The Inhibitory Effect Of ¹²⁵I Radioactive Granules On Human Lung Adenocarcinoma Nude Mice Transplantation Tumor Growth And Apoptosis Mechanism

Objective:To prepare a tumor model of human lung adenocarcinoma cell line A549 in nude mice,and to place radioactive ¹²⁵I particles of different intensity in the transplanted tumor of nude mice to investigate the effect of radioactive ¹²⁵I particles on human lung adenocarcinoma cell line A549.The inhibition of tumor growth in xenograft nude mice and the effect on apoptotic and apoptotic factors of transplanted tumor cells in nude mice were determined by the exact experimental data.Methods:The transplanted tumor tissue cells were cultured in vitro and 40 BALA/c-nu mice subcutaneously transplanted tumor models were constructed.After successful construction of the nude mouse transplant tumor model,the tumor bearing mice were divided into 4 groups with random number table method,10 mice in each group.,0 m Ci group,0.6 mCi group,0.8 mCi group and control group,respectively.Radioactive ¹²⁵I particles with radioactivity of 0 mCi,0.6 mCi,and 0.8 mCi were implanted into the transplanted tumors of nude mice using an 18 G implant needle.The control group contained no particles.After transplantation of implanted tumors,nude mice were measured for body weight every 4 days for 32 days.After implantation of radioactive particles for 32 days,all nude mice transplanted tumor models were sacrificed,and the weight gain curves of nude mice were drawn,and the quality of transplanted tumors in each group was weighed.The transplanted tumors were resected and cut into sections.The sections were treated with HE staining and the pathological changes of the transplanted tumors were observed.The apoptosis of the transplanted tumor cells was observed by TUNEL method.The apoptotic factor p21 was detected by immunohistochemistry SP method,Caspase-9,Survivin,Livin protein expression in transplanted tumor cells.Results:The nude mice in each group survived without death and were generally in good condition.There were no cachexia and obvious radiation damage.A total of 40 nude mice were inoculated.One week after the nude mice were inoculated with human lung adenocarcinoma A549 cells,tumor nodules appeared in the nude mice inoculated,and then rapidly grew into transplanted tumors.A549 cells were inoculated for about 20 days.All transplanted tumors reached the standard volume.There was no obvious erosion and ulceration in the transplanted tumor.The next experiment can be used normally.From the20th day after implantation of radioactive ¹²⁵I seeds,body weights of nude mice of 0.6m Ci and 0.8 mCi group were smaller than those of the control group（all P<0.05）;and weights of 0.6 mCi group and 0.8 mCi group of nude mice were compared,0 mCi group and control group.There was no significant difference in the body weight of nude mice（P>0.05）.The body weights of nude mice at 0.6 mCi and 0.8 mCi on the 28th and 30th days were significantly smaller than those of the control group（P<0.05）.The weights of the 0.6 mCi group and 0.8 mCi group were compared between the 0 mCi group and the control group.There was no significant difference in body weight between nude mice（all P>0.05）.Thirty-two days after radioactive ¹²⁵I seed implantation,the nude mice were sacrificed and the transplanted tumors were weighed.The tumor weights of 0.6 mCi and0.8 mCi groups（1.20±0.44,0.99±0.404）g were all less than the control group（2.35±0.64 g,average P<0.05）,the tumor inhibition rates were approximately 49%and 62%,respectively,compared with the tumor weights of the 0.6 mCi group and the 0.8 m Ci group.There was no significant difference in tumor weight between the 0 mCi group and the control group.All P>0.05).Hematoxylin-eosin（HE）staining of the transplanted tumor tissue showed that a large number of necrotic cells appeared in the 0.6 mCi and 0.8mCi groups.The normal structure of the cells was destroyed,and it was not easy to distinguish.The cells near the necrotic area had complete cell structure,but the intercellular space was changed.Large,uneven distribution.There was no or only a small amount of tissue degeneration and necrosis in the control group and 0 mCi group.Nearly all the cell structures were intact,but the tumor-like cell morphology was present.Tumor cells were examined by TUENL.The apoptotic index of 0.6 mCi and 0.8 mCi groups was（50.00±2.58）and（62.33±4.51）,respectively,and the difference was statistically significant（27.00±4.69）%in the control group.（P<0.05）.Immunohistochemistry showed that the expression of p21 and Caspase-9 protein in the 0.6 mCi and 0.8 m Ci groups was significantly increased compared with the control group（P=0.018,P<0.01）.The expression of survivin and Livin protein in the 0.6 mCi and 0.8 mCi groups was significantly decreased compared with the control group（P=0.044-0.006,P<0.01）.The correlation between the apoptotic factors detected in this experiment showed that the expression of Survivin and Caspase-9 was negatively correlated with tumor tissue in nude mice（r=-0.984,P=0.037）;the expression of Survivin and p21 was negatively correlated（r=-0.996,P=0.004）;Survivin is positively correlated with Livin protein expression（r=0.975,P=0.0,25）.Conclusion:Radioactive ¹²⁵I seed implantation can inhibit the proliferation of tumor cells,delay tumor growth,and promote the apoptosis of human lung adenocarcinoma A549cells by up-regulating the expression of p21 and Caspase-9 proteins and down-regulating the expression of Survivin and Livin proteins.