The In Vivo Experimental Study Of The Enhancement Of Radiosensitivity Of Recombinant Adenovirus-mediated Wild Type P53 Gene On Human Lung Adenocarcinoma Cell Lines With Different P53 Status

PURPOSE: To investigate the combined effects of adenoviral-mediated p53(Ad-p53) transgene expression and irradiation response in nude mice models of lung adenocarcinoma (A549 and GLC-82).To determine whether wtp53 sensitizes cells to radiation independently of their p53 status and to investigate the interaction mechanism.METHODS AND MATERIALS: The test was divided two parts. The first part: Expand Ad-wtp53 that a recombinant adenovirus vector contained a CMV promotor, wild-type p53-cDNA (Ad-p53) and green fluorescence protein(GFP) gene. The second part: Nude mice were injected subcutaneously with lung adenocarcinoma cell line A549 and GLC-82 to build nude mice models of lung adenocarcinoma.40 nude mice were randomly divided into A549 and GLC-82 groups, then each group was divided into 5 little groups(control, adeno virus, Ad-p5 3,radiation, Ad-p53+radiation).The size of tumor was measured after treatment and made the tumor growth curve. After 40 days , we killed all the nude mice and picked out the tumor tissue to make tissue slice. By those measures we can investigate the effect of gene p53 replacement therapy and its enhancement of radiosensitivity.RESULTS The test result of the group of A549 showed us:( 1) the volume of the group of Ad-p53 combined with radiation was smaller than the other four groups, there was significantly statistic difference (p<0.05); (2) the volume of the group of Ad-p53 and the group of radiation was smaller than the control group and the group of adenovirus, there was significantly statistic difference (p<0.05);(3) the group of Ad-p53 was as small as the group of radiation, there was no significantly statistic difference (p>0.05);(4) the control group was as big as the group of adenovirus, there was no significantly statistic difference (p>0.05).The test result of the group of GLC-82 showed us:(l) the volume of the group of Ad-p53 combined with radiation was smaller than the other four groups, there was significantly statistic difference (p<0.05); (2) the volume of the group of Ad-p53 and the group of radiation was smaller than the control group and thegroup of adenovirus, there was significantly statistic difference (p<0.05);(3) the group of Ad-p53 was as small as the group of radiation, there was no significantly statistic difference (p>0.05);(4) the control group was as big as the group of adenovirus, there was no significantly statistic difference (p>0.05).There was no significantly statistic difference between the GLC-82 group of Ad-p53 combined with radiation and the A549 group of Ad-p53 combined with radiation (p=0.201).Pathology: There were many apoptosis and necrosis in the group of Ad-p53 combined with radiation .On the contrary, there were little apoptosis and necrosis in both the control group and the group of adenovirus, but in center of the tumor there was a big piece of necrosis because of the shortage of the blood and oxygen. There were many apoptosis and little necrosis in the group of Ad-p53 , there were little apoptosis and many necrosis in the group of radiation. CONCLUSION: The results demonstrate that wtp53 transgene expression sensitizes human lung adenocarcinoma in vivo to irradiation. As this effect was observed in both the A549 and GLC-82 groups, radiosensitization was independent of endogenous p53 status.