Submitted on October 4, 2007
Accepted on January 26, 2008
Hepatocyte Growth Factor Regulates Cyclooxygenase-2 Expression via 
-Catenin, Akt and p42/p44 MAPK in Human Bronchial Epithelial Cells
Young H Lee1, Yuichiro J. Suzuki2, Autumn J Griffin1, and Regina M. Day1*
1 Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States
2 Pharmacology, Georgetown University, Washington, District of Columbia, United States
* To whom correspondence should be addressed. E-mail: rday{at}usuhs.mil.
Hepatocyte growth factor (HGF) is up-regulated in response to lung injury and has been implicated in tissue repair through its anti-apoptotic and proliferative activities. Cyclooxygenase-2 (COX-2) is an inducible enzyme in the biosynthetic pathway of prostaglandins, and its activation has been shown to play a role in cell growth. We here report that HGF induces gene transcription of COX-2 in human bronchial epithelial cells (HBEpC). Treatment of HBEpC with HGF resulted in phosphorylation of the HGF receptor (c-Met), activation of Akt, and upregulation of COX-2 mRNA. Adenovirus-mediated gene transfer of dominant negative (DN) Akt mutant revealed that HGF increased COX-2 mRNA in an Akt-dependent manner. COX-2 promoter analysis in luciferase reporter constructs showed that HGF regulation required the 
-catenin-responsive TBE element. The HGF activation of the COX-2 gene transcription was blocked by DN mutant of -catenin, or by inhibitors that blocked activation of Akt. Inhibition of p42/p44 MAPK pathway blocked HGF-mediated activation of -catenin gene transcription but not Akt activation, suggesting that p42/p44 MAPK acts in a parallel mechanism for -catenin activation. We also found that inhibition of COX-2 with NS-398 blocked HGF-induced growth in HBEpC. Together, the results show that the HGF increases COX-2 gene expression via an Akt-, MAPK- and -catenin-dependent pathway in HBEpC.
