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

Abstract

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.