Antiproliferative effects of Bortezomib in endothelial cells transformed by viral G protein-coupled receptor associated to Kaposi's sarcoma.
The Kaposi's Sarcoma-associated Herpes virus G Protein-Coupled Receptor (vGPCR) is a key molecule in the pathogenesis of Kaposi Sarcoma. We have previously demonstrated that the proteasome inhibitor Bortezomib inhibits NF-κB pathway, which is required for tumor maintenance in endothelial cells that express vGPCR (vGPCR cells). In this work, we further investigated Bortezomib anti-proliferative mechanism of action. We demonstrated that Bortezomib decreases vGPCR cell number in a dose-dependent manner and induces cell morphology changes. Bortezomib decreases ERK1/2 phosphorylation whereas induces the accumulation of MKP-3 - a specific ERK1/2 MAP kinase phosphatase - in time and concentration dependent manner (1.5-32h; 0.25-1nM). The transcription factor FOXO1 is activated by dephosphorylation and regulates p21 expression. Here, we demonstrated that Bortezomib increases FOXO1 protein and decreases its phosphorylation in a concentration dependent manner (0.25-1nM). Bortezomib (0.5nM, 24h) also increase nuclear FOXO1 protein, in line with FOXO1 dephosphorylation induced by the drug. Consistent with FOXO1 dephosphorylation/activation, p21 mRNA expression is increased by Bortezomib in a MKP-3-dependent way. Bortezomib (0.5nM, 24h) also decreases VEGF, an ERK1/2 -dependent effect. It is concluded that in vGPCR cells, Bortezomib decreases ERK1/2 and FOXO1 phosphorylation through MKP-3 accumulation, leading ERK1/2 deactivation and FOXO1 activation respectively and, consequently, to cell proliferation inhibition, p21 induction and VEGF repression. Taken together, all these events contribute to the anti-tumoral effect of Bortezomib.
Institute of Science Biology and Biomedical Research (INBIOSUR, UNS-CONICET), Department of Biology, Biochemistry and Pharmacy, Universidad Nacional del Sur, San Juan 670, 8000 Bahia Blanca, Argentina.
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Suares
Institute for Biomedical Research (INBIOMED, UBA-CONICET), Department of Biochemistry, School of Medicine, Universidad de Buenos Aires, Paraguay 2155, C1121ABG Buenos Aires, Argentina.
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Mori Sequeiros Garcia
Institute for Biomedical Research (INBIOMED, UBA-CONICET), Department of Biochemistry, School of Medicine, Universidad de Buenos Aires, Paraguay 2155, C1121ABG Buenos Aires, Argentina.
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Paz
Institute of Science Biology and Biomedical Research (INBIOSUR, UNS-CONICET), Department of Biology, Biochemistry and Pharmacy, Universidad Nacional del Sur, San Juan 670, 8000 Bahia Blanca, Argentina. Electronic address: vgpardo@criba.edu.ar.
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González-Pardo
D000818:Animals; D000069286:Bortezomib / Q000494:pharmacology*; D002452:Cell Count; D049109:Cell Proliferation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D054642:Dual Specificity Phosphatase 6 / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D000071161:Forkhead Box Protein O1 / Q000378:metabolism; D019288:Herpesvirus 8, Human / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D008954:Models, Biological; D010766:Phosphorylation / Q000187:drug effects; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D012514:Sarcoma, Kaposi / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D050759:Cyclin-Dependent Kinase Inhibitor p21; D000071161:Forkhead Box Protein O1; D043562:Receptors, G-Protein-Coupled; D042461:Vascular Endothelial Growth Factor A; D000069286:Bortezomib; D048049:Extracellular Signal-Regulated MAP Kinases; D054642:Dual Specificity Phosphatase 6
Bortezomib; ERK 1/2; FOXO1; MKP-3; vGPCR