The African natural product knipholone anthrone and its analogue anthralin (dithranol) enhance HIV-1 latency reversal

Khumoekae Richard,Mark A Brockman,Ian Tietjen,Natalie N Kinloch,Luis J Montaner,Aniqa Shahid,Ruth Feilcke,Toshitha Kannan,Jocelyn Rivera-Ortiz,Silven Read,Peter Imming,Leila B Giron,Karam Mounzer,Zabrina L Brumme,Simone Wappler,Cole Schonhofer,Andrew V Kossenkov,Marianne Harris,Mohamed Abdel‐Mohsen ,Kerstin Andrae‐Marobela

doi:10.1074/jbc.ra120.013031

Abstract

A sterilizing or functional cure for HIV is currently precluded by resting CD4+ T cells that harbor latent but replication-competent provirus. The "shock-and-kill" pharmacological ap-proach aims to reactivate provirus expression in the presence of antiretroviral therapy and target virus-expressing cells for elimination. However, no latency reversal agent (LRA) to date effectively clears viral reservoirs in humans, suggesting a need for new LRAs and LRA combinations. Here, we screened 216 compounds from the pan-African Natural Product Library and identified knipholone anthrone (KA) and its basic building block anthralin (dithranol) as novel LRAs that reverse viral latency at low micromolar concentrations in multiple cell lines. Neither agent's activity depends on protein kinase C; nor do they inhibit class I/II histone deacetylases. However, they are differentially modulated by oxidative stress and metal ions and induce distinct patterns of global gene expression from established LRAs. When applied in combination, both KA and anthralin synergize with LRAs representing multiple functional classes. Finally, KA induces both HIV RNA and protein in primary cells from HIV-infected donors. Taken together, we describe two novel LRAs that enhance the activities of multiple "shock-and-kill" agents, which in turn may inform ongoing LRA combination therapy efforts.

Highlights

A sterilizing or functional cure for HIV is currently precluded by resting CD41 T cells that harbor latent but replicationcompetent provirus
We identified and characterized knipholone anthrone (KA), in addition to its synthetic analog anthralin, as novel LRAs that synergize with established HIV latency reversal agents
To identify new LRAs from natural product sources, we used the Jurkat-derived J-Lat 9.2 cell line, which contains a noninfectious HIV provirus where premature stop codons are engineered into env and where nef is replaced with a GFP reporter [20]

Summary

Introduction

A sterilizing or functional cure for HIV is currently precluded by resting CD41 T cells that harbor latent but replicationcompetent provirus. Following a 24-h treatment with LRAs, additional cotreatment with 1 mM GÖ-6983 resulted in complete suppression of GFP expression induced by a 10 mM concentration of the PKC activator prostratin (0.4% GFP-positive cells relative to cells treated with only prostratin), but not by a 0.3 mM concentration of the HDAC inhibitor panobinostat (Fig. 4A).

Results

Conclusion