Endocrine Abstracts

Prostaglandin F_2a (PGF) is biosynthesised by cyclooxygenase (COX) enzymes and mediates its activity following FP receptor activation. Recently, we have shown elevated FP receptor expression and signalling in endometrial adenocarcinomas. This study investigated FP receptor signalling in human endometrial adenocarcinoma (Ishikawa) cells.

Ishikawa cells were stably transfected with FP receptor cDNA in the sense (FPS) and antisense (FPAS) orientation. Western blot analysis and immunofluorescensce microscopy showed elevated expression of FP receptor in FPS cells compared with Wild-type (WT) and FPAS cells. Treatment of cells with 100nM PGF elevated inositol phosphate (IP) in FPS cells compared with WT and FPAS cells (P less than 0.05). Co-treatment of FPS cells with the FP receptor antagonist AL8810 reduced the IP accumulation (P less than 0.05). We next investigated MAPK (ERK1/2, p38, JNK) activation by PGF-FP receptor signalling by Western blot analysis. Ishikawa cells were treated with 100nM PGF in the presence or absence of AL8810 or inhibitors of MEK (PD98059), EGF receptor (EGFR) kinase (AG1478), matrix metalloproteinase (GM6001), PLC (U73122) and cSrc (PP2). An elevated phosphorylation of ERK1/2 (but not p38 or JNK) was observed in FPS cells, compared with WT and FPAS cells (P less than 0.01). Co-treatment of cells with AL8810, AG1478, PD98059, U73122 and PP2 significantly reduced the ERK1/2 phosphorylation (P less than 0.05).

PGF-FP receptor activation on target gene expression was determined by RT-PCR analysis in response to treatment with 100nM PGF or PGF and AL8810, PD98059 or AG1478. An increase in expression of COX-2, VEGF and FGF2 was observed in FPS cells (P less than 0.01). Co-treatment of FPS cells with AL8810, AG1478 or PD98059 abolished the expression of COX2, FGF and VEGF. These findings demonstrate that PGF-FP receptor coupling can modulate the expression of inflammatory and angiogenic genes by activation of EGFR and the ERK1/2 pathway.