Diffuse Gastric Cancer Patients Research Articles

Frequency of CDH1, CTNNA1 and CTNND1 Germline Variants in Families with Diffuse and Mixed Gastric Cancer.

The most well-characterized hereditary form of gastric cancer is hereditary diffuse gastric cancer (HDGC), an autosomal dominant syndrome characterized by an increased risk of diffuse gastric and lobular breast cancer. HDGC is predominantly caused by germline pathogenic variants in the CDH1 gene, and more rarely in the CTNNA1 gene. Furthermore, the International Gastric Cancer Linkage Consortium (IGCLC) guidelines do not clarify whether or not mixed gastric cancer (with a diffuse component) should be considered in the HDGC genetic testing criteria. We aimed to evaluate the contribution of CTNNA1 and CTNND1 germline variants to HDGC. Additionally, we also intended to compare the frequencies of CDH1 and CTNNA1 (and eventually CTNND1) germline variants between patients with diffuse and mixed gastric carcinomas to evaluate if genetic testing for these genes should or should not be considered in patients with the latter. We analyzed the CDH1 gene in 67 cases affected with early-onset/familial mixed gastric carcinomas and the CTNNA1 and CTNND1 genes in 208 cases with diffuse or mixed gastric cancer who had tested negative for CDH1 pathogenic germline variants. A deleterious CTNNA1 germline variant was found in 0.7% (1/141) of diffuse gastric cancer patients meeting the 2020 IGCLC criteria, as compared to the rate of 2.8% of CDH1 deleterious variants found by us in this setting. No deleterious variants were found in CTNND1, but six variants of uncertain significance were identified in this gene. We did not find any pathogenic CDH1, CTNNA1 or CTNND1 variant in index patients with early-onset/familial mixed gastric cancer, so there is no evidence that supports including this tumor type in the testing criteria for germline variants in these genes. The role of the CTNND1 gene in inherited gastric cancer predisposition is still unclear.

Abstract 5821: Synergism of FAK and ROS1 inhibitors in the treatment of CDH1-deficient cancers mediated by FAK-YAP-TRX signaling

Abstract CDH1 deficiency is common in triple negative breast cancer and diffuse gastric cancer patients, both of which lack effective therapeutics. Although inhibiting ROS1 function results in synthetic lethality in CDH1-deficient cancers, adaptive resistance limits their potential clinical benefits. Hyperactive focal adhesion kinase (FAK) signaling contributes to adaptive drug resistance, and FAK inhibitors are partially effective against CDH1–deficient cancers. Thus, co-treatment with ROS1 and FAK inhibitors may provide stronger anti-cancer effects by targeting CDH1 deficiency and potentially overcome drug resistance. Here, we evaluated the effects and mechanisms of combined treatment with FAK inhibitor IN10018 and ROS1 inhibitors. Cell-based assays and in vivo animal experiments revealed that FAK and ROS1 inhibitor combination treatment showed stronger anti-cancer effects than either monotherapy. ROS1 inhibitors induced FAK-YAP-TRX signaling, decreasing oxidative stress–related DNA damage, and consequently reducing its anti-cancer effects. However, the combination treatment suppressed the aberrant FAK-YAP-TRX signaling, reinforcing the cytotoxicity of ROS1 inhibitor towards cancer cells. This mechanism of action was confirmed by inhibiting the activity of FAK-YAP-TRX downstream signaling molecules and by pretreatment with oxidative stress scavengers. These findings support the co-administration of FAK and ROS1 inhibitors as a therapeutic strategy in CDH1-deficient triple negative breast cancer and diffuse gastric cancer patients and support further clinical testing of this combination regimen. Citation Format: Jiaming Gao, Yunying Yao, Zaiqi Wang, Baoyuan Zhang, Ruibao Ren. Synergism of FAK and ROS1 inhibitors in the treatment of CDH1-deficient cancers mediated by FAK-YAP-TRX signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5821.

Low expression of E-Cadherin and CDH1 variants associated with diffuse gastric cancer.

