Prostaglandin E2 upregulates survivin expression via the EP1 receptor in hepatocellular carcinoma cells.

Aims: Cyclooxygenase-2 (COX-2)-controlled production of prostaglandin E(2) (PGE(2)) has been implicated in cell growth and metastasis in many cancers. Recent studies have found that COX-2 is co-expressed with survivin in many cancers. Survivin is a member of the inhibitor-of-apoptosis protein family. Some COX-2 inhibitors (e.g., celecoxib) can reduce the expression of survivin. However, little is known about the mechanism of PGE(2)-mediated expression of survivin. This study was designed to uncover the effect of PGE(2) on survivin expression in hepatocellular carcinoma cells.
Main Methods: The effects of PGE(2) and EP1 agonist on survivin expression were examined in HUH-7 and HepG2 cells. Plasmid transfection and EP1 siRNA were used to regulate the expression of COX-2 and the EP1 receptor protein.
Key Findings: PGE(2) treatment increased survivin expression 2.3-fold. COX-2 overexpression resulted in a similar level of survivin upregulation. However, this effect was suppressed by treatment with celecoxib. EP1 receptor transfection or treatment with a selective EP1 agonist mimicked the effect of PGE(2) treatment. Conversely, the PGE(2)-induced upregulation of survivin was blocked by treatment with a selective EP1 antagonist or siRNA against the EP1 receptor. The phosphorylation of EGFR and Akt were elevated in EP1 agonist-treated cells, and both EGFR and PI3K inhibitors suppressed the upregulation of survivin induced by PGE(2) or EP1 agonist.
Significance: PGE(2) regulates survivin expression in hepatocellular carcinoma cells through the EP1 receptor by activating the EGFR/PI3K pathway. Targeting the PGE(2)/EP1/survivin signaling pathway may aid the development of new therapeutic strategies for both the prevention and treatment of this cancer.
(Copyright 2009 Elsevier Inc. All rights reserved.)