How Can Gastric Cancer Molecular Profiling Guide Future Therapies?

(-)-Epigallocatechin-3-gallate induced apoptosis by dissociation of c-FLIP/Ku70 complex in gastric cancer cells

Anti-cancer properties of (-)-epigallocatechin-3-gallate (EGCG) are mediated via apoptosis induction, as well as inhibition of cell proliferation and histone deacetylase. Accumulation of stabilized cellular FLICE-inhibitory protein (c-FLIP)/Ku70 complex in the cytoplasm inhibits apoptosis through interruption of extrinsic apoptosis pathway. In this study, we evaluated the anti-cancer role of EGCG in gastric cancer (GC) cells through dissociation of c-FLIP/Ku70 complex. MKN-45 cells were treated with EGCG or its antagonist MG149 for 24 h. Apoptosis was evaluated by flow cytometry and quantitative RT-PCR. Protein expression of c-FLIP and Ku70 was analysed using western blot and immunofluorescence. Dissociation of c-FLIP/Ku70 complex as well as Ku70 translocation were studied by sub-cellular fractionation and co-immunoprecipitation. EGCG induced apoptosis in MKN-45 cells with substantial up-regulation of P53 and P21, down-regulation of c-Myc and Cyclin D1 as well as cell cycle arrest in S and G2/M check points. Moreover, EGCG treatment suppressed the expression of c-FLIP and Ku70, decreased their interaction while increasing the Ku70 nuclear content. By dissociating the c-FLIP/Ku70 complex, EGCG could be an alternative component to the conventional HDAC inhibitors in order to induce apoptosis in GC cells. Thus, its combination with other cancer therapy protocols could result in a better therapeutic outcome.

System Analysis Based on Lipid-Metabolism-Related Genes Identifies AGT as a Novel Therapy Target for Gastric Cancer with Neoadjuvant Chemotherapy

Gastric cancer (GC) is one of the most common causes of cancer-related deaths worldwide, and chemotherapy is still a standard strategy for treating patients with advanced GC. Lipid metabolism has been reported to play an important role in the carcinogenesis and development of GC. However, the potential values of lipid-metabolism-related genes (LMRGs) concerning prognostic value and the prediction of chemotherapy responsiveness in GC remains unclear. A total of 714 stomach adenocarcinoma patients were enrolled from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. Using univariate Cox and LASSO regression analyses, we developed a risk signature based on LMRGs that can distinguish high-GC-risk patients from low-risk patients with significant differences in overall survival. We further validated this signature prognostic value using the GEO database. The R package “pRRophetic” was applied to calculate the sensitivity of each sample from high- and low-risk groups to chemotherapy drugs. The expression of two LMRGs, AGT and ENPP7, can predict the prognosis and response to chemotherapy in GC. Furthermore, AGT significantly promoted GC growth and migration, and the downregulation of AGT enhanced the chemotherapy response of GC both in vitro and in vivo. Mechanistically, AGT induced significant levels of epithelial–mesenchymal transition (EMT) through the PI3K/AKT pathway. The PI3K/AKT pathway agonist 740 Y-P can restore the EMT of GC cells impaired by AGT knockdown and treatment with 5-fluorouracil. Our findings suggest that AGT plays a key role in the development of GC, and targeting AGT may help to improve the chemotherapy response of GC patients.

TTN-AS1 delivered by gastric cancer cell-derived exosome induces gastric cancer progression through in vivo and in vitro studies

Extracellular communication within the tumor microenvironment exerts critical functions in tumor progression. Moreover, exosomes are capable of packaging into long non-coding RNAs (lncRNAs) to regulate extracellular communication. We tried to discuss the role of exosomal lncRNA TTN-AS1 and its molecular mechanism on gastric cancer (GC) progression. Bioinformatics analysis depicted increased TTN-AS1 in GC which shared correlation with poor prognosis. Clinical tissue and cellular experiments also confirmed the elevation of TTN-AS1 in GC tissues and cells. GC cell (AGS)-derived Exo could be uptake by NCI-N87 cells to induce malignant features of GC cells. Functionally, TTN-AS1 could upregulate ZEB1 expression by binding to miR-499a-5p. In addition, in vitro experiments demonstrated that ZEB1 targeted and activated CDX2 transcription and promoted CDX2 expression; silencing CDX2 inhibited malignant phenotypes of AGS and NCI-N87 cells. Furthermore, Exo-TTN-AS1 promoted GC cell growth and migration by promoting CDX2 expression. Exosomal TTN-AS1 from GC cells could also promote metastasis of GC in vivo. In conclusion, our findings provided evidence describing that exosomes derived from GC cells transferred TTN-AS1 to GC cells, which aggravate GC through the miR-499a-5p/ZEB1/CDX2 axis. 1. Exo derived from GC cells promotes the growth and metastasis of GC cells by carrying TTN-AS1. 2. TTN-AS1 acts as a ceRNA to adsorb miR-499a-5p to regulate the expression of ZEB1. 3. ZEB1 targets and activates CDX2 transcription. 4. GC cell-derived Exo-TTN-AS1 enhances the growth and metastasis of GC cell xenografts in vivo.