Reduced or null expression of E-cadherin protein is a frequent cause of diffuse gastric cancer (DGC). More than 50% of patients with DGC present somatic variants in CDH1 gene. The objectives of this study were to study E-cadherin expression and identify variants in the CDH1 gene in gastric tumors of patients with DGC. We studied 18 Mexican DGC patients who attended a hospital of the Mexican Social Security Institute; E-cadherin expression was determined by immunohistochemistry, and variants were identified by Sanger sequencing in promoter and coding regions. Predictive analysis was performed using PolyPhen-2 and HOPE software. We found that 56% of DGC patients showed reduced expression of E-cadherin. All patients carried CDH1 variants; overall, 12 different CDH1 variants were identified. Predictive analysis revealed that the rs114265540 variant was probably damaging, with a value of 0.985, indicating a functional impact on the E-cadherin protein. Variants rs34939176 and rs33964119 were identified as risk factors for DGC (odds' ratios [OR] = 31.3, 95% CI 6.3-154.0, p < 0.001; OR = 6.1, 95% CI 2.0-19.0, p < 0.001, respectively) given their elevated frequency and by comparing it with those reported for MXL population in the 1000 Genomes Project database. In this Mexican population, the percentage of diffuse gastric tumors with reduced expression of E-cadherin was similar to that reported in other populations. All gastric tumors of DGC patients studied had somatic CDH1 gene variants; however, the rs114265540, rs34939176, and rs33964119 variants were importantly related to DGC.

Synergism of FAK and ROS1 inhibitors in the treatment of CDH1-deficient cancers mediated by FAK-YAP signaling.

CDH1 deficiency is common in diffuse gastric cancer and triple negative breast cancer patients, both of which still lack effective therapeutics. ROS1 inhibition results in synthetic lethality in CDH1-deficient cancers, but often leads to adaptive resistance. Here, we demonstrate that upregulation of the FAK activity accompanies the emergence of resistance to ROS1 inhibitor therapy in gastric and breast CDH1-deficient cancers. FAK inhibition, either by FAK inhibitors or by knocking down its expression, resulted in higher cytotoxicity potency of the ROS1 inhibitor in CDH1-deficient cancer cell lines. Co-treatment of mice with the FAK inhibitor and ROS1 inhibitors also showed synergistic effects against CDH1-deficient cancers. Mechanistically, ROS1 inhibitors induce the FAK-YAP-TRX signaling, decreasing oxidative stress-related DNA damage and consequently reducing their anti-cancer effects. The FAK inhibitor suppresses the aberrant FAK-YAP-TRX signaling, reinforcing ROS1 inhibitor's cytotoxicity towards cancer cells. These findings support the use of FAK and ROS1 inhibitors as a combination therapeutic strategy in CDH1-deficient triple negative breast cancer and diffuse gastric cancer patients.

PD-1 inhibitors combined with apatinib for advanced diffuse gastric cancer: A retrospective study.

