Kamei D, Murakami M, Sasaki Y, Nakatani Y, Majima M, Ishikawa Y, Ishii T, Uematsu S, Akira S, Hara S, Kudo I
Microsomal prostaglandin E synthase-1 in both cancer cells and hosts contributes to tumour growth, invasion and metastasis. [JOURNAL ARTICLE]
Biochem J 2009 Oct 21.
Microsomal prostaglandin E synthase-1 (mPGES-1) is a stimulus-inducible enzyme that functions downstream of cyclooxygenase (COX)-2 in the prostaglandin E2 (PGE2)-biosynthetic pathway. Although COX-2-derived PGE2 is known to play a role in the development of various tumours, the involvement of mPGES-1 in carcinogenesis has not yet been fully understood. Here, we used Lewis lung carcinoma (LLC) cells with mPGES-1 knockdown or overexpression as well as mPGES-1-deficient mice to examine the roles of cancer cell- and host-associated mPGES-1 in the processes of tumorigenesis in vitro and in vivo. We found that siRNA silencing of mPGES-1 in LLC cells decreased PGE2 synthesis markedly, accompanied by reduced cell proliferation, attenuated Matrigel invasiveness and increased extracellular matrix adhesion. Conversely, mPGES-1-overexpressing LLC cells showed increased proliferating and invasive capacities. When implanted subcutaneously into wild-type mice, mPGES-1-silenced cells formed smaller xenograft tumours than did control cells. Furthermore, LLC tumours grafted subcutaneously into mPGES-1 KO mice grew more slowly than did those grafted into littermate wild-type mice, with concomitant decreases in the density of microvascular networks, the expression of proangiogenic vascular endothelial growth factor, and the activity of matrix metalloproteinase-2. Lung metastasis of intravenously injected LLC cells was also significantly less obvious in mPGES-1-null mice than in wild-type mice. Thus, our present approaches provide unequivocal evidence for critical roles of the mPGES-1-dependent PGE2 biosynthetic pathway in both cancer cells and host microenvironments in tumour growth and metastasis.
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