Weipiling decoction alleviates N-methyl-N-nitro-N′-nitrosoguanidine-induced gastric precancerous lesions via NF-κB signalling pathway inhibition

Aim of the study

We aimed to explore how weipiling (WPL) decoction WPL alleviates gastric precancerous lesions (GPLs) and uncover its anti-inflammatory roles in GPL treatment.

Materials and methods

The anti-GPL action mechanisms of WPL were analysed using a network pharmacological method. The WPL extract was prepared in a traditional way and evaluated for its major components using high-performance liquid chromatography with tandem mass spectrometry (HPLC–MS/MS). BALB/c mice were exposed to N-methyl-N-nitro-N-nitrosoguanidine (MNNG) (150 μg/mL) for 6 weeks to induce GPLs. GPL mice were administered WPL (3.75 g/kg/day and 15 g/kg/day) for an additional 8 weeks. Haematoxylin and eosin (H&E) staining was used to investigate histological alterations in gastric tissues. Expression of the T helper 1 (Th1) cell markers CD4⁺ and interferon-gamma (INF-γ) were tested using immunohistochemistry (IHC). Inflammatory protein and mRNA levels in the nuclear factor kappa B (NF-κB) pathway were detected using western blotting and a quantitative reverse transcription polymerase chain reaction (RT-qPCR), respectively.

Results

We identified and selected 110 active compounds and 146 targets from public databases and references. Four representative components of WPL were established and quantified by HPLC–MS/MS analysis. WPL attenuated MNNG-induced GPLs, including epithelial shedding, cavity fusion, basement membranes with asymmetrical thickness, intestinal metaplasia, dysplasia, pro-inflammatory Th1-cell infiltration, and INF-γ production, indicating that WPL prevents inflammation in the gastric mucosa. Furthermore, WPL reversed MNNG-induced activation of the IκB/NF-κB signalling pathway and subsequently attenuated the upregulation of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase (NOX)) family members NOX2 and NOX4.

Conclusion

WPL attenuated GPLs by controlling the generation of pro-inflammatory elements and inhibiting the NF-κB signalling pathway in vivo.

CircRNA ACVR2A Sponges miR-1290 to Modulate Cell Progression in Gastric Cancer

Background

In recent years, the abnormal expression of circRNAs has been identified to be strongly associated with tumor tissues. In this study, we focused on circACVR2A with a remarkably upregulated expression in gastric tissues and further explored its role in the pathogenic progression of gastric cancer (GC).

Methods

The differentially expressed circACVR2A in GC tissues and four cell lines (MKN-45, SNU-1, HGC-27, and SGC-7901) was identified by qRT-PCR method. Then, the effect of circACVR2A and miR-1290 on HGC-27 cell proliferation was measured by CCK8 and the colony formation methods. The effect of circACVR2A and miR-1290 on HGC-27 cell metastasis was estimated by transwell assay. The interaction of circACVR2A and miR-1290 was further detected.

Results

The relative level of circACVR2A in GC tissues and cell lines is remarkably upregulated. The downregulation of circACVR2A promotes GC cell proliferation and metastasis and suppressed the expression level of E-cadherin and Vimentin. The miR-1290 inhibitor reversed the effect of circACVR2A on cell progression in GC cell.

Conclusion

circACVR2A competitively sponged miR-1290 and was exerted as a tumor suppressor gene oncogene via a circACVR2A/miR-1290 axis, suggesting it as a possible biomarker for GC therapy.

Anatomic Subsites and Prognosis of Gastric Signet Ring Cell Carcinoma: A SEER Population-Based 1 : 1 Propensity-Matched Study

Background. The dismal prognosis of gastric signet ring cell carcinoma (GSRC) is a global problem. The current study is conducted to comprehensively evaluate clinicopathological features and survival outcomes in GSRC patients stratified by anatomic subsites. Then, predictive nomograms are constructed and validated to improve the effectiveness of personalized management. Method. The patients diagnosed with GSRC were recruited from the online SEER database. The influence of anatomic subsites on overall survival (OS) and cancer-specific survival (CSS) was evaluated using multivariate Cox regression and Kaplan-Meier analysis. Then, we employed propensity score matching (PSM) technique to decrease selection bias and balance patients’ epidemiological factors. Predictive nomograms were constructed and validated. Sensitivity analysis was performed to validate the conclusion. Results. Multivariate Cox regression demonstrated that the patients with overlapping gastric cancer (OGC) suffered the highest mortality risk for OS (HR, 1.29; 95% CI, 1.23-1.36; $P<0.001$ ) and CSS (HR, 1.33; 95% CI, 1.28-1.37; $P<0.001$ ). Age, TNM stage, tumor localization, tumor size, surgery, and chemotherapy presented a highly significant relationship with OS and CSS. Following subgroup and PSM analysis, OGC patients were confirmed to have the worst OS and CSS. Then, nomograms predicting 6-month, 12-month, and 36-month survival were constructed. The area under the curve (AUC) value in ROC was 0.775 (95% CI, 0.761-0.793) for 6-month survival, 0.789 (95% CI, 0.776-0.801) for 12-month survival, and 0.780 (95% CI, 0.765-0.793) for 36-month survival in the OS group, while in the CSS group, it was 0.771 (95% CI, 0.758-0.790) for 6-month survival, 0.781 (95% CI, 0.770-0.799) for 12-month survival, and 0.773 (95% CI, 0.762-0.790) for 36-month survival. Conclusion. We identified anatomic subsites as a predictor of survival in those with GSRC. Patients with OGC suffered the highest mortality risk. The proposed nomograms allowed a relatively accurate survival prediction for GSRC patients.