e16009 Background: Numerous studies have shown that immunotherapy has a synergistic effect when combined with targeted drug therapy. Apatinib has been proven effective in advanced gastric cancer. Based on these facts and to assess the efficacy and safety of programmed death 1 (PD-1) inhibitors and apatinib as combination therapy in patients (pts) with unresectable locally advanced or metastatic diffuse gastric cancer(DGC), a retrospective clinical research study was carried out. Methods: Retrospective analysis of a cohort of pts with advanced diffuse gastric cancer received treatment of apatinib combined with PD-1 inhibitors enrolled in our institution between January 2019 and January 2021.Pts (n = 34) received PD-1 inhibitors and apatinib (250mg once daily) in this retrospective study. Overall survival (OS) and progression free survival (PFS) were estimated by Kaplan Meier curves, and other endpoints included objective response rate(ORR), disease control rate(DCR), prognostic factors. Results: A total of 34 pts were enrolled in a real-world dataset from Henan Cancer Hospital. 2 pts achieved partial response(PR),17 pts had stable disease(SD),and 15 pts had progressive disease (PD). The ORR and DCR were 5.88% (2/34) and 55.88% (19/34), respectively. The median PFS(mPFS) was 2.47 months (95%CI:1.9-3.0), and the median OS (mOS) was 6.80 months (95%CI 3.7-9.9). Pts with less than 3 metastatic sites had longer mOS than those with more metastatic sites(2.70 vs. 7.73 P &lt; 0.05). And in this study, the levels of platelet, albumin, CEA, CA199, CA125 and LDH affect patients’ prognosis. Kaplan-Meier analyses revealed that patients with normal platelet had better mOS than those with higher platelet(mOS 7.10 vs 0.3; P &lt; 0.05).And similar results were found in the pts with normal albumin. The mOS of those was longer than the pts with lower or higher albumin(7.73 vs 2.20 vs 2.53, P &lt; 005). And we demonstrated that positive groups of CEA(&gt; 4.7ng/ml), CA125(&gt; 35U/ml), CA199(&gt; 27U/ml) and LDH(&gt; 245U/L) were significantly associated with worse outcomes than that of negative groups(all P &lt; 0.05). The incidence of grade 3 or 4 treatment-related adverse events (TRAEs) was 26.5%(9/34). These adverse events (AEs) included pruritus, rash, hand-foot syndrome, hypertension and increased aspartate aminotransferase (AST) or alanine aminotransferase (ALT). No treatment-related deaths occurred. Conclusions: Combination therapy of PD-1 inhibitors and apatinib showed encouraging clinical activity and demonstrated tolerable toxicity in pts with advanced DGC. The level of platelet, albumin, CEA, CA199, CA125 and LDH could predict the prognosis of DGC patients.

LMOD1, an oncogene associated with Lauren classification, regulates the metastasis of gastric cancer cells through the FAK-AKT/mTOR pathway

BackgroundThe Lauren classification of gastric tumors strongly correlates with prognosis. The purpose of this study was to explore the specific molecular mechanism of Lauren classification of gastric cancer and provide a possible theoretical basis for the treatment of gastric cancer.MethodsWe standardized the gene expression data of five Gene Expression Omnibus gastric cancer databases and constructed a Weighted Co-expression Network Analysis (WGCNA) model based on clinicopathological information. The overall survival (OS) and disease-free survival (DFS) curves were extracted from the Cancer Genome Atlas (TCGA) and GSE62254 databases. Western blotting was used to measure protein expression in cells and tissues. Scratch and transwell experiments were used to test the migration ability of tumor cells. Immunohistochemistry was used to measure tissue protein expression in clinical tissue samples to correlate to survival data.ResultsThe WGCNA model demonstrated that blue cyan was highly correlated with the Lauren classification of the tumor (r = 0.24, P = 7 × 1016). A protein-protein interaction network was used to visualize the genes in the blue cyan module. The OS and PFS TCGA analysis revealed that LMOD1 was a gene of interest. The proportion of diffuse gastric cancer patients with high expression of LMOD1 was significantly higher than that of intestinal type patients. LMOD1 promoted the migration of gastric cancer cells by regulating the FAK-Akt/mTOR pathway in vitro. Additionally, a Gene Set Enrichment Analysis using the TCGA and GSE62254 databases, and western blot data, showed that LMOD1 could promote an epithelial-mesenchymal transition (EMT), thus potentially affecting the occurrence of peritoneal metastasis of gastric cancer. Immunohistochemistry showed that LMOD1 was highly expressed in cancer tissues, and the prognosis of patients with high LMOD1 expression was poor.ConclusionLMOD1 is an oncogene associated with diffuse gastric cancer and can affect the occurrence and development of EMT by regulating the FAK-Akt/mTOR pathway. LMOD1 can therefore promote peritoneal metastasis of gastric cancer cells and can be used as a novel therapeutic target for gastric cancer.

Methylation and Polymorphism in CDH1 Gene Promoter Among Patients with Diffuse Gastric Cancer.

