The role of the murine EP3 receptor variants on cell function.

Abstract

Prostaglandin E2 (PGE2), which exerts its functions by binding to four G protein-coupled receptors (EP1-4), is implicated in tumorigenesis. Among the four EP receptors, EP3 is unique in that it exists as alternatively spliced variants, characterized by differences in the cytoplasmic C-terminal tail. Although three EP3 variants á, â and ã have been described in mice, their functional significance in regulating tumorigenesis is unknown. In this study we provide evidence that expressing murine EP3 á, â and ã receptor variants in tumor cells reduces to the same degree their tumorigenic potential in vivo. In addition, activation of each of the three mEP3 variants induces enhanced cell-cell contact and reduces cell proliferation in vitro in a Rho-dependent manner. Finally, we demonstrate that EP3- mediated RhoA activation requires the engagement of the heterotrimeric G protein G12. Thus, our study provides strong evidence that selective activation of each of the three variants of the EP3 receptor suppresses tumor cell function by activating a G12-RhoA pathway.