[The cell-type-specific HSV-tk gene expression of suicide gene therapy system regulated by lens-specific promoter
Yong-xiang Jiang1, Yi Lu, Tian-jin Liu
1Department of Ophthalmology, Fudan University, Shanghai, China.
Objective:
To explore the specific expression of HSV-tk gene and killing effects on ocular leading cells of the enhanced specific HSV-tk/GCV gene therapy system regulated by lens-specific promoter LEP503.
Methods:
Experimental research. The enhanced specific HSV-tk/GCV gene system of two vectors were constructed (Lenti-LEP503-HSVtk-Cre and Lenti-HPGK-Loxp-EGFP-pA-Loxp-HSVtk). The lentiviral vectors were produced by transient transduction of transfering vectors, packaging vectors and enveloping vector into 293T cells. Virus was collected with ultracentrifugation and resuspended with 1 ml phosphate buffered saline and stored at -80°C. The HLEC and RPEC, NIH3T3, 293T cells were transduced with the enhanced specific HSV-tk gene system. The specific expressions of EGFP and HSV-tk were detected by fluorescence microscopy, flow cytometry and RT-PCR. The killing effects of HLEC and RPEC at the concentration of 20 mg/L GCV were assayed and compared by flow cytometry and CCK-8 kit. Difference of RPE cell viability among groups was evaluated by analysis of variance (ANOVA).
Results:
Expression efficiency of EGFP in RPEC group was 62.3%, 68.3% in NIH3T3 group, 75.8% in 293T group, whereas 17.5% in HLEC group. There was higher expression of HSV-tk at mRNA level in HLEC group than that in RPEC group. The relative intensity of HSV-tk mRNA in HLEC group transduced with the enhanced specific HSV-tk gene system was 4.01, whereas 0.29 in RPEC group. At the concentration of 20 mg/L GCV after 72 hours, the percentage of apoptosis detected by the flow cytometry in HLEC group transduced by the enhanced specific HSV-tk gene system was 76.51%, and 2.44% in RPEC group. There was no significant difference in the RPE cell viability among the enhanced specific HSV-tk gene combination-RPE group, normal-RPE group and negative-RPE control group at the concentration of 20 mg/L GCV after 72 hours (MD(1) = -0.047, P = 0.671; MD(2) = 0.027, P = 0.912).
Conclusions:
The enhanced specific HSV-tk gene system express HSV-tk selectively in HLEC. At the concentration of 20 mg/L GCV, it is effective against the proliferation of HLEC in vitro, but has less kill effect on RPEC.
