Objective Post-transcription RNA interference (RNAi) is more and more widely applied in multigene therapy.This study aimed to establish an subcutaneous xenotransplanted tumor (SXT) model of human HT-29 colon carcinoma in nude mice and investigate the effects of the survivin shRNA-APC double gene co-expression lentiviral vector on the growth of SXT.Methods Thirty-five nude mice were equally divided into five groups, double-gene survivin shRNA, survivin shRNA, APC, empty vector, and blank, and injected into the left anterior axillary with respective stably transfected cell lines and human HT-29 colon carcinoma cells, all at 2×106/mL, to establish an SXT model of human HT-29 colon carcinoma.The inhibition rate of tumor growth was calculated by measuring the size and weight of the SXT, the expressions of survivin mRNA and protein in the tumor tissue detected by real time PCR and immunohistochemistry respectively, and the apoptosis of the HT-29 colon carcinoma cells determined by TUNEL.Results The mean size and weight of the SXT were significantly reduced in the double-gene survivin shRNA-APC, survivin shRNA, and APC groups as compared with the blank and empty vector groups (P<0.05), though increased in the survivin shRNA and APC groups in comparison with the double-gene group (P<0.05).The expressions of survivin mRNA and protein in the tumor tissue were remarkably lower in the double-gene survivin shRNA-APC, survivin shRNA, and APC groups than in the blank and empty vector groups (P<0.05), even lower in the double-gene group than in the survivin shRNA, and APC groups (P<0.05).The apoptosis rate of the HT-29 colon carcinoma cells was markedly up-regulated in the double-gene survivin shRNA-APC ([56.72±3.17]%), survivin shRNA ([33.64±2.03]%), and APC groups ([31.19±1.79]%) as compared with the blank ([9.89±0.31]%) and empty vector groups ([10.06±0.43]%) (P<0.05), even more significantly in the double-gene than in the survivin shRNA and APC groups (P<0.05).Conclusion The survivin shRNA-APC double gene co-expression lentiviral vector can reduce the expression level the survivin gene, promote the apoptosis of colon carcinoma cells, and suppress the growth of the subcutaneous xenotransplanted tumor.

Objective Studies show that the abnormal ex-pressions of APC and survivin play important roles in the development and progression of colon cancer .Survivin shRNA and APC double gene co-expression lentiviral vector was constructed to observe whether it could be successfully expressed in HT-29 colon cancer cells and whether it could impact on colon cancer cell apoptosis . Methods We selected the best shRNA interference fragment from the construc-tion of three pairs of complementary shRNA fragments and connected it with the effective fragment of APC ( aa1020-1698 ) to construct a double gene co-expression lentiviral vector .HT-29 cells were divid-ed into experimental group , empty loading group and blank group .HT-29 cells were observed by fluorescence microscopy after infec-tion.Survivin and APC expression levels were observed by real time PCR and western blot .Apoptosis was detected by caspase-3 activi-ty assay. Results ①We successfully constructed three pairs of shRNA sequences and proved that they had no human gene homolo -gous to the rest.Real time PCR analysis showed that the best sequence was shRNA 3.②After the sequence alignment of constructed shRNA vectors, three pairs of shRNA sequences were completely the same with the first designed sequence .Green fluorescence was observed in HT-29 cells by fluorescence microscope .The survivin content in experiment group (31.71 ±1.49) was significantly de-creased compared with empty loading group (100 ±0) and blank group(95.12 ±2.15)(P<0.05).The expression level of APC mR-NA was significantly increased compared with empty loading group (0 ±0) and blank group(0.51 ±0.15)(P<0.05).③The relative ratio of apoptosis in experiment group (0.573 ±0.050) was significantly increased compared with empty loading group (0.390 ± 0.040) and blank group(0.407 ±0.030)(P<0.05). Conclusion We have successfully constructed survivin-shRNA-APC double gene co-expression lentiviral vector which can be successfully expressed in HT-29 colon cancer cells , providing references for subse-quent gene therapy by the use of the carrier .