Objective:To observe the treating effect of focused ultrasound on human cervical tumor transplanted subcutaneously in nude mice.Methods:After irradiated with different dose of focused ultrasound

the thirty-two nude mice which transplanted subcutaneously with human cervical cancer were observed for the growth of the subcutaneously transplanted tumor and general vital sign and its effects on the biological characteristics of tumor tissues on the rim of the targeted areas at the different time.Target areas and the rim of the targeted areas in tumor samples were examined by light microscope and electron microscope for the change of histopathology and ultra-structure.Apoptosis was detected by TUNEL.The immunohistochemical method was applied to investigate the expressions of Bax

Bcl-2

PCNA and MMP-9.Results:Focused ultrasound had evident inhibitory effect on the growth of transplanted subcutaneously human cervical tumor in nude mice and the effect was positively related to the dose.Denaturation

necrosis and the damage of nuclear structure were found in targeted areas of each treatment group through pathohistological observation.Tumor cell that on the rim of the targeted areas were swelling and loosing arranged.Ultrastructural investigations showed mitochondrion swelling and the formation of cytoplasm cavitations bubbles

but the change of nuclear structure was not significant.Compared with that of unirradiated areas

apoptosis rate of tumor cell in the rim of the targeted areas was increasing

the expression of Bax was up-regulated and Bcl-2 was down regulated

and the expressions of PCNA and MMP-9 protein weakened.Conclusions:Focused ultrasound could significantly damage the tumor cells of human cervical cancer transplanted subcutaneously in nude mice tumor and induced apoptosis of tumor cell on the rim of the targeted areas significantly.The process maybe related to the mitochondria-mediated cell apoptosis signal passage that activated by the thermal effect of focused ultrasound.