Hu C.-M.ZEE-FEN CHANG2021-05-312021-05-3120080008-5472https://www.scopus.com/inward/record.uri?eid=2-s2.0-42349114776&doi=10.1158%2f0008-5472.CAN-07-3069&partnerID=40&md5=e26e73df49805f6516d0c20c690ae938https://scholars.lib.ntu.edu.tw/handle/123456789/564367Intracellular supply of dTTP is a highly regulated process and has been a key target for chemotherapeutic drug development. Thymidylate kinase (TMPK) is the key enzyme for dTTP formation in both de novo and salvage pathways. In this study, we used lentiviral-based small hairpin RNA to silence TMPK expression in p53(+/+) and p53(-/-) HCT-116 colon cancer cells. This approach was sufficient to decrease the dTTP pool gradually without affecting p53 expression and generating cytotoxicity. TMPK knockdown significantly increased doxorubicin sensitivity dramatically in p53-proficient, p53-null HCT-116, and LoVo colon cancer cells. The decrease in the dTTP pool using this approach augmented the DNA damage response and enhanced apoptotic induction after exposure to low-dose doxorubicin, leading to cell death. In contrast, silencin g of thymidylate synthase which blocks the de novo pathway was incapable of sensitizing p53-null HCT-116 cells to doxorubicin-induced apoptosis because of the compensation by the salvage pathway. Our results suggest the lentiviral delivery of small hairpin RNA targeting TMPK in combination with a low dose of doxorubicin as a new approach to kill colon cancer cells regardless of p53 status. ?2008 American Association for Cancer Research.[SDGs]SDG3doxorubicin; lentivirus vector; short hairpin RNA; thymidine triphosphate; thymidylate synthase; apoptosis; article; cancer cell culture; cell killing; cell strain HCT116; colon cancer; concentration response; controlled study; culture medium; DNA damage; drug cytotoxicity; human; human cell; lethality; priority journal; protein expression; tumor suppressor gene; Antibodies, Monoclonal; Cell Line, Tumor; Colonic Neoplasms; DNA Damage; Doxorubicin; Gene Silencing; Genetic Vectors; Humans; Lentivirus; Nucleoside-Phosphate Kinase; RNA, Catalytic; RNA, Small Interfering; RNA, Viral; Tumor Suppressor Protein p53journal article10.1158/0008-5472.CAN-07-3069184137512-s2.0-42349114776