LINC01133 hampers the development of gastric cancer through increasing somatostatin via binding to microRNA-576-5p

Aim: Our study aimed at investigating how LINC01133 functions in gastric cancer (GC) progression. Materials & methods: Gain-of-function and loss-of-function approaches were applied to analyze the effects of LINC01133, microRNA-576-5p (miR-576-5p) and somatostatin (SST) on the biological behaviors of GC cells and in tumor-bearing nude mice. Results: GC tissues and cells showed low expression of LINC01133, and LINC01133 overexpression decreased malignant phenotypes of GC cells. Moreover, LINC01133 upregulated SST through binding to miR-576-5p. Overexpressing miR-576-5p or suppressing SST reversed the functions of LINC01133 in biological potentials of GC cells and tumor growth. Conclusion: LINC01133 overexpression may inhibit GC development by downregulation of miR-576-5p and upregulation of SST, which suggests new therapeutic targets for GC.

Comparing immunotherapies to other frequently used treatments of gastric cancer

Introduction: Although standard doublet chemotherapy represents the upfront gold standard to increase survival and improve quality of life of gastric cancer patients, overall improvements in long-term outcomes are modest and novel treatments are urgently needed. Among these, immunotherapy is an increasingly attractive option.Areas covered: A number of clinical trials have shown that checkpoint inhibitors may be of value, but many unclear issues remain controversial and should be promptly untangled. In our short review, we offer the current available data regarding immunotherapies in gastric cancers, discuss potential limits of the reported trials, compare outcomes of checkpoints inhibitor to those of standard chemotherapy or other novel treatments, and present basic principles of immune surveillance and immune escape that may be embraced in the near future with novel drug combinations.Expert opinion: Gastric cancer patients may benefit from immunotherapy, both given alone in advanced lines and upfront in combination with chemotherapy. We believe that appropriate patients' and tumor's selection are crucial issues to maximize its potential efficacy. In addition, we think that assay standardization, biomarker agreement, and translational studies will improve the benefit-to-risk ratio of these agents in the clinical practice.

Optimized EGFR Blockade Strategies in EGFR Addicted Gastroesophageal Adenocarcinomas

PURPOSE

Gastric and gastroesophageal adenocarcinomas represent the third leading cause of cancer mortality worldwide. Despite significant therapeutic improvement, the outcome of patients with advanced gastroesophageal adenocarcinoma is poor. Randomized clinical trials failed to show a significant survival benefit in molecularly unselected patients with advanced gastroesophageal adenocarcinoma treated with anti-EGFR agents.

EXPERIMENTAL DESIGN

We performed analyses on four cohorts: IRCC (570 patients), Foundation Medicine, Inc. (9,397 patients), COG (214 patients), and the Fondazione IRCCS Istituto Nazionale dei Tumori (206 patients). Preclinical trials were conducted in patient-derived xenografts (PDX).

RESULTS

The analysis of different gastroesophageal adenocarcinoma patient cohorts suggests that EGFR amplification drives aggressive behavior and poor prognosis. We also observed that EGFR inhibitors are active in patients with EGFR copy-number gain and that coamplification of other receptor tyrosine kinases or KRAS is associated with worse response. Preclinical trials performed on EGFR-amplified gastroesophageal adenocarcinoma PDX models revealed that the combination of an EGFR mAb and an EGFR tyrosine kinase inhibitor (TKI) was more effective than each monotherapy and resulted in a deeper and durable response. In a highly EGFR-amplified nonresponding PDX, where resistance to EGFR drugs was due to inactivation of the TSC2 tumor suppressor, cotreatment with the mTOR inhibitor everolimus restored sensitivity to EGFR inhibition.

CONCLUSIONS

This study underscores EGFR as a potential therapeutic target in gastric cancer and identifies the combination of an EGFR TKI and a mAb as an effective therapeutic approach. Finally, it recognizes mTOR pathway activation as a novel mechanism of primary resistance that can be overcome by the combination of EGFR and mTOR inhibitors.See related commentary by Openshaw et al., p. 2964.

