Germline E-cadherin mutations in hereditary diffuse gastric cancer: assessment of 42 new families and review of genetic screening criteria

Hereditary diffuse gastric cancer: implications of genetic testing for screening and prophylactic surgery

Approximately 10% of patients with gastric cancer show familial clustering, and 3% show autosomal dominance and high penetrance. Hereditary diffuse gastric cancer (HDGC) is an autosomal-dominant, inherited cancer syndrome in which affected individuals develop diffuse-type gastric cancer at a young age. Inactivating mutations in the E-cadherin gene CDH1 have been identified in 30% to 50% of patients. CDH1 mutation carriers have an approximately 70% lifetime risk of developing DGC, and affected women carry an additional 20% to 40% risk of developing lobular breast cancer. Because endoscopic surveillance is ineffective in identifying early HDGC, gene-directed prophylactic total gastrectomy currently is offered for CDH1 mutation carriers. In series of asymptomatic individuals undergoing total gastrectomy for CDH1 mutations, the removed stomachs usually contain small foci of early DGC, making surgery not prophylactic but curative. The authors of this review recommend consideration of total gastrectomy in CDH1 mutation carriers at an age 5 years younger than the youngest family member who developed gastric cancer. Individuals who choose not to undergo prophylactic gastrectomy should be followed with biannual chromoendoscopy, and women with CDH1 mutations also should undergo regular surveillance with magnetic resonance imaging studies of the breast. Because of the emergence of gene-directed gastrectomy for HDGC, today, a previously lethal disease is detected by molecular techniques, allowing curative surgery at an early stage.

Gastric cancer among American Indians and Alaska Natives in the United States, 1999-2004

BACKGROUND

Gastric cancer incidence rates for American Indians and Alaska Natives (AI/ANs) historically have exceeded those for non-Hispanic whites (NHWs). Previous reports may have underestimated the true burden of gastric cancer in AI/AN populations because of misclassification of AI/AN race in cancer registries.

METHODS

Population-based cancer registry data from 1999 through 2004 were used to describe gastric cancer incidence in AI/ANs and NHWs in the US. To address misclassification of race, registry data were linked with Indian Health Service administrative records, and analyses were restricted to residents of Contract Health Service Delivery Areas (CHSDA). Disease patterns were assessed for 6 geographic regions and for all regions combined. Rates were expressed per 100,000 population and were age-adjusted to the 2000 US standard population.

RESULTS

In CHSDA counties, gastric cancer incidence rates for AI/ANs were higher than the rates for NHWs across most regions. For both sexes combined, AI/AN rates ranged from 6.1 in the East region to 24.5 in Alaska; there was relatively little regional variation in NHW rates. Most patients with gastric cancer were diagnosed with late-stage disease, regardless of race, age, or sex. In some regions, cancer rates in the central/distal portions of the stomach were higher among AI/ANs than among NHWs, whereas rates in the proximal stomach were similar between the 2 populations.

CONCLUSIONS

AI/ANs are generally at greater risk for gastric cancer than NHWs. Relatively high rates of cancer in the central/distal portions of the stomach among AI/ANs in some geographic regions may indicate a disproportional burden of Helicobacter pylori-associated disease.

Hereditary diffuse gastric cancer: prophylactic surgical oncology implications

Hereditary diffuse gastric cancer (HDGC) is an autosomal dominantly inherited syndrome attributed to mutations of the E-cadherin gene, CDH1. There is no proven effective screening for early HDGC, and symptomatic disease is almost universally fatal. The only available effective option for CDH1 carriers is prophylactic total gastrectomy, but the variable age of onset of HDGC and the reduced penetrance (about 70%) of the CDHI gene further complicate patients' decision making.

Hereditary diffuse gastric cancer: surgery, surveillance and unanswered questions

Hereditary diffuse gastric cancer (HDGC) is an inherited cancer-susceptibility syndrome characterized by autosomal dominance and high penetrance. In 30–50% of cases, a causative germline mutation in CDH1, the E-cadherin gene, may be identified. Female carriers of CDH1 mutations also have an increased (20–40%) risk of lobular breast cancer. Endoscopic surveillance of patients with CDH1 mutations is ineffective because early foci of HDGC are typically small and underlie normal mucosa. CDH1 mutation carriers are therefore offered the option of prophylactic gastrectomy, which commonly reveals early foci of invasive signet-ring cell cancer. We review recommendations for genetic testing, surveillance and prophylactic surgery in HDGC. Areas for future research are discussed, including development of new screening modalities, optimal timing of prophylactic gastrectomy, identification of additional causative mutations in HDGC, management of patients with CDH1 missense mutations and prevention/early detection of lobular breast cancer in CDH1 mutation carriers.

Risk-reducing total gastrectomy for germline mutations in E-cadherin (CDH1): pathologic findings with clinical implications

Hereditary diffuse gastric cancer is a rare autosomal dominant cancer susceptibility syndrome caused by germline E-cadherin (CDH1) mutations in 40% of cases with a high degree of penetrance. Screening endoscopy has not been useful in identifying early cancer, in part owing to conflicting data concerning site(s) of involvement in the stomach and the lack of endoscopically detectable pathology. Risk-reducing total gastrectomy specimens from 8 asymptomatic adults with germline mutations in the CDH1 gene (3 different pedigrees) were studied using a sequential serial sectioning protocol with submission of the entire stomach for histologic analysis. The presence, size, and distribution of signet ring cell clusters were determined for each section and geographic maps of the invasive foci were constructed and compared with gastrectomy specimens from patients with germline E-cadherin mutation and symptomatic gastric cancer. All but 1 of the asymptomatic patients with germline mutations in the CDH1 gene had negative endoscopic screening. All risk-reducing gastrectomy specimens were macroscopically normal. All contained multiple foci (mean, 10.9) of microscopic intramucosal signet ring cell carcinoma confined to the superficial gastric mucosa; no invasion of submucosa was identified. In situ carcinoma was present in 6/8 cases. The majority of signet ring foci were located in the proximal one third of the stomach, most within oxyntic-type mucosa. The number and size of foci were not related to age, but there was a trend toward more severe disease burden in women. Stomachs from the symptomatic group of patients with germline CDH1 mutations exhibited infiltrative foci with higher Ki-67 labeling that extended well beyond the superficial mucosa. In addition, while superficial signet ring cancer exhibited decreased or absent E-cadherin and beta-catenin protein expression in all cases studied, deeply invasive signet ring cancer showed reversion to E-cadherin and beta-catenin protein expression in a subset of mutation carriers. Our study indicates that superficial intramucosal signet ring carcinoma, although widespread, is predominantly located in the proximal one third of the stomach in patients with E-cadherin gene mutations. The observed site predilection suggests a possible role for geographically targeted endoscopic surveillance biopsy in patients who elect to delay surgical intervention.

