Eradication of Cancer Cells Using Doxifluridine and Mesenchymal Stem Cells Expressing Thymidine Phosphorylase.

Gene-directed enzyme prodrug therapy (GDEPT) has been developed over several decades as a targeted cancer treatment aimed at minimizing toxicity to healthy cells. This approach involves three key components: a non-toxic prodrug, a gene encoding an enzyme that converts the prodrug into an active chemotherapy drug, and a gene carrier to target cancer cells. In this study, the prodrug doxifluridine was enzymatically converted into the chemotherapy drug 5-fluorouracil via thymidine phosphorylase, using human mesenchymal stem cells (hMSCs) as delivery vehicles. The hMSCs were first transduced with thymidine phosphorylase-encoded lentiviral vectors produced by HEK293T cells, then co-cultured with A549 adenocarcinoma cells in the presence of doxifluridine. The results showed that after 3 days of prodrug treatment, cell viability in both A549 cancer cells and hMSCs dropped by about 50%, and by day 5, viability had decreased to 10%. In summary, exogenous thymidine phosphorylase expressed in hMSCs successfully converted the non-toxic prodrug doxifluridine into the chemotherapy agent 5-fluorouracil, effectively eliminating both cancer cells and hMSCs within a short period.