Brief Article
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World J Gastroenterol. Aug 7, 2012; 18(29): 3896-3903
Published online Aug 7, 2012. doi: 10.3748/wjg.v18.i29.3896
Differential roles of EPS8 in carcinogenesis: Loss of protein expression in a subset of colorectal carcinoma and adenoma
Wael M Abdel-Rahman, Salla Ruosaari, Sakari Knuutila, Päivi Peltomäki
Wael M Abdel-Rahman, Department of Medical Laboratory Sciences, College of Health Sciences, University of Sharjah, Sharjah 27272, United Arab Emirates
Wael M Abdel-Rahman, Päivi Peltomäki, Department of Medical Genetics, University of Helsinki, FIN-00014 Helsinki, Finland
Salla Ruosaari, Sakari Knuutila, Department of Pathology, Haartman Institute, University of Helsinki, FIN-00014 Helsinki, Finland
Salla Ruosaari, Sakari Knuutila, HUSLAB, Helsinki University Central Hospital, FIN-00014 Helsinki, Finland
Author contributions: Abdel-Rahman WM supported the study, designed and performed experiments, provided study material, analyzed and interpreted the data and wrote the paper; Ruosaari S analyzed the data; Knuutila S provided critical insights and partially supported the study; Peltomäki P supported the study, designed experiments, provided study material, analyzed and interpreted the data, and approved the manuscript; all authors revised the last draft.
Supported by The Academy of Finland; Sigrid Juselius Foundation; University of Sharjah; Terry Fox Fund; Finnish Cancer Foundation; Biocentrum Helsinki; and the European Research Council
Correspondence to: Dr. Wael M Abdel-Rahman, MD, PhD, Department of Medical Laboratory Sciences, College of Health Sciences, University of Sharjah, Sharjah 27272, United Arab Emirates. whassan@sharjah.ac.ae
Telephone: +791-6-5057556 Fax: +791-6-5057502
Received: January 29, 2011
Revised: March 6, 2011
Accepted: May 12, 2012
Published online: August 7, 2012
Abstract

AIM: To analyze the epidermal growth factor receptor pathway substrate 8 (EPS8) expression status and role in colorectal carcinogenesis given that EPS8 has a conserved actin barbed-end capping function that is required for proper maturation in intestinal cells.

METHODS: We studied 8 colon cancer cell lines and 58 colorectal tumors (19 adenomas and 39 carcinomas). We performed expression microarray analysis of colon cancer cell lines followed by loss of heterozygosity (LOH) analysis and immunohistochemistry for EPS8 expression in colon tumors. Subsequently, we performed mutation analysis by direct sequencing and methylation analysis by bisulfite sequencing and methylation-specific polymerase chain reaction assays.

RESULTS: Expression microarray analysis of colon cancer cell lines showed overexpression of EPS8 transcript in all lines but RKO. Genome wide loss of heterozygosity (LOH) analysis of colon tumors, showed considerable LOH at the EPS8 gene locus. Immunohistochemically, EPS8 was constitutively expressed in normal colonic mucosa with a dot-like supranuclear localization with accentuation at the luminal surface supporting its proposed role in epithelial maturation. Nineteen colon tumors (4 adenoma, 15 carcinoma) out of 51 (37%) showed strikingly tumor specific EPS8 protein loss. Of the remaining tumors, 5/51 (2 adenoma, and 3 carcinoma, 10%) showed marked overexpression, while 27/51 tumors (53%) showed retained expression. Mutation analysis revealed a missense mutation (c.794C>T, p.R265C) in exon 8 in RKO. The EPS8 promoter was also methylated in RKO, but there was no significant methylation in other cell lines or carcinoma specimens.

CONCLUSION: The loss of EPS8 expression in colorectal adenomas and carcinomas suggests that down regulation of this gene contributes to the development of a subset of colorectal cancers, a finding which could have applications in diagnosis and treatment.

Keywords: Actin capping, Colon cancer, Epidermal growth factor receptor pathway substrate 8, Hypermethylation, Immunohistochemistry, RKO