Hereditary diffuse gastric cancer: diagnosis, genetic counseling, and prophylactic total gastrectomy

BACKGROUND

A subset of patients with diffuse gastric cancer harbor deleterious cancer-causing germline mutations in the type 1 E-cadherin (epithelial) gene (CDH1), which predisposes to the autosomal dominantly inherited hereditary diffuse gastric cancer (HDGC) syndrome. These mutations are associated with a 70% life-time risk for diffuse gastric cancer (DGC) and an additional 40% risk for lobular breast cancer in women. Management options for unaffected mutation carriers include prophylactic total gastrectomy.

METHODS

Four HDGC pedigrees from a cohort of 56 CDH1 mutation-positive families were subjected to further analysis. Cancer diagnoses, whenever possible, were verified with pathology reports and/or slides/tissue block review. Genetic counseling for family members covered the natural history of HDGC, the pros and cons of mutation testing, the lack of effective screening procedures available to CDH1 mutation-positive individuals, and the option for them of prophylactic total gastrectomy.

RESULTS

Within the 4 families, carrier testing for mutations in the CDH1 gene was carried out on 52 individuals, including 25 individuals who were positive for mutation. Prophylactic gastrectomies were performed on a total of 17 individuals from 3 of the families, including 11 first cousins from 1 of the families. Occult DGC was diagnosed in gastrectomy specimens from 13 of 17 individuals (76.5%). During follow-up questioning, each of the 11 cousins stated that the decision for the prophylactic procedure was the "right one" for them.

CONCLUSIONS

Unaffected mutation carriers from HDGC families face difficult decisions and can be assisted best through education and interactions with counseling by an informed multidisciplinary team.

A novel computational and structural analysis of nsSNPs in CFTR gene

Single Nucleotide Polymorphisms (SNPs) are being intensively studied to understand the biological basis of complex traits and diseases. The Genetics of human phenotype variation could be understood by knowing the functions of SNPs. In this study using computational methods, we analyzed the genetic variations that can alter the expression and function of the CFTR gene responsible candidate for causing cystic fibrosis. We applied an evolutionary perspective to screen the SNPs using a sequence homology-based SIFT tool, which suggested that 17 nsSNPs (44%) were found to be deleterious. The structure-based approach PolyPhen server suggested that 26 nsSNPS (66%) may disrupt protein function and structure. The PupaSuite tool predicted the phenotypic effect of SNPs on the structure and function of the affected protein. Structure analysis was carried out with the major mutation that occurred in the native protein coded by CFTR gene, and which is at amino acid position F508C for nsSNP with id (rs1800093). The amino acid residues in the native and mutant modeled protein were further analyzed for solvent accessibility, secondary structure and stabilizing residues to check the stability of the proteins. The SNPs were further subjected to iHAP analysis to identify htSNPs, and we report potential candidates for future studies on CFTR mutations.

Predicting the effects of amino acid substitutions on protein function

Nonsynonymous single nucleotide polymorphisms (nsSNPs) are coding variants that introduce amino acid changes in their corresponding proteins. Because nsSNPs can affect protein function, they are believed to have the largest impact on human health compared with SNPs in other regions of the genome. Therefore, it is important to distinguish those nsSNPs that affect protein function from those that are functionally neutral. Here we provide an overview of amino acid substitution (AAS) prediction methods, which use sequence and/or structure to predict the effect of an AAS on protein function. Most methods predict approximately 25-30% of human nsSNPs to negatively affect protein function, and such nsSNPs tend to be rare in the population. We discuss the utility of AAS prediction methods for Mendelian and complex diseases as well as their broader applications for understanding protein function.

DNA polymorphisms in exon 1 and promoter of the CDH1 gene and relevant risk of transitional cell carcinoma of the urinary bladder

OBJECTIVE

To investigate the association between DNA polymorphisms, including single-nucleotide polymorphisms (SNPs) and insertion/deletion polymorphisms, in exon 1 and promoter of the CDH1 gene, and the risk of transitional cell carcinoma (TCC) of the urinary bladder (TCCB).

PATIENTS, SUBJECTS AND METHODS

This was a hospital-based case-control study of 180 patients with TCCB and 110 normal controls. Genomic DNA was extracted from blood samples of all participants and genotypes determined using polymerase chain reaction and DNA sequencing techniques. Haplotypes were analysed using appropriate software.

RESULTS

SNPs were detected at -160A/C, -73A/C and 178C/T; an inserted oligonucleotide of 5'-CCGTGCCCCAGCC-3' was identified at 234 bp. The -160A allele frequency in the case group was 0.67, statistically higher than in the control group (0.42; P < 0.001), and higher in invasive carcinoma (0.77) than in superficial carcinoma (0.60). For -73C/A and 178C/T SNPs there was no difference among genotypes. The 234 repeat oligonucleotide insertion (2I) frequencies in cases was 0.27, statistically higher than in the control group (0.17; P = 0.01). The most common haplotype in controls was C-A-T-I (28%), the frequency of which was higher than in the TCCB group (6%). The A-A-T-2I was the only variation distribution carrying the -160A allele and was at a statistically higher frequency in the TCCB group (37%, the most common haplotype in cases) than in the control group.

CONCLUSION

The -160A, 234 2I allele and haplotype A-A-T-2I were risk factors of TCCB. Haplotype C-A-T-I might act as a protective factor for TCCB.