Silencing of long non-coding RNA XIST represses gastric cancer progression through blocking NFκB pathway via inhibiting HNF4A-mediated transcription of EPHA1

Gastric cancer (GC) is a common cancer and a leading cause of cancer-related deaths worldwide. Recent studies have supported the important role of long non-coding RNAs (lncRNAs) in GC progression. This study identified functional significance of X inactive specific transcript (XIST) in GC. The expression of XIST and EPHA1 in GC tissues and cells was measured. Then, dual luciferase reporter gene assay, RNA immunoprecipitation (RIP) assay and Chromatin Immunoprecipitation (ChIP) assay were performed to explore the interaction among XIST, EPHA1 and HNF4A. The effects of XIST on GG progression were evaluated by determining expression of proliferation- and invasion-related proteins (Ki67, PCNA, MMP-2, and MMP-9). Further, the functional role of XIST in GC with the involvement of NFκB pathway was also analyzed. Subsequently, the tumor growth in nude mice was evaluated. High expression of XIST and EPHA1 was observed in GC. XIST elevated EPHA1 expression by recruiting HNF4A. In addition, silencing of XIST inhibited GC progression in vitro and in vivo. Overexpressed XIST and EPHA1 yielded a reversed effect on cell proliferation and invasion. SN50 treatment (inhibitor of NFκB pathway) counteracted the promotive effect on GC cell proliferation and invasion mediated by XIST. The present study unveils that XIST increases the enrichment of HNF4A in the promoter region of EPHA1, thus promoting the deterioration of GC.

The Significance of HOXC11 and LSH in Survival Prediction in Gastric Adenocarcinoma

Purpose

Gastric adenocarcinoma is one of the most important causes of cancer death and lacks effective treatment. Eighty-four gastric adenocarcinoma tissue samples along with the clinical information were collected. After analyzing the expression of HOXC11 and LSH in the gastric adenocarcinoma tissues, we explored the prognosis of patients and its correlation with clinical characteristics. Both HOXC11 and LSH were over-expressed in MKN-45 cell lines to verify the effect of high expression of HOXC11 and LSH on GAC.

Methods

The expression of HOXC11 and LSH in 84 cases with gastric adenocarcinoma (GAC) was detected via immunohistochemistry, including 17 cases in stage I, 7 cases in stage II, 27 cases in stage III and 33 cases in stage IV. The expression levels of HOXC11 and LSH, and the clinicopathological characteristics of the samples, were also studied. Cell proliferation, migration, cell cycle and apoptosis assays were utilized for demonstrating malignancy of HOXC11 and LSH over-expressed cells.

Results

Among 84 GAC pathological samples, 12 high HOXC11 expression, and 72 showed low expression; 54.8% (46/84) high LSH expression, and 45.2% (38/84) exhibited low expression. Survival analysis of the Kaplan-Meier plotter gastric cancer datasets showed that subjects with low expression of HOXC11 and LSH had a longer survival time, with a median survival time of 40.2 and 36.4 months, while the subjects with high HOXC11 and LSH expression were only 20.5 and 10 months, respectively. Meanwhile, HOXC11 and LSH over-expressed cells showed a stronger proliferous and migratory ability, and a sped up cell cycle.

Conclusion

The high expression level of HOXC11 and LSH both manifested the poor survival prognosis of GAC patients, and more pronounced malignant phenotype in GAC cells indicated that HOXC11 and LSH can be a strong predictive factor of inferior disease-free survival. From this, we can consider that HOXC11 and LSH both have significant status in GAC stage and survival prediction.

Three-Dimensional Ex Vivo Culture for Drug Responses of Patient-Derived Gastric Cancer Tissue

Gastric cancer (GC) is one of the most common malignancies with high mortality and substantial morbidity. Although the traditional treatment strategies for GC revolve around surgery, radiotherapy, and chemotherapy, none have been able to optimally treat most affected patients. To improve clinical outcomes and overcome potential GC resistance, we established a three-dimensional (3D) culturing platform that accurately predicts drug responses in a time- and cost-effective manner. We collected tumor tissues from patients following surgeries and cultured them for 3 days using our protocol. We first evaluated cell proliferation, viability, and apoptosis using the following markers: Ki67 and cleaved caspase 3 (Cas3). We demonstrated that cell viability was maintained for 72 h in culture and that the tumor microenvironments and vascular integrities of the tissues were intact throughout the culture period. We then administered chemotherapeutics to assess drug responses and found differential sensitivity across different patient-derived tissues, enabling us to determine individualized medication plans. Overall, our study validated this rapid, cost-effective, scalable, and reproducible protocol for GC tissue culture that can be employed for drug response assessments. Our 3D culture platform paves a new way for personalized medication in GC and other tumors and can greatly impact future oncological research.

hsa_circ_001653 up-regulates NR6A1 expression and elicits gastric cancer progression by binding to microRNA-377

NEW FINDINGS

What is the central question of this study? Does hsa_circ_001653 influence the development of gastric cancer (GC) and if so how? What is the main finding and its importance? Bioinformatics analysis revealed the presence of differentially expressed hsa_circ_001653 in GC and adjacent normal tissues, and this was strongly related to the pathology of patients with GC. Knockdown of hsa_circ_001653 suppressed the proliferation, invasion and migration of GC cells, while inducing cell apoptosis via miR-377-mediated NR6A1 inhibition. The effect of hsa_circ_001653 and miR-377 on tumour growth in GC was further confirmed in vivo.

