Hendrik Bläker

Genetics of adenocarcinomas of the small intestine: frequent deletions at chromosome 18q and mutations of the SMAD4 gene.

The small intestinal mucosa makes up about 90% of the total surface of the gastrointestinal tract. However, adenocarcinomas arise rarely in this location. To elucidate genetic alterations underlying tumour development in the small intestine we investigated 17 sporadic adenocarcinomas. By comparative genomic hybridization recurrent gains of chromosomal material were found at chromosomes 7, 8, 13q, and 20 (5/17, each), while non-random losses were seen at 8p, 17p (4/17, each), and 18 (8/17 cases). Deletions at 5q, the location of the APC tumour suppressor gene, were seen in three cases. Microsatellite analysis with markers on chromosomal arms 1p, 5q, 8p, 17p, 18q, 19p, and 22q revealed a microsatellite instable phenotype in two cases and a high frequency of loss at 18q21-q22 (80%). Given the high incidence of 18q21-q22 deletions, we performed sequencing analysis of SMAD4, a downstream component of the TGFβ-pathway, located at 18q21. Four tumours displayed mutations in highly conserved domains of the gene indicating disruption of TGFβ-signalling. Our data reveal complex genetic alterations in sporadic small intestinal carcinomas. However, most tumours share deletions of 18q21-q22, which frequently target SMAD4. This indicates that disruption of TGFβ-signalling plays a critical role in small intestinal tumorigenesis.

Fruit and vegetable intake and the risk of gastric adenocarcinoma: a reanalysis of the European Prospective Investigation into Cancer and Nutrition (EPIC-EURGAST) study after a longer follow-up.

In a previous European prospective investigation into cancer and nutrition (EPIC) analysis, we found an inverse association between total intake of vegetables, onion and garlic, and risk of intestinal gastric cancer (GC) and between citrus fruit and risk of cardia GC. The aim of this study is to reanalyze the effect of fruit and vegetables (F&V), based on a longer follow‐up and twice the number of GC cases. Subjects are 477,312 men and women mostly aged 35 to 70 years participating in the EPIC cohort, including 683 gastric adenocarcinomas with 11 years of follow‐up. Information on diet and lifestyle was collected at baseline. A calibration study in a subsample was used to correct for dietary measurement errors. When comparing the highest vs. lowest quintile of intake, we found an inverse association between total intake of V&F and GC risk [hazard ratio (HR) 0.77; 95% confidence interval (CI) 0.57–1.04; p for trend 0.02], between fresh fruit and risk of the diffuse type (HR 0.59; 95% CI 0.36–0.97; p for trend 0.03) and an inverse association between citrus fruit and risk of cardia cancer (HR 0.61; 95% CI 0.38–1.00, p for trend 0.01). Although calibration revealed somewhat stronger inverse associations, none of the risks reached statistical significance. There was no association between total or specific vegetables intake and GC risk. The inverse association between fresh fruit and citrus fruits and risk of GC seems to be restricted to smokers and the Northern European countries. Fresh fruit and citrus fruit consumption may protect against diffuse and cardia GC, respectively.

β-catenin accumulation and mutation of the CTNNB1 gene in hepatoblastoma

Hepatoblastoma is a rare malignant tumor of the liver that occurs in children at an average age of 2 to 3 years. Epidemiologic studies have shown an increased frequency of this tumor type in families affected by adenomatous polyposis coli. In addition to the epidemiologic data, molecular genetic studies suggest that inactivation of the APC tumor suppressor may be involved in hepatoblastoma tumorigenesis. A major function of APC is the downregulation of β‐catenin, a transcription‐activating protein with oncogenic potential. In an ongoing immunohistochemical study of β‐catenin expression in sporadic cases of tumor types that are associated with adenomatous polyposis coli, we observed increased β‐catenin levels in the cytoplasm and in the nuclei of three investigated hepatoblastomas. Sequencing of exon 3 of the β‐catenin gene (CTNNB1) revealed an activating mutation in one of the tumor samples. Our data indicate for the first time that β‐catenin accumulation may play a role in the development of hepatoblastoma and that activating mutations of the β‐catenin gene may substitute biallelic APC inactivation in this tumor type. Genes Chromosomes Cancer 25:399–402, 1999.

The Immune Reconstitution Inflammatory Syndrome in Whipple Disease: A Cohort Study

