Objective   To explore the inhibitory effect of recombinant human adenovirus p53 (rAd-p53) combined with radiotherapy on human hepatocarcinoma in nude mouse model.     Methods   Nude mice hepatocarcinoma model was established by inoculating SMMC-7721 cells into the back of 18 nude mice. Firstly

two nude mice were taken out randomly

one was administered by intratumoral injection of rAd-p53

another was administered with PBS. After 48 h

the expression of P53 protein was detected by Western blotting. The rest 16 nude mice were divided into 4 groups randomly: the control group

the radiotherapy group

rAd-p53 group and rAd-p53 plus radiotherapy group. The tumor growth curve was plotted and the mice were sacrificed on the 16th day after the treatment and the tumor mass was taked. Meanwhile

the histology of specimens was examined by HE staining. The expression of Ki-67 protein was detected by immunohistochemistry. The apoptotic index was detected by Terminal dUTP nick end labeling (TUNEL) assay.    Results   The infection of rAd-p53 in SMMC-7721 xenograft was succeeded in the animal model and the expression of P53 protein was increased in 48 h after injection. The tumor inhibitory rate  were 81.49%

30.74% and 33.67% in rAd-p53 plus radiotherapy group

radiotherapy group and rAd-p53 group respectively. Compared to the other groups

the inhibitory rate of rAd-p53 plus radiotherapy group was significantly higher (P0.01). Tumor necrosis was observed in overall groups and mostly found in rAd-p53 plus radiotherapy group. The Ki-67 expression in the group of rAd-p53 plus radiotherapy was significantly lower than other groups (P0.01)

while the apoptosis index was much higher (P0.01).    Conclusion   rAd-p53 combined with radiotherapy can significantly inhibit the growth and enhance radio-sensitivity of hepatocarcinoma in SMMC-7721 xenotransplant in animal model.