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Objective: Pheochromocytomas (PCCs) are neuroendocrine tumors that occur in the adrenal medulla, whereas paragangliomas (PGLs) arise from paraganglia in the head, neck, thorax, or abdomen. In a variety of tumors, cancer cells with stem cell-like properties seem to form the basis of tumor initiation because of their ability to self-renew and proliferate. Specifically targeting this small cell population may lay the foundation for more effective therapeutic approaches. In the present study, we intended to identify stem cells in PCCs/PGLs. Design:We examined the immunohistochemical expression of 11 stem cell markers (SOX2, LIN28, NGFR, THY1, PREF1, SOX17, NESTIN, CD117, OCT3/4, NANOG, and CD133) on tissue microarrays containing 208 PCCs/PGLs with different genetic backgrounds from five European centers. Results: SOX2, LIN28, NGFR, and THY1 were expressed in more than 10% of tumors, and PREF1, SOX17, NESTIN, and CD117 were expressed in !10% of the samples. OCT3/4, NANOG, and CD133 were not detectable at all. Double staining for chromogranin A/SOX2 and S100/SOX2 demonstrated SOX2 immunopositivity in both tumor and adjacent sustentacular cells. The expression of SOX2, SOX17, NGFR, LIN28, PREF1, and THY1 was significantly associated with mutations in one of the succinate dehydrogenase (SDH) genes. In addition, NGFR expression was significantly correlated with metastatic disease. Conclusion: Immunohistochemical expression of stem cell markers was found in a subset of PCCs/PGLs. Further studies are required to validate whether some stem cell-associated markers, such as SOX2, could serve as targets for therapeutic approaches and whether NGFR expression could be utilized as a predictor of malignancy. [ABSTRACT FROM AUTHOR]

Background and aims: In Lynch syndrome, the clinical phenotype in MSH6 mutation families differs from that in MLHI and MSH2 families. Therefore, MSH6 mutation families are less likely to fulfil diagnostic criteria such as the Amsterdam II criteria (AC II) and the revised Bethesda guidelines (rBG), and will be underdiagnosed. The aim of the present study was to evaluate the contribution of MSH6 gene mutations in families that were analysed for Lynch syndrome in a diagnostic setting. Methods: Families that had molecular analysis for Lynch syndrome were included in this study. Complete molecular screening of the MLH1, MSH2 and MSH6 genes was performed in all families. Microsatellite instability (MSI) and immunohistochemical (IHC) analysis was performed in almost all families. Clinical data were collected from medical records and family pedigrees. Results: A total of 108 families were included. MSI and IRC analysis was performed in 97 families, and in 40 an MSI-high phenotype with absent protein expression was found. Germline mutation analysis detected mutations in 23 families (7 MLHJ, 4 MSH2 and 12 MSH6). The majority of MSH6 families were AC II negative, but fulfilled the rBG. Conclusions: There is a high incidence of MSH6 mutations in families tested for Lynch syndrome in a diagnostic setting. Many of these families remain underdiagnosed using the AC II. The rBG are more useful to select these families for further analysis. However, to optimise the detection of MSH6 families, MSI and IHC analysis should also be performed in families with clustering of late-onset endometrial carcinoma. [ABSTRACT FROM AUTHOR]

