title: Epigenetic inactivation of endothelin-2 and endothelin-3 in colon cancer.
abstract: Endothelin-1 (ET-1) and its receptors are overexpressed in human cancers, but much less is known about the roles of ET-2 and ET-3 in cancer etiology. We sought to examine human and rat colon tumors for dysregulation of ET-2 and ET-3 expression and determine the underlying mechanisms. Human primary colon cancers and carcinogen-induced rat colon tumors were subjected to real-time RT-PCR, immunoblotting and immunohistochemistry; EDN2 and EDN3 genes were examined by methylation-specific PCR, bisulfite sequencing and pyrosequencing; and forced expression of ET-2 and ET-3 was conducted in human colon cancer cells followed by real-time cell migration and invasion assays. Rat and human colon tumors had markedly reduced expression of ET-2 and ET-3 mRNA and protein compared with matched controls. Mechanistic studies revealed hypermethylation of EDN2 and EDN3 genes in human primary colon cancers and in a panel of human colon cancer cell lines. Forced expression of ET-2 and ET-3 attenuated significantly the migration and invasion of human colon cancer cells. We conclude that epigenetic inactivation of ET-2 and ET-3 occurs frequently in both rat and human colon cancers. Current therapeutic strategies target overexpressed members of the ET axis via small molecule inhibitors and receptor antagonists, but this work supports a complementary approach based on the re-expression of ET-2 and ET-3 as natural antagonists of ET-1 in colon cancer.
authors.affiliation: Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.forename: Christiane V
authors.initials: CV
authors.lastname: Löhr
authors.forename: Kay
authors.initials: K
authors.lastname: Fischer
authors.forename: W Mohaiza
authors.initials: WM
authors.lastname: Dashwood
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Greenwood
authors.forename: Emily
authors.initials: E
authors.lastname: Ho
authors.forename: David E
authors.initials: DE
authors.lastname: Williams
authors.forename: Hassan
authors.initials: H
authors.lastname: Ashktorab
authors.forename: Michael R
authors.initials: MR
authors.lastname: Dashwood
authors.forename: Roderick H
authors.initials: RH
authors.lastname: Dashwood
mesh_terms: D000818:Animals; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D003110:Colonic Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D019175:DNA Methylation; D019333:Endothelin-2 / Q000096:biosynthesis / Q000235:genetics*; D019334:Endothelin-3 / Q000096:biosynthesis / Q000235:genetics*; D044127:Epigenesis, Genetic; D057890:Epigenomics / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D009361:Neoplasm Invasiveness; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats
chemical_list: D019333:Endothelin-2; D019334:Endothelin-3; D012333:RNA, Messenger