Analyses of pathophysiological functions of prostaglandin E synthases as a potential target for novel anti-inflammatory drugs

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In this study, we examined the pathophysiological roles of PGE_2 synthase (mPGES-1), a terminal PGE_2-biosynthetic enzyme in the arachidonic acid metabolism, using mPGES-1 knockout mice.1. mPGES-1 and cancer : Luwis lung carcinoma (LLC) cells stably overexpressing mPGES-1 proliferated more rapidly in vitro and, when implanted into C57BL/6 mice, formed larger and more subcutaneous tumors and lung metastatic foci than did parental cells. Conversely, mPGES-knockdown LLC cells produced smaller and fewer tumors in implanted mice mPGES-1-null mice implanted with LLC cells showed resistance to tumor growth and metastasis associated with reduced angiogenesis compared with replicate wild-type mice Moreover, azoxymethanie-induced colon carcinogenesis was markedly reduced in mPGES-1-null mice relative to that in wild-type mice These results indicate that mPGES-1 expressed in tumor cells as well as in host tissues participates in tumorigenesis.2. mPGES-1 and inflammation : In carageenan- and thioglycolate-induced peritonitis models, leukocyte infiltration was markedly mitigated in mPGES-1-deficient mice as compared with that m control mice.3. mPGES-1 and bone : mPGES-1 deficiency was associated with impaired fracture healing, but not with bone loss or osteoarthritis, in mouse models of skeletal disorders.4. mPGES-1 and colitis : Dextran sulfate-induced colitis (a model of inflammatory bowel disease), as evaluated by intestinal histology, bleeding and cytokine expression, was significantly exacerbated in mPGES-1 knockout mice compared with control mice.Thus, novel drugs that could inhibit mPGES-1 would be useful for treatments of cancer and inflammation, yet they might have some adverse effects on bone and gastrointestinal tract.