Loss of E-cadherin is the fundamental defect in diffuse-type gastric carcinoma and infiltrating lobular carcinoma of the breast

Dynamic contrast-enhanced magnetic resonance imaging for risk-stratified screening in women with BRCA mutations or high familial risk for breast cancer: are we there yet?

PURPOSE

Women at an elevated lifetime risk for breast cancer (BC), including carriers of pathogenic mutations in BC predisposition genes, are recommended intensified BC screening that includes annual mammography (MG) and annual breast MRI. Controversy exists regarding the clinical utility of MRI as a screening tool in high-risk women. This paper is intended to review recent advances and remaining areas of uncertainty in order to further facilitate the incorporation of breast MRI into an intensified BC screening protocol for women at high familial risk and BRCA carriers.

METHODS

A multidisciplinary team of medical oncologists and a radiologist specializing in the treatment of BC and high-risk patients searched PubMed to identify studies deemed to have the highest scientific value. Since none of the initial MRI studies were randomized, meta-analyses examining breast MRI screening in high-risk women were prioritized for inclusion.

RESULTS

Breast MRI performs well in high-risk women, including mutation carriers. Breast MRI screening allows for the detection of early stage, likely curable invasive BC. It is mandatory that radiologists receive appropriate MRI training to reduce false positives and unnecessary biopsies. MRI screening is cost-effective in the highest risk patients and new clinical trials are open examining abbreviated and ultra-fast MRI techniques as a tool to drive down costs and improve specificity.

CONCLUSIONS

As breast MRI is recommended as part of an intensified screening program in addition to mammography for high-risk women, it important that health care providers understand the benefits and limitations of this screening modality for high-risk women, as well as areas for further investigation.

Subcellular Localization of Immunohistochemical Signals

In the literature, sufficient attention has not been paid to the precise subcellular localization of immunohistochemical signals, the knowledge of which is essential for proper interpretation of immunostains and distinction of genuine staining from biotin-associated or other nonspecific stainings. The subcellular localization of the signals can in fact be easily deduced from the known biologic or ultrastructural characteristics of the antigens. Extracellular antigens obviously are located in the extracellular compartment. Cellular antigens fall into 3 major groups: membranous, nuclear, and cytoplasmic. Membranous antigens include cell adhesion molecules (such as E-cadherin, N-CAM), cell surface/transmembrane receptors and proteins (such as tyrosine kinase receptors, most leukocyte antigens, CD10, CEA), and molecules linking surface molecules to cytoskeleton (such as β-catenin, dystrophin). Nuclear antigens include cell cycle-associated proteins (such as cyclins, p16, Ki-67), nuclear enzymes (such as TdT), transcription factors (such as TTF-1, CDX-2, myogenin, PAX-5), tumor suppressor gene products (such as p53, p63, WT1, Rb), steroid hormone receptors (such as ER, PR), calcium-binding proteins (such as S-100 protein, calretinin), and some viral proteins (such as CMV, herpes). Cytoplasmic antigens can take up a granular pattern due to localization in organelles, granules, or secretory vesicles (such as chromogranin, hormones, lysozyme, HMB-45), fibrillary pattern attributable to the filamentous nature of the molecules (intermediate filaments and microfilaments), or diffuse or patchy pattern due to localization in the cytosol or large vesicles (such as myoglobin, albumin, thyroglobulin). Aberrant localization of the molecules, when present, can provide important insight into disease processes and aid in their diagnosis, such as loss of membranous E-cadherin expression in lobular breast carcinoma, aberrant nuclear localization of β-catenin in colorectal adenocarcinoma, pattern of ALK staining in anaplastic large cell lymphoma correlating with the different types of chromosomal translocations, presence of additional cytoplasmic CD10 staining in the enterocytes indicative of microvillous inclusion disease, and “reversed” staining for EMA in micropapillary mammary carcinoma.

