MUC2 gene suppression in human colorectal carcinomas and their metastases: in vitro evidence of the modulatory role of DNA methylation

Item Type:	Article
Title:	MUC2 gene suppression in human colorectal carcinomas and their metastases: in vitro evidence of the modulatory role of DNA methylation
Creators Name:	Hanski, C. and Riede, E. and Gratchev, A. and Foss, H.D. and Boehm, C. and Klussmann, E. and Hummel, M. and Mann, B. and Buhr, H.J. and Stein, H. and Kim, Y.S. and Gum, J. and Riecken, E.O.
Abstract:	The development of the majority of colorectal carcinomas is associated with a diminished expression of the intestinal mucin MUC2 in the tumor cells. The significance and the mechanism of this alteration are not yet known. We sought to determine the molecular basis of this tumor-associated change and to investigate the extent to which it might also relate to metastases. MUC2 gene expression was compared in normal (N), carcinomatous (T), and metastatic tissues (M) from nine patients by immunohistochemistry, in situ hybridization, and Northern blotting. Immunohistochemistry and in situ hybridization showed consistently lower amounts of the expressed protein and mRNA in T and in M than in N; quantitative analysis by Northern blotting confirmed that the differences between MUC2 mRNA expression between N, T, and M were significant, the expression in metastases being less than 5% of that in the normal colonic tissue. The influence of DNA methylation as a possible regulatory mechanism of MUC2 gene expression was tested after the 5' and 3'-regions flanking the first exon of MUC2 were recovered from a genomic DNA library and used as probes in Southern blot. The DNA was isolated from colon carcinoma cell lines expressing MUC2 strongly (LS174T) or moderately (T84) and from that which was nonexpressing (Colo 205), and it was digested with the methylation-sensitive enzyme HpaII. The Southern blot patterns indicated that the increased methylation in the promoter region was concomitant with the decrease of MUC2 mRNA expression. Methylation of the promoter region ligated into a reporter vector suppressed the expression of the luciferase reporter gene in the three investigated cell lines. Furthermore, the expression of MUC2 gene was enhanced by treating the MUC2-expressing colon carcinoma cells with 5-aza-2'-deoxycytidine, a methylation-inhibiting agent. To our knowledge this is the first report to show that: (a) MUC2 gene is strongly suppressed in liver and lymph node metastases of colorectal carcinomas, and (b) suppression of MUC2 gene in colon carcinoma cells in vitro is associated with methylation of the promoter region.
Keywords:	Base Sequence, Carcinoma, Colorectal Neoplasms, DNA Methylation, Neoplasm DNA, Molecular Sequence Data, Mucin-2, Mucins, Neoplasm Metastasis, Neoplasm Proteins, Cultured Tumor Cells
Source:	Laboratory Investigation
ISSN:	0023-6837
Publisher:	Lippincott Williams & Wilkins
Volume:	77
Number:	6
Page Range:	685-695
Date:	December 1997
PubMed:	View item in PubMed

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