Transitions between epithelial and mesenchymal states in development and disease

The ancestors of modern Metazoa were constructed in large part by the foldings and distortions of two-dimensional sheets of epithelial cells. This changed approximately 600 million years ago with the evolution of mesenchymal cells. These cells arise as the result of epithelial cell delamination through a reprogramming process called an epithelial to mesenchymal transition (EMT) [Shook D, Keller R. Mechanisms, mechanics and function of epithelial-mesenchymal transitions in early development. Mech Dev 2003;120:1351-83; Thiery JP, Sleeman JP. Complex networks orchestrate epithelial-mesenchymal transitions. Nat Rev Mol Cell Biol 2006;7:131-42]. Because mesenchymal cells are free to migrate through the body cavity, the evolution of the mesenchyme opened up new avenues for morphological plasticity, as cells evolved the ability to take up new positions within the embryo and to participate in novel cell-cell interactions; forming new types of internal tissues and organs such as muscle and bone [Thiery JP, Sleeman, JP. Complex networks orchestrate epithelial-mesenchymal transitions. Nat Rev Mol Cell Biol 2006;7:131-42; Hay ED, Zuk A. Transformations between epithelium and mesenchyme: normal, pathological, and experimentally induced. Am J Kidney Dis 1995;26:678-90]. After migrating to a suitable site, mesenchymal cells coalesce and re-polarize to form secondary epithelia, in a so-called mesenchymal-epithelial transition (MET). Such switches between mesenchymal and epithelial states are a frequent feature of Metazoan gastrulation [Hay ED, Zuk A. Transformations between epithelium and mesenchyme: normal, pathological, and experimentally induced. Am J Kidney Dis 1995;26:678-90] and the neural crest lineage [Duband JL, Monier F, Delannet M, Newgreen D. Epitheliu-mmesenchyme transition during neural crest development. Acta Anat 1995;154:63-78]. Significantly, however, when hijacked during the development of cancer, the ability of cells to undergo EMT, to leave the primary tumor and to undergo MET at secondary sites can have devastating consequences on the organism, allowing tumor cells derived from epithelia to invade surrounding tissues and spread through the host [Thiery JP, Sleeman JP. Complex networks orchestrate epithelial-mesenchymal transitions. Nat Rev Mol Cell Biol 2006;7:131-42; Hay ED, Zuk A. Transformations between epithelium and mesenchyme: normal, pathological, and experimentally induced. Am J Kidney Dis 1995;26:678-90]. Thus, the molecular and cellular mechanisms underpinning EMT are both an essential feature of Metazoan development and an important area of biomedical research. In this review, we discuss the common molecular and cellular mechanisms involved in EMT in both cases.

Genetics of gastroesophageal cancer: paradigms, paradoxes, and prognostic utility

Hereditary diffuse gastric cancer and tylosis are autosomal dominant cancer susceptibility syndromes. Accumulating evidence also suggests a genetic contribution to Barrett's esophagus and adenocarcinoma, traditionally considered acquired disorders. In this article we review the current knowledge on the genetic mechanisms underlying hereditary diffuse gastric cancer, tylosis, and Barrett's esophagus. Hereditary diffuse gastric cancer is a paradigm for hereditary cancer susceptibility syndromes with E-cadherin implicated as the dominant oncogene in up to one-third of cases. Tylosis in contrast remains the paradox as whilst the putative abnormality has been localized to the long arm of chromosome 17, sequencing of this region has failed to reveal a disease causing mutation. In the case of Barrett's esophagus and adenocarcinoma, although a validated specific disease-associated gene is yet to be identified, the increasing body of evidence of a possible genetic link is paving the way for subsequent prognostic studies such as AspECT (Aspirin Esomeprazole Chemoprevention Trial). For the clinician these advances in understanding are already having implications for practice in terms of improved screening and the stratification of management strategies. As the mechanisms continue to be defined, there is the real possibility that these mechanisms could be exploited or subverted in the design of new therapies. In the meantime, however, clinicians should undertake rigorous biopsy programs to ensure early invasive lesions are detected.

Identification of an intronic single nucleotide polymorphism leading to allele dropout during validation of a CDH1 sequencing assay: implications for designing polymerase chain reaction-based assays

PURPOSE

The CDH1 gene encodes the cell adhesion protein E-cadherin, and CDH1 germline mutations are associated with hereditary diffuse gastric cancer. Identification of individuals at high risk of developing diffuse gastric cancer affords the opportunity for endoscopic screening or elective prophylactic gastrectomy. We set out to develop a CDH1 sequencing assay for clinical use.

METHODS

All exons of the CDH1 gene were amplified and sequenced with published and modified primers.

RESULTS

While validating the assay, we encountered a case in which a single nucleotide polymorphism located in intron 15 led to allele dropout and therefore to a false-negative result. The polymorphism leading to allele dropout was located within a primer-binding sequence, five bases away from the 3' end of the primer. A frameshift mutation in exon 15 was detected by an alternative primer that binds away from the polymorphic site. A search of the University of California Santa Cruz single nucleotide polymorphism database revealed other polymorphisms located within primer-binding sites. A total of 12 primers in nine primer sets were modified to minimize allele dropout risk.

CONCLUSION

The approach of designing primers to avoid known single nucleotide polymorphisms can be generalized to the design of any polymerase chain reaction-based assay and should be employed whenever possible.

Hereditary diffuse gastric cancer: association with lobular breast cancer

Hereditary diffuse gastric cancer (HDGC) has been shown to be caused by germline mutations in the gene CDH1 located at 16q22.1, which encodes the cell-cell adhesion molecule, E-cadherin. Not only does loss of expression of E-cadherin account for the morphologic differences between intestinal and diffuse gastric cancer (DGC) variants, but it also appears to lead to distinct cellular features which appear to be common amongst related cancers that have been seen in the syndrome. As in most hereditary cancer syndromes, multiple organ sites may be commonly affected by cancer, in HDGC, lobular carcinoma of the breast (LBC) and possibly other organ sites have been shown to be associated with the familial cancer syndrome. Given the complexity of HDGC, not only with regard to the management of the DGC risk, but also with regard to the risk for other related cancers, such as LBC, a multi-disciplinary approach is needed for the management of individuals with known CDH1 mutations.

A short guide to hereditary diffuse gastric cancer

Hereditary diffuse gastric cancer (HDGC) is the only known predisposition syndrome dominated by carcinoma of the stomach and with a recognised genetic cause. Germline mutations in the E-cadherin gene (CDH1) co-segregate with the disease in about half of the families with multiple diffuse gastric cancer. In these families, identification of the CDH1 mutation allows for clinical measures to be taken. Importantly, clinical intervention is likely to be therapeutic and associated with tolerable morbidity. This review is thus aimed at providing a current overview of the clinical management and the underlying biology of HDGC.

A systematic evaluation of the ataxia telangiectasia mutated gene does not show an association with non-Hodgkin lymphoma

The ataxia telangiectasia mutated (ATM) gene is critical for the detection and repair of DNA double-stranded breaks. Mutations in this gene cause the autosomal recessive syndrome ataxia telangiectasia (AT), an attribute of which is an increased risk of cancer, particularly lymphoma. We have undertaken a population-based case/control study to assess the influence of genetic variation in ATM on the risk of non-Hodgkin lymphoma (NHL). A number of the subtypes that constitute NHL have in common the occurrence of specific somatic translocations that contribute to lymphomagenesis. We hypothesize that ATM function is slightly attenuated by some variants, which could reduce double-stranded break repair capacity, contributing to the occurrence of translocations and subsequent lymphomas. We sequenced the promoter and all exons of ATM in the germline DNA of 86 NHL patients and identified 79 variants. Eighteen of these variants correspond to nonsynonymous amino acid differences, 6 of which were predicted to be deleterious to protein function; these variants were all rare. Eleven common variants make up 10 haplotypes that are specified by 7 tagSNPs. Linkage disequilibrium across the ATM gene is high but incomplete. TagSNPs and the 6 putatively deleterious variants were genotyped in 798 NHL cases and 793 controls. Our results indicate that common variants of ATM do not significantly contribute to the risk of NHL in the general population. However, some rare, functionally deleterious variants may contribute to an increased risk of development of rare subtypes of the disease.