Background:The promoter methylation and single nucleotide polymorphisms (SNPs) affect the transcription activity of cancer-related genes in several cancers including diffuse gastric cancer (DGC). Here we aimed to evaluate the promoter methylation status and the rs16260 at the promoter region of the CDH1 gene in DGC.Methods:This case-control study was performed of 48 formalin-fixed paraffin-embedded (FFPE) blocks of DGC patients and 41 fresh frozen tissue samples of healthy individuals. Methylation status was evaluated using methylation-specific polymerase chain reaction (PCR) and the rs16260 at the promoter region of the CDH1 gene was assessed using PCR and sequencing method.Results:The occurrence of methylation at the promoter region of the CDH1 gene in DGC patients was significantly higher than control samples (P < 0.0001). The methylated status was significantly associated with the poor differentiated histological type of DGC (P = 0.0428). The frequency of AC genotype and the A allele in DGC patients was significantly higher than the control subjects (P = 0.006 and 0.003, respectively).Conclusions:Here we showed that methylation at the CDH1 promoter may contribute to the DGC development, and also the AC genotype was associated with the risk of DGC.

Abstract P221: Discovery of a covalent inhibitor for an oncogenic mutant RhoAY42C

Abstract Ras homolog family member A (RhoA) is a member of a larger family of Rho proteins of small GTPases, with structural and signaling similarities to Ras proteins. RhoA is involved in multiple cellular processes including cytoskeleton regulation and actin-myosin contractility, etc. Recent studies have shown that the most common RhoA mutation in diffuse gastric cancer (DGC), Y42C, causes a gain-of-function and is associated with the loss of the E-cadherin gene CDH (CDH1). Inhibitors of RhoAY42C could be promising agents for treating DGC that harbors CDH1 mutation/deletion. BridGene expressed RhoAY42C in cells, screened our proprietary covalent library against the RhoAY42C live cells, and employed our chemoproteomic platform IMTACTM (Isobaric Mass Tagged Affinity Characterization) to detect covalent labeling of the mutant RhoA protein. A pilot screening led to the successful identification of a covalent ligand of RhoAY42C, BGS1933. Mass spec analysis has confirmed the covalent modification of Cys42 in RhoA by BGS1933. Dose-dependent binding of BGS1933 to RhoAY42C was measured using an orthogonal fluorescence-based assay. The Cancer Genome Atlas (TCGA) study shows that ~1% DGC patients harbor the oncogenic mutant RhoAY42C. The discovery of a covalent inhibitor of RhoAY42C will enable us to validate the role of RhoAY42C in DGC and facilitate the development of new first-in-class targeted therapies for the treatment of gastric cancer. Citation Format: Shirley Guo, Ping Cao. Discovery of a covalent inhibitor for an oncogenic mutant RhoAY42C [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P221.

Novel somatic variants in CTNNA1 gene in Iranian patients with diffuse gastric cancer.

we aimed to evaluate somatic mutations of CTNNA1 in DGC patients. Diffuse gastric cancer (DGC) is a major type of gastric cancer where most cases are sporadic diffuse gastric cancer (SDGC). It has been shown that mutations in CTNNA1 are responsible for some cases of hereditary diffuse gastric cancer (HDGC). In the present work, 48 formalin-fixed paraffin-embedded tissues, including samples of 38 SDGC and 10 HDGC patients were examined through Sanger sequencing approach on PCR products amplified from 18 exons and boundaries of intron/exon of CTNNA1 gene. We revealed 9 novel somatic mutations in CTNNA1 gene in patients with HDGC and SDGC, from which one variant was intronic. Eight patients had at least one disease-causing mutation (16.6%). Most of the patients were in the III stage of cancer (50%). Except for one patient, histological type of the rest of mutation-harboring patients was signet ring cell carcinoma, and only one HDGC patient had CTNNA1 mutation. Our study showed several novel variants in the CTNNA1 gene in Iranian sporadic and hereditary DGC patients, and implies that the CTNNA1 gene mutations could be involved in the pathogenesis of DGC, either hereditary or in sporadic cases.

A cohort study and meta-analysis of the evidence for consideration of Lauren subtype when prescribing adjuvant or palliative chemotherapy for gastric cancer.

