Trifluridine Induces p53-Dependent Sustained G2 Phase Arrest with Its Massive Misincorporation into DNA and Few DNA Strand Breaks.

Abstract

Trifluridine (FTD) is a key component of the novel oral antitumor drug TAS-102, which consists of FTD and a thymidine phosphorylase inhibitor. Like 5-fluoro-2'-deoxyuridine (FdUrd), a deoxynucleoside form of 5-fluorouracil metabolite, FTD is sequentially phosphorylated and not only inhibits thymidylate synthase activity, but is also incorporated into DNA. Although TAS-102 was effective for the treatment of refractory metastatic colorectal cancer in clinical trials, the mechanism of FTD-induced cytotoxicity is not completely understood. Here, we show that FTD as well as FdUrd induce transient phosphorylation of Chk1 at Ser345, and that this is followed by accumulation of p53 and p21 proteins in p53-proficient human cancer cell lines. In particular, FTD induced p53-dependent sustained arrest at G2 phase, which was associated with a proteasome-dependent decrease in the Cyclin B1 protein level and the suppression of CCNB1 and CDK1 gene expression. In addition, a p53-dependent increase in p21 protein was associated with an FTD-induced decrease in Cyclin B1 protein. Although numerous ssDNA and dsDNA breaks were induced by FdUrd, few DNA strand breaks were detected in FTD-treated HCT-116 cells despite massive FTD misincorporation into genomic DNA, suggesting that the antiproliferative effect of FTD is not due to the induction of DNA strand breaks. These distinctive effects of FTD provide insights into the cellular mechanism underlying its antitumor effect and may explain the clinical efficacy of TAS-102.

• Authors: Kazuaki Matsuoka, Makoto Iimori, Shinichiro Niimi, Hiroshi Tsukihara, Sugiko Watanabe, Shinichi Kiyonari, Mamoru Kiniwa, Koji Ando, Eriko Tokunaga, Hiroshi Saeki, Eiji Oki, Yoshihiko Maehara, Hiroyuki Kitao
• Journal: Molecular cancer therapeutics (Mol Cancer Ther) Vol. 14 Issue 4 Pg. 1004-13 (Apr 2015) ISSN: 1538-8514 [Electronic] United States
• PMID: 25700705 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: ©2015 American Association for Cancer Research.

Chemical References

• 5-fluoro-2'-deoxyuridine
• Antineoplastic Agents
• Cyclin B1
• Tumor Suppressor Protein p53
• CDC2 Protein Kinase
• Proteasome Endopeptidase Complex
• Oncogene Protein p21(ras)
• Trifluridine
• Deoxyuridine

Topics

• Antineoplastic Agents (metabolism, pharmacology)
• CDC2 Protein Kinase (genetics, metabolism)
• Cell Line, Tumor
• Cyclin B1 (genetics, metabolism)
• DNA Breaks
• DNA Replication
• Deoxyuridine (analogs & derivatives)
• G2 Phase Cell Cycle Checkpoints (genetics)
• Gene Expression Regulation, Neoplastic (drug effects)
• Gene Knockout Techniques
• Humans
• Inhibitory Concentration 50
• Oncogene Protein p21(ras) (genetics, metabolism)
• Proteasome Endopeptidase Complex (metabolism)
• Transcription, Genetic
• Trifluridine (metabolism, pharmacology)
• Tumor Suppressor Protein p53 (genetics, metabolism)