Antiproliferative effects of Bortezomib in endothelial cells transformed by viral G protein-coupled receptor associated to Kaposi's sarcoma

SUARES A; MORI SEQUEIROS GARCÍA MM; PAZ C; GONZÁLEZ-PARDOV

CELLULAR SIGNALLING

ELSEVIER SCIENCE INC

Lugar: Amsterdam; Año: 2017 p. 124 - 132

0898-6568

The Kaposi´s Sarcoma-associated Herpes virus G Protein-Coupled Receptor (vGPCR) is a keymolecule 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 mechanismof 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 ? aspecific ERK1/2 MAP kinase phosphatase ? in time and concentration dependent manner (1.5?32 h; 0.25?1 nM). 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?1 nM). Bortezomib (0.5 nM, 24 h) 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 (0.5 nM, 24 h) also decreases VEGF, an ERK1/2 -dependent effect. It is concluded that in vGPCR cells, Bortezomib decreases ERK1/2and 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.