Background:The association between the survival or efficacy of chemotherapy and the Lauren subtype of gastric cancer (GC) remains unclear. We aimed to clarify whether patients with different Lauren subtypes have different survival after treatment with systemic chemotherapy: intestinal gastric cancer (IGC) patients survived better than patients with mixed type gastric cancer (MGC) or diffuse gastric cancer (DGC) after treatment with systemic chemotherapy.Patients & methods:Relevant studies for the meta-analysis were identified through searching Pubmed, Embase, Cochrane and Ovid up to March 2020. We also included our own prospectively collected cohort of patients that were followed over a 10-year period. Sub-group and sensitivity analyses were also performed.Results:In our prospective cohort, the overall survival (OS) of IGC patients receiving systemic chemotherapy (chemoIGC) [median OS 5.01 years, interquartile range (IQR) 2.63–6.71] was significantly higher than that of DGC patients receiving the same chemotherapy (chemoDGC) (median OS 1.33 years, IQR 0.78–3.33, p = 0.0001). After adjusting for age, gender and cancer stage, there was a significant difference in OS in patients treated with chemotherapy based on the Lauren classification of GC {hazard ratio (HR) for OS of the IGC versus DGC 0.33, [95% confidence interval (CI), 0.17–0.65; p < 0.001]}. In the IGC patients, the adjusted HR associated with chemotherapy was 0.26 (95% CI, 0.12–0.56; p = 0.001), whereas the association was 0.64 (95% CI, 0.30–1.33; p = 0.23) in the DGC patient group.In our meta-analysis, 33 studies comprising 10,246 patients treated with systemic chemotherapy (chemoIGC n = 4888, chemoDGC n = 5358) met all the selection criteria. While we accounted for much of the heterogeneity in these studies, we found that chemoIGC patients showed significantly improved OS [HR, 0.76 (95% CI, 0.71–0.82); p < 0.00001] when compared with similarly treated chemoDGC patients.Conclusion:Our results support the consideration of Lauren subtype when prescribing systemic chemotherapy for GC, particularly for MGC or DGC, which may not benefit from chemotherapy. Lauren classification should be considered to stratify chemotherapy regimens to GC patients in future clinical trials, with particular relevance to MGC or DGC, which is more difficult to treat with current regimens.

P-183 - Legumain is a predictive effector of peritoneal metastasis for diffuse gastric cancer patients

P-183 - Legumain is a predictive effector of peritoneal metastasis for diffuse gastric cancer patients

C-Met-dependent phosphorylation of RhoA plays a key role in gastric cancer tumorigenesis.

RhoA has been identified as having a gain-of-function mutation in approximately 20% of diffuse gastric cancer patients. However, the carcinogenic role of RhoA mutations in gastric cancer (GC) is unclear. In the present study, we report that RhoA directly interacts with c-Met and can be phosphorylated by c-Met at Y42 before subsequent K48-linked polyubiquitination and proteasome-mediated protein degradation. Y42C-mutated RhoA exhibits higher protein levels and promotes the proliferation and motility of GC cells. Interestingly, a c-Met inhibitor significantly repressed the growth of GC cells transfected with WT RhoA but not RhoA mutated at Y42 in vivo and in vitro. Analyses of human GC tissues showed that the combined levels of p-c-Met and p-RhoA are a better predictor for prognosis than either factor alone. Taken together, our findings unravel the mechanism by which the RhoA Y42 mutant is linked to poor prognosis in GC. Moreover, this study helps to identify a strategy for patient stratification and optimization of targeted c-Met therapy. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Pathological features of total gastrectomy specimens from asymptomatic hereditary diffuse gastric cancer patients and implications for clinical management.

Hereditary diffuse gastric cancer (HDGC) is an autosomal dominant syndrome characterised by multigenerational diffuse gastric cancer, and is mainly caused by germline alterations in the CDH1 gene. Currently, endoscopy has limited diagnostic accuracy, and total gastrectomy (TG) is the treatment of choice for asymptomatic CDH1 carriers. In this study, we aimed to obtain a better understanding of HDGC syndrome by exploring the histopathological findings of TG specimens from asymptomatic HDGC patients. A comprehensive literature review was carried out, searching for TGs performed in asymptomatic HDGC patients. Fourteen unpublished cases, analysed in our institution, were also included. The series encompassed 174 CDH1 carriers. Preoperative endoscopic biopsies were positive in 28.3%. A macroscopic lesion was apparent in 11.7% of TGs. Histopathological analysis revealed intraepithelial lesions and/or intramucosal signet ring cell carcinoma in 87.9% of TGs. When we explored the type of protocol used for handling the specimens, we found that microscopic cancer foci were detected in 95.3% of TGs when a total-embedding protocol (assessment of the totality of gastric mucosa) was applied, and only in 62.5% when no specific protocol was used (P<0.001). Helicobacter pylori infection was found in 23.4% cases. In conclusion, a thorough histopathological examination of gastric mucosa remains the gold standard for detection of cancer foci in HDGC gastrectomy specimens, requiring experienced pathologists for an accurate diagnosis. A better understanding of the natural history of HDGC will enable better clinical management of HDGC patients, particularly regarding the optimal timing for the performance of TG.

