Experimental study of the RV-HSV-TK/GCV suicide gene therapy system in gastric cancer.

OBJECTIVE

The aim of this study was to study in vitro and in vivo the killing effect and the bystander effect of herpes simplex virus-thymidine kinase gene/ganciclovir (HSV-TK/GCV) suicide gene system on the gastric cancer cell line, SGC-7901.

METHODS

GINaTK retroviral vector containing the HSV-TK gene was transduced into the PA317 packaging cell by lipofectin. The gastric cancer cell line, SGC-7901, was infected by a high-titer viral supernatant. SGC-7901/TK cells and SGC-7901 cells were used in the in vitro and in vivo studies. In the in vitro study, sensitivity of the SGC-7901/TK cells to GCV and the bystander effect were observated by a mononuclear cell direct cytotoxicity assay test. In the in vivo study, SGC-7901/TK cells and SGC-7901 cells were injected subcutaneously into the flanks of BALB/C nude mice, GCV was administrated intraperitoneally, a reverse transcriptase polymerase chain reaction was applied to detect the expression of the HSV-TK gene. A statistical analysis of the data was performed by using the analysis of variance.

RESULTS

The SGC-7901 cells transferred with the GINaTK gene displayed a higher antitumor effect than the parent cells. In the in vitro study, when the ratio of SGC-7901/TK cells reached 10%, the tumor cell-killing proportion was 53%. In the in vivo study, all BALB/C nude mice developed tumors in 7 days after tumor cells were implanted, the ratio of tumors formation is 100%. GCV could suppress tumor formation of the SGC-7901/TK cells. After the BALB/C nude mice treated with GCV, compared with the control tumors the median tumor volume of the mice implanted with SGC-7901/TK cells and BALB/C nude mice with cells mixed was, respectively, decreased to 52.8% and 69.4%.

CONCLUSIONS

The test showed that the HSV-TK gene can be transducted into the gastric cancer cell line, SGC-7901, under the mediation of a retrovirus and be stably expressed, and that the HSV-TK/GCV suicide gene therapy system could improve antitumoral efficiency. The bystander effect could be observated in the HSV-TK/GCV system both in vitro and in vivo.