ABSTRACT

Gastric cancer (GC) is one of the leading causes of human mortality through malignant tumours. Circular RNAs (circRNAs) have been identified as binding to microRNAs (miRNAs) to modulate the progression of tumours. This study explores the role of hsa_circ_001653, a newly identified circRNA, in the development of GC. hsa_circ_001653 expression was measured in 86 paired normal and tumour tissues surgically resected from GC patients. Cross-talk between hsa_circ_001653 and microRNA-377 (miR-377)/nuclear receptor subfamily 6, group A, member 1 (NR6A1) was assessed using bioinformatics analysis, dual-luciferase reporter assay, Ago2 immunoprecipitation and western blot analysis. A series of functional experiments were carried out to elucidate the role of hsa_circ_001653 in GC cell proliferation, invasion, migration and apoptosis, and its underlying molecular mechanisms. Nude mice were inoculated with GC cells for in vivo analysis. hsa_circ_001653 was found to be an up-regulated circRNA in GC tissues and cells. Down-regulation of hsa_circ_001653 inhibited GC cell proliferation, migration and invasion, while stimulating cell apoptosis. hsa_circ_001653 was found to bind to miR-377, which targeted NR6A1 and repressed its expression. Inhibition of miR-377 and overexpression of NR6A1 restored the proliferation, migration and invasion in GC cells lacking hsa_circ_001653. Furthermore, inhibition of hsa_circ_001653 attenuated tumour growth in nude mice inoculated with GC cells. Collectively, the demonstration that hsa_circ_001653 exerts its anticancer effects by regulating the miR-377-NR6A1 axis increases our understanding of gastric cancer pathophysiology. The findings uncover new potential therapeutic targets for GC.

Preoperative Radiotherapy Is Associated With Significant Survival Benefits for Patients With Gastric Signet Ring Cell Carcinoma: A SEER-Based Approach

Objective:

To explore the clinical and pathological features of gastric signet ring cell carcinoma, and evaluate the survival impact of preoperative radiotherapy on these patients.

Methods:

The Surveillance, Epidemiology, and End Results database was used to extract eligible patients from 2004 to 2015. The patients were divided into those with and without preoperative radiotherapy. The categorical variables were described by chi-square tests. The patients’ survival was compared between the 2 groups by Kaplan-Meier method with log-rank tests. Cox proportional hazard model was adopted to identify prognostic factors of cancer-specific survival.

Results:

Totally 4771 patients were recruited, of whom 218(4.6%) patients received preoperative radiotherapy, while 4553(95.4%) patients didn’t receive this treatment. Survival analysis of the entire cohort demonstrated that preoperative radiotherapy improved both cancer-specific survival and overall survival (p < 0.001) of the patients. Cox proportional hazard models identified age >60, tumor size >50 mm, TNM stage II-IV as independent risk factors for poor prognosis (HR > 1, p < 0.05). Notably, preoperative radiotherapy was identified as an independent protective factor for favorable prognosis (HR < 1, p < 0.05). Subgroup survival analysis showed that preoperative radiotherapy exerted significant survival benefits for the stages III and IV patients.

Conclusions:

In this population-based study, preoperative radiotherapy is associated with significant survival benefits for the patients with advanced gastric signet ring cell carcinoma. Hence preoperative radiotherapy is feasible for these patients.

The importance of Epstein-Barr virus infection in the systemic treatment of patients with gastric cancer

The Epstein-Barr virus (EBV) may directly cause the development of EBV-associated gastric cancer (EBVaGC). The prevalence of EBVaGC ranges from 4% to 18%, with a 2-fold higher frequency in males, and in tumors arising in the gastric cardia or corpus and 4 times higher frequency in gastric stump carcinoma. The vast majority of EBVaGC are lymphoepithelioma-like carcinomas. Despite extensive nodal involvement and distant metastases at initial diagnosis, EBVaGC seems to be a distinct etiologic entity with a favorable prognosis. However, the lymphoepithelioma-like carcinomas subtype in EBVaGC cannot be recognized in the current molecular classifications. Neither is there an association between EBV positivity and survival of patients after curative gastrectomy if they received standard adjuvant chemotherapy, nor EBV positivity and prediction of response to neoadjuvant platinum/5-FU-based chemotherapy. Alterations in chemokines and PD-L1 provide theoretical justification for clinical evaluation of immune checkpoint therapy in EBVaGC. Moreover, a higher degree of host immune response was demonstrated in EBVaGC. The current histologic and molecular GC classification does not influence clinical practice. Further research is expected to find convenient methods to assess gastric subtypes in day-to-day practice and to tailor therapy to improve overall survival.

Prognostic and Predictive Value of Microsatellite Instability, Inflammatory Reaction and PD-L1 in Gastric Cancer Patients Treated with Either Adjuvant 5-FU/LV or Sequential FOLFIRI Followed by Cisplatin and Docetaxel: A Translational Analysis from the ITACA-S Trial

BACKGROUND

Patients with high microsatellite instability (MSI) gastric cancer (GC) show improved survival and no benefit or harm from adjuvant and/or perioperative chemotherapy. The role of immune microenvironment in GC is largely unknown.

MATERIALS AND METHODS

In the present study, 256 tumor tissue blocks were centrally collected from patients enrolled in ITACA-S, a randomized adjuvant trial of 5-FU/LV versus sequential FOLFIRI and cisplatin-docetaxel. MSI status was assessed by multiplex PCR, inflammatory reaction by H&E morphological assessment, and programmed death-ligand 1 (PD-L1) expression by immunohistochemistry.