Application of immunohistochemistry in breast pathology: a review and update

CONTEXT

Immunohistochemistry is a valuable tool in routine breast pathology, used for both diagnostic and prognostic parameters. The diagnostic immunomarkers are the scope of this review. Most breast lesions can be diagnosed on routine hematoxylin-eosin sections; however, in several scenarios, such as morphologically equivocal cases or metastatic tumors of unknown primary, the appropriate application of immunohistochemistry adds true value in reaching an accurate diagnosis.

OBJECTIVE

To evaluate the diagnostic utility of the most commonly studied immunomarkers in the field of breast pathology by review of the literature, using the database of indexed articles in PubMed (US National Library of Medicine, Bethesda, Maryland) from 1976 to 2013.

DATA SOURCES

Literature review, and author's research data and personal practice experience.

CONCLUSIONS

The appropriate use of immunohistochemistry by applying a panel of immunomarkers and using a standardized technical and interpretational method will complement the morphologic assessment and aid in the accurate classification of difficult breast lesions and the identification of metastasis from a breast primary.

Breast cancer biomarkers and molecular medicine: part II

In this second part of the two-part review of breast cancer biomarkers and molecular medicine, the first section will consider additional breast cancer prognostic factors, including oncogenes, tumor suppressor genes, cell adhesion molecules, invasion-associated proteins and proteases, hormone receptor proteins, drug resistance proteins, apoptosis regulators, transcription factors, telomerase, DNA repair and methylation and transcriptional profiling using high-density genomic microarrays. The second section will consider the prediction of therapy response using the techniques of pharmacogenetics and pharmacogenomics.

The Utility of Immunohistochemistry for Providing Genetic Information on Tumors

With advances in immunohistochemical technology and growing knowledge of the molecular genetics of tumors, immunohistochemistry is playing an increasingly important role in providing genetic information for tumors. Specific chromosomal translocations can be demonstrated through detection of the protein product of one of the genes involved in gene fusion (such as BCL2, cyclin D, and ALK). Some mutations can be detected by (1) aberrant localization of the protein product (such as β-catenin and nucleophosmin), (2) abnormal accumulation of the protein product as a result of stabilization of the protein (such as p53), and (3) mutation-specific antibodies directed against the mutant protein (such as isocitrate dehydrogenase gene R132H mutation, epidermal growth factor receptor gene L858R and exon 19 deletion mutations, and BRAF gene V600E mutation). Gene deletion or loss of function can be demonstrated by the loss of immunostaining for the protein product (such as mismatch repair proteins in microsatellite-unstable tumors, E-cadherin in lobular carcinoma of the breast, and INI1 in rhabdoid tumors, atypical teratoid/rhabdoid tumors, and epithelioid sarcomas). Gene amplification can be demonstrated by overexpression of the protein product (such as HER2 in breast and gastric cancers, and MDM2 or CDK4 in well-differentiated/dedifferentiated liposarcomas). Viruses associated with tumors can be demonstrated directly (such as Epstein-Barr virus latent membrane protein-1 in Hodgkin lymphomas, human herpesvirus 8 in Kaposi sarcomas, and Merkel cell polyomavirus in Merkel cell carcinomas) or by a surrogate marker (such as p16 in human papillomavirus infection). In this review, examples are given to illustrate the principles and pitfalls of these applications.

Interleukin 6 gene polymorphism -174 is associated with the diffuse type gastric carcinoma