Up to 60% of gastro-oesophageal junction (GEJ) adenocarcinomas show nuclear ß-catenin expression, pointing to activated T-cell factor (TCF)/ß-catenin-driven gene transcription. We demonstrate in five human GEJ adenocarcinoma cell lines that nuclear ß-catenin expression indeed correlates with enhanced TCF-mediated transcription of a reporter gene. In several tumour types, TCF/ß-catenin activation is caused by mutations in either adenomatous polyposis coli (APC), ß-catenin exon 3, AXIN1, AXIN2 or ß-transducin repeat-containing protein (ß-TrCP). In GEJ adenocarcinomas, very few APC and ß-catenin mutations have been found. Therefore, the mechanism of Wnt pathway activation remains unclear. In the present study, we did not find AXIN1 gene mutations in 17 GEJ tumours with nuclear ß-catenin expression (without ß-catenin exon 3 mutations). Six intragenic single nucleotide polymorphisms (SNPs) were identified. One of these, the AXIN1 gene T1942C SNP, has a frequency of 21% but is only very recently described despite numerous AXIN1 gene mutational studies. We provide evidence why this SNP was missed in single strand conformation polymorphism analyses. The AXIN1 gene G2063A variation was previously described as a gene mutation but we demonstrate that this is a polymorphism. With these six SNPs loss of heterozygosity (LOH) was found in 11 of 15 (73%) informative tumours. To investigate a possible AXIN1 gene dosage effect in GEJ tumours expressing nuclear ß-catenin, AXIN1 locus LOH was determined in 20 tumours expressing membranous and no nuclear ß-catenin. LOH was found in 10 of 13 (77%) informative cases. AXIN1 protein immunohistochemistry revealed cytoplasmic expression in all tumours irrespective of the presence of AXIN1 locus LOH. These data indicate that nuclear ß-catenin expression is indicative for activated Wnt signalling and that neither AXIN1 gene mutations nor AXIN1 locus LOH are involved in Wnt pathway activation in GEJ adenocarcinomas.British Journal of Cancer (2004) 90, 892-899. doi:10.1038/sj.bjc.6601589 www.bjcancer.com [ABSTRACT FROM AUTHOR]

In response to DNA damage, the cell cycle checkpoint kinase 2 (CHEK2) may phosphorylate p53, Cdc25A and Cdc25C, and regulate BRCA1 function, leading to cell cycle arrest and DNA repair. The truncating germline mutation CHEK2*1100delC abrogates kinase activity and confers low-penetrance susceptibility to breast cancer. We found CHEK2*1100delC in 0.5% of 190 oesophageal squamous cell carcinomas and in 1.5% of 196 oesophageal adenocarcinomas. In addition, we observed the mutation in 3.0% of 99 Barrett's metaplasias and 1.5% of 66 dysplastic Barrett's epithelia, both known precursor lesions of oesophageal adenocarcinoma. Since CHEK2*1100delC mutation frequencies did not significantly differ among oesophageal squamous cell carcinomas, adenocarcinomas and (dysplastic) Barrett's epithelia, as compared to healthy individuals, we conclude that the CHEK2*1100delC mutation has no major contribution in oesophageal carcinogenesis.British Journal of Cancer (2004) 90, 888-891. doi:10.1038/sj.bjc.6601551 www.bjcancer.com [ABSTRACT FROM AUTHOR]

Reduced expression of E-cadherin, a cell-cell adhesion molecule, is observed in oesophageal adenocarcinomas and correlates with less favourable pathological parameters and survival. To determine if genetic events lead to reduced E-cadherin expression in these patients, we screened all 16 exons of the E-cadherin gene for mutations with the polymerase chain reaction single-strand conformation polymorphism analysis (PCR-SSCP) technique in 49 resection specimens, including four loco-regional lymph node metastases, four established cell lines and four xenografts. Fifteen exon-spanning primer pairs were used, and in nine amplicons aberrant bands were detected. Sequencing of the amplicons revealed a one base-pair deletion (codon 120; exon 3) in cell lines JROECL 47 and JROECL 50 leading to a premature downstream stop codon. Polymorphisms were identified for amplicons 1, 4/5, 11, 12, 13, 14 and 16 corresponding with data from the literature. Three new polymorphisms were detected for amplicons 2, 3 and 4/5. Loss of heterozygosity (LOH) of the E-cadherin locus on 16q22.1 was examined with four polymorphic markers. LOH was found in 31 of the 48 informative cases (65%). These results show that, despite the frequent LOH of the E-cadherin locus, mutations in the E-cadherin gene are rare events and can not be held responsible for down-regulation of E-cadherin observed in the majority of adenocarcinomas of the oesophagus. [ABSTRACT FROM AUTHOR]