EFFECT OF LOW DOSE RADIATION ON TUMOR EXPRESSIONS OF MMP-2 AND TIMP-2 IN S180 SARCOMA-BEARING MICE

Objective To investigate the effect of low dose radiation(LDR)on expressions of MMP-2 and TIMP-2 in S180 sarcoma-bearing mice. Methods A tumor model of S180 sarcoma-bearing mice was created by subcutaneous inoculation of S180 sarcoma cells into Kunming strain mice.The mice were then divided into sham-radiation group(N group,40 mice) and low dose radiation group(LDR group,40 mice).The mice in LDR group were given single dose of 75 mGy for whole-body γ-ray radiation;those in N group were radiated with no ray,and sacrificed 12 h after sham-radiation;those in LDR group were sacrificed 12 h(LDR-12 h group),24 h(LDR-24 h group),48 h(LDR-48 h group) and 72 h(LDR-72 h group) after radiation.Tumor weight was determined,and the expressions of MMP-2 and TIMP-2 detected by immunohistochemical method. Results Compared with N group,whole-body exposure to 75 mGy γ-ray in LDR group significantly slowed down the tumor growth of mice(t=2.19,P0.05).After low dose radiation,the expression of TIMP-2 at different time points in LDR group were not significantly different from those observed in N group(P0.05).The MMP-2 expression was significantly reduced in LDR-24 h group(u=2.15,P0.05) and LDR-48 h group(u=2.04,P0.05) compared with that of N group. Conclusion Low dose whole-body radiation could significantly suppress the growth of tumor and reduce the expression of MMP-2,therefore inhibit the infiltration and metastasis of tumors.