tetrahydrouridine inhibits cell proliferation through cell cycle regulation regardless of cytidine deaminase expression levelstetrahydrouridine抑制细胞增殖通过细胞周期调控无论胞嘧啶核苷脱氨酶的表达水平.pdf

Tetrahydrouridine Inhibits Cell Proliferation through Cell Cycle Regulation Regardless of Cytidine Deaminase Expression Levels 1,4 2 3 4 4 Naotake Funamizu *, Curtis Ray Lacy , Kaori Fujita , Kenei Furukawa , Takeyuki Misawa , Katsuhiko Yanaga4, Yoshinobu Manome1 1 Department of Molecular Cell Biology, Institute of DNA Medicine, The Jikei University School of Medicine, Tokyo, Japan, 2 University of California Irvine, Irvine, California, United States of America, 3 Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan, 4 Department of Surgery, The Jikei University School of Medicine, Tokyo, Japan Abstract Tetrahydrouridine (THU) is a well characterized and potent inhibitor of cytidine deaminase (CDA). Highly expressed CDA catalyzes and inactivates cytidine analogues, ultimately contributing to increased gemcitabine resistance. Therefore, a combination therapy of THU and gemcitabine is considered to be a potential and promising treatment for tumors with highly expressed CDA. In this study, we found that THU has an alternative mechanism for inhibiting cell growth which is independent of CDA expression. Three different carcinoma cell lines (MIAPaCa-2, H441, and H1299) exhibited decreased cell proliferation after sole administration of THU, while being unaffected by knocking down CDA. To investigate the mechanism of THU-induced cell growth inhibition, cell cycle analysis using flow cytometry was performed. This analysis revealed that THU caused an increased rate of G1-phase occurrence while S-phase occurrence was diminished. Similarly, Ki-67 staining further supported that THU reduces cell proliferation. We also found that THU regulates cell cycle progression