ABSTRACT
The small molecule S9a was derived from an established tumor necrosis factor-alpha (TNF-alpha) inhibitor (Canventol) by replacement of the isopropylidine group with a phenyl ring. S9a at 10 to 100 nM inhibited HIV production as potently as 3'-azido-3'-deoxythymidine (AZT), an inhibitor of viral reverse transcriptase. Furthermore, S9a and AZT in combination, at noncytoxic concentrations strongly inhibited HIV-1 replication that was more than additive and substantially prolonged the appearance of virus both in acutely infected CD4+ lymphocytes (SupT) in culture and in peripheral blood mononuclear cells (PBMCs) infected with a primary HIV-1 isolate. S9a inhibited TNF-alpha promoter-driven reporter gene activity. It was proposed that the mechanism of antiviral action of S9a was on the host cell, by blocking TNF-alpha transcription via a Tat-induced tar-independent loop, which decreases downstream NF-kappaB activation of HIV-1 long terminal repeat (LTR). S9a was superior to the first generation compound Canventol, which was superior to the natural compound sarcophytol A, demonstrating that further structure-based enhancement of potency of these compounds is feasible. This study suggests a therapeutic approach against AIDS by application of two drugs, one against a cellular and the other a viral target, which may provide an approach to the problem of frequent emergence of resistant variants to combinations of drugs that target only HIV genes.
Subject(s)
Anti-HIV Agents/pharmacology , Anticarcinogenic Agents/pharmacology , Cyclohexanols/pharmacology , HIV-1/drug effects , Tumor Necrosis Factor-alpha/antagonists & inhibitors , Virus Replication/drug effects , Zidovudine/pharmacology , Anticarcinogenic Agents/chemistry , Antineoplastic Agents/pharmacology , CD4-Positive T-Lymphocytes/virology , Cell Line , Cyclohexanols/chemistry , Diterpenes/chemistry , Diterpenes/pharmacology , Drug Combinations , Drug Synergism , Gene Products, tat/antagonists & inhibitors , HIV-1/genetics , HIV-1/physiology , Humans , Jurkat Cells/virology , NF-kappa B/antagonists & inhibitors , Repetitive Sequences, Nucleic Acid/drug effects , Reverse Transcriptase Inhibitors/pharmacology , Transfection , tat Gene Products, Human Immunodeficiency VirusABSTRACT
Canventol, a synthetic compound, is a new inhibitor of tumor promotion on mouse skin by okadaic acid. We previously reported that canventol acts by inhibiting both protein isoprenylation and tumor necrosis factor-alpha (TNF-alpha) release. In this study we examined the potencies of 10 newly synthesized canventol analogs through their effect on mevalonate metabolism, and then examined 3 representative analogs for inhibition of protein isoprenylation. Since canventol in vitro did not directly inhibit farnesyl protein transferase or geranylgeranyl protein transferase-I, the effects of canventol and its synthetic analogs on the fate of [3H]mevalonate in cells were studied. Canventol at 500 microM changed the ratio of newly synthesized sterols (cholesterol and lathosterol) to ubiquinones from 0.7 to 8.2 in NIH/3T3 cells which had previously been labeled with [3H]mevalonate, suggesting that the altered pattern of mevalonate metabolism is associated with inhibition of protein isoprenylation in the cells. We named this ratio the inhibition of protein isoprenylation index (IPI index). The 10 analogs showed a wide range of IPI indices. Two analogs, S3 and S9 had effects similar to, or stronger than, canventol. Three analogs, C44, C46 and C47, with lower IPI indices, inhibited tumor promotion on mouse skin slightly less than canventol itself did. This study shows that inhibition of protein isoprenylation in the cells, indicated by an increase in the IPI index, is a new biomarker for estimating inhibition of tumor promotion.