RESULTS

Overall, 9% patients had MSI-high tumors, 23% had high inflammatory reaction, 11% had tumor PD-L1 ≥ 1%, and 11% had stromal PD-L1 ≥ 1%. A significant association with disease-free survival (DFS) and overall survival (OS) was found for MSI-high (hazard ratio [HR], 0.43; p = .02; HR, 0.40; p = .02) and high inflammatory reaction (HR, 0.55; p = .010; HR, 0.53; p = .008) but not for PD-L1. At multivariable analysis, only MSI showed an independent association with both DFS (p = .02) and OS (p = .01), whereas inflammatory reaction showed an independent association only with OS (p = .04). Patients with tumor PD-L1 ≥ 1% had a significantly longer DFS in sequential chemotherapy than in than 5-FU/LV arm (interaction p = .04) and a trend for OS (interaction p = .12).

CONCLUSION

Our data suggest that MSI status could be a useful prognostic biomarker in patients with radically resected stage II-III GC and should be used as stratification factor in future trials. Tumor PD-L1 ≥ 1% should be further investigated as a potential predictor of benefit from intensive chemotherapy.

IMPLICATIONS FOR PRACTICE

In this post hoc analysis of patients with radically resected gastric cancer randomized to an intensive sequential chemotherapy regimen versus 5-FU/LV monotherapy as adjuvant treatment in the ITACA-S trial, MSI-high status was independently associated with better disease-free survival and overall survival (OS) and inflammatory reaction was independently associated with better OS. Moreover, tumor PD-L1 expression ≥1% was associated with greater benefit from intensive sequential chemotherapy compared with 5-fluorouracil plus leucovorin (5-FU/LV), whereas PD-L1 expression <1% was not, conditioning a statistically significant interaction between such biomarker and treatment arms. The meta-analysis of individual patients' data from available studies could yield data on the role of MSI status that could inform clinical decisions.

Gastric cancer is associated with a high rate of microsatellite instability versus chronic gastritis: A retrospective study

Objective: Microsatellite instability (MSI) in gastric cancer contributes to genetic complexities of gastric cancer. In the current study, we employed a panel of mononucleotide and dinucleotide markers to detect MSI in 99 gastric cancer patients and 91 chronic gastritis patients and further analyzed the association of MSI with clinicopathologic variables of the study patients.

Methods: We retrospectively analyzed the clinicopathologic data of primary gastric cancer patients and chronic gastritis patients. MSI was analyzed using five microsatellite markers, including D2S12, D5S346, D17S799, BAT26, and D18S34. MSI was defined as either a band shift or the appearance of a novel band in DNA. Multivariate logistic regression analysis was used to predict risk of MSI.

Results: Seventeen (17.2%) gastric cancer patients and 7 (7.7%) chronic gastritis patients were positive for MSI (P=0.012). Multivariate analysis further showed that gastric cancer was associated with a significantly higher likelihood for MSI versus gastritis (OR 3.73; 95% CI 1.19, 11.72; P=0.024) while age, drinking or smoking was not associated with increased MSI.

Conclusion: Gastric cancer is associated with a high rate of MSI. MSI should be further explored in future studies with a larger sample size for its role in gastric cancer development and as a predictive biomarker.

Arsenic sulfide induces RAG1-dependent DNA damage for cell killing by inhibiting NFATc3 in gastric cancer cells

Background

Arsenic sulfide was found to have potential anti-cancer activities, especially in gastric cancer. However, the underlying mechanism need to be further explored. This study was aimed to investigate the mechanism of arsenic compounds on gastric cancer.

Methods

Gastric cancer cell lines were infected with lentiviral vector carrying shNFATc3 and/or treated with arsenic sulfide. MTT assay were performed to assess cell growth. Flow cytometer assays were used to detect cell cycle and reactive oxygen species (ROS) level of gastric cancer cells. Western blot was carried out to detect nuclear factor of activated T-cells, cytoplasmic 3 (NFATc3), cell cycle markers, DNA damage pathway protein expression as well as other protein expression in gastric cancer cell lines. The expression of recombination activating gene 1 (RAG1) in gastric cancer cell lines was determined by RNA-sequencing analyses and Real-Time qPCR. The effect of NFATc3 on RAG1 were determined by CHIP-qPCR assay. The effect of arsenic sulfide on AGS cells was evaluated in vivo.

Results

We show that arsenic sulfide as well as knockdown of NFATc3 resulted in increased double-strand DNA damage in gastric cancer cells by increasing the expression of RAG1, an endonuclease essential for immunoglobulin V(D) J recombination. Overexpression of NFATc3 blocked the expression of RAG1 expression and DNA damage induced by arsenic sulfide. Arsenic sulfide induced cellular oxidative stress to redistribute NFATc3, thereby inhibiting its transcriptional function, which can be reversed by N-acetyl-L-cysteine (NAC). We show that NFATc3 targets the promoter of RAG1 for transcriptional inhibition. We further showed that NFATc3 upregulation and RAG1 downregulation significantly associated with poor prognosis in patients with gastric cancer. Our in vivo experiments further confirmed that arsenic sulfide exerted cytotoxic activity against gastric cancer cells through inhibiting NFATc3 to activate RAG1 pathway.

