The objective of this proposal is to determine and compare the cellular pharmacology and the molecular mechanisms of action of arabinosylcytosine (ara-C), fludarabine (F-ara-A), and 2', 2'-difluorodeoxycytidine (dFdc) with a view to optimizing their anticancer activity alone and in combinations. This application extends ongoing investigations and utilizes new technical capacities that will provide an understanding of the actions of these drugs at a molecular level. First, the molecular action of DNA-directed nucleoside analogues will be determined with respect to the substrate properties of their 5'-triphosphates for purified human DNA polymerase alpha delta, and epsilon using a defined-sequence primer extension assay. In addition, the ability of DNA polymerase delta and epsilon to excise incorporated analogues will be characterized, and the effect of free and incorporated analogues on DNA ligation will be evaluated. Second, the consequences of incorporation of F-ara-A nucleotide into RNA of exponentially growing cells and quiescent cells will be evaluated with respect to premature termination of transcription, translational efficiency, and cell viability. Third, the biochemical and molecular bases for metabolic modulation of nucleoside analogues which results in synergistic cytotoxicity will be studied. These investigations will focus on the mechanisms by which F-ara-A and dFdC enhance the cellular accumulation of ara-C triphosphate, an action that is associated with synergistic cytotoxicity. Finally, mechanisms by which dFdC """"""""self- potentiates"""""""" its own anabolism and action will be defined. The actions of nucleotides of dFdC against dCMP deaminase, ribonucleotide reductase, and DNA polymerases will be investigated to gain an understanding of the substrate and inhibitory properties of the analogues. Together, these investigations of the metabolism and mechanisms of action of clinically useful drugs and related compounds under development will provide new information to be used in the rational design of combination treatment protocols.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA028596-18
Application #
2653971
Study Section
Experimental Therapeutics Subcommittee 1 (ET)
Program Officer
Johnson, George S
Project Start
1980-08-01
Project End
2000-01-31
Budget Start
1998-02-01
Budget End
1999-01-31
Support Year
18
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of Texas MD Anderson Cancer Center
Department
Internal Medicine/Medicine
Type
Other Domestic Higher Education
DUNS #
001910777
City
Houston
State
TX
Country
United States
Zip Code
77030
Liu, Xiaojun; Jiang, Yingjun; Nowak, Billie et al. (2018) Targeting BRCA1/2 deficient ovarian cancer with CNDAC-based drug combinations. Cancer Chemother Pharmacol 81:255-267
Al Abo, Muthana; Sasanuma, Hiroyuki; Liu, Xiaojun et al. (2017) TDP1 is Critical for the Repair of DNA Breaks Induced by Sapacitabine, a Nucleoside also Targeting ATM- and BRCA-Deficient Tumors. Mol Cancer Ther 16:2543-2551
Liu, Xiaojun; Jiang, Yingjun; Nowak, Billie et al. (2016) Mechanism-Based Drug Combinations with the DNA Strand-Breaking Nucleoside Analog CNDAC. Mol Cancer Ther 15:2302-2313
Lai, Tsung-Huei; Ewald, Brett; Zecevic, Alma et al. (2016) HDAC Inhibition Induces MicroRNA-182, which Targets RAD51 and Impairs HR Repair to Sensitize Cells to Sapacitabine in Acute Myelogenous Leukemia. Clin Cancer Res 22:3537-49
Liu, Xiao-Jun; Nowak, Billie; Wang, Ya-Qing et al. (2012) Sapacitabine, the prodrug of CNDAC, is a nucleoside analog with a unique action mechanism of inducing DNA strand breaks. Chin J Cancer 31:373-80
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Guo, Lei; Liu, Xiaojun; Jiang, Yingjun et al. (2011) DNA-dependent protein kinase and ataxia telangiectasia mutated (ATM) promote cell survival in response to NK314, a topoisomerase II? inhibitor. Mol Pharmacol 80:321-7
Zecevic, Alma; Sampath, Deepa; Ewald, Brett et al. (2011) Killing of chronic lymphocytic leukemia by the combination of fludarabine and oxaliplatin is dependent on the activity of XPF endonuclease. Clin Cancer Res 17:4731-41
Liu, Xiaojun; Wang, Yaqing; Benaissa, Sherri et al. (2010) Homologous recombination as a resistance mechanism to replication-induced double-strand breaks caused by the antileukemia agent CNDAC. Blood 116:1737-46
Wang, Yaqing; Liu, Xiaojun; Matsuda, Akira et al. (2008) Repair of 2'-C-cyano-2'-deoxy-1-beta-D-arabino-pentofuranosylcytosine-induced DNA single-strand breaks by transcription-coupled nucleotide excision repair. Cancer Res 68:3881-9

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