BACKGROUND Whipple disease, which is caused by infection with Tropheryma whipplei, can be treated effectively with antimicrobials. Occasionally, inflammation reappears after initial improvement; this is often interpreted as refractory or recurrent disease. However, polymerase chain reaction for T. whipplei in tissue is sometimes negative during reinflammation, indicating absence of vital bacteria, and this reinflammation does not respond to antimicrobials but does respond to steroids. OBJECTIVE To demonstrate that the immune reconstitution inflammatory syndrome (IRIS) occurs in patients treated for Whipple disease. DESIGN Cohort study. (International Standard Randomised Controlled Trial Number Register registration number: ISRCTN45658456) SETTING 2 academic medical centers in Germany. METHODS 142 patients treated for Whipple disease out of a cohort of 187 were observed for reappearance of inflammatory signs after effective antibiotic therapy. Definitions of IRIS in HIV infection, tuberculosis, and leprosy were adapted for application to Whipple disease. RESULTS On the basis of study definitions, IRIS was diagnosed in 15 of 142 patients. Symptoms included fever, arthritis, pleurisy, erythema nodosum, inflammatory orbitopathy, small-bowel perforation, and a hypothalamic syndrome. Two patients died. There was a positive correlation with previous immunosuppressive treatment and a negative correlation with previous diarrhea and weight loss. LIMITATIONS The study was observational and thus has inherent weaknesses, such as incomplete and potentially selective data recording. CONCLUSION The immune reconstitution inflammatory syndrome was diagnosed in about 10% of patients with Whipple disease in the study cohort; the outcome varied from mild to fatal. Patients who had had previous immunosuppressive therapy were at particular risk. An immune reconstitution syndrome should be considered in patients with Whipple disease in whom inflammatory symptoms recur after effective treatment. Early diagnosis and treatment with steroids may be beneficial; prospective studies are needed. PRIMARY FUNDING SOURCE European Commission and Deutsche Forschungsgemeinschaft.

Analysis of somatic APC mutations in rare extracolonic tumors of patients with familial adenomatous polyposis coli

Patients with familial adenomatous polyposis coli (FAP) carry heterozygous mutations of the APC gene. At a young age, these patients develop multiple colorectal adenomas that consistently display a second somatic mutation in the remaining APC wild‐type allele. Inactivation of APC leads to impaired degradation of β‐catenin, thereby promoting continuous cell‐cycle progression. The role of APC inactivation in rare extracolonic tumors of FAP patients has not been characterized sufficiently. Among tissue specimen from 174 patients with known APC germ‐line mutations, we identified 8 tumors infrequently seen in FAP. To investigate the pathogenic role of APC pathway deregulation in these lesions, they were analyzed for second‐hit somatic mutations in the mutational cluster region of the APC gene. Immunohistochemistry was performed to compare the expression pattern of β‐catenin to the mutational status of the APC gene. Exon 3 of the β‐catenin gene (CTNNB1) was analyzed for activating mutations to investigate alternative mechanisms of elevated β‐catenin concentration. Although CTNNB1 mutations were not observed, second somatic APC mutations were found in 4 of the 8 tumors: a uterine adenocarcinoma, a hepatocellular adenoma, an adrenocortical adenoma, and an epidermal cyst. These tumors showed an elevated concentration of β‐catenin. No APC mutations were seen in focal nodular hyperplasia of the liver, angiofibrolipoma, and seborrheic wart. This is the first study reporting second somatic APC mutations in FAP‐associated uterine adenocarcinoma and epidermal cysts. Furthermore, our data strengthen a role for impaired APC function in the pathogenesis of adrenal and hepatic neoplasms in FAP patients.

Prevalence of mismatch repair-deficient crypt foci in Lynch syndrome: A pathological study

BACKGROUND Lynch syndrome is an inherited tumour predisposition syndrome caused by germline mutations of DNA mismatch repair (MMR) genes. Mutation carriers have a high risk of developing colorectal cancer, but do not present with polyposis, a typical feature of other colorectal cancer syndromes such as familial adenomatous polyposis, in which polyposis reflects the high frequency of biallelic APC gene inactivation. We asked whether in Lynch syndrome biallelic inactivation of MMR genes occurred at a similar frequency to that of APC gene, and whether MMR inactivation resulted in detectable lesions within the intestinal mucosa. METHODS Resections done for small and large bowel cancer between January, 2002, and January, 2011, were retrieved. We systematically analysed non-tumorous mucosa from carriers of a Lynch syndrome mutation (set 1: ten patients) and control patients without Lynch syndrome (set 1: nine patients) for MMR protein expression (MLH1, MSH2, and EPCAM) with immunohistochemistry. We validated the findings in an independent sample set (set 2: 30 Lynch syndrome patients, 79 controls). We did an analysis of microsatellite instability by PCR analysis to test lesions for mismatch repair deficiency. We applied a Poisson regression model to analyse the distribution of MMR-deficient crypt foci counts and a Fishers exact test to compare the prevalence of these foci between mutation carriers and control patients. FINDINGS 20 crypt foci with no MMR protein expression were detected in 20·1 cm(2) of non-tumorous mucosa from Lynch syndrome patients (set 1), an additional five were detected upon resectioning of two samples. In an independent validation set (set 2), two MMR-deficient crypt foci were noted in 2·2 cm(2) of mucosa. No MMR-deficient crypt foci were noted in non-tumorous mucosa from control patients without evidence for Lynch syndrome (set 1: 3·7 cm(2), set 2: 4·8 cm(2)). Microsatellite instability was detected in all seven MMR-deficient crypt foci analysed. A subset of these foci displayed unusual architectural and cytological abnormalities, although they had no polypous or adenomatous appearance. INTERPRETATION We identified a novel type of lesion, the MMR-deficient crypt focus, as the manifestation of biallelic MMR gene inactivation in Lynch syndrome. The abundance of MMR-deficient crypt foci indicates a high frequency of biallelic MMR gene inactivation, which is in sharp contrast with the low number of clinically manifest cancers in Lynch syndrome. This discrepancy suggests that most MMR-deficient crypt foci do not progress to cancer. We propose Lynch syndrome as a unique model syndrome for studying initial steps of MMR deficiency, tumour initiation and, possibly, elimination. FUNDING German Cancer Aid and German Research Foundation.

