Inhibition of human immunodeficiency virus type 1 transcription by chemical cyclin-dependent kinase inhibitors

Cyclin-dependent kinases (cdk's) have recently been suggested to regulate h uman immunodeficiency virus type 1 (HIV-1) transcription. Previously, we ha ve shown that expression of one cdk inhibitor, p21/Waf1, is abrogated in HI V-1 latently infected cells. Based on this result, we investigated the tran scription of HIV-1 in the presence of chemical drugs that specifically inhi bited cdk activity and functionally mimicked p21/Waf1 activity. HIV-1 produ ction in virally integrated lymphocytic and monocytic cell lines, such as A CH(2), 8E5, and U1, as well as activated peripheral blood mononuclear cells infected with syncytium-inducing (SI) or non-syncytium-inducing (NSI) HIV- 1 strains, were all inhibited by Roscovitine, a purine derivative that reve rsibly competes for the ATP binding site present in cdk's. The decrease in viral progeny in the HIV-1-infected cells was correlated with a decrease in the transcription of HIV-1 RNAs in cells treated with Roscovitine and not with the non-cdk general cell cycle inhibitors, such as hydroxyurea (G(1)/S blocker) or nocodazole (NI-phase blocker). Cyclin A- and E-associated hist one HI kinases, as well as cdk 7 and 9 activities, were all inhibited in th e presence of Roscovitine. The 50% inhibitory concentration of Roscovitine on cdks 9 and 7 was determined to be similar to0.6 muM. Roscovitine could s electively sensitize HIV-1-infected cells to apoptosis at concentrations th at did not impede the growth and proliferation of uninfected cells. Apoptos is induced by Roscovitine was found in both latent and activated infected c ells, as evident by Annexin V staining and the cleavage of the PARP protein by caspase-3. More importantly, contrary to many apoptosis-inducing agents , where the apoptosis of HIV-1-infected cells accompanies production and re lease of infectious HIV-1 viral particles, Roscovitine treatment selectivel y killed HIV-1-infected cells without virion release. Collectively, our dat a suggest that cdks are required for efficient HIV-1 transcription and, the refore, we propose specific cdk inhibitors as potential antiviral agents in the treatment of AIDS.