Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/84942
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Type: Journal article
Title: Thrombospondin-4 is a putative tumour-suppressor gene in colorectal cancer that exhibits age-related methylation
Author: Greco, S.
Chia, J.
Inglis, K.
Cozzi, S.
Ramsnes, I.
Buttenshaw, R.
Spring, K.
Boyle, G.
Worthley, D.
Leggett, B.
Whitehall, V.
Citation: BMC Cancer, 2010; 10(9):494:1-494:10
Publisher: BioMed Central
Issue Date: 2010
ISSN: 1471-2407
1471-2407
Statement of
Responsibility: 
Sonia A Greco, June Chia, Kelly J Inglis, Sarah-Jane Cozzi, Ingunn Ramsnes, Ronald L Buttenshaw, Kevin J Spring, Glen M Boyle, Daniel L Worthley, Barbara A Leggett, Vicki LJ Whitehall,
Abstract: Background: Thrombospondin-4 (THBS4) is a member of the extracellular calcium-binding protein family and is involved in cell adhesion and migration. The aim of this study was to evaluate the potential role of deregulation of THBS4 expression in colorectal carcinogenesis. Of particular interest was the possible silencing of expression by methylation of the CpG island in the gene promoter. Methods: Fifty-five sporadic colorectal tumours stratified for the CpG Island Methylator Phenotype (CIMP) were studied. Immunohistochemical staining of THBS4 protein was assessed in normal and tumour specimens. Relative levels of THBS4 transcript expression in matched tumours and normal mucosa were also determined by quantitative RT-PCR. Colony forming ability was examined in 8 cell lines made to overexpress THBS4. Aberrant promoter hypermethylation was investigated as a possible mechanism of gene disruption using MethyLight. Methylation was also assessed in the normal colonic tissue of 99 patients, with samples biopsied from four regions along the length of the colon. Results: THBS4 expression was significantly lower in tumour tissue than in matched normal tissue. Immunohistochemical examination demonstrated that THBS4 protein was generally absent from normal epithelial cells and tumours, but was occasionally expressed at low levels in the cytoplasm towards the luminal surface in vesicular structures. Forced THBS4 over-expression caused a 50-60% repression of tumour colony growth in all eight cell lines examined compared to control cell lines. Tumours exhibited significantly higher levels of methylation than matched normal mucosa, and THBS4 methylation correlated with the CpG island methylator phenotype. There was a trend towards decreased gene expression in tumours exhibiting high THBS4 methylation, but the correlation was not significant. THBS4 methylation was detectable in normal mucosal biopsies where it correlated with increasing patient age and negatively with the occurrence of adenomas elsewhere in the colon. Conclusions: THBS4 shows increased methylation in colorectal cancer, but this is not strongly associated with altered gene expression, either because methylation has not always reached a critical level or because other factors influence THBS4 expression. THBS4 may act as a tumour suppressor gene, demonstrated by its suppression of tumour colony formation in vitro. THBS4 methylation is detectable in normal colonic mucosa and its level may be a biomarker for the occurrence of adenomas and carcinoma.
Keywords: Colon; Rectum; Humans; Adenoma; Colorectal Neoplasms; Thrombospondins; DNA; Immunoenzyme Techniques; Prognosis; Colony-Forming Units Assay; Cohort Studies; Polymerase Chain Reaction; Age Factors; DNA Methylation; Gene Expression Regulation, Neoplastic; CpG Islands; Phenotype; Genes, Tumor Suppressor; Middle Aged; Promoter Regions, Genetic
Rights: © 2010 Greco et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
RMID: 0020138953
DOI: 10.1186/1471-2407-10-494
Appears in Collections:Medicine publications

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