The aim of this study was to assess the significance of the interleukin 6 gene polymorphism -174 in gastric cancer risk. The interleukin 6 -174 G/C (rs1800795) gene polymorphisms was analyzed in gastric cancer, peptic ulcer, and nonulcer dyspepsia patients and in healthy control subjects and the data were correlated with the histopathological features of the patients' biopsies. The interleukin 6 -174 GG and GC genotypes have been previously associated with high interleukin 6 serum levels. We discovered that the interleukin 6 -174 GG and GC genotypes are associated with an increased risk of the diffuse histologic subtype of gastric carcinomas (OR: 6.809, P = 0.034), but absent in the intestinal type carcinomas (OR: 1.109, P = 0.908). No significant associations with peptic ulcer, gastric atrophy, or intestinal metaplasia were seen. Our results demonstrate that the interleukin 6 -174 GG and GC genotypes increase the risk of the diffuse type gastric carcinoma, but not the intestinal type gastric carcinoma or its precursor conditions, including atrophy or intestinal metaplasia. Thus, interleukin 6 seems to be an important carcinogenetic factor in the diffuse type gastric adenocarcinoma and its carcinogenetic effect could be noninflammatory.

Immunohistochemistry applied to the differential diagnosis between ductal and lobular carcinoma of the breast

The distinction between classic lobular and ductal carcinoma, both in situ and invasive, has important therapeutic and management implications. Most ductal and lobular carcinomas are distinguished readily on hematoxylin-eosin-stained sections because of distinct histomorphologic features. In cases with ambiguous morphologic features, however, categorization in one or another type can be a challenge. Several immunohistochemical markers, including epithelial cadherin, p120, β-catenin, and low-molecular-weight and high-molecular-weight cytokeratins among others, have been introduced to help better discriminate between lobular neoplasia and ductal carcinoma. In this critical review of the literature, we comment about the usefulness and the limitations of these markers to improve the accuracy in the differential diagnosis of breast pathology.

LIFR is a breast cancer metastasis suppressor upstream of the Hippo-YAP pathway and a prognostic marker

There is a pressing need to identify prognostic markers of metastatic disease and targets for treatment. Combining high-throughput RNA sequencing, functional characterization, mechanistic studies and clinical validation, we identify leukemia inhibitory factor receptor (LIFR) as a breast cancer metastasis suppressor downstream of the microRNA miR-9 and upstream of Hippo signaling. Restoring LIFR expression in highly malignant tumor cells suppresses metastasis by triggering a Hippo kinase cascade that leads to phosphorylation, cytoplasmic retention and functional inactivation of the transcriptional coactivator YES-associated protein (YAP). Conversely, loss of LIFR in nonmetastatic breast cancer cells induces migration, invasion and metastatic colonization through activation of YAP. LIFR is downregulated in human breast carcinomas and inversely correlates with metastasis. Notably, in approximately 1,000 nonmetastatic breast tumors, LIFR expression status correlated with metastasis-free, recurrence-free and overall survival outcomes in the patients. These findings identify LIFR as a metastasis suppressor that functions through the Hippo-YAP pathway and has significant prognostic power.

Familial gastric cancer: genetics, diagnosis, and management

This article focuses on the diagnosis and management of familial gastric cancer, particularly hereditary diffuse gastric cancer (HDGC). First, existing consensus guidelines are discussed and then the pathology and genetics of HDGC are reviewed. Second, patient management is covered, including surveillance gastroscopy, prophylactic total gastrectomy, and management of the risk of breast cancer.

Clinical and biological significance of E-cadherin protein expression in invasive lobular carcinoma of the breast

BACKGROUND

Although virtually all cases of lobular carcinoma in situ lack E-cadherin expression, a proportion of morphologically typical invasive lobular carcinomas (ILCs) retain its expression. The frequency and significance of E-cadherin expression in ILC remain to be elucidated. In this study, we have assessed E-cadherin protein expression in a well-characterized series of histologically defined ILC (239 cases) with a long-term clinical follow-up to determine the frequency, clinical and biological significance of its expression. E-cadherin-positive ILCs (ILC+) were subsequently examined to assess the expression of component members of the E-cadherin membrane complex (E-cadherin, p120, α, β, and γ-catenins) to determine its integrity.

