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: Rong Wang, Christiane V Löhr, Kay Fischer, W Mohaiza Dashwood, Jeffrey A Greenwood, Emily Ho, David E Williams, Hassan Ashktorab, Michael R Dashwood, Roderick H Dashwood
• Journal: International journal of cancer (Int J Cancer) Vol. 132 Issue 5 Pg. 1004-12 (Mar 01 2013) ISSN: 1097-0215 [Electronic] United States
• PMID: 22865632 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
• Copyright: Copyright © 2012 UICC.

Chemical References

• Endothelin-2
• Endothelin-3
• RNA, Messenger

Topics

• Animals
• Caco-2 Cells
• Cell Line, Tumor
• Cell Movement (genetics)
• Colonic Neoplasms (genetics, metabolism, pathology)
• DNA Methylation
• Endothelin-2 (biosynthesis, genetics)
• Endothelin-3 (biosynthesis, genetics)
• Epigenesis, Genetic
• Epigenomics (methods)
• Gene Expression Regulation, Neoplastic
• Gene Silencing
• HCT116 Cells
• HT29 Cells
• Humans
• Immunohistochemistry (methods)
• Neoplasm Invasiveness
• RNA, Messenger (biosynthesis, genetics)
• Rats