Thromboxane A2 receptor induces proliferation of rheumatoid arthritis synovial cells by up-regulation of cyclooxygenase-2

AIM：To examine the effects of thromboxane A2 receptor (TXA2R), the downstream product of cyclooxygenase-2 (COX-2), on the proliferative ability and COX-2 expression in rheumatoid arthritis (RA) synovial cells. METHODS：The effects of TXA2R antagonist SQ29548 and agonist U46619 on the proliferation of RA synovial cell line MH7A were detected by MTS cell proliferation assay, and their effects on COX-2 mRNA expression in MH7A cells were also examined by real-time PCR. In addition, the possible effect of U46619 on the proliferation of MH7A cells, when COX-2 was knocked down by siRNA, was determined by BrdU cell proliferation assay. RESULTS：SQ29548 inhibited the cell proliferation and the mRNA level of COX-2 while U46619 enhanced them. Moreover, U46619 reconstitute the proliferative ability of MH7A cells to some extent that inhibited by COX-2 siRNA. CONCLUSION：In RA synovial cells, TXA2R is able to control COX-2 expression, while it also mediates the effects of COX-2, suggesting that TXA2R might be an ideal candidate for RA treatment.