RESULTS

Thirty-eight ILC cases (16%) showed positive E-cadherin expression (ILC+). Membranous expression of E-cadherin was mainly circumferential with frequent coexisting perimembranous cytoplasmic expression. No association between E-cadherin expression and any of the clinicopathologic variables, immunophenotype, or tumor behavior was identified, apart from an association with lobular histologic subtype and vascular invasion. Analysis of the E-cadherin-catenin complex showed abnormal expression of one or more of the catenin complex members in the majority of cases. The most frequent observation was the diffuse cytoplasmic expression of catenins, in particular p120, which showed similar expression to that reported in E-cadherin-negative ILCs.

CONCLUSIONS

These results provide evidence that E-cadherin is expressed in a proportion of ILC, however, unlike ductal carcinoma, its expression seems to be of limited significance and it is usually associated with evidence of impaired integrity of the E-cadherin-catenin membrane complex. Our data offer a possible explanation for the presence but lack functionality of E-cadherin in some cases of ILC and imply that immunohistochemical expression of E-cadherin per se in ILC histologic phenotypic tumors should not preclude its diagnosis.

Hereditary diffuse gastric cancer: a manifestation of lost cell polarity

Hereditary diffuse gastric cancer is a cancer syndrome caused by germline mutations in the gene for the cell adhesion protein E-cadherin (CDH1). E-cadherin plays a central role in the maintenance of cell polarity and its loss during tumorigenesis is associated with poorly differentiated cancers and a poor prognosis. Hereditary diffuse gastric cancer is dominated by diffuse-type gastric adenocarcinoma, often with signet ring cell morphology. Large numbers of stage T1a signet ring cell carcinomas exist in the stomachs of CDH1 mutation carriers from a young age, and these foci sometimes show enrichment to the transition zone between the body and antrum. Generally these signet ring cell carcinomas are hypoproliferative, lack Wnt pathway activation, and are relatively indolent. However, a small proportion of the T1a foci contain cells that are poorly differentiated, display mesenchymal features, and express activated c-Src and its downstream targets. These same features are observed in more advanced stages of hereditary diffuse gastric cancer progression, suggesting that an epithelial-mesenchymal transition is required for tumor invasion beyond the muscularis mucosae. Hereditary diffuse gastric cancer initiation requires somatic down-regulation of the second CDH1 allele, which in most cases is caused by DNA promoter hypermethylation. Subsequent to CDH1 down-regulation, lost polarity in gastric stem or progenitor cells would be predicted to interfere with mitotic spindle orientation and the segregation of cell fate determinants. We predict that this disruption of cell division results in daughter cells being deposited in the lamina propria where their population expands and partially differentiates, resulting in the formation of foci of signet ring cells.

Hereditary diffuse gastric cancer and lost cell polarity: a short path to cancer

The mechanisms that underlie the initiation of human cancer are poorly understood. Here, we describe the development of hereditary diffuse gastric cancer and argue that it arises from the disruption of the regenerative processes that are inherent to all epithelial tissues. This model supports the cancer stem cell hypothesis, in which tumors contain a subpopulation of cells with the key stem cell characteristics of capacity for self renewal, differentiation and limitless replication. We argue that epigenetic modifications induced by common environmental and physiological pressures are able to initiate this disruption. The carcinogenic effects of these modifications are potentially reversible through the use of epigenetic therapies such as DNA demethylating agents and histone deacetylation inhibitors.

Absence of E-cadherin expression distinguishes noncohesive from cohesive pancreatic cancer

PURPOSE

The role of E-cadherin in carcinogenesis is of great interest, but few studies have examined its relevance to pancreatic carcinoma.

EXPERIMENTAL DESIGN

We evaluated E-cadherin protein expression by immunohistochemistry in pancreatobiliary cancers having a noncohesive histologic phenotype (21 undifferentiated adenocarcinomas and 7 signet ring carcinomas), comparing the results with pancreatic cancers having a cohesive phenotype (25 moderately differentiated and 14 poorly differentiated adenocarcinomas).