Genetic variation in H2AFX contributes to risk of non-Hodgkin lymphoma

Non-Hodgkin lymphoma (NHL) comprises a group of lymphoid tumors that have in common somatic translocations. H2AFX encodes a key histone involved in the detection of the DNA double-stranded breaks that can lead to translocations. H2afx is a dosage-dependent gene that protects against B-cell lymphomas in mice, making its human orthologue an ideal candidate gene for susceptibility to lymphoma. We did a population-based genetic association study of H2AFX variants in 487 NHL cases and 531 controls. Complete resequencing of the human H2AFX gene in 95 NHL cases was done to establish the spectrum of variation in affected individuals; this was followed by both direct and indirect tests for association at the level of individual single nucleotide polymorphisms (SNP) and as haplotypes. Homozygosity for the AA genotype of a SNP 417 bp upstream of the translational start of H2AFX is strongly associated [odds ratio (OR), 0.54; P = 0.001] with protection from NHL. We find a strong association of this SNP with the follicular lymphoma subtype of NHL (AA genotype: OR, 0.40; P = 0.004) and with mantle cell lymphoma (AA genotype: OR, 0.20; P = 0.01) that remains significant after adjustment for the false discovery rate, but not with diffuse large B-cell lymphoma. These data support the hypothesis that genetic variation in the H2AFX gene influences genetic susceptibility or resistance to some subtypes of NHL by contributing to the maintenance of genome stability.

Germline E-cadherin mutations in familial lobular breast cancer

BACKGROUND

The cell surface glycoprotein E-cadherin (CDH1) is a key regulator of adhesive properties in epithelial cells. Germline mutations in CDH1 are well established as the defects underlying hereditary diffuse gastric cancer (HDGC) syndrome, and an increased risk of lobular breast cancer (LBC) has been described in HDGC kindreds. However, germline CDH1 mutations have not been described in patients with LBC in non-HDGC families. This study aimed to investigate the frequency of germline CDH1 mutations in patients with LBC with early onset disease or family histories of breast cancer without DGC.

METHODS

Germline DNA was analysed in 23 women with invasive lobular or mixed ductal and lobular breast cancers who had at least one close relative with breast cancer or had themselves been diagnosed before the age of 45 years, had tested negative for a germline BRCA1 or BRCA2 mutation, and reported no personal or family history of diffuse gastric cancer. The full coding sequence of CDH1 including splice junctions was amplified using PCR and screened for mutations using DHPLC and sequencing.

RESULTS

A novel germline CDH1 truncating mutation in the extracellular portion of the protein (517insA) was identified in one woman who had LBC at the age of 42 years and a first degree relative with invasive LBC.

CONCLUSIONS

Germline CDH1 mutations can be associated with invasive LBC in the absence of diffuse gastric cancer. The finding, if confirmed, may have implications for management of individuals at risk for this breast cancer subtype. Clarification of the cancer risks in the syndrome is essential.

CDH1 truncating mutations in the E-cadherin gene: an indication for total gastrectomy to treat hereditary diffuse gastric cancer

BACKGROUND

Approximately 1% to 3% of all gastric cancers are associated with families exhibiting an autosomal dominant pattern of susceptibility. E-cadherin (CDH1) truncating mutations have been shown to be present in approximately 30% of families with hereditary diffuse gastric cancer (HDGC) and are associated with a significantly increased risk of gastric cancer and lobular breast cancer.

METHODS

Individuals from a large kindred with HDGC who were identified to have a CDH1 mutation prospectively underwent comprehensive screening with stool occult blood testing, standard upper gastrointestinal endoscopy with random gastric biopsies, high-magnification endoscopy with random gastric biopsies, endoscopic ultrasonography, CT, and PET scans to evaluate the stomach for occult cancer. Subsequently, they each underwent total gastrectomy with D-2 node dissection and Roux-en-Y esophagojejunostomy. The stomach and resected lymph nodes were evaluated pathologically.

RESULTS

Six patients were identified as CDH1 carriers from a single family. There were 2 men and 4 women. The mean age was 54 years (range, 51-57 years). No patient had any signs or symptoms of gastric cancer. Exhaustive preoperative stomach evaluation was normal in each case, and the stomach and adjacent lymph nodes appeared normal at surgery. However, each patient (6 of 6, 100%) was found to have multiple foci of T1 invasive diffuse gastric adenocarcinoma (pure signet-ring cell type). No patient had lymph node or distant metastases. Each was staged as T1N0M0. Each patient recovered uneventfully without morbidity or mortality.

CONCLUSIONS

CDH1 mutations in individuals from families with HDGC are associated with gastric cancer in a highly penetrant fashion. CDH1 mutations are an indication for total gastrectomy in these patients. This mutation will identify patients with cancer before other detectable symptoms or signs of the disease.

Allogeneic transplantation and the risk for transmission of genetic disease: the heritable cancer disorders

With the development of new approaches to transplantation therapy, such as those building upon the potential found in stem cells, it is vital to pursue a clear understanding of transplantation risks. Allogeneic transplantation presents risk for the transmission of disease of various types, including genetic disease. Predisposition to develop cancer is a feature of numerous genetic disorders, and it may be transmissible by transplantation. Some genetic disorders predisposing to cancer are remarkably common, either worldwide or in specific populations, and they could pose significant risk. Hence, to reduce risk to recipients, there is reason to exclude from donation those potential donors (including embryos) harboring certain germ-line mutations. However, the frequent absence of readily identifiable features might confound the effort to exclude those who harbor mutation. Thus, it is also important to consider the magnitude of risk that they represent. For some disorders, life-threatening cancer is highly likely to develop in those individuals born with germ-line mutation, but whether recipients would face the same risk from transplanted mutation is not always evident. Given the diversity of pathways that lead to cancer, there may be diverse factors that impact the likelihood for cancer to develop in the recipient, with some factors decreasing and others increasing the risk. One factor of special concern is the possibility that manipulation of donor cells, prior to transplantation, might introduce additional genetic or epigenetic abnormality, thereby increasing the risk.

