Gene methylation profiles of normal mucosa, and benign and malignant colorectal tumors identify early onset markers

<p>Abstract</p> <p>Background</p> <p>Multiple epigenetic and genetic changes have been reported in colorectal tumors, but few of these have clinical impact. This study aims to pinpoint epigenetic markers that can discriminate between non-malignant and malignant tissue from the large bowel, i.e. markers with diagnostic potential.</p> <p>The methylation status of eleven genes (<it>ADAMTS1</it>, <it>CDKN2A</it>, <it>CRABP1</it>, <it>HOXA9</it>, <it>MAL</it>, <it>MGMT</it>, <it>MLH1</it>, <it>NR3C1</it>, <it>PTEN</it>, <it>RUNX3</it>, and <it>SCGB3A1</it>) was determined in 154 tissue samples including normal mucosa, adenomas, and carcinomas of the colorectum. The gene-specific and widespread methylation status among the carcinomas was related to patient gender and age, and microsatellite instability status. Possible CIMP tumors were identified by comparing the methylation profile with microsatellite instability (MSI), <it>BRAF</it>-, <it>KRAS</it>-, and <it>TP53 </it>mutation status.</p> <p>Results</p> <p>The mean number of methylated genes per sample was 0.4 in normal colon mucosa from tumor-free individuals, 1.2 in mucosa from cancerous bowels, 2.2 in adenomas, and 3.9 in carcinomas. Widespread methylation was found in both adenomas and carcinomas. The promoters of <it>ADAMTS1</it>, <it>MAL</it>, and <it>MGMT </it>were frequently methylated in benign samples as well as in malignant tumors, independent of microsatellite instability. In contrast, normal mucosa samples taken from bowels without tumor were rarely methylated for the same genes. Hypermethylated <it>CRABP1, MLH1</it>, <it>NR3C1</it>, <it>RUNX3</it>, and <it>SCGB3A1 </it>were shown to be identifiers of carcinomas with microsatellite instability. In agreement with the CIMP concept, MSI and mutated <it>BRAF </it>were associated with samples harboring hypermethylation of several target genes.</p> <p>Conclusion</p> <p>Methylated <it>ADAMTS1</it>, <it>MGMT</it>, and <it>MAL </it>are suitable as markers for early tumor detection.</p

Hypermethylated MAL gene – a silent marker of early colon tumorigenesis

Background Tumor-derived aberrantly methylated DNA might serve as diagnostic biomarkers for cancer, but so far, few such markers have been identified. The aim of the present study was to investigate the potential of the MAL (T-cell differentiation protein) gene as an early epigenetic diagnostic marker for colorectal tumors. Methods Using methylation-specific polymerase chain reaction (MSP) the promoter methylation status of MAL was analyzed in 218 samples, including normal mucosa (n = 44), colorectal adenomas (n = 63), carcinomas (n = 65), and various cancer cell lines (n = 46). Direct bisulphite sequencing was performed to confirm the MSP results. MAL gene expression was investigated with real time quantitative analyses before and after epigenetic drug treatment. Immunohistochemical analysis of MAL was done using normal colon mucosa samples (n = 5) and a tissue microarray with 292 colorectal tumors. Results Bisulphite sequencing revealed that the methylation was unequally distributed within the MAL promoter and by MSP analysis a region close to the transcription start point was shown to be hypermethylated in the majority of colorectal carcinomas (49/61, 80%) as well as in adenomas (45/63, 71%). In contrast, only a minority of the normal mucosa samples displayed hypermethylation (1/23, 4%). The hypermethylation of MAL was significantly associated with reduced or lost gene expression in in vitro models. Furthermore, removal of the methylation re-induced gene expression in colon cancer cell lines. Finally, MAL protein was expressed in epithelial cells of normal colon mucosa, but not in the malignant cells of the same type. Conclusion Promoter hypermethylation of MAL was present in the vast majority of benign and malignant colorectal tumors, and only rarely in normal mucosa, which makes it suitable as a diagnostic marker for early colorectal tumorigenesis

Identification of an epigenetic biomarker panel with high sensitivity and specificity for colorectal cancer and adenomas

Background The presence of cancer-specific DNA methylation patterns in epithelial colorectal cells in human feces provides the prospect of a simple, non-invasive screening test for colorectal cancer and its precursor, the adenoma. This study investigates a panel of epigenetic markers for the detection of colorectal cancer and adenomas. Methods Candidate biomarkers were subjected to quantitative methylation analysis in test sets of tissue samples from colorectal cancers, adenomas, and normal colonic mucosa. All findings were verified in independent clinical validation series. A total of 523 human samples were included in the study. Receiver operating characteristic (ROC) curve analysis was used to evaluate the performance of the biomarker panel. Results Promoter hypermethylation of the genes CNRIP1, FBN1, INA, MAL, SNCA, and SPG20 was frequent in both colorectal cancers (65-94%) and adenomas (35-91%), whereas normal mucosa samples were rarely (0-5%) methylated. The combined sensitivity of at least two positives among the six markers was 94% for colorectal cancers and 93% for adenoma samples, with a specificity of 98%. The resulting areas under the ROC curve were 0.984 for cancers and 0.968 for adenomas versus normal mucosa. Conclusions The novel epigenetic marker panel shows very high sensitivity and specificity for both colorectal cancers and adenomas. Our findings suggest this biomarker panel to be highly suitable for early tumor detection

Advances in Lithium-Sulfur Rechargeable Batteries Powering the Electronic Future

This viewgraph presentation discusses the Moltech Corporation's history and structure, power systems development, product attributes, Li-S adapted products, cell construction, specific energy comparisons, and product requirements necessary for use in spacecraft applications