[In situ gene therapy for murine gastric carcinoma with UPRT/5-FU enzyme/prodrug system mediated by retrovirus].

Background & Objective: 5-Fluorouracil(5-FU), a widely used chemotherapeutic drug, has a limited overall effect in the treatment of human solid tumors due to resistance. This study was designed to investigate if antitumor activation of 5-FU could be enhanced by transfection of uracil phosphoribosyltransferase(UPRT) gene.

Methods: The UPRT gene encoding uracil phosphoribosyltransferase was amplified from Escherichia Coli K12 genome and subcloned into retrovirus expression vector pLXSN, Recombinant retrovirus was packaged and used further to infect murine gastric cancer cell line MFC. The sensitivity of MFC transfected with UPRT gene to 5-FU was determined by MTT method. In situ gene therapy was performed by regional repeated injections of concentrated and purified recombinant retrovirus carrying UPRT gene intratumorally and followed by administration of 5-FU intraperitoneally(i.p.).

Results: The 5-FU sensitivity in MFC transfected with the UPRT gene increased 17.26-fold compared to the control cells. In situ transfection of the UPRT gene mediated by retrovirus vector followed by the administration of 5-FU (10 mg/kg) significantly inhibited the tumor growth (P < 0.005) with an inhibition rate of 87.18% and prolonged the survival.

Conclusion: Transfection of UPRT gene can render the murine gastric cancer cell line MFC be more sensitive to low concentration of 5-FU and significantly improve the antitumor effect of 5-FU both in vitro and in vivo.