Germline Mutations In E-cadherin Gene Research Articles

E-cadherin mediated cellular effects and molecular partners. Gastric cancer as an invasive model

Germline mutations of E-cadherin gene (CDH1) occur in 30% of families with Hereditary Diffuse Gastric Cancer (HDGC); of these, 23% are missense mutations. The CDH1 missense mutations described to date span the entire gene and most of them are functionally relevant and constitute a invaluable model do study E-cadherin dependent signaling pathways and find new molecular targets for therapy. Recently, we explored the hypothesis that mutations affecting different E-cadherin protein domains have distinct effects on cell motility. To verify this hypothesis we characterized the effect of eleven HDGC CDH1 germline missense mutations (T118R, L214P, G239R, A298T, T340A, P373L, R749W, E757K, E781D, P799R and V832M) on cell motility. Further, we studied their effect on the activation of signaling pathways known to be relevant for cell motility, such as the EGFR signaling. We found that all cell lines expressing extracellular mutant forms of E-cadherin (T118R, L214P, G239R, A298T and P373L) displayed higher EGFR activation than cells expressing wild-type E-cadherin. This phenotype is similar to what we observed for cells negative for E-cadherin, which also displayed increased EGFR phosphorylation in comparison to the wild-type expressing cells. The same pattern was observed for the cells expressing the intracellular mutations within the juxtamembrane region, R749W and E757K, which is in accordance with the motility analysis results. Our results allowed the identification of the E-cadherin domains pivotal for cell motility, further demonstrated a genotype–phenotype correlation, and defined a subset of HDGC cases which may benefit from EGFR inhibitors. The role of E-cadherin in tumor development is well established, with many human carcinomas exhibiting E-cadherin loss at the invasive front. In many invasive carcinomas, the mechanisms leading to the loss of E-cadherin remains elusive. We recently hypothesize that trafficking deregulation has a role in the regulation of E-cadherin missense mutations. We first analyzed the intracellular trafficking of two HDGC-associated missense mutations, R749W and E757K, localized in the justamembranar domain of E-cadherin, know to have higher impact in E-cadherin trafficking. We found that these mutations frequently accumulate in the endoplasmic reticulum. Moreover, treatment of the mutant cells with specific chemical chaperones, restored mutant E-cadherin to the cell membrane and rescued its function. The protein-stabilizing power of chemical chaperones has been show to be effective on rescuing different disease-associated mutant proteins, but the mechanism is not understood. In order to understand and further explore the therapeutic power of such organic molecules in the context of HDGC, be believe its crucial to dissect their mode of action in the regulation of E-cadherin mutants. We are now investigating the mechanism by which the chemical chaperone DMSO rescues mutant E-cadherin expression by analyzing its effect on different known E-cadherin trafficking regulators.

Associations of E-cadherin gene (CDH1) and hereditary gastric cancer in China

To investigate the protein expression, methylation promoter, somatic and germ-line mutations of E-cadherin gene (CDH1) in hereditary gastric cancer in China and to investigate its possible roles. Eight probands diagnosed with ICG-HGC criterion were enrolled in our database from June 1994 to October 2007. Tumor tissues were detected for CDH1 expression by using immunohistochemistry (IHC) methods. CDH1 DNA sequencing was performed for all its 16 exons both in tumor and normal tissues of the same patients to detect somatic and germ-line mutations. Methylation promoter study was performed by using specific primers and polymerase chain reaction (PCR) methods. IHC analysis confirmed that the CDH1 expression was negative in 7 probands and downregulated in the other on proband. Six mutations in five probands were found with DNA sequencing: two silent mutations and four missense mutations. All six mutations were absent in normal tissues, thereby excluded its presence in germ-line cells. Both DNA missense mutations and gene silencing through promoter methylation was found in 4 probands. Two probands has only promoter methylation and one proband had only silent mutation. No DNA missense mutations or promoter methylation was found in one proband. CDH1 gene germ-line mutations are relatively rare in hereditary gastric cancer in China, and whereas CDH1 somatic mutations and promoter methylation synergistically induce CDH1 downregulation in these patients.

E-cadherin mutations and cell motility: A genotype–phenotype correlation

E-cadherin has a determinant role in tumour progression, acting as an invasion and metastasis suppressor. Germline mutations of E-cadherin gene ( CDH1) occur in 30% of families with Hereditary Diffuse Gastric Cancer (HDGC); of these 23% are missense mutations. The CDH1 missense mutations described to date span the entire gene and some lead to significant functional consequences. In this study, we explored the hypothesis that mutations affecting different E-cadherin protein domains have distinct effects on cell motility. To accomplish our objective we characterized the effect of eleven HDGC CDH1 germline missense mutations (T118R, L214P, G239R, A298T, T340A, P373L, R749W, E757K, E781D, P799R and V832M) on cell motility. Further, we studied their effect on the activation of signalling pathways known to be relevant for cell motility such as the EGFR, Src kinase and MAPKs. CDH1 mutations localized on the extracellular and juxtamembrane domains, both affecting the integrity of the extracellular domain, led to increased cell motility accompanied by increased EGFR activation. Moreover, we observed that cells expressing extracellular mutants exhibit increased activation of Src kinase and p38 MAPK. Our results allowed the identification of the E-cadherin domains pivotal for cell motility, further demonstrated a genotype–phenotype correlation, and defined a subset of HDGC cases which may benefit from EGFR inhibitors.

The germline mutaion pattern of CDH1 gene in 12 Chinese hereditary diffuse gastric cancer kindred

9548 Background: E-cadherin is responsible for the cell-cell adhesion. Germline mutations in E-cadherin gene (CDH1) was firstly recognized in Maori kindred with hereditary gastric cancer(HGC) in Ne...