Kinetic Interaction of the Diphosphates of 9-(2-phosphonylmethoxyethyl)adenine and Other anti-HIV Active Purine Congeners with HIV Reverse Transcriptase and Human DNA Polymerases α, β and γ

Abstract

SummaryThe inhibitory effects of the diphosphates of 9-(2-phosphonylmethoxyethyl)adenine (PMEA) and its analogues on HIV reverse transcriptase and human DNA polymerases a,~, and y have been studied. The analogues investigated are the diphosphates of 9-(2-phosphonylmethoxypropyl)adenine (PMPApp), 9-(2-phosphonylmethoxypropyl)-2,6-diaminopurine (PMPDAPpp), and (2R,5R)-9-[2,5-dihydro-5-(phosphonyl methoxy)-2-furanyl]adenine (D4APpp). These four compounds are much more inhibitory to HIV reverse transcriptase when an RNA template rather than a DNA template is used. The K; values for the four compounds range from 11 to 22 nM with an RNA template. The K; values for ddCTP and AZTTP are 54 nM and 8 nM, respectively. PMEApp and its analogues show varying degrees of inhibition of the human DNA polymerases. The K; values for PMEApp, PMPApp and PMPDAPpp against DNA polymerase a are in the micromolar range, while D4APpp is a poor inhibitor of this enzyme with a K; value of 65.9 11M. The lnhlbltlon of DNA polymerase~by PMEApp, PMPApp and D4APpp is minimal, while PMPDAPpp shows higher inhibition of DNA polymerase~with a K; value of 9.71 11M. The K; values for PMEApp and D4APpp against DNA polymerase yare submicromolar, while PMPApp and PMPDAPpp are much less inhibitory to this enzyme. For comparison, ddCTP was found to be a more potent inhibitor of DNA polymerases~and y than the diphosphates of PMEA and its analogues.

Assessment of Mitochondrial Toxicity in Human Cells Treated with Tenofovir: Comparison with Other Nucleoside Reverse Transcriptase Inhibitors

“…One of the proposed mechanisms by which NRTIs interfere with mitochondrial functions is the depletion of mtDNA due to the inhibition of DNA pol ␥ by NRTI triphosphates (22,23). Some NRTI triphosphates such as ddCTP inhibit DNA pol ␥ and HIV type 1(HIV-1) reverse transcriptase with similar potencies, resulting in a narrow therapeutic window (9). Inhibition studies with DNA pol ␥ are Tenofovir-DP, the active metabolite of tenofovir and a structural analog of dATP, is a weaker inhibitor of DNA pol ␥ than most of the other NRTI triphosphates, with a K i of 60 M (9).…”

Mitochondrial DNA Depletion, Oxidative Stress, and Mutation: Mechanisms 0f Dysfunction from Nucleoside Reverse Transcriptase Inhibitors

“…As current clinical guidelines recommend combined therapy, usually including NRTI (Centers for Disease Control and Prevention, 1999), such regimens may be important to the development of mitochondrial toxicity in new tissue targets as treatment is prolonged because of the increased longevity of patients with AIDS. [The following references were cited only in Table 1: Barile et al, 1994Barile et al, , 1997Benbrik et al, 1997;Browne et al, 1993;Chen and Cheng, 1992;Cherrington et al, 1995;Corcuera et al, 1996;Cui et al, 1997;Dalakas et al, 1990;Elimadi et al, 1997. The following references were cited only in Table 1: Feldman and Anderson, 1994;Feldman et al, 1992;Hart et al, 1992;Hertzberg et al, 1992;Hobbs et al, 1992Hobbs et al, , 1995; Institute of Medicine (US) Committee to Review the Fialuridine (FIAU/FIAC) Clinical Trials, 1995;Izuta et al, 1991.…”

“…Mitochondrial structural changes and lipid accumulation in nerves of DDC-treated rabbits. Anderson et al, 1992Chen and Cheng, 1992Chen and Cheng, 1989Chen et al, 1991Cherrington et al, 1995Eriksson et al, 1995Feldman et al, 1992Feldman and Anderson, 1994Keilbaugh et al, 1993Kukhanova et al, 1995Martin et al, 1994Starnes and Cheng, 1987Tsai et al, 1994 3TC Kinetics with HeLa DNA pol-␥ Hart et al, 1992Martin et al, 1994 Carbovir K m with gapped duplex DNA Parker et al, 1991White et al, 1989 Continued…”

“…Mixed (competitive and noncompetitive) K i with cardiac DNA pol-␥ against various templates. Benbrik et al, Cherrington et al, 1995Corcuera et al, 1996Corcuera Pindado et al, 1994Eriksson et al, 1995Hobbs et al, 1995Martin et al, 1994Nusbaum and Joseph, 1996Semino-Mora et al, 1994Schroder et al, 1996Wang et al, 1996 Modica-Napolitano, 1993 AZT inhibits mitochondrial permeability transition:…”

K65R mutation of human immunodeficiency virus type 1 reverse transcriptase encodes cross-resistance to 9-(2-phosphonylmethoxyethyl)adenine

“…This compound is an acyclic adenine derivative; its active intracellular form is PMEA diphosphate (PMEApp), a competitive inhibitor of HIV type 1 (HIV-1) RT with regard to dATP substrate (2). HIV resistance to PMEA has occurred in tissue culture protocols, and a K65R mutation has been observed to develop in HIV cultured in the presence of this drug (21a, 24).…”