PGE2/EP3/SRC signaling induces EGFR nuclear translocation and growth through EGFR ligands release in lung adenocarcinoma cells

Prostaglandin E-2 (PGE(2)) interacts with tyrosine kinases receptor signaling in both tumor and stromal cells supporting tumor progression. Here we demonstrate that in non-small cell lung carcinoma (NSCLC) cells, A549 and GLC82, PGE(2) promotes nuclear translocation of epidermal growth factor receptor (nEGFR), affects gene expression and induces cell growth. Indeed, cyclin D1, COX-2, iNOS and c-Myc mRNA levels are upregulated following PGE(2) treatment. The nuclear localization sequence (NLS) of EGFR as well as its tyrosine kinase activity are required for the effect of PGE(2) on nEGFR and downstream signaling activities. PGE(2) binds its bona fide receptor EP3 which by activating SRC family kinases, induces ADAMs activation which, in turn, releases EGFR-ligands from the cell membrane and promotes nEGFR. Amphiregulin (AREG) and Epiregulin (EREG) appear to be involved in nEGFR promoted by the PGE2/EP3-SRC axis. Pharmacological inhibition or silencing of the PGE(2)/EP3/SRC-ADAMs signaling axis or EGFR ligands i.e. AREG and EREG expression abolishes nEGFR induced by PGE(2). In conclusion, PGE(2) induces NSCLC cell proliferation by EP3 receptor, SRC-ADAMs activation, EGFR ligands shedding and finally, phosphorylation and nEGFR. Since nuclear EGFR is a hallmark of cancer aggressiveness, our findings reveal a novel mechanism for the contribution of PGE(2) to tumor progression.