Conclusion

These results demonstrate that arsenic sulfide targets NFATc3 to induce double strand DNA break (DSB) for cell killing through activating RAG1 expression. Our results link arsenic compound to the regulation of DNA damage control and RAG1 expression as a mechanism for its cytotoxic effect.

Gramicidin inhibits human gastric cancer cell proliferation, cell cycle and induced apoptosis

Background

Gastric cancer is a common malignant tumor with high morbidity and mortality worldwide, which seriously affects human health. Gramicidin is a short peptide antibiotic which could be used for treating infection induced by bacteria or fungi. However, the anti-cancer effect of gramicidin on gastric cancer cells and its underlying mechanism remains largely unknown.

Results

Gastric cancer cells SGC-7901, BGC-823 and normal gastric mucosal cells GES-1 were treated with different concentrations of gramicidin respectively. The results of CCK-8 experiment revealed cellular toxicity of gramicidin to cancer cells while cell colony formation assay showed that gramicidin significantly inhibited the proliferation of gastric cancer cells, but had little effect on normal gastric mucosal cells. In addition, the wound healing assay showed that gramicidin inhibited the migration of SGC-7901 cell. Meanwhile, apoptosis and cell cycle analysis revealed that gramicidin induced cell apoptosis with G2/M cell cycle inhibition. Furthermore, western blot analysis demonstrated that gramicidin down-regulated the expression of cyclinD1 and Bcl-2 as well as the FoxO1 phosphorylation.

Conclusions

The current study illustrated the anti-tumor activity of gramicidin on gastric cancer cells, providing a possibility for gramicidin to be applied in clinical practice for the treatment of gastric cancer.

Predictive value of WHO classification for PD-L1 and Her2/Neu expression and distinct associations with protein expression based classification in gastric carcinoma

The Cancer Genome Atlas data on gastric carcinoma has identified four biologic pathways as potential drivers of gastric carcinogenesis and suggested targeted therapies based on the genomic alterations underscoring each subset. The correlation between morphology, biologic groups and their corresponding biomarkers has been eluded in several previous studies; however, a comprehensive analysis in consideration of the recent advancements has not been performed. In this study we explored the predictive value of morphology for biomarker expression and its association with protein expression based classification of gastric carcinoma. Four hundred eighty six gastric carcinomas which had been classified into protein expression-based groups formed the case cohort. Upon analysis, we found a low positive predictive value of an individual morphologic pattern for biomarker-expression, indicating that an individual morphologic pattern alone cannot predict PD-L1, Her2/neu expression and EBV- or MSI-gastric cancer. A combination approach targeting the test in certain WHO patterns can be employed for maximizing the positive predictive values. These include, PD-L1 testing in tubular, carcinoma with lymphoid stroma, undifferentiated and poorly cohesive patterns and Her2/neu testing in tubular, mixed, papillary, mucinous and solid patterns. The predictive values and morphologic associations presented here have the potential to select patients for personalized therapy.

A Comprehensive PDX Gastric Cancer Collection Captures Cancer Cell-Intrinsic Transcriptional MSI Traits

Gastric cancer is the world's third leading cause of cancer mortality. In spite of significant therapeutic improvements, the clinical outcome for patients with advanced gastric cancer is poor; thus, the identification and validation of novel targets is extremely important from a clinical point of view. We generated a wide, multilevel platform of gastric cancer models, comprising 100 patient-derived xenografts (PDX), primary cell lines, and organoids. Samples were classified according to their histology, microsatellite stability, Epstein-Barr virus status, and molecular profile. This PDX platform is the widest in an academic institution, and it includes all the gastric cancer histologic and molecular types identified by The Cancer Genome Atlas. PDX histopathologic features were consistent with those of patients' primary tumors and were maintained throughout passages in mice. Factors modulating grafting rate were histology, TNM stage, copy number gain of tyrosine kinases/KRAS genes, and microsatellite stability status. PDX and PDX-derived cells/organoids demonstrated potential usefulness to study targeted therapy response. Finally, PDX transcriptomic analysis identified a cancer cell-intrinsic microsatellite instability (MSI) signature, which was efficiently exported to gastric cancer, allowing the identification, among microsatellite stable (MSS) patients, of a subset of MSI-like tumors with common molecular aspects and significant better prognosis. In conclusion, we generated a wide gastric cancer PDX platform, whose exploitation will help identify and validate novel "druggable" targets and optimize therapeutic strategies. Moreover, transcriptomic analysis of gastric cancer PDXs allowed the identification of a cancer cell-intrinsic MSI signature, recognizing a subset of MSS patients with MSI transcriptional traits, endowed with better prognosis. SIGNIFICANCE: This study reports a multilevel platform of gastric cancer PDXs and identifies a MSI gastric signature that could contribute to the advancement of precision medicine in gastric cancer.

