Abstract
HIV-1 transcription is activated by HIV-1 Tat protein, which recruits cyclin-dependent kinase 9 (CDK9)/cyclin T1 and other host transcriptional coactivators to the HIV-1 promoter. Tat itself is phosphorylated by CDK2, and inhibition of CDK2 by small interfering RNA, the iron chelator 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (311), and the iron chelator deferasirox (ICL670) inhibits HIV-1 transcription. Here we have analyzed a group of novel di-2-pyridylketone thiosemicarbazone- and 2-benzoylpyridine thiosemicarbazone-based iron chelators that exhibit marked anticancer activity in vitro and in vivo (Proc Natl Acad Sci USA 103:7670–7675, 2006; J Med Chem 50:3716–3729, 2007). Several of these iron chelators, in particular 2-benzoylpyridine 4-allyl-3-thiosemicarbazone (Bp4aT) and 2-benzoylpyridine 4-ethyl-3-thiosemicarbazone (Bp4eT), inhibited HIV-1 transcription and replication at much lower concentrations than did 311 and ICL670. Neither Bp4aT nor Bp4eT were toxic after a 24-h incubation. However, longer incubations for 48 h or 72 h resulted in cytotoxicity. Analysis of the molecular mechanism of HIV-1 inhibition showed that the novel iron chelators inhibited basal HIV-1 transcription, but not the nuclear factor-κB-dependent transcription or transcription from an HIV-1 promoter with inactivated SP1 sites. The chelators inhibited the activities of CDK2 and CDK9/cyclin T1, suggesting that inhibition of CDK9 may contribute to the inhibition of HIV-1 transcription. Our study suggests the potential usefulness of Bp4aT or Bp4eT in antiretroviral regimens, particularly where resistance to standard treatment occurs.
Footnotes
This project was supported by the National Institutes of Health National Heart, Lung, and Blood Institute and Office of Research on Minority Health [Grants 2R25-HL003679-08,R-1-HL55605, F31-HL090025]; the National Institutes of Health National Center for Research Resources [Grant 2M01-RR10284]; the National Institutes of Health National Institute of General Medical Sciences [1SC1-GM082325]; the National Institutes of Health Research Centers in Minority Institutions (RCMI) Program of the Division of Research Infrastructure, National Center for Research Resources [Grant 2G12-RR003048]; the National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases [R01-DK49419]; the National Institutes of Health National Center for Complimentary and Alternative Medicine [R21AT002278]; and by the National Health and Medical Research Council of Australia [Senior Principal Research Fellowship 571123, Project Grant 570952].
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
doi:10.1124/mol.110.069062.
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The online version of this article (available at http://molpharm.aspetjournals.org) contains supplemental material.-
ABBREVIATIONS:
- DFO
- desferrioxamine
- RT
- reverse transcriptase
- CP502
- 1,6-dimethyl-3-hydroxy-4-(1H)-pyridinone-2-carboxy-(N-methyl)-amide hydrochloride
- 311
- 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone
- ICL670
- deferasirox
- CDK
- cyclin-dependent kinase
- DpT
- di-2-pyridylketone thiosemicarbazone
- BpT
- 2-benzoylpyridine thiosemicarbazone
- Dp44mT
- di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone
- LTR
- long terminal repeat
- GFP
- green fluorescent protein
- ARC
- 4-amino-6-hydrazino-7-β-d-ribofuranosyl-7H-pyrrolo[2,3-d]-pyrimidine-5-carboxamide
- PBMC
- peripheral blood mononuclear cell
- NF-κB
- nuclear factor-κB
- WT
- wild type
- ONPG
- o-nitrophenyl-β-d-galactopyranoside
- AM
- acetoxymethyl ester
- PI
- propidium iodide
- DTT
- dithiothreitol
- CMV
- cytomegalovirus
- EGFP
- enhanced green fluorescent protein
- PVDF
- polyvinylidene difluoride
- PAGE
- polyacrylamide gel electrophoresis
- CTD
- C-terminal domain
- LS
- low salt
- HS
- high salt
- Dp2mT
- di-2-pyridylketone 2-methyl-3-thiosemicarbazone
- Bp44mT
- 2-benzoylpyridine 4,4-dimethyl-3-thiosemicarbazone
- Bp4eT
- 2-benzoylpyridine 4-ethyl-3-thiosemicarbazone
- Bp4aT
- 2-benzoylpyridine 4-allyl-3-thiosemicarbazone
- Bp4pT
- 2-benzoylpyridine 4-phenyl-3-thiosemicarbazone
- CP511
- 6-dimethyl-3-hydroxy-4-(1H)-pyridinone-2-carboxy-(N-methyl)-amide hydrochloride
- PKTBH
- di-2-pyridylketone thiobenzoyl hydrazone
- CTDo
- hyperphosphorylated C-terminal domain of RNA polymerase II
- CTDa
- hypophosphorylated C-terminal domain of RNA polymerase II
- eIF5α
- host elongation factor 5A.
- Received September 26, 2010.
- Accepted October 18, 2010.
- Copyright © 2011 The American Society for Pharmacology and Experimental Therapeutics
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