RESULTS

Twenty of 21 undifferentiated cancers had complete absence of E-cadherin expression, as did two signet ring carcinomas. In contrast, cohesive cancers (n = 39) had E-cadherin labeling at the plasma membrane (P < 0.001). Subsets of cancers were also evaluated for beta-catenin expression. All of the cohesive lesions (n = 28) showed a membranous beta-catenin expression pattern, whereas noncohesive foci (n = 7) were characterized by either cytoplasmic labeling or complete absence of beta-catenin protein expression, suggestive of a deficient zonula adherens in noncohesive cancers. E-cadherin promoter hypermethylation was observed in an undifferentiated pancreatic cancer cell line, MiaPaCa-2, whereas two pancreatic cancer cell lines derived from differentiated lesions lacked any evidence of E-cadherin promoter methylation. No pattern of E-cadherin promoter methylation could be determined in three primary cancers having mixed histologic patterns (contained both cohesive and noncohesive foci). No somatic mutations in E-cadherin were identified in noncohesive pancreatic cancers having inactivated E-cadherin.

CONCLUSIONS

Noncohesive pancreatic cancers were characterized by the loss of E-cadherin protein expression. Promoter hypermethylation is a possible mechanism of E-cadherin gene silencing in a subset of these cancers.

Genetic susceptibility for breast cancer: How many more genes to be found?

Today, breast cancer is the most commonly occurring cancer among women. It accounts for 22% of all female cancers and the estimated annual incidence of breast cancer worldwide is about one million cases. Many risk factors have been identified but a positive family history remains among the most important ones established for breast cancer, with first-degree relatives of patients having an approximately two-fold elevated risk. It is currently estimated that approximately 20-25% of this risk is explained by known breast cancer susceptibility genes, mostly those conferring high risks, such as BRCA1 and BRCA2. However, these genes explain less than 5% of the total breast cancer incidence, even though several studies have suggested that the proportion of breast cancer that can be attributed to a genetic factor may be as high as 30%. It is thus likely that there are still breast cancer susceptibility genes to be found. It is presently not known how many such genes there still are, nor how many will fall into the class of rare high-risk (e.g. BRCAx) or of common low-risk susceptibility genes, nor if and how these factors interact with each other to cause susceptibility (a polygenic model). In this review we will address this question and discuss the different undertaken approaches used in identifying new breast cancer susceptibility genes, such as (genome-wide) linkage analysis, CGH, LOH, association studies and global gene expression analysis.

MDM2 promotes cell motility and invasiveness by regulating E-cadherin degradation

Gene amplification and protein overexpression of MDM2, which is often found in certain types of cancers, indicate that MDM2 plays an important role in tumorigenesis. Interestingly, several clinical reports have demonstrated that amplification of the MDM2 gene correlates with the metastatic stage. Using an antibody array assay, we identified E-cadherin as an MDM2-binding protein and confirmed that E-cadherin is a substrate for the MDM2 E3 ubiquitin ligase. We demonstrate that MDM2 interacts in vivo with E-cadherin, resulting in its ubiquitination and degradation. This regulation appears to be clinically relevant, as we found a significant correlation between high MDM2 and low E-cadherin protein levels in resected tumor specimens recovered from breast cancer patients with lymph node metastases. Ectopic expression of MDM2 in breast cancer cells was found to disrupt cell-cell contacts and enhance cell motility and invasive potential. We found that E-cadherin and MDM2 colocalized on the plasma membrane and in the early endosome, where ubiquitin moieties were attached to E-cadherin. Blocking endocytosis with dominant-negative mutants of dynamin abolished the association of MDM2 with E-cadherin, prevented E-cadherin degradation, and attenuated cell motility as observed by fluorescence microscopy. Thus, we provide evidence to support a novel role for MDM2 in regulating cell adhesions by a mechanism that involves degrading and down-regulating the expression of E-cadherin via an endosome pathway. This novel MDM2-regulated pathway is likely to play a biologically relevant role in cancer metastasis.

