The long term goal of the proposed research in this application is to determine the selective basis of host cell response (sensitivity or resistance) to antiviral dideoxynucleosides (ddN). Prolonged therapy of AIDS patients with anti-HIV ddN, in addition to selecting drug resistant HIV-1 variants, may induce cellular resistance because of their dependence on the host cells' activating enzymes. The research effort in this area remains extremely limited. The Principal Investigator observed that chronic exposure to 0.5 ZM dideoxycytidine (ddC) in vitro induced drug resistance H9 lymphocytic cells (H9-ddC cells). These cells compensated for impaired mitochondrial functions and had lower deoxycytidine kinase (dC kinase) activity and ddCTP levels.
The aim of this proposal is to study biochemical basis of the ddC resistance and whether such a mechanism operates in the patients undergoing ddC therapy. Therefore, the following specific aims will be investigated (i) mechanisms of the reduced dC kinase activity and ddCTP levels; (ii) compensatory mechanisms for impaired mitochondrial functions in the resistant cells; (iii); differences in ddC resistance from that of its analog arabinosyl-cytosine (ara-C); and (iv) development of cellular resistance in the patients treated with ddC. These goals will be achieved by studying kinetics and genetic expression of dC kinase gene, cellular nucleotide pool, cross resistance to other nucleoside analogs, and mitochondrial DNA content structure and number per cell H9, H9-ddC, CEM, CEM-araC cells and the lymphocytes and autopsy specimens from the patients who had been treated with ddC. It is expected that these studies will enhance understanding of the host cell determinants responsible for ddC antiviral activity and may lead to strategies for improved chemotherapy.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI029155-09
Application #
2671985
Study Section
Special Emphasis Panel (ZRG5-AAR (04))
Project Start
1989-09-30
Project End
2000-08-31
Budget Start
1998-09-01
Budget End
1999-08-31
Support Year
9
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of Miami School of Medicine
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
City
Miami
State
FL
Country
United States
Zip Code
33146
Han, Tieran; Fernandez, Marilyn; Chou, Ting-Chao et al. (2005) Quantitation of synergism of arabinosylcytosine and cladribine against the growth of arabinosylcytosine-resistant human lymphoid cells. J Cancer Res Clin Oncol 131:609-16
Han, Tieran; Fernandez, Marilyn; Sarkar, Malancha et al. (2004) 2', 3'-Dideoxycytidine represses thymidine kinases 1 and 2 expression in T-lymphoid cells. Life Sci 74:835-42
Han, Tieran; Fernandez, Marilyn; Chou, Ting-Chao et al. (2004) 2-Chloro-2'-deoxyadenosine synergistically enhances azidothymidine cytotoxicity in azidothymidine resistant T-lymphoid cells. Biochem Biophys Res Commun 316:518-22
Han, Tieran; Fernandez, Marilyn; Sarkar, Malancha et al. (2003) Arabinosylcytosine downregulates thymidine kinase and induces cross-resistance to zidovudine in T-lymphoid cells. Biochem Biophys Res Commun 307:564-8
Agarwal, R P; Han, T; Fernandez, M (2001) Reduced cellular transport and activation of fluoropyrimidine nucleosides and resistance in human lymphocytic cell lines selected for arabinosylcytosine resistance. Biochem Pharmacol 61:39-47
Agarwal, R P; Wang, W; Yo, P et al. (1999) Cross-resistance of dideoxycytidine-resistant cell lines to azidothymidine. Biochem Pharmacol 58:1603-8
Agarwal, R P; Han, T; Fernandez, M (1999) Collateral resistance of a dideoxycytidine-resistant cell line to 5-fluoro-2'-deoxyuridine. Biochem Biophys Res Commun 262:657-60
Agarwal, R P; Olivero, O A (1997) Genotoxicity and mitochondrial damage in human lymphocytic cells chronically exposed to 3'-azido-2',3'-dideoxythymidine. Mutat Res 390:223-31
Agarwal, R P (1994) Increased activation of 2',3'-dideoxycytidine by acivicin. Biochem Biophys Res Commun 202:1524-9
Agarwal, R P; He, J (1994) Effect of hydroxyurea on 2',3'-dideoxycytidine activation. Biochem Biophys Res Commun 205:92-7

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