Absence of microsatellite instability and germline mutations of E-cadherin, APC and p53 genes in Japanese familial gastric cancer

Screening E-Cadherin Germline Mutations in Italian Patients with Familial Diffuse Gastric Cancer: An Analysis in the District of Urbino, Region Marche, Central Italy

Aims & Background

Hereditary diffuse gastric cancer is a recently defined cancer syndrome caused by inactivating, heterozygous germline mutations in the E-cadherin gene (CDH1). To date, 16 truncating germline CDH1 mutations have been described in hereditary diffuse gastric cancer families in different ethnic groups, but so far, no investigation has been addressed to Italian patients. In the District of Urbino, Region Marche, Central Italy, gastric cancer is the most common tumor in men and it is the second in women after breast cancer. In this area, we investigated CDH1 mutations in patients who fulfilled the hereditary diffuse gastric cancer criteria.

Material and Methods

Consecutive patients with diffuse gastric cancer were considered eligible for the study. After pedigree analysis, patients who met the International Gastric Cancer Linkage Consortium criteria were studied for CDH1 mutations. After blood samples collection and DNA extraction, standard polymerase chain reaction and sequencing techniques were used for CDH1 analysis.

Results

In a study population of 98 patients with diffuse gastric cancer, 11 patients (11%) showed familial clustering and 3 of them met the International Gastric Cancer Linkage Consortium criteria for hereditary diffuse gastric cancer. None of the 3 patients showed inactivating germline mutation in CDH1.

Conclusions

According to recent studies, the frequency of CDH1 inactivating germline mutations in patients who fulfil the hereditary diffuse gastric cancer criteria may be lower than that reported in early investigations. The results of the present study in a population of Italian patients seem to confirm these data. It is likely that unidentified mutations in CDH1 or other involved genes contribute to diffuse gastric cancer susceptibility.

Hereditary gastrointestinal cancer

Gastrointestinal (GI) cancer, including gastric and colorectal cancer, is a major cause of death worldwide. A substantial proportion of patients with GI cancer have a familial history, and several causative genes have been identified. Gene carriers with these hereditary GI syndromes often harbor several kinds of cancer at an early age, and genetic testing and specific surveillance may save their lives through early detection. Gastroenterologists and GI surgeons should be familiar with these syndromes, even though they are not always associated with a high penetrance of GI cancer. In this review, we provide an overview and discuss the diagnosis, genetic testing, and management of four major hereditary GI cancers: familial adenomatous polyposis, Lynch syndrome, hereditary diffuse gastric cancer, and Li-Fraumeni syndrome.

A systematic review of the indications for genetic testing and prophylactic gastrectomy among patients with hereditary diffuse gastric cancer

BACKGROUND

Hereditary diffuse gastric cancer (HDGC) is a familial cancer syndrome specifically associated with germline mutations to the E-cadherin (CDH1) gene. HDGC is characterized by autosomal dominance and high penetrance and a high cumulative risk for advanced gastric cancer. Our purpose in this study was to identify and synthesize findings from all articles on: (1) current recommendations for CDH1 screening and prophylactic gastrectomy; (2) CDH1 testing results in HDGC patients; and (3) prophylactic gastrectomy results in HDGC patients.

METHODS

Systematic electronic literature searches were conducted using Medline, Embase, and the Cochrane Central Register of Controlled Trials from 1985 to 2009.

RESULTS

Seventy articles were included in this review. Among patients with a positive family history of gastric cancer, 1085 were screened from 454 families, and 38.4% tested positive. Mutation-positive families also had a considerable family history of breast and colon cancer. Of the 322 patients screened for CDH1 mutations by current HDGC screening criteria, 29.2% tested positive. Among the 76.8% of patients who underwent prophylactic gastrectomy following positive CDH1 test results, 87.0% had positive final histopathology results and 64.6% had signet ring cells identified. Some of the patients with negative final histopathology results had opted to undergo prophylactic gastrectomy prior to CDH1 testing, and were ultimately found to be negative for CDH1 mutations.

CONCLUSION

CDH1 mutation testing in families with a history of gastric cancer and prophylactic gastrectomy in mutation-positive patients are recommended for the management of HDGC.

Familial gastric cancer: update for practice management

About 90% of gastric carcinoma presents a sporadic setting and only 10% shows a familial cluster; among this group, 1-3% are considered as hereditary syndromes, with a clear genetic pathway. The most important genetic mechanisms are associated with CDH1 germline mutations, causing the hereditary diffuse gastric cancer syndrome. Other inherited predispositions with gastric carcinoma are the hereditary nonpolyposis colorectal cancer, Li-Fraumeni and Peutz-Jeghers syndromes. In this brief update, we described these principal hereditary syndromes offering a simple management to physicians where are these diseases diagnosed.

Mutations in components of the Wnt signaling pathway in gastric cancer

AIM: To explore the contribution of AXIN1, AXIN2 and beta-catenin, components of Wnt signaling pathway, to the carcinogenesis of gastric cancer (GC), we examined AXIN1, AXIN2 exon7 and CTNNB1 (encoding beta-catenin) exon3 mutations in 70 GCs.