Characterization of long non-coding RNAs and MEF2C-AS1 identified as a novel biomarker in diffuse gastric cancer

Previous studies proved that long noncoding RNAs (lncRNAs) play important role in human cancer. However, the knowledge of genome scale expression of lncRNAs and their potential biological function in gastric cancer is still lacking. Next generation RNA sequencing (RNA-seq) was performed on tumor tissues and matched adjacent normal tissues of six diffuse gastric cancer (DGC) patients. Then we performed a comprehensive analysis on lncRNAs and mRNA. Fifty-eight lncRNAs were upregulated and 54 lncRNAs were downregulated in diffuse gastric cancer tissue compared with adjacent tissue. The numbers of up- and downregulated mRNAs were 306 and 161, respectively. In addition, we inferred the function of lncRNAs by construction of a co-expression network for deregulated mRNAs and lncRNAs. Co-expressed genes of MEF2C-AS1 and FENDRR were enriched to RAS and TGF-beta signaling pathway. MEF2C-AS1 and FENDRR expression were re-evaluated by Real-time Quantitative PCR in 42 DGC patients' tumor and normal tissues, and other 46 DGC patents' and 21 healthy controls' plasma. Validation data showed MEF2C-AS1 and FENDRR were significantly downregulated in tumor tissues compared with normal tissues. And decreased FENDRR are associated with aggressive tumor characteristics including more advanced stage (P = .030), poor differentiation (P = .043) and lymphatic metastasis (P = .001). The expression level MEF2C-AS1 was significantly lower in DGC patients' plasma than that in healthy controls' plasma. In gastric cancer cell lines, knock-down of MEF2C-AS1 or FENDRR reduced the protein levels of FAT3, NTN1 and LYVE1 (the co-expressed genes), which were related with gastric cancer cell proliferation and invasion by previous studies. In addition, knock-down of MEF2C-AS1 or FENDRR promoted aggressive tumor behaviors in in-vitro assays. In this study, we provide a valuable resource of lncRNAs which might play important roles in the function of oncogenes or tumor suppressors affecting the development and progression of diffuse gastric cancer.

Distinct Expression and Prognostic Value of MS4A in Gastric Cancer.

Gastric cancer has high malignancy and early metastasis, which lead to poor survival rate. In this study, we assessed the expressions and prognostic values of MS4A family, a newly recently discovered family, by two online dataset, GEPIA and Kaplan Meier-plotter. From these results eight members, MS4A2, MS4A6, MS4A7, MS4A8, MS4A14, MS4A15, TMEM176A and TMEM176B showed positive expression in gastric cancer or normal tissues, and these genes were screened for further analysis of prognostic values. We observed that low mRNA expressions of MS4A2, MS4A7, MS4A14, MS4A15, TMEM176A and TMEM176B were correlated with better overall survival (OS) in all gastric cancer patients, while high mRNA expression of MS4A6 was observed to be associated with good prognosis. MS4A8’s high mRNA level was correlated to better OS in diffuse gastric cancer patients. Further, we estimated prognostic values of MS4A family in gastric cancer patients with different clinic-pathological features, including clinical stages, differentiation level, lymph node status and HER2 status. Our results indicate that these eight MS4A members can estimate prognosis in patients with different pathological groups. In conclusion, MS4A family members are potential biomarkers, and may contribute to tumor progression in gastric cancer.

Incidence rate and clinical-pathological features of hereditary diffuse gastric cancer patients in China.

