IntroductionTargeting tumor suppressor genes by epigenetic silencing especially in the promotor region is one of the probable mechanisms of carcinogenesis. 1 However, differential methylation may also occur outside of the promoter region and previous studies have shown that gene expression and tissue differentiation are powerfully affected by such methylation sites. 1,2 So far, there are limited data available on claudin (CLDN), epigenetics, and the relation to claudin protein expression as well as its role in the development of colorectal carcinoma (CRC). While DNA methylation of claudin 6 has been shown to be involved in the invasion of breast cancer cells 3 Abstract Altered claudin expression has been described in colon, prostatic, ovarian, and breast carcinoma. However, the role of epigenetic modifications in these genes and their role in colorectal cancer is unknown. We aimed our study to investigate whether claudin protein expression and methylation of CLDN can influence the tumorigenesis of colorectal cancer. A total of 31 patients diagnosed with colorectal carcinoma was used in this study. Immunohistochemical staining was used to study protein expression in both tumor and the adjacent nonneoplastic mucosa of claudin 1, 4, and 7. To detect the DNA methylation pattern of CLDN1, 4, and 7, genomic DNA was extracted from both the tumor and the adjacent nonneoplastic mucosa. Methylation analysis was carried out using bisulfite pyrosequencing. Cell membrane staining intensity of all claudins was found significantly lower in colorectal cancer tissues when compared to paired normal mucosa (p ≤ 0.001). For claudin 4, the percentage of cells staining positively was also significantly reduced (p = 0.04). In normal mucosa, cytoplasm showed no staining for claudins in any patient, whereas in paired colorectal cancer tissues, significant cytoplasmic staining appeared both for claudin 1 (p = 0.04) and claudin 4 (p = 0.01). Tumor samples were significantly hypomethylated in CLDN1 (p < 0.05). In conclusion, our results show that CLDN1 is significantly hypomethylated in tumor samples and that the membrane staining intensity for claudin 1, 4, and 7 is significantly lower in colorectal cancer tissues than in adjacent nonneoplastic tissue. Colorectal cancer cells showed dystopic cytoplasmic location of claudins.

Abstract.The invasive front of carcinomas may vary in complexity from smooth to highly complex when the front splits up into small cell clusters or even single cancer cells. The degree of complexity is usually estimated visually and semiquantitatively by a pathologist, although more objective methods based on computer-assisted image analysis are available. In this study, we compared the visual estimation of the irregularity of the tumour invasion front of colon carcinomas to different quantitative image analytical techniques and defined a complexity index for the invasive margin. Sections from 29 archived colon carcinomas were stained immunohistochemically for cytokeratin 8. Images of the tumour invasion front were read into a computer and thresholded so that the tumour tissue became black and the background white or so that the tumour front was outlined by a single pixel line. The invasive front was visually classified into four degrees of irregularity by a pathologist. The complexity of the front was then assessed using four different image analysis techniques, i.e. the estimation of fractal dimension, tumour front length, number of tumour cell clusters and lacunarity. Fractal dimension and tumour cell clusters together gave the best correlation to visual grading using a discriminant analysis. A cluster analysis and a tree diagram analysis were then performed and were found to be superior to visual estimation. The clusters represent different degrees of complexity and the result of the tree diagram analysis can be used to assign complexity indices to colon tumours. The fractal dimension separated tumours up to a certain level (1.5-1.6) of complexity. When the tumour front split up into small cell clusters, the counting of tumour cell clusters separated the cells over and above the fractal dimension. This new technique can be used to objectively and quantitatively describe the complexity of the invasive front of tumours.

Background and aim: The mechanisms behind increased f-Calprotectin (FC) in healthy

Adhesion proteins are responsible for the structural integrity of epithelial tissue and in tumors this integrity is often lost, resulting in a disorganization of the tissue. In the present study the complexity of the invasive front of colon carcinomas was correlated with cell adhesion protein expression and with polymorphisms in their genes. A complexity index was constructed from 32 colon carcinomas using computer-assisted morphometry estimating fractal dimension and tumor cell clusters followed by tree analysis. Immunohistochemical staining of beta-catenin, E-cadherin, occludin and claudin 2 was used for assessment of protein expression. Genetic screening of tissue from the tumor invasion front with laser microdissection was performed using SSCP and DNA sequencing. Adhesion protein distribution was significantly disturbed in most carcinomas. A single mutation in the gene of beta-catenin was found but there was no correlation between protein expression and genetic polymorphism. Nor was there any correlation between the complexity of the invasive border and protein distribution or genetic alterations. The results indicate that the complexity of colon carcinoma invasion is not dependent on genetic derangements in the genes of adhesion proteins or the protein distribution. Rather, aberrations in the function of other proteins related to the adhesive proteins could be responsible.