Deciphering the underlying genetic and epigenetic events leading to gastric carcinogenesis

Gastric cancer is a common aggressive malignancy. Although its incidence shows considerable variation among different countries, gastric cancer is still a major health problem worldwide. The causes of stomach cancer are not completely understood. What is clear is that gastric cancer is a multi-stage process involving genetic and epigenetic factors. This review is an in-depth study of the known genetic and epigenetic processes in the development of this tumor, and delineates possible approaches in gene and epigenetic therapy.

Characterization of the P373L E-cadherin germline missense mutation and implication for clinical management

AIM

Hereditary diffuse gastric cancer (HDGC) is a cancer susceptibility syndrome caused by E-cadherin germline mutations. One-third of these mutations are of the missense type, representing a burden in genetic counselling. A new germline missense mutation (P373L) was recently identified in a HDGC Italian family. The present work aimed at addressing the disease-causative nature of the P373L mutant.

METHODS

Assessment of the P373L mutation effect was based on cell aggregation and invasion assays. LOH analysis at the E-cadherin locus, search for somatic E-cadherin mutations and for promoter hypermethylation were performed to identify the mechanism of inactivation of the E-cadherin wild-type allele in the tumour.

RESULTS

In vitro the P373L germline mutation impaired the E-cadherin functions. E-cadherin promoter hypermethylation was observed in the tumour of the P373L mutation carrier.

CONCLUSION

We conclude that the combination of clinical, in vitro and molecular genetic data is helpful for establishing an accurate analysis of HDGC-associated CDH1 germline missense mutations and subsequently for appropriate clinical management of asymptomatic mutation carriers.

Lobular in situ neoplasia and columnar cell lesions: diagnosis in breast core biopsies and implications for management

Histopathologists are encountering intra-lobular epithelial proliferations more frequently in core biopsies taken from lesions identified in mammographic breast screening programmes. In particular, columnar cell lesions are increasingly being seen in core biopsies taken for the histological assessment of mammographically detected microcalcifications. The morphological features of lobular neoplasia are relatively well known, but columnar cell lesions, particularly forms with atypical features, are less widely recognised. The biological and clinical significance of both of these intra-lobular processes is controversial, (1) as indicators of adjacent malignancy when encountered in core biopsy, (2) the relative risk conferred of development of subsequent malignancy, and (3) their precursor behaviour. For this reason, the optimal clinical management of these lesions, particularly when encountered on core biopsy, is unclear. This review provides an update on the histological diagnosis of lobular neoplasia and columnar cell lesions and outlines recent clinico-pathological and molecular findings with discussion on clinical management.

[Hereditary diffuse gastric cancer]

Some diffuse type gastric cancers are of hereditary origin. Their histological characteristics are poor cell differentiation and the presence of signet-ring cells. The cause is a mutation of the CDH1 gene which is responsible for abnormal E-cadherin. The transmission mode is autosomal dominant. Because of serious prognosis of symptomatic hereditary diffuse gastric cancer (HDGC), the high penetrance of the gene (67% in men and 83% in women) and the young age of onset of these tumors (before the age of 40), a prophylactic gastrectomy is recommended to the mutation carriers. The search for the genetic mutation should be recommended to families corresponding to clinical criteria such as the number of affected family members, degree of relationship and age of onset of these tumors.

Non-operative breast pathology: lobular neoplasia

Lobular neoplasia is a relatively uncommon lesion, which is frequently diagnosed in biopsy specimens taken for other reasons. Although the histological features of this lesion are well known, its biological significance as a "risk indicator" or "breast cancer precursor" has been a matter of debate. This review provides an update on recent clinicopathological and molecular data on lobular neoplasia and how these have changed the way these lesions are perceived and, most importantly, managed. Furthermore, the current recommendations for the management of lobular neoplasia diagnosed on core needle biopsies proposed in the National Health Service Breast Cancer Screening guidelines are discussed.

A novel mutation in the E-cadherin gene in the first family with hereditary diffuse gastric cancer reported in Spain

AIMS

Mutations of the E-cadherin gene (CDH1) result in dominantly inherited hereditary diffuse gastric cancer (HDGC). We report a study in the first family diagnosed with HDGC in Spain, examining the presence of mutations in the CDH1 gene.

METHODS

The presence of mutations was studied by direct sequencing of all CDH1 exons. Immunohistochemical analysis with specific antibodies was used to detect the expression of E-cadherin in normal and tumour tissue.

RESULTS

A novel 1610delC mutation in exon 11 has been found in a Spanish family diagnosed with HDGC. This mutation generates a premature stop codon at position 1667 giving rise to a truncated protein that lacks the transmembrane and beta-catenin-binding domains. The presence of a 1610delC germline mutation was confirmed in three family members diagnosed with diffuse gastric cancer, and also in six asymptomatic members. Of note, the diffuse gastric cancer coexisted with a gastric lymphoma in the proband. Furthermore, immunohistochemical analyses of tumour tissue showed the complete absence of E-cadherin in the proband, revealing a second genetic hit at the CDH1 locus.

CONCLUSIONS

We have identified a HDGC family in Spain that carries a novel germline truncating mutation in the CDH1 gene.

Hereditary diffuse gastric cancer and E-cadherin: description of the first germline mutation in an Italian family

AIMS

Germline mutation of the E-cadherin gene (CDH1) accounts for the Hereditary Diffuse Gastric Cancer (HDGC) syndrome. Fourteen pedigrees with Diffuse Gastric Cancer that fulfilled the International Gastric Cancer Linkage Consortium (IGCLC) criteria were selected and screened for CDH1 germline mutations.

METHODS

The entire coding region of the CDH1 gene and all intron-exon boundaries were analyzed by direct sequencing in the 14 families fulfilling the IGCLC criteria. E-cadherin immunohistochemical expression was evaluated on tumour as well as normal formalin-fixed paraffin embedded tissues.

RESULTS

A novel germline missense mutation was found. It was a single C-->T substitution in exon 8, resulting in a transition of CCG-->CTG (C1118T; Pro373Leu) demonstrated in the proband and her brother. At immunohistochemical analysis, the staining intensity was reduced and considered weakly positive (15%).

CONCLUSIONS

The first CDH1 germline mutation of an Italian family is herein reported. The present missense mutation has never been described so far.