Early-onset gastric cancers have a different molecular expression profile than conventional gastric cancers

Many studies examine the molecular genetics of gastric cancer, but few look at young patients in particular and there is no comparison of molecular expression between early-onset gastric cancer (< or = 45 years old) and conventional gastric cancers. Expression of cycloxygenase-2 (COX-2) is elevated in gastric adenocarcinomas compared to non-neoplastic mucosa, and in light of studies showing reduced risk of gastric cancer in nonsteroidal anti-inflammatory drug users, we have chosen to investigate the expression of COX-2 and related molecules in 113 early-onset gastric cancers and compare it with 91 conventional gastric cancers, using tissue microarrays. These markers include molecules known to be important in conventional gastric carcinogenesis, such as E-Cadherin, p53, COX-2, Trefoil Factor-1 (TFF1), beta-catenin, p16 and c-myc; as well as molecules not yet described as being important in gastric cancer, such as the transcription factor c-jun, the COX-2 mRNA stabilizer HuR, and C/EBP-beta, a transcription factor for COX-2. All markers showed a statistically significant difference between early-onset gastric cancers and conventional gastric cancers, using a chi2 test. In particular, early-onset gastric cancers displayed a COX-2 Low, TFF1-expressing phenotype, whereas COX-2 overexpression and loss of TFF1 was found in conventional cancers, and this difference between early-onset gastric cancers and conventional cancers remained statistically significant when adjusted for location and histology (P<0.0001 and P = 0.002 respectively). We found that COX-2 overexpression correlates significantly with loss of TFF1 (P = 0.001), overexpression of C/EBP-beta (P<0.001) and cytoplasmic HuR (P = 0.016). COX-2 was significantly associated with p53 positivity (P = 0.003). Abnormalities in E-Cadherin correlated significantly with diffuse phenotype, whereas high expression of COX-2, loss of TFF1 and overexpression of C/EBP-beta correlated with the intestinal phenotype. Our results provide further evidence that early-onset gastric cancer exhibits a distinctive expression profile that may have practical implications.

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.

Breast cancer biomarkers

Substantial progress has been made over the past three decades in our understanding of the epidemiology, clinical course and basic biology of breast cancer. This chapter considers the existing ancillary tests and emerging molecular markers in breast cancer prognosis assessment and the prediction of response of breast cancer to treatment of the disease.

Expression of oestrogen receptor and loss of E-cadherin are diagnostic for gastric metastasis of breast carcinoma

AIMS

To investigate whether immunohistochemical staining for oestrogen receptor (ER)alpha, progesterone receptor (PgR) and E-cadherin might be useful to differentiate between metastatic breast carcinoma and primary gastric carcinoma.

METHODS

Gastric biopsies of 75 patients containing adenocarcinoma were stained for ERalpha, PgR and E-cadherin. Included were: Group A, 28 patients with primary gastric cancer; Group B, 28 patients with an adenocarcinoma containing gastric biopsy and a clinical diagnosis of metastatic breast carcinoma; Group C, all consecutive patients with a positive gastric biopsy in 2001 (n = 19) without clinical history of breast carcinoma and not followed by gastric resection (control group).

RESULTS

All ERalpha+ or PgR+ carcinomas (n = 20) were of patients with a previous or concurrent history of breast carcinoma: 19 in group B, one in group C. In addition, absence of E-cadherin staining was seen significantly more often in patients with metastatic breast carcinoma than in patients with primary gastric cancer (P < 0.001).

CONCLUSION

Positive immunohistochemical staining for ERalpha or PgR of an adenocarcinoma in a gastric biopsy is diagnostic for metastatic breast carcinoma. Moreover, when carcinoma in a gastric biopsy is negative for E-cadherin staining, metastatic breast carcinoma should be considered.