4065 Background: Familial clustering is seen in 10 % of gastric cancer cases and approximately 1-3 % of gastric cancer arises in the setting of hereditary diffuse gastric cancer (HDGC). Little is known about the incidence rate and clinical-pathologic features of HDGC in Chinese patients. Methods: We retrospectively collected gastric adenocarcinoma patients who were diagnosed in Sun Yat-sen University Cancer Center between January 2002 and December 2014. All the patients had detailed record of family history and Lauren classification. All of statistical analyses were performed using the Intercooled Stata 13.0 (Stata Corporation, College Station, TX). Results: 7431 patients were enrolled for analysis. The incidence rate of HDGC was 3.97% (295/7431). There were 124 (42.03%) male and 171 (57.97%) female patients. The median age was 35 (Mean ±SD: 35.23±7.50). The most common sites were gastric body (49.47%) and fundus (35.09%) . The distribution of AJCC 7thTNM stage was 47 (16.32%) stage I, 59 (20.49%) stage II, 88 (30.55%) stage III and 94 (32.64%) stage IV. Only 92 patients received the HER2 immunohistochemistry test. 4 (4.35%) patients were HER2 IHC +++ and 8 (8.70%) patients were ++. The median survival was 80 months for the whole population and 15 months for stage IV patients. Conclusions: The incidence rate of HDGC was 3.97% in China. About one third of the patients were diagnosed at stage IV. Early detection of HDGC was warranted in China.

Integrated Analysis Identifies Molecular Signatures and Specific Prognostic Factors for Different Gastric Cancer Subtypes

BACKGROUND: Gastric cancer (GC) is the fifth leading cause of cancer-related deaths worldwide. As an effective and easily performed method, microscopy-based Lauren classification has been widely accepted by gastrointestinal surgeons and pathologists for GC subtyping, but molecular characteristics of different Lauren subtypes were poorly revealed. METHODS: GSE62254 was used as a derivation cohort, and GSE15459 was used as a validation cohort. The difference between diffuse and intestinal GC on the gene expression level was measured. Gene ontology (GO) enrichment analysis was performed for both subgroups. Hierarchical clustering and heatmap exhibition were also performed. Kaplan-Meier plot and Cox proportional hazards model were used to evaluate survival grouped by the given genes or hierarchical clusters. RESULTS: A total of 4598 genes were found differentially expressed between diffuse and intestinal GC. Immunity- and cell adhesion–related GOs were enriched for diffuse GC, whereas DNA repair– and cell cycle–related GOs were enriched for intestinal GC. We proposed a 40-gene signature (χ2=30.71, P<.001) that exhibits better discrimination for prognosis than Lauren classification (χ2=12.11, P=.002). FRZB [RR (95% CI)=1.824 (1.115-2.986), P=.017] and EFEMP1 [RR (95% CI)=1.537 (0.969-2.437), P=.067] were identified as independent prognostic factors only in diffuse GC but not in intestinal GC patients. KRT23 [RR (95% CI)=1.616 (0.938-2.785), P=.083] was identified as an independent prognostic factor only in intestinal GC patients but not in diffuse GC patients. Similar results were achieved in the validation cohort. CONCLUSION: We found that GCs with different Lauren classifications had different molecular characteristics and identified FRZB, EFEMP1, and KRT23 as subtype-specific prognostic factors for GC patients.

Complementary molecular approaches reveal heterogeneous CDH1 germline defects in Italian patients with hereditary diffuse gastric cancer (HDGC) syndrome