FGFR1 Emerges as a Potential Therapeutic Target for Lobular Breast Carcinomas

PURPOSE

Classic lobular carcinomas (CLC) account for 10% to 15% of all breast cancers. At the genetic level, CLCs show recurrent physical loss of chromosome16q coupled with the lack of E-cadherin (CDH1 gene) expression. However, little is known about the putative therapeutic targets for these tumors. The aim of this study was to characterize CLCs at the molecular genetic level and identify putative therapeutic targets.

EXPERIMENTAL DESIGN

We subjected 13 cases of CLC to a comprehensive molecular analysis including immunohistochemistry for E-cadherin, estrogen and progesterone receptors, HER2/neu and p53; high-resolution comparative genomic hybridization (HR-CGH); microarray-based CGH (aCGH); and fluorescent and chromogenic in situ hybridization for CCND1 and FGFR1.

RESULTS

All cases lacked the expression of E-cadherin, p53, and HER2, and all but one case was positive for estrogen receptors. HR-CGH revealed recurrent gains on 1q and losses on 16q (both, 85%). aCGH showed a good agreement with but higher resolution and sensitivity than HR-CGH. Recurrent, high level gains at 11q13 (CCND1) and 8p12-p11.2 were identified in seven and six cases, respectively, and were validated with in situ hybridization. Examination of aCGH and the gene expression profile data of the cell lines, MDA-MB-134 and ZR-75-1, which harbor distinct gains of 8p12-p11.2, identified FGFR1 as a putative amplicon driver of 8p12-p11.2 amplification in MDA-MB-134. Inhibition of FGFR1 expression using small interfering RNA or a small-molecule chemical inhibitor showed that FGFR1 signaling contributes to the survival of MDA-MB-134 cells.

CONCLUSIONS

Our findings suggest that receptor FGFR1 inhibitors may be useful as therapeutics in a subset of CLCs.

A model to infer the pathogenic significance of CDH1 germline missense variants

Germline mutations of the E-cadherin gene (CDH1) are involved in the tumorigenesis of hereditary diffuse gastric cancer (HDGC). Recent studies have highlighted the lifesaving potential of total prophylactic gastrectomy for CDH1 germline mutation carriers. In this regard, CDH1 germline mutations of the missense type represent a clinical burden in genetic counseling, as their pathogenic relevance is not straightforward. In this work, we have outlined a possible multivariate approach to infer the significance of such variants. We reviewed all HDGC-associated E-cadherin germline missense mutations reported to date. The information collected included: co-segregation of the mutation within pedigrees, frequency in healthy population control, recurrence in independent families, and functional in vitro and in silico data. We used the neighbor-joining method to group mutations according to the collected information and assessed the robustness of mutation clusters with a bootstrap test. CDH1 germline missense variants were classified according to the parameters defined in the multivariate analysis. This analysis allowed the distribution of the variants into two distinct groups: neutral variants vs mutations. The model described in this study provides an important tool that can ultimately improve the genetic counseling offered to the carriers of the germline CDH1 missense variants.

CDH1/E-cadherin germline mutations in early-onset gastric cancer

BACKGROUND

Gastric cancer remains a leading cause of cancer deaths worldwide. Genetic factors, including germline mutations in E-cadherin (CDH1, MIM#192090) in hereditary diffuse gastric cancer (HDGC, MIM#137215), are implicated in this disease. Family studies have reported CDH1 germline mutations in HDGC but the role of CDH1 germline mutations in the general population remains unclear.

AIMS

To examine the frequency of CDH1 germline mutations in a population-based series of early-onset gastric cancer (EOGC <50 years old).

METHODS

211 cases of EOGC were identified in Central-East Ontario region from 1989 to 1993, with archival material and histological confirmation of non-intestinal type gastric cancer available for 81 subjects. Eligible cases were analysed for CDH1 germline mutations by single-strand conformation polymorphism, variants were sequenced, and tumours from cases with functional mutations were stained for E-cadherin (HECD-1) using immunohistochemistry.

RESULTS

1155 (89%) of 1296 polymerase chain reactions amplified successfully. One new germline deletion (nt41delT) was identified in a 30-year-old patient with isolated cell gastric cancer. The overall frequency of germline CDH1 mutations was 1.3% (1/81) for EOGC and 2.8% (1/36) for early-onset isolated cell gastric cancer.

CONCLUSION

This is the first population-based study, in a low-incidence region, of genetic predisposition to gastric cancer. Combined with our previous report of germline hMLH1 mutations in two other subjects from this series, it is suggested that 2-3% of EOCG cases in North Americans may be owing to high-risk genetic mutations. These data should inform cancer geneticists on the utility of searching for specific genetic mutations in EOGC.

Establishing a cancer genetics programme in Asia - the singapore experience

Cancer genetics is now an established oncology subspecialty with the primary prevention role of identifying high-risk individuals through genetic information for enrolment into screening and preventive programmes. Integrated into major Western centres since the late 1990s, such a programme has been established in Singapore since 2001. Our programme has evaluated 367 index patients comprising mainly breast and colorectal cancer cases. Cancer patients were receptive to genetic counselling, but cost posed a major barrier to genetic testing. However, when the cost barrier was removed through government subsidy plans, more than half of high-risk patients still declined testing. The major barriers were reluctance to involve family members, perception that the information would not change management, and fears of negative feelings. Confirmed mutation carriers were compliant to screening and receptive to prophylactic surgery. Uptake of predictive testing among cancer-free family members has been low, possibly arising from the stigma associated with cancer in our Asian culture. These potential barriers are being addressed through government subsidy plans, continuing education to increase awareness, and being culturally sensitive when dealing with the Asian family.

Genetics of hereditary diffuse gastric cancer: progress and future challenges

Hereditary diffuse gastric cancer (HDGC) is a rare cancer susceptibility syndrome. One third of HDGC syndrome families carry germline mutations of the E-cadherin gene. Owing to the limitation of the current endoscopic screening techniques and since no chemoprevention is yet available, total prophylactic gastrectomy is the only option offered to carriers of inactivating mutations in genetic counseling. In this regard, 30% of the E-cadherin germline mutations reported to date are of the missense type, and since their pathogenic significance is not straightforward, the management of carriers of such mutations is suboptimal. In the absence of definitive clinical evidence, functional in vitro studies together with in silico analysis have been used to infer the pathogenic significance of germline missense mutations. Since most of the HDGC families reported to date are negative for E-cadherin germline mutations, the identification of alternative genes underlying the tumorigenesis of diffuse gastric has become an important target for research.

