PURPOSE - Cyclooxygenase-2 has been reported to be ubiquitously expressed in Wilms tumor, the most common malignant renal tumor in children. However, to our knowledge the regulation mechanism of cyclooxygenase-2 expression remains unexplored.
MATERIALS AND METHODS - Quantitative real-time polymerase chain reaction and Western blot were performed to detect cyclooxygenase-2 mRNA and protein expression in WiT49 cells upon stimulation by S1P (Biomol(R)), and S1P(2) and cyclooxygenase-2 mRNA expression in 10 freshly frozen Wilms tumor tissues and matched normal tissues. Over expression, blockade and down-regulation of S1P(2) were determined using adenoviral transduction, the S1P(2) antagonist JTE-013 (Tocris Bioscience, Ellisville, Missouri) and small interfering RNA (Dharmacon, Lafayette, Colorado) transfection, respectively. The prostaglandin E(2) level in WiT49 cells was determined by gas chromatography/mass spectrometry.
RESULTS - S1P induced cyclooxygenase-2 mRNA and protein expression in WiT49 cells in a concentration dependent manner. Over expression of S1P(2) in WiT49 cells led to a significant increase in cyclooxygenase-2 mRNA and protein expression as well as subsequent prostaglandin E(2) synthesis. In addition, pretreatment of those cells that over expressed S1P(2) with the S1P(2) selective antagonist JTE-013 completely blocked S1P induced cyclooxygenase-2 protein expression. In accordance with these results silencing S1P(2) in WiT49 cells down-regulated S1P induced cyclooxygenase-2 expression. Further research in 10 Wilms tumor specimens showed that S1P(2) mRNA is greatly increased in Wilms tumor.
CONCLUSIONS - S1P induced cyclooxygenase-2 expression in Wilms tumor and this effect was mediated by S1P(2). This finding extends the biological function of S1P(2) and provides the biochemical basis for developing inhibitors targeting the S1P/cyclooxygenase-2 signaling pathway.