Germline inactivation of the E-cadherin gene (CDH1) is associated with hereditary diffuse gastric cancer (HDGC), a rare autosomal dominant syndrome predisposing to both diffuse gastric cancer (DGC) and lobular breast cancer (LBC). We searched for CDH1 germline defects in 32 HDGC Italian probands selected according to international consensus criteria and in 5 selected relatives. We used a series of molecular methods, including: DNA sequencing, multiplex ligation-dependent probe amplification, single-nucleotide primer extension, bisulfite sequencing, reverse-transcription PCR, and bioinformatics tools. We identified pathogenic mutations in 6 out of 32 probands (19%): one truncating and two missense mutations, one large deletion, one allelic expression imbalance and one splicing defect. Three out of six CDH1 constitutive alterations were novel. Our data support the need for a multimethod approach for CDH1 genetic testing, demonstrating that both DNA and RNA analyses are required to increase the detection rate of pathogenic mutations, thus reducing the number of patients without a clear molecular diagnosis. On the whole, our results indicate that not only DGC patients, but also subjects with personal or family history of LBC might benefit from CDH1 genetic testing. Moreover, our findings support the notion that prophylactic gastrectomy should be offered to asymptomatic CDH1 mutation carriers; indeed, while endoscopic analysis with histological examination of random gastric biopsies can miss cancer foci, gastrectomy performed in these subjects always revealed foci of cancer cells.

E-cadherin genetic screening and clinico-pathologic characteristics of early onset gastric cancer

Aim CDH1 germline alterations occur in about 40% of hereditary diffuse gastric cancer (HDGC) families. CDH1 germline mutations are also documented in few early onset diffuse gastric cancer patients (EODGC) without family history, but the real frequency in this setting in unknown. In these patients, the advanced stage at the time of diagnosis remains a clinical burden due to the poor long term survival. Methods The entire coding region and exon flanking sequences of the CDH1 gene was analysed by direct sequencing in 21 EODGC patients aged ⩽50 years. The potential deleterious nature for a new CDH1 missense variant was assessed by cell–cell aggregation and invasion assays. Somatic CDH1 mutation, loss of heterozigosity (LOH) and promoter hypermethylation was explored in the tumour from one CDH1 germline mutation carrier. Results Two novel CDH1 germline variants were identified in 21 EODGC cases, c.670C>T and –63C>A. Functional analysis of the c.670C>T missense variant classified this mutation as non-pathogenic. The analysis of CDH1 somatic second hits failed to demonstrate E-cadherin structural and epigenetic alterations in the tumour sample. Conclusion Data from the present work and a systematic review of the literature revealed that CDH1 germline mutations occurred in 7.2% of EOGC patients invariably with diffuse of mixed histology. From these, proved CDH1 mutation pathogenicity has been assigned only to 2.3% of the cases who were recurrently diagnosed before 35 years old. Germline CDH1 mutation remain the only germline genetic defect described in this type of patients and CDH1 mutation screening should be recommended for patients with these characteristics.

Phosphoglycerate kinase 1 a promoting enzyme for peritoneal dissemination in gastric cancer

Peritoneal carcinomatosis is a frequent finding in gastric cancer associated with a poor prognosis. The features that enable gastric tumors to disseminate are poorly understood until now. Previously, we showed elevated mRNA levels of phosphoglycerate kinase 1 (PGK1), an adenosine triphosphate-generating enzyme in the glycolytic pathway, the chemokine receptor 4 (CXCR4), the corresponding chemokine ligand 12 (CXCL12) and beta-catenin in specimens from gastric cancer patients with peritoneal carcinomatosis. In this study, the influence of PGK1 on CXCR4 and beta-catenin was assessed as well as the invasiveness of PGK1 overexpressing cancer cells. In this current study, we found that PGK1 regulates the expression of CXCR4 and beta-catenin at the mRNA and protein levels. On the other hand, CXCR4 regulates the expression of PGK1. Plasmid-mediated overexpression of PGK1 dramatically increased the invasiveness of gastric cancer cells. Interestingly, inhibition of CXCR4 in cells overexpressing PGK1 produced only a moderate reduction of invasiveness suggesting that, PGK1 itself has a critical role in tumor invasiveness. Immunohistochemistry in specimens from diffuse gastric cancer patients also revealed an overexpression of PGK1 in patients with development of peritoneal carcinomatosis. Therefore, PGK1 may be a crucial enzyme in peritoneal dissemination. Together these findings suggest that the enhanced expression of PGK1 and its signaling targets CXCR4 and beta-catenin in gastric cancer cells promote peritoneal carcinomatosis. Thus, PGK1 may serve as prognostic marker and/or be a potential therapeutic target to prevent dissemination of gastric carcinoma cells into the peritoneum.