the expressions of HIF-1α and VEGF, improving the hypoxia of tumor and inhibiting the formation of tumor angiogenesis.

Key words: low-dose radiation, adriamycin, breast neoplasms, transplantation tumor, hypoxia-inducible factor-1 alpha, vascular endothelial growth factor