Epigenetic inactivation of endothelin-2 and endothelin-3 in colon cancer

Linus Pauling Institute, Oregon State University, Corvallis, OR.
International Journal of Cancer (Impact Factor: 5.09). 03/2013; 132(5). DOI: 10.1002/ijc.27762
Source: PubMed


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.

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Available from: Roderick Dashwood, Oct 07, 2015
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    • "While in premalignant adenomas and malignant colon carcinomas, exhibit increased levels of pre- proET-1, endothelin-converting enzymes, and ET-1 [7] [8], there is no consensus about how the ETA and ETB receptors behave [9] [10]. On the other hand, it has been recently proved that ET-2 and ET-3 are silenced in colon cancer and their induced overexpressions inhibit cell migration and invasion [11]. In that work, it was hypothesized that ET-2 and ET-3 might be silenced in early stages of cancer avoiding " mixed messages " in the ET axis. "
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    ABSTRACT: The endothelin family has been related with several pathological diseases including cardiovascular disorders, hyperten-sion and cancer. However, little is known about endothelin system in early stages of colorectal cancer and there are no studies evaluating differences in proximal and distal colon segments. To deepen in this issue, we have studied the en-dothelin's family gene and protein expression in normal mice and early stage of a mice model of Azoxymethane (AOM) and Dextran Sodium Sulphate (DSS) induced colorectal cancer in proximal and distal segments. Additionally, using nonlinear microscopy (NLM) techniques, we have characterized collagen changes in early stages of cancer disease de-velopment. In the present study, we have found significant differential gene expression and protein localization between these colon regions, which allow us to hypothesize a new role for the ET-2 as an early marker of colon cancer devel-opment.
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    • "Reduced KLF4 expression was also confirmed under the same experimental conditions (data not shown). Cells were loaded onto E-plates (xCELLigence system, Roche) for real-time monitoring assays [26], which revealed a significant increase in cell proliferation kinetics following the enforced increase of miR-206 levels (Figure 6C, inset, P < 0.05). "
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