Critical interactions between TGF-beta signaling/ELF, and E-cadherin/beta-catenin mediated tumor suppression

Inactivation of the transforming growth factor-beta (TGF-beta) pathway occurs often in malignancies of the gastrointestinal (GI) system. However, only a fraction of sporadic GI tumors exhibit inactivating mutations in early stages of cancer formation, suggesting that other mechanisms play a critical role in the inactivation of this pathway. Here, we show a wide range of GI tumors, including those of the stomach, liver and colon in elf+/- and elf+/- / Smad4+/- mutant mice. We found that embryonic liver fodrin (ELF), a beta-Spectrin originally identified in endodermal stem/progenitor cells committed to foregut lineage, possesses potent antioncogenic activity and is frequently inactivated in GI cancers. Specifically, E-cadherin accumulation at cell-cell contacts and E-cadherin-beta-catenin-dependent epithelial cell-cell adhesion is disrupted in elf+/- / Smad4+/- mutant gastric epithelial cells, and could be rescued by ectopic expression of full-length elf, but not Smad3 or Smad4. Subcellular fractionation revealed that E-cadherin is expressed mainly at the cell membrane after TGF-beta stimulation. In contrast, elf+/- / Smad4+/- mutant tissues showed abnormal distribution of E-cadherin that could be rescued by overexpression of ELF but not Smad3 or Smad4. Our results identify a group of common lethal malignancies in which inactivation of TGF-beta signaling, which is essential for tumor suppression, is disrupted by inactivation of the ELF adaptor protein.

Genetics, pathology, and clinics of familial gastric cancer

Gastric cancer is relatively common worldwide, mainly in its sporadic form, but familial aggregation of the disease may be seen in approximately 10% of the cases. This suggests a genetic cause for the cancer in those families that has not been identified in most cases. Despite all efforts to determine its genetic basis, a single syndrome has been characterized-the hereditary diffuse gastric cancer (HDGC)-which is specifically associated with CDH1 (E-cadherin) germline mutations in one third of the families. The other two thirds and all the gastric cancer families not fulfilling the HDGC criteria remain without molecular diagnosis. In this article we review the state of the art of familial gastric cancer regarding the molecular aspects, the clinical criteria, the pathology features, and the management recommendations described so far to be associated with this cancer disease.

Hereditary diffuse gastric cancer: diagnosis and management

Hereditary diffuse gastric cancer (HDGC) is a familial cancer syndrome defined by germline mutation of the E-cadherin gene (CDH-1). The cumulative risk for advanced gastric cancer in HDGC is 67% in men and 83% in women by 80 years of age. Early HDGC is characterized by multiple microscopic foci of intramucosal signet-ring cell carcinoma. The time to progression of these foci appears to be variable and currently is not predictable--the carcinoma foci may remain confined to the mucosa for many years. The management options for mutation carriers include prophylactic gastrectomy or surveillance gastroscopy. The only extensive published surveillance experience used chromogastroscopy, which detected early HDGC foci not visible on white-light endoscopy. The use of new techniques such as confocal microscopy, spectroscopy, or autofluorescence may prove useful, but have not been studied in HDGC. In patients up to 20 years of age, the risk for gastric cancer is less than 1%; this risk is outweighed by the mortality and morbidity associated with total gastrectomy. It is therefore recommended that genetic testing should occur at 16 years of age and that annual surveillance chromogastroscopy also should begin at age 16 in identified CDH-1 mutation carriers. After 20 years of age, delaying prophylactic gastrectomy carries significant risk, particularly if the alternative is surveillance by white-light gastroscopy. Surveillance chromogastroscopy (Congo red/methylene blue technique) should be considered for individuals younger than 20 years and patients unwilling to undergo prophylactic gastrectomy. Sufficient evidence for an increased risk for lobular breast cancer in CDH-1 carriers exists to justify breast screening in female carriers older than 35 years of age, however, evidence is insufficient to recommend prophylactic mastectomy.

Twist overexpression induces in vivo angiogenesis and correlates with chromosomal instability in breast cancer

Aggressive cancer phenotypes are a manifestation of many different genetic alterations that promote rapid proliferation and metastasis. In this study, we show that stable overexpression of Twist in a breast cancer cell line, MCF-7, altered its morphology to a fibroblastic-like phenotype, which exhibited protein markers representative of a mesenchymal transformation. In addition, it was observed that MCF-7/Twist cells had increased vascular endothelial growth factor (VEGF) synthesis when compared with empty vector control cells. The functional changes induced by VEGF in vivo were analyzed by functional magnetic resonance imaging (MRI) of MCF-7/Twist-xenografted tumors. MRI showed that MCF-7/Twist tumors exhibited higher vascular volume and vascular permeability in vivo than the MCF-7/vector control xenografts. Moreover, elevated expression of Twist in breast tumor samples obtained from patients correlated strongly with high-grade invasive carcinomas and with chromosome instability, particularly gains of chromosomes 1 and 7. Taken together, these results show that Twist overexpression in breast cancer cells can induce angiogenesis, correlates with chromosomal instability, and promotes an epithelial-mesenchymal-like transition that is pivotal for the transformation into an aggressive breast cancer phenotype.

Characterization of a recurrent germ line mutation of the E-cadherin gene: implications for genetic testing and clinical management

PURPOSE

To identify germ line CDH1 mutations in hereditary diffuse gastric cancer (HDGC) families and develop guidelines for management of at risk individuals.

EXPERIMENTAL DESIGN

We ascertained 31 HDGC previously unreported families, including 10 isolated early-onset diffuse gastric cancer (DGC) cases. Screening for CDH1 germ line mutations was done by denaturing high-performance liquid chromatography and automated DNA sequencing.

RESULTS

We identified eight inactivating and one missense CDH1 germ line mutation. The missense mutation conferred in vitro loss of protein function. Two families had the previously described 1003C>T nonsense mutation. Haplotype analysis revealed this to be a recurrent and not a founder mutation. Thirty-six percent (5 of 14) of the families with a documented DGC diagnosed before the age of 50 and other cases of gastric cancer carried CDH1 germ line mutations. Two of 10 isolated cases of DGC in individuals ages <35 years harbored CDH1 germ line mutations. One mutation positive family was ascertained through a family history of lobular breast cancer (LBC) and another through an individual with both DGC and LBC. Occult DGC was identified in five of six prophylactic gastrectomies done on asymptomatic, endoscopically negative 1003C>T mutation carriers.

CONCLUSIONS

In addition to families with a strong history of early-onset DGC, CDH1 mutation screening should be offered to isolated cases of DGC in individuals ages <35 years and for families with multiple cases of LBC, with any history of DGC or unspecified GI malignancies. Prophylactic gastrectomy is potentially a lifesaving procedure and clinical breast screening is recommended for asymptomatic mutation carriers.