METHODS: The presence of mutations was identified by polymerase chain reaction (PCR)-based denaturing high-performance liquid chromatography and direct DNA sequencing. Beta-catenin expression was detected by immunohistochemical analysis.

RESULTS: Among the 70 GCs, 5 (7.1%) had mutations in one or two of these three components. A frameshift mutation (1 bp deletion) in exon7 of AXIN2 was found in one case. Four cases, including the case with a mutation in AXIN2, had frameshift mutations and missense mutations in AXIN1. Five single nucleotide polymorphisms (SNPs), 334 C>T, 874 C>T, 1396 G>A, 1690 C>T and 1942 T>G, were identified in AXIN1. A frameshift mutation (27 bp deletion) spanning exon3 of CTNNB1 was observed in one case. All four cases with mutations in AXIN1 and AXIN2 showed nuclear beta-catenin expression.

CONCLUSION: These data indicate that the mutations in AXIN1 and AXIN2 may contribute to gastric carcinogenesis.

Familial gastric cancers with Li-Fraumeni Syndrome: A case repast

We report a case of the rare solid-pseudopapillary tumor of the pancreas. In contrast to other.

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.

Mutation analysis of APC gene in gastric cancer with microsatellite instability

AIM: To evaluate the role of APC mutation in gastric carcinogenesis and to correlate APC mutation with microsatellite instability (MSI) in gastric carcinomas.

METHODS: APC mutation was measured with multiplex PCR, denaturing gradient gel electrophoresis and DNA sequencing; and MSI was analyzed by PCR-based methods.

RESULTS: Sixty-eight cases of sporadic gastric carcinoma were studied for APC mutation at exon 15 and MSI. APC mutaions were detected in 15 (22.1%) gastric cancers. Frequence of APC mutation (33.3%) in intestinal type of gastric cancer was significantly higher than that in diffuse type (13.1%, P < 0.05). On the contrary, no association was observed between APC mutation and tumor size, differentiation, depth of invasion, metastasis or clinical stages. Using five microsatellite markers, MSI in at least one locus was detected in 17 of 68 (25%) of the tumors analyzed. APC mutations were all detected in MSI-L (only one locus, n = 9) or MSS (tumor lacking MSI or stable, n = 51), but no mutation was found in MSI-H (≥ 2 loci, n = 8).

CONCLUSION: APC mutation is involved in carcinogenesis of intestinal type of gastric cancer and is independent of MSI phenotype but related to the LOH pathway in gastric cancer.

E-cadherin gene variants in gastric cancer families whose probands are diagnosed with diffuse gastric cancer

To identify germline E-cadherin mutations responsible for the predisposition to diffuse gastric cancer (DGC) among the Japanese, we screened 17 patients with familial aggregation of gastric cancer by sequencing analysis. All the patients were diagnosed with DGC and had at least 1 sibling with gastric cancer. Two novel E-cadherin gene variants were detected. One was detected in 1 patient only and associated with an amino acid substitution (Val/Met) at codon 832 in the region essential for binding to beta-catenin. The M832 variant was detected not only in the proband but also in 2 other gastric cancer patients in the family. Immunohistochemical analysis of gastric cancer tissue from the proband revealed that E-cadherin expression was markedly reduced and beta-catenin expression was also reduced in cancer cells. However, no significant difference in the activity of beta-catenin binding was detected between the M832 variant and V832 wild-type E-cadherin in immunofluorescence and immunoprecipitation/Western blot analyses. The other was detected in 5 patients and was located in the splice donor site (IVS1+6T/C); however, RT-PCR analysis indicated that the IVS+6C variant did not cause an aberrant splicing. Thus, the M832 variant could be a germline mutation causative of familial aggregation of DGC, although further functional studies are needed to understand the pathogenic significance of this variant.

Novel germline CDH1 mutations in hereditary diffuse gastric cancer families

Hereditary diffuse gastric cancer (HDGC) is a recently defined cancer syndrome caused by inactivating, heterozygous germline mutations in the gene for the cell-to-cell adhesion protein E-cadherin (CDH1). Here, we describe the search for CDH1 mutations in 10 newly identified gastric cancer families. Seven of 10 families met the clinical criteria for HDGC. Germline mutations were identified in four of these seven families and one family that was borderline for the clinical criteria. Of the mutations identified in the five new families, four were previously unreported and consisted of two frameshift and two donor splice site mutations. One splice site mutation occurred at the 100% conserved +1 position. The second splice site mutation occurred at the +5 position and was shown to lead to abnormal splicing. Additional CDH1 variants detected include the heterozygous -160 C-->A promoter polymorphism, which has previously been reported to be associated with decreased CDH1 transcription. We, however, found this polymorphism to be common in a control population, suggesting that a major role for this polymorphism in gastric cancer susceptibility is unlikely.