HYPOTONIC STRESS INCREASES CYCLOOXYGENASE-2 EXPRESSION AND PROSTAGLANDIN RELEASE FROM AMNION-DERIVED WISH CELLS

This report examines the effect of cell volume expansion on cyclooxyge nase-a (COX-2) mRNA expression, COX-2 protein expression, and prostagl andin E-2 release from human amnion-derived WISH cells, Earle's balanc ed salts solution (EBSS) with limited NaCl concentration was utilized as the induction medium. COX-2 mRNA was elevated 6-fold in cells incub ated for 1 h in hypotonic EBSS. COX-2 mRNA expression was not increase d when raffinose or sucrose were used to reconstitute low NaCl, Actino mycin D blocked COX-2 mRNA increase by hypotonic stress, while cyclohe ximide enhanced COX-2 mRNA expression. COX-2 mRNA and protein concentr ations increased as a function of decreasing media osmolarity and incu bation time in hypotonic EBSS. Hypotonic EBSS induced a 3-fold increas e in prostaglandin E-2 release, WISH cells transiently transfected wit h a luciferase expression vector driven by the human COX-2 promoter fo r the COX-2 gene show a 3-fold increase in luciferase activity when in cubated in hypotonic EBSS. COX-2 mRNA levels in primary human amnion c ells were also increased by hypotonic stress. This study suggests that amnion cell COX-2 gene expression is regulated by cell volume expansi on and/or increased plasma membrane tension.