Familial gastric cancer - aetiology and pathogenesis

Gastric cancer is the second most common cause of cancer death worldwide. It is estimated that 5-10% of gastric cancer cases have a familial association; however, knowledge concerning the genetic predisposition to familial gastric cancer is currently limited. In this chapter we discuss what is known about the aetiology and pathogenesis of both the diffuse and intestinal forms of familial gastric cancer. We focus particularly on hereditary diffuse gastric cancer because the discovery of germ-line E-cadherin mutations in a number of affected families has opened the prospect of identifying gene carriers, with implications for clinical management. The interplay of other conventional risk factors, such as Helicobacter pylori infection, with genetic factors is also discussed. It is hoped that understanding the genetic basis for familial gastric cancer will facilitate the development of clinically useful screening and preventative procedures.

[Prophylactic gastric surgery]

A premalignant condition with high risk of gastric cancer is the basis for prophylactic gastric surgery. The germline mutation carrier in the E-cadherin gene has a lifetime risk of 70-80% for diffuse-type gastric cancer, and high-grade intraepithelial neoplasia has a 60-70% gastric cancer risk. Other premalignant conditions such as HNPCC syndrome (5% gastric cancer) and low-grade intraepithelial neoplasia (10% risk) are moderate risk factors for developing gastric cancer. They do not justify prophylactic surgery, but surveillance is required. In case high-grade intraepithelial neoplasia or early gastric cancer is detected, an option is extended radicality with total gastrectomy instead of subtotal gastric resection. Positive family history and early-onset of gastric cancer are risk factors to consider when discussing prophylactic gastrectomy or extended radicality.

Lobular breast cancer: excess familiality observed in the Utah Population Database

Family history of breast cancer (BC) is a strong predictor for developing female BC. Whether this excess familiality differs within morphological BC subgroups remains unclear. We assessed the risk of lobular breast cancer (LOB) and any BC among relatives of probands with LOB. We used the Utah Population Database (UPDB) to estimate familial relative risks (FRR) as well as average relatedness, using the genealogical index of familiality (GIF) statistic. The UPDB, a population-based resource, links genealogical data from over 2 million individuals to the Utah Cancer Registry. Consistent with other studies, analysis of all BC cases showed significantly increased risk of BC to relatives (first-degree relative [FDR]: FRR = 1.83, 95% confidence interval [CI] = 1.75-1.90). Morphology-specific risks showed that relatives of LOB probands had an increased risk of LOB (FDR: FRR = 4.51, 95% CI = 2.79-6.89) and an increased risk of any BC (FDR: FRR = 2.47, 95% CI = 2.12-2.85); both measures were significantly greater than the all BC FRR estimates, and surpassed even generalized early-onset BC risk. GIF analyses corroborated the FRR results and indicated that the excess relatedness of LOB cases extended to third-degree relatives. Our findings suggest that LOB has a heritable component and may represent a genetically homogeneous form of BC. Pedigrees with excess LOB may be useful in isolating additional BC predisposition genes. Relatives of women with LOB are at higher risk for BC than relatives of other BC subtypes; a more rigorous BC screening regime may be warranted for these individuals.

Desmoglein 2 is expressed abnormally rather than mutated in familial and sporadic gastric cancer

Alterations of the cell adhesion molecule E-cadherin have been demonstrated in sporadic and hereditary gastric carcinomas. A cell adhesion molecule with functional similarity to E-cadherin is desmoglein 2 (Dsg2), a major component of the desmosomes. In this study, we investigated whether alterations of Dsg2 are involved in gastric carcinogenesis and whether germline mutations contribute to a genetic predisposition in familial gastric cancer patients with no germline mutations in the E-cadherin gene. Seventy-five formalin-fixed, paraffin-embedded tissues from 37 familial and 38 sporadic gastric carcinomas were analysed for Dsg2 expression by immunohistochemistry. DNA from 31 familial gastric cancer patients was analysed for germline mutations and five sporadic tumours were analysed for somatic mutations by DHPLC. Of the 75 tumours, 25 (33%) demonstrated abnormal (reduced and/or non-membrane-associated) Dsg2 expression. There was a trend towards more frequent abnormal expression in diffuse type (42%) than in intestinal type tumours (18%) (p = 0.066). One germline missense variant leading to a non-conservative amino acid change (c. 2810 C > A, Thr 937 Asn) was found in a familial gastric cancer patient with a diffuse type tumour. No somatic mutations were identified. The observed abnormal expression of Dsg2 protein suggests that this molecule is involved in the carcinogenesis of a subset of gastric carcinomas, in particular of the diffuse type. Somatic mutations in the gene do not seem to be a very frequent inactivation event and the finding of no clear pathogenic germline mutation rules out Dsg2 as a major gastric cancer predisposition gene.

The E-cadherin–β-catenin complex and its implication in lung cancer progression and prognosis

The E-cadherin–β−catenin complex plays a pivotal role in epithelial cell–cell adhesion and in the maintenance of differentiated adult epithelia. Perturbation of its expression or function is widely involved in tumor progression and metastasis. Recent years have seen a rapid expansion in the understanding of the biology and the clinical relevance of the E-cadherin adhesion complex in human lung cancer. During human lung cancer progression genomic, transcriptionnal and post-transcriptionnal alterations of the E-cadherin–β-catenin adhesion system are implicated and comprise deletion of the chromosomic region 3p21 that comprise the locus of the gene encoding β-catenin, transcriptionnal downregulation of E-cadherin, cytoplasmic redistribution, phosphorylation of both proteins and proteolysis of E-cadherin. E-cadherin-inactivating mutations and oncogenic-activating mutation of β-catenin are not reported.

Gene deregulation in gastric cancer

Despite its decreasing frequency in the Western world during recent decades, gastric cancer is still one of the leading causes of cancer-related deaths worldwide. Due to the oligosymptomatic course of early gastric cancer, most cases are diagnosed in the advanced stages of the disease. The curative potential of current standard treatment continues to be unsatisfactory, despite multimodal approaches involving surgery, chemotherapy and radiotherapy. Novel therapeutics including small molecules and monoclonal antibodies are being developed and have been partially introduced into clinical use in connection with neoplastic diseases such as chronic myeloid leukemia, non-Hodgkin's lymphoma and colorectal cancer. Thorough understanding of the changes in gene expression occurring during gastric carcinogenesis may help to develop targeted therapies and improve the treatment of this disease. Novel molecular biology techniques have generated a wealth of data on up- and down-regulation, activation and inhibition of specific pathways in gastric cancer. Here, we provide an overview of the different aspects of aberrant gene expression patterns in gastric cancer.