Increased cytotoxicity and bystander effect of 5-fluorouracil and 5 -deoxy-5-fluorouridine in human colorectal cancer cells transfected with thymidine phosphorylase

• Published in: British Journal of Cancer 1999-08, Vol.80 (11), p.1726-1733
• Main Authors: Evrard, A, Cuq, P, Ciccolini, J, Vian, L, Cano, J-P
• Format: Article
• Language: English
• Subjects: Adenocarcinoma; Antineoplastic Agents; Antineoplastic Agents - toxicity; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Cancer; Cancer Research; Cell Survival; Cell Survival - drug effects; Cell Survival - physiology; Cloning, Molecular; Colorectal Neoplasms; Combined treatments (chemotherapy of immunotherapy associated with an other treatment); DNA, Complementary; Drug Resistance; Epidemiology; Floxuridine; Floxuridine - toxicity; Fluorouracil; Fluorouracil - pharmacokinetics; Fluorouracil - toxicity; Human health and pathology; Humans; Life Sciences; Medical sciences; Molecular Medicine; Oncology; Pharmacology. Drug treatments; Recombinant Proteins; Recombinant Proteins - metabolism; Regular; regular-article; Thymidine Phosphorylase; Thymidine Phosphorylase - genetics; Thymidine Phosphorylase - metabolism; Transfection; Tumor Cells, Cultured
• ISSN: 0007-0920; 1476-5381; 1532-1827
• DOI: 10.1038/sj.bjc.6690589

Summary 5-Fluorouracil (5-FU) and 5′-deoxy-5-fluorouridine (5′-DFUR), a prodrug of 5-FU, are anticancer agents activated by thymidine phosphorylase (TP). Transfecting the human TP cDNA into cancer cells in order to sensitize them to these pyrimidine antimetabolites may be an important approach in human cancer gene therapy research. In this study, an expression vector containing the human TP cDNA (pcTP5) was transfected into LS174T human colon carcinoma cells. Eight stable transfectants were randomly selected and analysed. The cytotoxic effects of 5-FU and 5′-DFUR were higher in TP-transfected cells as compared to wild-type cells. The maximal decreases in the IC 50 were 80-fold for 5-FU and 40-fold for 5′-DFUR. The increase in sensitivity to these pyrimidines of TP-transfected cells significantly correlated with the increase in both TP activity and TP expression. Transfected clone LS174T-c2 but not wild-type cells exhibited formation of [ 3 H]FdUMP from [ 3 H]5-FU. In addition the LS174T-c2 clone enhanced the cytotoxic effect of 5′-DFUR, but also that of 5-FU, towards co-cultured parental cells. For both anti-cancer agents, this bystander effect did not require cell–cell contact. These results show that both 5-FU or 5′-DFUR could be used together with a TP-suicide vector in cancer gene therapy.