Cystic lymphangioma of the small-bowel mesentery : Case report and a review of the literature

Cystic lymphangioma of the small-bowel mesentery is a rare manifestation of an intraabdominal tumor in elderly patients. We present a case of a small-bowel mesentery lymphangioma, causing fever and chills and present clinical and pathologic features. Furthermore, etiology and differential diagnosis of this tumor are discussed.

Mutational activation of the RAS-RAF-MAPK and the Wnt pathway in small intestinal adenocarcinomas.

Background: Adenocarcinomas of the small and the large intestine share risk factors and morphological features but both tumor types seem to follow different genetic pathways. The aim of this study on small intestinal carcinomas was to analyze alternative mechanisms of activation of pathways that are typically affected in colorectal cancer. Methods: Twenty‐one sporadic carcinomas were investigated for mutations in KRAS, BRAF, the β‐catenin gene CTNNB1, and the mutational cluster region of APC. Immunohistochemical analysis was performed with a monoclonal antibody for β‐catenin, the transcriptionally active downstream component of wnt signaling. Results: Oncogene mutations were found in 13 (62%) small intestinal adenocarcinomas. Twelve tumors displayed a KRAS mutation, and a novel BRAF mutation at codon 603/604 was seen in one carcinoma without KRAS mutation. One tumor harbored a CTNNB1 mutation consisting of an insertion of 247 nucleotides deriving from chromosome 9. APC mutations were identified in 2 tumors. Immunohistochemistry demonstrated nuclear accumulation of β‐catenin in 5 carcinomas. These carcinomas included the tumor with a CTNNB1 mutation but not those with APC mutations. Conclusions: Our data show frequent activation of the RAS‐RAF‐MAPK pathway through mutations of either KRAS or, infrequently, BRAF. Activation of the wnt pathway through accumulation of β‐catenin may have a role in a subset of small intestinal adenocarcinomas but in contrast to colorectal carcinoma, accumulation of β‐catenin is generally not caused by inactivating APC or activating CTNNB1 mutations.

Pathology findings and validation of gastric and esophageal cancer cases in a European cohort (EPIC/EUR-GAST)

Objective. Cardia, non-cardia and intestinal and diffuse subtypes of gastric cancer may have different trends and etiological factors. However, the available information is not always collected in population cancer registries, and heterogeneous criteria have been applied for the histopathological classification of tumors. We describe the pathological features of incident gastric and esophageal cancers identified within the European Prospective Investigation into Cancer and Nutrition (EPIC). Material and methods. In an investigation on gastric and esophageal cancer (EUR-GAST) in the EPIC project, a validation study of diagnoses reported by EPIC centers was conducted by a European panel of pathologists. Original pathology reports, stained slides of tumors and the respective paraffin blocks were requested from the centers. Results. The whole series encompassed 467 cancer cases (gastric and esophageal cancers). Material was available for histopathological validation in 263 cases (56%); in the remaining cases, information was retrieved from the original reports (n=110; 24%) or codes provided by the EPIC centers (n=94; 20%). Among cases submitted to histopathological validation reported originally as unknown histotype or unknown site, a specific diagnosis was made in 95% and 74% of the cases, respectively. In cases for which only the original reports were available, the respective percentages were 46% and 67%. Gastric adenocarcinomas were classified according to site (cardia (29.4%), non-cardia (48.2%) and unknown (22.4%)) and histological type (intestinal (33.4%), diffuse (33.7%) and mixed, unclassified or unknown (32.9%)). Frequency of cardia was higher in Northern countries (35%) than in Mediterranean countries (18%). Conclusions. In addition to providing epidemiological data within the EPIC cohort on gastric and esophageal adenocarcinomas, the results reported here confirm the relevance of a validation study, notably for multicenter studies.

Comparison of losses of heterozygosity and replication errors in primary colorectal carcinomas and corresponding liver metastases

In order to investigate genetic alterations specific to liver metastases of colorectal carcinomas, losses of heterozygosity and replication errors have been compared in 15 cases of primary colorectal carcinoma and in the corresponding metastatic liver tumours. Fifteen microsatellite markers located on 13 different chromosomal arms were used in the study. The LOH patterns of the primary and the metastatic tumours were identical in eight cases and showed differences in seven cases. Areas of deletion predominantly or completely common to the colorectal and the metastatic tumour were detected on chromosomes 5q, 8p, 17p, 18q, and 22q. Preferential loss in metastatic tumours was observed on chromosomal arm 3p. Replication errors were found in four primary tumours and in three of the corresponding secondaries. A replication error phenotype specific to a metastasis was not observed. Copyright