Characterization of the molecular mechanism involved in the activation of hyaluronan synthetase by platelet-derived growth factor in human mesothelial cells

Abstract

The molecular mechanism involved in the stimulation of hyaluronan synthetase in normal human mesothelial cells was investigated. Exposure of mesothelial cells to platelet-derived growth factor (PDGF)-BB stimulated hyaluronan synthetase activity, measured in isolated membrane preparations, as well as hyaluronan secretion into the medium. The effect on hyaluronan synthetase was maximal after 6 h of treatment. In contrast, the stimulatory effect of transforming growth factor-beta 1 reached a maximum after 24 h. The stimulatory effect of PDGF-BB was inhibited by cycloheximide. The phosphotyrosine phosphatase inhibitor vanadate was found to stimulate hyaluronan synthetase activity, and to potentiate the effect of PDGF-BB. The protein kinase C (PKC) stimulator phorbol 12-myristate 13-acetate (PMA) also stimulated hyaluronan synthetase; furthermore, depletion of PKC by preincubation of the cells with PMA led to an inhibition of the PDGF-BB-induced stimulation of hyaluronan synthetase activity. Thus the PDGF-BB-induced stimulation of hyaluronan synthetase activity is dependent on protein synthesis and involves tyrosine phosphorylation and activation of PKC.

Plasma Membrane Residence of Hyaluronan Synthase Is Coupled to Its Enzymatic Activity

“…GFP-HAS3 Protein Turnover Time in REKs-Cycloheximide caused ϳ50% reduction in hyaluronan synthesis in 4 h, a result in line with reports on cultured chondrocytes, mesothelioma cells, and orbital fibroblasts (23)(24)(25)(26). Although the reduction of hyaluronan synthesis can be due to protein targets of cycloheximide other than HAS, the present microscopic observations indicating a 4 -5 h turnover time of GFP-HAS3 were completely in line with a 2-3 h-half-life of HAS3 protein and the observed decline in hyaluronan synthesis.…”

“…If only overexpressed or GFP-HAS used the Golgi pathway, an inhibition by brefeldin A would not take place in non-transfected cells. Also, cycloheximide-induced inhibition of hyaluronan synthesis follows the same kinetics in non-transfected cells (23)(24)(25)(26) and the GFP-Has-transfected cells in this work.…”

Transforming growth factor-beta 1 (TGF-β1)- and β2-like activities in malignant pleural effusions caused by malignant mesothelioma or primary lung cancer

“…Moreover, TGF-/3 augments hyaluronic acid production by normal human mesothelial cells and fibroblasts [10,13]. These findings and our data suggest that TGF-/3 may greatly contribute to the formation of clinical features of MESO, characterized by thickening pleura on chest films and large amounts of hyaluronic acid in MPE in MESO.…”

“…In addition, TGF-/? augments hyaluronic acid production by normal human mesothelial cells [13]. Although it is suggested that TGF-/?…”

Hyaluronan stimulates pancreatic cancer cell motility

“…To modulate the endogenous HA production, we treated PDAC cells with 4-methylumbelliferone (4-MU) which is a potent inhibitor of HA synthesis [19,20] and 12-O-tetradecanoyl-phorbol-13-acetate (TPA), a stimulator of HA synthesis through activating protein kinase C [21,22]. We also used another model of HA induction by coculturing PDAC cells with tumor-derived stromal fibroblasts [23].…”