E-Cadherin Destabilization Accounts for the Pathogenicity of Missense Mutations in Hereditary Diffuse Gastric Cancer

E-cadherin is critical for the maintenance of tissue architecture due to its role in cell-cell adhesion. E-cadherin mutations are the genetic cause of Hereditary Diffuse Gastric Cancer (HDGC) and missense mutations represent a clinical burden, due to the uncertainty of their pathogenic role. In vitro and in vivo, most mutations lead to loss-of-function, although the causal factor is unknown for the majority. We hypothesized that destabilization could account for the pathogenicity of E-cadherin missense mutations in HDGC, and tested our hypothesis using in silico and in vitro tools. FoldX algorithm was used to calculate the impact of each mutation in E-cadherin native-state stability, and the analysis was complemented with evolutionary conservation, by SIFT. Interestingly, HDGC patients harbouring germline E-cadherin destabilizing mutants present a younger age at diagnosis or death, suggesting that the loss of native-state stability of E-cadherin accounts for the disease phenotype. To elucidate the biological relevance of E-cadherin destabilization in HDGC, we investigated a group of newly identified HDGC-associated mutations (E185V, S232C and L583R), of which L583R is predicted to be destabilizing. We show that this mutation is not functional in vitro, exhibits shorter half-life and is unable to mature, due to premature proteasome-dependent degradation, a phenotype reverted by stabilization with the artificial mutation L583I (structurally tolerated). Herein we report E-cadherin structural models suitable to predict the impact of the majority of cancer-associated missense mutations and we show that E-cadherin destabilization leads to loss-of-function in vitro and increased pathogenicity in vivo

Frequency of CDH1 germline mutations in gastric carcinoma coming from high- and low-risk areas: metanalysis and systematic review of the literature

<p>Abstract</p> <p>Background</p> <p>The frequency of E-cadherin germline mutations in countries with different incidence rates for gastric carcinoma has not been well established. The goal of this study was to assess the worldwide frequency of <it>CDH1 </it>germline mutations in gastric cancers coming from low- and high-risk areas.</p> <p>Methods</p> <p>English articles using MEDLINE access (from 1998 to 2011). Search terms included <it>CDH1</it>, E-cadherin, germline mutation, gastric cancer, hereditary, familial and diffuse histotype.</p> <p>The study included all E-cadherin germline mutations identified in gastric cancer patients; somatic mutations and germline mutations reported in other tumors were excluded.</p> <p>The method of this study was scheduled in accordance with the "PRISMA statement for reporting systematic reviews and meta-analyses". Countries were classified as low- or middle/high risk-areas for gastric carcinoma incidence. Statistical analysis was performed to correlate the <it>CDH1 </it>mutation frequency with gastric cancer incidence areas.</p> <p>Results</p> <p>A total of 122 E-cadherin germline mutations have been identified; the majority (87.5%) occurred in gastric cancers coming from low-risk areas. In high-risk areas, we identified 16 mutations in which missense mutations were predominant. (68.8%). We verified a significant association between the mutation frequency and the gastric cancer risk area (<it>p </it>< 0.001: overall identified mutations in low- vs. middle/high-risk areas).</p> <p>Conclusions</p> <p>E-cadherin genetic screenings performed in low-risk areas for gastric cancer identified a higher frequency of <it>CDH1 </it>germline mutations. This data could open new approaches in the gastric cancer prevention test; before proposing a proband candidate for the <it>CDH1 </it>genetic screening, geographic variability, alongside the family history should be considered.</p

Epidermal growth factor receptor structural alterations in gastric cancer

<p>Abstract</p> <p>Background</p> <p>EGFR overexpression has been described in many human tumours including gastric cancer. In NSCLC patients somatic EGFR mutations, within the kinase domain of the protein, as well as gene amplification were associated with a good clinical response to EGFR inhibitors. In gastric tumours data concerning structural alterations of EGFR remains controversial. Given its possible therapeutic relevance, we aimed to determine the frequency and type of structural alterations of the <it>EGFR </it>gene in a series of primary gastric carcinomas.</p> <p>Methods</p> <p>Direct sequencing of the kinase domain of the <it>EGFR </it>gene was performed in a series of 77 primary gastric carcinomas. FISH analysis was performed in 30 cases. Association studies between <it>EGFR </it>alterations and the clinical pathological features of the tumours were performed.</p> <p>Results</p> <p>Within the 77 primary gastric carcinomas we found two <it>EGFR </it>somatic mutations and several <it>EGFR </it>polymorphisms in exon 20. Six different intronic sequence variants of <it>EGFR </it>were also found. Four gastric carcinomas showed balanced polysomy or <it>EGFR </it>gene amplification. We verified that gastric carcinoma with alterations of <it>EGFR </it>(somatic mutations or copy number variation) showed a significant increase of tumour size (<it>p </it>= 0.0094) in comparison to wild-type <it>EGFR </it>carcinomas.</p> <p>Conclusion</p> <p>We demonstrate that <it>EGFR </it>structural alterations are rare in gastric carcinoma, but whenever present, it leads to tumour growth. We considered that searching for <it>EGFR </it>alterations in gastric cancer is likely to be clinically important in order to identify patients susceptible to respond to tyrosine kinase inhibitors.</p

