Background & objective: Improving the transfection efficiency and targeted delivery of gene vector are 2 critical problems in the field of gene therapy. Polycationic polyethylenimine (PEI), as a new kind of gene vector, provides an effective solution. This study aimed to investigate the antitumor and targeted delivery effects of PEI-mediated transfection of suicide gene HSV-tk regulated by ovarian-specific promoter OSP1 on human ovarian carcinoma cell line SKOV3.
Methods: SKOV3 cells were separately transfected with PEI, liposome DOTAP, and naked DNA mediated by plasmid pGL3-Luc; the transfection efficiency was measured by relative luciferase unit (RLU). SKOV3 cells and human hepatocellular carcinoma cell line SMMC7721 were transfected with pOSP1-HSVtk mediated by PEI. Cytotoxicity of ganciclovir (GCV) to SKOV3 and SMMC7721 cells was measured by MTT assay; the concentration of GCV in SKOV3 cells was detected by high performance liquid chromatography (HPLC). Cell apoptosis was detected by flow cytometry (FCM) and TdT-mediated dUTP nick end labeling (TUNEL) technique.
Results: RLU was significantly higher in PEI group than in DOTAP and naked DNA groups (187.35+/-6.48 vs. 45.74+/-5.98, and 0.03+/-0.00,P<0.01). Evident GCV cytotoxicity was observed in SKOV3 cells, but negligible in SMMC7721 cells. The concentration of GCV in SKOV3 cells was gradually decreased with treatment prolonging. FCM showed that the apoptotic rate of pOSP1-HSVtk-transfected SKOV3 cells was increased when exposed to GCV for 24, 48, and 72 h [(8.42+/-0.76)%, (18.50+/-1.78)%, (34.80+/-3.46)%]. A lot of apoptotic SKOV3 cells were detected by TUNEL.
Conclusion: PEI-mediated transfection of suicide gene regulated by ovarian-specific promoter has an in vitro tissue-specific killing effect on ovarian cancer cells, which may improve the efficiency and the targeting of gene therapy.