1α,25(oh)2d3 modulates inflammation in endothelial cells transformed by vgpcr as part of its antineoplastic mechanism

Abstract

KS-associated herpesvirus G protein-coupled receptor (KSHV/vGPCR) is the key molecule in Kaposi?s sarcoma. vGPCR continuous expression and activity are required for tumor preservation. We have previously shown 1α,25(OH)2D3 antineoplastic effect in endothelial cells expressing vGPCR by negative modulation of NF-κB pro-inflammatory pathway. In this work, we further explored 1α,25(OH)2D3 anti-inflammatory mechanism of action. For this purpose, the activity and expression of COX-2, head enzyme to produce prostaglandins (PGs), 15-hydroxy-prostaglandin dehydrogenase (15-PGDH) which inactivates PGE2 and the four different PGs receptors (EP1-4) were analyzed after 1α,25(OH)2D3 treatment. MTS and proliferation assays were used to determine cell metabolism and proliferation before and after 1α,25(OH)2D3 (10 nM); ATK (10-20 µM), PLA2 inhibitor; and Celecoxib (10-20 µM), COX-2 selective inhibitor. Morphological changes and cell number decrease were observed in a dose-dependent manner. Contrary to what was expected, COX-2 gene expression increased after different times of 1α,25(OH)2D3 (10 nM) treatment. This increment was found to be VDR dependent, using a stable VDR knock-down cell line vGPCR-shVDR. However, when COX-2 expression was higher (up to 24 h), its peroxidase activity was lower. Finally, after longer 1α,25(OH)2D3-treatment periods (12 h or more) 15-PGDH and EP1 and EP2 low affinity receptors gene expression was elevated counter to EP3 and EP4 high affinity receptors, which gene expression was found decayed. All together, these results suggest that despite 1α,25(OH)2D3 enhances vGPCR-induced endothelial inflammation due to COX-2 increased expression, it also behaves as an attenuator of inflammation. Supported by grants from CONICET 11220150100057CO and FONCyT PICT-2013-0552 to Veronica Gonzalez-Pardo.