15-Hydroxyprostaglandin dehydrogenase (15-PGDH) is up-regulated by flurbiprofen and other non-steroidal anti-inflammatory drugs in human colon cancer HT29 cells

Non-steroidal anti-inflammatory drugs (NSAIDs) are known to inhibit prostaglandin synthetic enzyme, cyclooxygenases (COXs), as well as to exhibit anti-tumor activity although at much higher concentrations. 15-Hydroxyprostaglandin dehyrogenase (15-PGDH), a key prostaglandin catabolic enzyme, was recently shown to be a tumor suppressor. Effects of NSAIDs on 15-PGDH expression were therefore examined. Flurbiprofen and several other NSAIDs were found to induce 15-PGDH expression in human colon cancer HT29 cells. Flurbiprofen, the most active one, was also shown to induce 15-PGDH expression in other types of cancer cells. Induction of 15-PGDH expression appeared to occur at the stage of mRNA as levels of 15-PGDH mRNA were increased by flurbiprofen in HT29 cells. Levels of 15-PGDH were also found to be regulated at the stage of protein turnover. MEK inhibitors, PD98059 and U-0126, which inhibited ERK phosphorylation were shown to elevate 15-PGDH levels very significantly. These inhibitors did not appear to alter 15-PGDH mRNA levels but down-regulate matrix metalloproteinase-9 (MMP-9). This protease was shown to degrade and inactivate 15-PGDH suggesting that elevation of 15-PGDH levels could be due to inhibition of MMP-9 expression by these inhibitors. Similarly, flurbiprofen was also demonstrated to inhibit ERK activation and to down-regulate MMP-9 expression. Furthermore, flurbiprofen was shown to induce the expression of tissue inhibitor of metalloproteinase-1 (TIMP-1), an inhibitor of MMP-9. The turnover of 15-PGDH was found to prolong in the presence of flurbiprofen as compared to that in the absence of this drug. Taken together, these results indicate that flurbiprofen up-regulates 15-PGDH by increasing the expression and decreasing the degradation of 15-PGDH in HT29 cells.