CDH1 gene mutations do not contribute in hereditary diffuse gastric cancer in Poland

Hereditary diffuse gastric cancer (HDGC) is a cancer susceptibility syndrome characterized by a high risk of diffuse stomach cancer and lobular breast cancer. HDGC is caused by germline mutations in the CDH1 gene encoding the E-cadherin which is a member of the transmembrane glycoprotein family responsible for calcium-dependent, cell-to-cell adhesion and plays a fundamental role in the maintenance of cell differentiation and the normal architecture of epithelial tissues. Mutations in the CDH1 gene are detected in 30–46% of families that fulfil strong clinical criteria for HDGC and in about 11% of families fulfilling the modified criteria. In the present study, we investigated germline mutations in the CDH1 gene in Polish patients with HDGC. The entire coding sequence of CDH1 gene was analyzed by sequencing in 86 Polish cancer patients from families fulfilling the modified criteria of HDGC. We found several silent mutations including one common variant (c.2076T>C) present in 56 patients, and three rare variants (c.2253C>T, c.1896C>T, c.2634C>T) detected in 2 patients. In addition, we found four rare sequence variants of unknown significance localized in introns. We did not detect any deleterious mutations of the CDH1 gene. CDH1 gene mutations are not present in Polish families with HDGC defined by the modified clinical criteria. Further studies of families with HDGC matching the restrictive criteria for HDGC are needed

TGFBR1 Intralocus Epistatic Interaction as a Risk Factor for Colorectal Cancer

In colorectal cancer (CRC), an inherited susceptibility risk affects about 35% of patients, whereas high-penetrance germline mutations account for <6% of cases. A considerable proportion of sporadic tumors could be explained by the coinheritance of multiple low-penetrance variants, some of which are common. We assessed the susceptibility to CRC conferred by genetic variants at the TGFBR1 locus. We analyzed 14 polymorphisms and the allele-specific expression (ASE) of TGFBR1 in 1025 individuals from the Spanish population. A case-control study was undertaken with 504 controls and 521 patients with sporadic CRC. Fourteen polymorphisms located at the TGFBR1 locus were genotyped with the iPLEX Gold (MassARRAY-Sequenom) technology. Descriptive analyses of the polymorphisms and haplotypes and association studies were performed with the SNPator workpackage. No relevant associations were detected between individual polymorphisms or haplotypes and the risk of CRC. The TGFBR1*9A/6A polymorphism was used for the ASE analysis. Heterozygous individuals were analyzed for ASE by fragment analysis using cDNA from normal tissue. The relative level of allelic expression was extrapolated from a standard curve. The cutoff value was calculated with Youden's index. ASE was found in 25.4% of patients and 16.4% of controls. Considering both bimodal and continuous types of distribution, no significant differences between the ASE values of patients and controls were identified. Interestingly, a combined analysis of the polymorphisms and ASE for the association with CRC occurrence revealed that ASE-positive individuals carrying one of the most common haplotypes (H2: 20.7%) showed remarkable susceptibility to CRC (RR: 5.25; 95% CI: 2.547–5.250; p<0.001) with a synergy factor of 3.7. In our study, 54.1% of sporadic CRC cases were attributable to the coinheritance of the H2 haplotype and TGFBR1 ASE. These results support the hypothesis that the allelic architecture of cancer genes, rather than individual polymorphisms, more accurately defines the CRC risk

Cell entry of a host targeting protein of oomycetes requires gp96

This work is supported by the [European Community’s] Seventh Framework Programme [FP7/2007–2013] under grant agreement no. [238550] (L.L., J.D.-U., C.J.S., P.v.W.); BBSRC [BBE007120/1, BB/J018333/1 and BB/G012075/1] (F.T., I.d.B., C.J.S., S.W., P.v.W.); Newton Global Partnership Award [BB/N005058/1] (F.T., P.v.W.), the University of Aberdeen (A.D.T., T.R., C.J.S., P.v.W.) and Deutsche Forschungsgemeinschaft [CRC1093] (P.B., T.S.). We would like to acknowledge the Ministry of Higher Education Malaysia for funding INA. We would like to thank Brian Haas for his bioinformatics support. We would like to acknowledge Neil Gow and Johannes van den Boom for critical reading of the manuscript. We would like to acknowledge Svetlana Rezinciuc for technical help with pH-studies.Peer reviewedPublisher PD

Heat-shock proteins in infection-mediated inflammation-induced tumorigenesis

Inflammation is a necessary albeit insufficient component of tumorigenesis in some cancers. Infectious agents directly implicated in tumorigenesis have been shown to induce inflammation. This process involves both the innate and adaptive components of the immune system which contribute to tumor angiogenesis, tumor tolerance and metastatic properties of neoplasms. Recently, heat-shock proteins have been identified as mediators of this inflammatory process and thus may provide a link between infection-mediated inflammation and subsequent cancer development. In this review, the role of heat-shock proteins in infection-induced inflammation and carcinogenesis will be discussed