CDH1 associated gastric cancer: a report of a family and review of the literature

AIMS

Hereditary diffuse gastric cancer (HDGC) is an autosomal-dominant inherited form of gastric cancer associated with inactivating germline mutations in the CDH1 gene. We set out to outline the role of CDH1 in HDGC. Investigation of a family suspected as having HDGC is discussed. The role of surgery in the management of affected individuals is then examined.

METHODS

A search was conducted of Medline and the National Library of Medicine to identify key articles concerning CDH1 gene mutations, familial gastric cancer and gastrectomy. Further, relevant articles were obtained by manual scanning of the reference lists of identified papers. Mutation-specific CDH1 genetic testing was performed on six living family members and on gastric tissue obtained from two deceased members.

RESULTS

CDH1 mutations cause inactivation of the cell adhesion protein E-cadherin. Carriers of the CDH1 germline gene mutation develop an aggressive, diffuse, submucosal gastric cancer at an early age. Current endoscopic screening is ineffective at detecting HDGC. The presence of a CDH1 germline gene mutation was confirmed in both deceased family members and also in four of the six living members tested.

CONCLUSION

Genetic counselling and CDH1 gene mutation testing is indicated in families with suspected HDGC. In the absence of a satisfactory surveillance mechanism, prophylactic total gastrectomy would appear to be an appropriate therapeutic option in mutation carriers.

The role of the E-cadherin gene (CDH1) in diffuse gastric cancer susceptibility: from the laboratory to clinical practice

Loss of function of the E-cadherin gene (CDH1) has been linked with diffuse gastric cancer susceptibility, and germline inactivating mutations in CDH1 characterise the hereditary diffuse gastric cancer (HDGC) syndrome. Hypermethylation in the CDH1 promoter region is a frequent phenomenon in poorly differentiated, diffuse gastric carcinomas and it was identified as the main mechanism for the inactivation of the remaining wild-type allele in HDGC cases. Specific criteria are used to identify patients with suspected HDGC and who should be investigated for CDH1 germline mutations. Accurate screening is mandatory for unaffected carriers of CDH1 mutations and selected high-risk individuals could be considered for prophylactic gastrectomy. Also, germline CDH1 mutations may predispose to lobular breast carcinoma and prostate cancer. Germline CDH1 mutations are not always detectable in patients who meet the HDGC criteria and the aetiological role of this gene is still under investigation. Families without recognised inactivating CDH1 mutations may have undisclosed CDH1 mutations or mutations in its regulatory sequences or germline mutations in unidentified genes that also contribute to the disease. In recent years, several germline missense CDH1 mutations have been identified, some of which showed a marked negative influence on E-cadherin function in experimental models. CDH1 promoter hypermethylation seems a key event in the carcinogenetic process of poorly differentiated, diffuse gastric cancer and it deserves further investigation as a new target for anticancer therapies with demethylating agents.

Effect of P-selectin monoclonal antibody on metastasis of gastric cancer and immune function

AIM: To investigate the effect of cell adhesion molecule P-selectin monoclonal antibody (Mab) on metastasis and immune function of mice orthototopically implanted with human gastric cancer tissue.

METHODS: SCID mice were implanted orthotopically with SGC-7901 human gastric carcinoma tissue. Starting from day 3 after operation, animals were given intravenously PBS or P-selectin Mab (100 μg/injection) (for both normal mice and tumor-implanted mice with tumors), twice weekly for 3 wk. Two animals in each group were sacrificed randomly at the 1st, 2nd, 4th week and 6th week. While T cell and B cell transformation indices were determined with the ³H TdR infiltration method, the NK cell activity was detected by the LDH release method.

RESULTS: The metastatic rate in the P-selectin Mab treated group was lower than that in the PBS treated group (with tumors). The NK activity of normal mice increased over time. The immune functions (T, B cell function, NK activity) of the tumor group in the 6th week were significantly lower than those in the 4th week, but the change was attenuated by P-selectin Mab.

CONCLUSION: P-selectin Mab could suppress the metastasis of gastric cancer with no adverse effect on host immune function.