1a25(OH)2D3 REGULATES COX-2 IN ENDOTHELIAL CELLS EXPRESSING vGPCR

CINTHYA TAPIA; VERÓNICA GONZALEZ PARDO; ALEJANDRA SUARES

Barcelona

Congreso; Vitamin D Workshop 2018; 2018

1α,25(OH)2D3 REGULATES COX-2 IN ENDOTHELIAL CELLS EXPRESSING vGPCR. C Tapia, A Suares, V González-Pardo. Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Departamento de Biología Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-CONICET, San Juan 670, (8000) Bahía Blanca, Argentina. Kaposi?s sarcoma (KS) is the most common cancer in HIV-infected untreated individuals. The infectious cause of this neoplasm is KS-associated herpes virus (or human herpes virus 8), and its GPCR receptor is the key molecule in this pathogenesis. Viral GPCR (vGPCR) continuous expression and activity are required for tumor preservation. In vGPCR cells, we have demonstrated 1α,25(OH)2D3 anti-proliferative effect in part by NF-κB pro-inflammatory pathway negative modulation. In this work, we studied if COX-2 regulation by 1α,25(OH)2D3 contributes to the anti-inflammatory action. The PLA2 inhibitor ATK (10-20 µM) or the COX-2 inhibitor Celecoxib (10-20 µM) decreased vGPCR cell number in a dose dependent manner, similarly to 1α,25(OH)2D3, showing morphological modifications at the microscope. MTS assays indicated that 1α,25(OH)2D3 or ATK (20 µM) or Celecoxib (20 µM) diminished cell viability after 48 h. But the combination of each inhibitor plus 1α,25(OH)2D3 had a contradictory effect, whereas ATK plus 1α,25(OH)2D3 showed no variations compared to control, opposite to the expected, Celecoxib plus 1α,25(OH)2D3 increased cell viability. COX-2 gene expression was evaluated by qRT-PCR. Results revealed a mRNA increase during 1α,25(OH)2D3 (10 nM) treatment at different times. This increment was found to be VDR dependent, using a stable VDR knock-down cell line vGPCR-shVDR. Moreover, the peroxidase activity of COX-2 was measured upon 1α,25(OH)2D3 treatment, which brought to light that when the gene expression is higher (at 6 h) the enzymatic activity is lower. All together, these results suggest that despite 1α,25(OH)2D3 enhances endothelial inflammation initiation through COX-2 upregulation, it also inactivates the enzymatic activity behaving as an attenuator of inflammation. Supported by grants from CONICET 11220150100057CO and FONCyT PICT-2013-0552 to Veronica Gonzalez-Pardo.