Background: We investigated the role of prostaglandin receptors (e.g. prostaglandin E2 receptor 2 (EP2), EP4) and the efficacy ofcelecoxib in urothelial tumourigenesis and cancer progression.Methods: We performed immunohistochemistry in bladder cancer (BC) tissue microarrays, in vitro transformation assay in anormal urothelial SVHUC line, and western blot/reverse transcription–polymerase chain reaction/cell growth assays in BC lines.Results: EP2/EP4 expression was elevated in BCs compared with non-neoplastic urothelial tissues and in BCs from those whowere resistant to cisplatin-based neoadjuvant chemotherapy. Strong positivity of EP2/EP4 in non-muscle-invasive tumours orpositivity of EP2/EP4 in muscle-invasive tumours strongly correlated with disease progression or disease-specific mortality,respectively. In SVHUC cells, exposure to a chemical carcinogen 3-methylcholanthrene considerably increased and decreased theexpression of EP2/EP4 and phosphatase and tensin homologue (PTEN), respectively. Treatment with selective EP2/EP4 antagonistor celecoxib also resulted in prevention in 3-methylcholanthrene-induced neoplastic transformation of SVHUC cells. In BC lines,EP2/EP4 antagonists and celecoxib effectively inhibited cell viability and migration, as well as augmented PTEN expression.Furthermore, these drugs enhanced the cytotoxic activity of cisplatin in BC cells. EP2/EP4 and PTEN were also elevated andreduced, respectively, in cisplatin-resistant BC sublines.Conclusions: EP2/EP4 activation correlates with induction of urothelial cancer initiation and outgrowth, as well aschemoresistance, presumably via downregulating PTEN expression.
MP54-08 PROSTAGLANDIN RECEPTORS INDUCE UROTHELIAL TUMOURIGENESIS AS WELL AS BLADDER CANCER PROGRESSION AND CISPLATIN RESISTANCE PRESUMABLY VIA MODULATING PTEN EXPRESSION
