Hereditary non-polyposis colorectal carcinoma (Lynch syndrome) is among the most common hereditary cancers in man and a model of cancers arising through deficient DNA mismatch repair (MMR). Lynch syndrome patients are predisposed to different cancers in a non-random fashion, the basis of which is poorly understood. We addressed this issue by determining the molecular profiles for different tumors from a nationwide cohort of Lynch syndrome families (approximately 150 tumors in total). We focused on some less prevalent cancers, affecting the brain (n = 7) and urinary tract (five bladder and five ureter uroepithelial cancers and four kidney adenocarcinomas), and compared their molecular characteristics to those of the most common cancers, colorectal, gastric and endometrial adenocarcinomas, from the same families. Despite origin from verified MMR gene mutation carriers, the frequency of high-level microsatellite instability in tumors varied between high (100-96% for ureter, stomach and colon), intermediate (63-60% for endometrium and bladder) and low (25-0% for kidney and brain). In contrast to gastrointestinal and endometrial carcinomas, active (nuclear) beta-catenin was rare and KRAS mutations were absent in brain and urological tumors. Compared with other tumors, frequent stabilization of p53 protein characterized urinary tract cancers. Promoter methylation of tumor suppressor genes discriminated the tumors in an organ-specific manner. Our findings suggest that different Lynch syndrome tumors develop along different routes. Uroepithelial cancers of the ureter (and bladder to lesser extent) share many characteristics of MMR deficiency-driven tumorigenesis, whereas brain tumors and kidney adenocarcinomas follow separate pathways.

Tumor suppressor genes (TSG) may be inactivated by methylation of critical CpG sites in their promoter regions, providing targets for early detection and prevention. Although sporadic cancers, especially colorectal carcinoma (CRC), have been characterized for epigenetic changes extensively, such information in familial/hereditary cancer is limited. We studied 108 CRCs and 63 endometrial carcinomas (EC) occurring as part of hereditary nonpolyposis CRC, as separate familial site-specific entities or sporadically, for promoter methylation of 24 TSGs. Eleven genes in CRC and 6 in EC were methylated in at least 15% of tumors and together accounted for 89% and 82% of promoter methylation events in CRC and EC, respectively. Some genes (e.g., CDH13, APC, GSTP1, and TIMP3) showed frequent methylation in both cancers, whereas promoter methylation of ESR1, CHFR , and RARB was typical of CRC and that of RASSF1(A) characterized EC. Among CRCs, sets of genes with methylation characteristic of familial versus sporadic tumors appeared. A TSG methylator phenotype (methylation of at least 5 of 24 genes) occurred in 37% of CRC and 18% of EC (P = 0.013), and the presence versus absence of MLH1 methylation divided the tumors into high versus low methylation groups. In conclusion, inactivation of TSGs by promoter methylation followed patterns characteristic of tumor type (CRC versus EC) and family category and was strongly influenced by MLH1 promoter methylation status in all categories. Paired normal tissues or blood displayed negligible methylation arguing against a constitutional methylation abnormality in familial cases. [Cancer Res 2008;68(12):4597-605]

Increased and decreased methylation at specific sequences (hypermethylation and hypomethylation, respectively) is characteristic of tumor DNA compared to normal DNA and promotes carcinogenesis in multiple ways including genomic instability. Long interspersed element (LINE), an abundant class of retrotransposons, provides a surrogate marker for global hypomethylation. We developed methylation-specific multiplex ligation-dependent probe amplification assays to study LINE-1 methylation in cases of colorectal, gastric, and endometrial cancer (N = 276), stratified by patient category [sporadic; Lynch syndrome (LS); familial colorectal cancer type X (FCCX)] and microsatellite instability status. Within each patient group, LINE-1 showed lower methylation in tumor DNA relative to paired normal DNA and hypomethylation was statistically significant in most cases. Interestingly, normal colorectal mucosa samples from different patient groups displayed differences in LINE-1 methylation that mirrored differences between the respective tumor tissues, with a decreasing trend for LINE-1 methylation from patients with sporadic colorectal cancer to LS to FCCX. Despite the fact that the degree of LINE-1 methylation is generally tissue specific, normal colorectal mucosa, gastric mucosa, and endometrium from LS patients showed similar levels of LINE-1 methylation. Our results suggest that the degree of LINE-1 methylation may constitute a “field defect” that may predispose normal tissues for cancer development.Electronic supplementary materialThe online version of this article (doi:10.1007/s00109-011-0854-z) contains supplementary material, which is available to authorized users.

Malignant mesothelioma is an aggressive cancer with poor prognosis. It is characterized by prominent extracellular matrix, mesenchymal tumor cell phenotypes and chemoresistance. In this study, the ability of pirfenidone to alter mesothelioma cell proliferation and migration as well as mesothelioma tumor microenvironment was evaluated. Pirfenidone is an anti-fibrotic drug used in the treatment of idiopathic pulmonary fibrosis and has also anti-proliferative activities. Mesothelioma cell proliferation was decreased by pirfenidone alone or in combination with cisplatin. Pirfenidone also decreased significantly Transwell migration/invasion and 3D collagen invasion. This was associated with increased BMP pathway activity, decreased GREM1 expression and downregulation of MAPK/ERK and AKT/mTOR signaling. The canonical Smad-mediated TGF-β signaling was not affected by pirfenidone. However, pirfenidone blocked TGF-β induced upregulation of ERK and AKT pathways. Treatment of mice harboring mesothelioma xenografts with pirfenidone alone did not reduce tumor proliferation in vivo. However, pirfenidone modified the tumor microenvironment by reducing the expression of extracellular matrix associated genes. In addition, GREM1 expression was downregulated by pirfenidone in vivo. By reducing two major upregulated pathways in mesothelioma and by targeting tumor cells and the microenvironment pirfenidone may present a novel anti-fibrotic and anti-cancer adjuvant therapy for mesothelioma.

(GENES CHROM CANCER=250 words)Molecular mechanisms underlying coordinated hypermethylation of multiple CpG islands in cancer remain unclear. In particular, expressional and other studies of methyltransferase enzymes have arrived at conflicting results. We focused on DNMT1 and DNMT3B, DNA methyltransferases responsible for (de novo) methylation, and EZH2, histone (H3K27) methyltransferase, and