Down-regulation of serum/glucocorticoid regulated kinase 1 in colorectal tumours is largely independent of promoter hypermethylation.

BACKGROUND: We have previously shown that serum/glucocorticoid regulated kinase 1 (SGK1) is down-regulated in colorectal cancers (CRC) with respect to normal tissue. As hyper-methylation of promoter regions is a well-known mechanism of gene silencing in cancer, we tested whether the SGK1 promoter region was methylated in colonic tumour samples. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the methylation profile of the two CpG islands present in the promoter region of SGK1 in a panel of 5 colorectal cancer cell lines by sequencing clones of bisulphite-treated DNA samples. We further confirmed our findings in a panel of 10 normal and 10 tumour colonic tissue samples of human origin. We observed CpG methylation only in the smaller and more distal CpG island in the promoter region of SGK1 in both normal and tumour samples of colonic origin. We further identified a single nucleotide polymorphism (SNP, rs1743963) which affects methylation of the corresponding CpG. CONCLUSIONS/SIGNIFICANCE: Our results show that even though partial methylation of the promoter region of SGK1 is present, this does not account for the different expression levels seen between normal and tumour tissue.

The Intestinal Wnt/TCF Signature.

BACKGROUND & AIMS: In colorectal cancer, activating mutations in the Wnt pathway transform epithelial cells through the inappropriate expression of a TCF4 target gene program, which is physiologically expressed in intestinal crypts. METHODS: We have now performed an exhaustive array-based analysis of this target gene program in colorectal cancer cell lines carrying an inducible block of the Wnt cascade. Independently, differential gene-expression profiles of human adenomas and adenocarcinomas vs normal colonic epithelium were obtained. RESULTS: Expression analyses of approximately 80 genes common between these data sets were performed in a murine adenoma model. The combined data sets describe a core target gene program, the intestinal Wnt/TCF signature gene set, which is responsible for the transformation of human intestinal epithelial cells. CONCLUSIONS: The genes were invariably expressed in adenomas, yet could be subdivided into 3 modules, based on expression in distinct crypt compartments. A module of 17 genes was specifically expressed at the position of the crypt stem cell.

Transcriptome profile of human colorectal adenomas.

Colorectal cancers are believed to arise predominantly from adenomas. Although these precancerous lesions have been subjected to extensive clinical, pathologic, and molecular analyses, little is currently known about the global gene expression changes accompanying their formation. To characterize the molecular processes underlying the transformation of normal colonic epithelium, we compared the transcriptomes of 32 prospectively collected adenomas with those of normal mucosa from the same individuals. Important differences emerged not only between the expression profiles of normal and adenomatous tissues but also between those of small and large adenomas. A key feature of the transformation process was the remodeling of the Wnt pathway reflected in patent overexpression and underexpression of 78 known components of this signaling cascade. The expression of 19 Wnt targets was closely correlated with clear up-regulation of KIAA1199, whose function is currently unknown. In normal mucosa, KIAA1199 expression was confined to cells in the lower portion of intestinal crypts, where Wnt signaling is physiologically active, but it was markedly increased in all adenomas, where it was expressed in most of the epithelial cells, and in colon cancer cell lines, it was markedly reduced by inactivation of the beta-catenin/T-cell factor(s) transcription complex, the pivotal mediator of Wnt signaling. Our transcriptomic profiles of normal colonic mucosa and colorectal adenomas shed new light on the early stages of colorectal tumorigenesis and identified KIAA1199 as a novel target of the Wnt signaling pathway and a putative marker of colorectal adenomatous transformation.

Fine needle biopsy of focal liver lesions: the hepatologist's point of view.

Guided biopsy of hepatocellular carcinoma has been recently discussed again due to the progress of imaging techniques and the risk of malignant seeding after the procedure. Ultrasound is probably still the most accurate imaging modality for early detection of nodules arising on cirrhosis, even when compared with more advanced imaging techniques. It can be easily employed in the surveillance of high-risk cirrhotic patients. Ultrasound-guided biopsy has very high sensitivity and almost absolute specificity, which allows the appropriate treatment to start after a positive diagnosis. It also allows correct diagnosis of lymphomatous nodules, the incidence of which is increased in hepatitis C virus-related cirrhosis. The risk of seeding appears limited according to the currently available epidemiological data; this should be considered against the risk of false-positive diagnosis of malignancy based on imaging studies alone. Ultrasound-guided biopsy is a valuable tool also for the diagnosis of small nodules (less than 10 mm in diameter). The best accuracy in the sampling of hepatocellular carcinoma nodules is obtained by combining smear cytology and microhistology. This can be achieved by a single biopsy with a fine cutting needle that furnishes pathologic material suitable for both examinations, reducing risks and costs.