MECHANISMS OF SELECTIVE ACTIONS OF ANTIVIRAL AGENTS

  • Agarwal, Ram P, (PI)

Project: Research project

Description

Current therapies for AIDS have been directed at the viral reverse
transcriptase (RT). 2',3'-Dideoxynucleosides (ddN), analogs of
endogenous deoxynucleosides (dNs), following sequential phosphorylation
to 5'-triphosphate (ddNTP), inhibit RT. Since ddNs metabolism is cell-
species dependent, the kinetics of their metabolism and the cellular
ddNTP pools will differ among target cells and be indicative of
sensitivity and resistance to the drug. Long term objective of present
investigation is to understand intracellular differences of ddN
metabolism, their interactions with endogenous nucleotide pool and
mechanisms of resistance in human interactions with endogenous nucleotide
pool and mechanisms of resistance in human target cells and exploit this
knowledge to selectively optimize their anti-AIDS efficacies. Therefore,
the specific aims of this proposal are: (1) to compare ddN metabolism in
human monocytic/macrophage cell line (U937), lymphocytic cell lines (CEM)
and macrophages; (2) to determine their effects on endogenous nucleotide
pool; (3) to determine how the nucleotide pool and the ddN metabolism
differ in resistant cells; and (4) to determine the effects of modulators
of ddN metabolism on ddNTP and endogenous nucleotide pool. Using human
cells of different lineage and stages of differentiation which are
permissive to HIV and the potential dideoxynucleosides currently
available (dideoxynucleosides of adenine, hypoxanthine, cytosine, guanine
and azido-dideoxythymidine), and the new drugs available through our drug
development program, the following studies will be carried out:
activities and the kinetic paramenters of the key anabolic and catabolic
enzymes using ddNs as substrates; intracellular accumulation and
degradation of dideoxynucleotides; interactions of ddNs on the existing
endogenous nucleotide pool, and their de novo and salvage synthetic
pathways will be determined by incorporating radiolabled purine and
pyrimidine nucleosides and their precursors (glycine and NaHCO3) in the
nucleotide pools. To determine the mechanisms of resistance, the above
studies will be performed in cells which had been continuously exposed to
the ddNs. Effects of a novel class of compound (nucleotide dimers) which
may provide cells with the prephosphorylated two active drugs; inhibitors
of ddI and ddG catabolism: and intervention at de novo and salvage
pathway of purine pyrimidine nucleotides synthesis to reduce levels of
dNTP will also be examined.
StatusFinished
Effective start/end date9/30/894/30/05

Funding

  • National Institutes of Health: $184,293.00
  • National Institutes of Health: $265,125.00
  • National Institutes of Health
  • National Institutes of Health: $259,733.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $265,125.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $190,158.00
  • National Institutes of Health

Fingerprint

Dideoxynucleosides
Antiviral Agents
Zalcitabine
Nucleotides
Dideoxynucleotides
Cytosine
Lamivudine
Deoxycytidine Kinase
Acquired Immunodeficiency Syndrome
Thymidine Kinase
Pharmaceutical Preparations
Macrophages
Drug Resistance
Pyrimidine Nucleotides
Purine Nucleosides
Purine Nucleotides
HIV
Cell Line
U937 Cells
Hypoxanthine

ASJC

  • Medicine(all)
  • Immunology and Microbiology(all)