A major role for Nrf2 transcription factors in cell transformation by KSHV encoded oncogenes

JULIÁN NAIPAUER; MONTANI MERCEDES; CABRERA MAIA; FEUERSTEIN EMILIA; RAIMONDI, ANA R.; ENRIQUE A. MESRI; RAMOS JUAN CARLOS; LORENZANO MENNA PABLO; COSO, O. A.

Conferencia; HIV/AIDS Malignancy U54 Consortia Conference; 2023

Kaposi’s sarcoma (KS) is the most common tumor in AIDS patients. The highly vascularized patient’s skin lesions are composed of cells derived from the endothelial/mesenchymal tissue transformed by the KSHV virus. We have found a major role of ERK1/2MAPK pathways as intermediates in signaling from vGPCR to Nrf2, influencing Nrf2 translocation to the cell nucleus, Nrf2 transactivation activity, and consequently HO-1 expression. Experiments in nude mice show that the tumorigenic effect of vGPCR is dependent on Nrf2. In the context of a complete KSHV genome, we show that the lack of vGPCR increased cytoplasmic localization of Nrf2 correlated with a downregulation of HO-1 expression. Moreover, we also found an increase in phospho-Nrf2 nuclear localization in mouse KS-like KSHV (positive) tumors compared to KSHV (negative) mouse KS-like tumors. Our data highlight the fundamental role of Nrf2 linking vGPCR signaling to the HO-1 promoter, acting upon HO-1 gene expression regulation and the tumorigenesis induced by vGPCR. In addition, we found that the expression of vGPCR is able to induce the expression of PDGFA and PDGFB ligands indicating a mechanism of activation of PDGFRA dependent on KSHV. The signal transduction pathways regulated by the viral oncogene vGPCR and the PDGFRA receptor could be involved in regulating HO-1, and Nrf2. We showed that PDGFRA activation is involved in vGPCR-mediated signaling through Nrf2 and HO-1. Finally, we aim to develop a rational design of novel pharmacological stabilizers of the Nrf2-Keap1 complex, oriented to increase Keap1-Nrf2 interface binding contacts via ligands with a molecular “clip” mode of action as a new strategy for therapeutic modulation of cell signaling in AIDS-related KS disease. This would contribute to down-regulate Nrf2 activity and promote its ubiquitination and further degradation by interfering with its release from the complex with Keap1 upon KSHV-induced oxidative stress. We identified 10 compounds obtained from High-Throughput screening docking using 500000 drug-like compounds (Enamine Advance collection). We ended with three compounds that showed downregulation of Nrf2 transcriptional activity in Luciferase assays, using a minimum promoter containing three ARE sites in tandem (3xARE Luc). We have already identified one of these compounds displaying a reduction in luciferase activity of the HO-1 promoter induced by vGPCR concomitantly with downregulation of Nrf2 and reduction of cell proliferation rates.