Prostaglandin E2 receptor subtype 2 (EP2) null mice are protected against murine lung tumorigenesis.

Background: Manipulating prostaglandin (PG) production modulates tumor development. Elevated PGI2 production prevents murine lung cancer, while decreasing PGE2 content protects against colon cancer. PGE2 receptor subtype 2 (EP2) -deficient mice were hypothesized to be resistant to lung tumorigenesis.
Materials and Methods: EP2 null BALB/c mice and their wild-type littermates were exposed to an initiation-promotion carcinogenesis protocol and lung tumorigenesis was examined. Chronic lung inflammation was induced to determine whether EP2 ablation influenced inflammatory cell infiltration.
Results: Tumor multiplicity in EP2 null mice was 34% lower than in their wild-type littermates (21.9+/-3.0 vs. 14.5+/-2.9 tumors/mouse, p<0.001). The lung tumor burden, an indicator of growth rate, also declined (57%, p<0.05). All the mice exhibited similar inflammatory cell infiltration.
Conclusion: PGE2, acting through EP2, enhanced lung tumorigenesis through a mechanism that may be distinct from its proinflammatory activity. Thus, EP2 is a potential target for novel chemoprevention strategies.