CENPO expression regulates gastric cancer cell proliferation and is associated with poor patient prognosis

Gastric cancer (GC) is one of the most common malignancies worldwide; however, understanding of its development and carcinogenesis is currently limited. Centromere protein O (CENPO), is a newly discovered constitutive centromeric protein, associated with cell death. The expression of CENPO in human cancers, including GC, is currently unknown. The aim of the present study was to investigate the clinical association between CENPO and GC, and to elucidate the potential mechanisms of CENPO in the process of GC progression. The results demonstrated that CENPO was expressed at high levels in GC and was correlated with p-TNM stage. In addition, CENPO was observed to be a marker of poor prognosis in patients with GC. Knockdown of CENPO contributed to GC cell growth inhibition and apoptosis induction. In addition, downregulation of CENPO expression suppressed GC cell growth in vivo. Furthermore, CENPO knockdown decreased ataxia telangiectasia mutated (ATM), cyclin D1 and c-Jun expression, indicating that the ATM signaling pathway may be involved in CENPO-mediated regulation of GC cell growth. In conclusion, increased CENPO expression may be associated with the aggressive tumor biology of GC and CENPO may present a novel therapeutic target and prognostic biomarker for patients with GC.

Identification of DNA methylation signature to predict prognosis in gastric adenocarcinoma

Gastric adenocarcinoma is an important death-related cancer. To find factors related to survival and prognosis, and thus improve recovery prospects, a powerful signature is needed. DNA methylation plays an important role in gastric adenocarcinoma processes and development, and here we report on the search for a significant DNA methylation gene to aid with the earlier diagnosis of gastric adenocarcinoma patients. A Cox proportional risk regression analysis and random survival forest algorithm were used to analyze gastric adenocarcinoma patients' DNA methylation data from The Cancer Genome Atlas, a public database. DNA methylation gene signature consisting of five genes (SERPINA3, AP000357.4, GZMA, AC004702.2, and GREB1L) were selected. As the most accurate predictor, the area under the curve in the training and test group were 0.72 and 0.61, respectively. The signature was able to sort patients into high- and low-risk groups with meaningful overall survival rates (median: 18.36 vs 72.23 months, log-rank test, P < 0.001) in the training group, which predictive ability was validated in a test data set (median: 25.56 vs 58.80 months, log-rank test, P < 0.016). A multivariate Cox regression analysis showed the significant DNA methylation was an independent prediction prognostic factor for gastric adenocarcinoma patients. Functional analysis suggests that these signature genes may be related to pathways and biological processes associated with tumorigenesis. The significant DNA methylation gene could be a novel prediction and prognostic biomarker that both aids in the treatment and predicts the overall survival likelihoods of gastric adenocarcinoma patients.

Somatic mutation of DNAH genes implicated higher chemotherapy response rate in gastric adenocarcinoma patients

Background

The dynein axonemal heavy chain (DNAH) family of genes encode the dynein axonemal heavy chain, which is involved in cell motility. Genomic variations of DNAH family members have been frequently reported in diverse kinds of malignant tumors. In this study, we analyzed the genomic database to evaluate the mutation status of DNAH genes in gastric adenocarcinoma and further identified the significance of mutant DNAH genes as effective molecular biomarkers for predicting chemotherapy response in gastric cancer patients.

Methods

We analyzed the clinical and genomic data of gastric cancer patients published in The Cancer Genome Atlas (TCGA) project. Data on chemotherapy response, overall survival (OS) and chemotherapy-free survival were retrieved. Then, we verified the results via targeted sequencing of gastric cancer patients with similar clinical characteristics but different chemotherapeutic outcomes.

Results

In total, 132 gastric adenocarcinoma patients undergoing chemotherapy treatment from TCGA were included in our study. Somatic mutations in all 13 members of the DNAH family of genes were associated with different chemotherapy responses. Compared with patients with wild-type DNAH genes (n = 59), a significantly higher proportion of those with mutations in DNAH genes (n = 73) (55.9% vs 80.8%) responded to chemotherapy (P = 0.002). Moreover, DNAH mutations were correlated with significantly better OS (P = 0.027), chemotherapy-free survival (P = 0.027), fluoropyrimidine-free survival (P = 0.048) and platinum-free survival (P = 0.014). DNAH mutation status was an independent risk factor for OS (P = 0.015), chemotherapy-free survival (P = 0.015) and platinum-free survival (P = 0.011). We identified somatic mutations in 27 (42.2%) of the 64 stage III gastric adenocarcinoma patients receiving fluoropyrimidine-based chemotherapy by targeted exon sequencing with strict screening conditions. In our own cohort, a significantly higher proportion of patients (n = 32) with DNAH mutations than patients with wild-type DNAH genes (n = 32) had a good prognosis (OS > 48 months) (70.4% vs 35.1%) (P = 0.005).

Conclusions

Dynein axonemal heavy chain gene mutations contribute positively to chemotherapy sensitivity in gastric cancer patients.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1867-6) contains supplementary material, which is available to authorized users.

Hyaluronan-mediated motility receptor confers resistance to chemotherapy via TGFβ/Smad2-induced epithelial-mesenchymal transition in gastric cancer

Chemotherapy is one of the vital treatments for gastric cancer (GC) patients, especially those suffering advanced stages. Chemoresistance results in tumor relapse, leading to poor prognosis in GC patients; thus, identifying key regulators in this process might provide novel clues for GC therapy. Herein, we identify hyaluronan-mediated motility receptor (HMMR) as a key regulator of chemoresistance in GC. HMMR was found to be substantially up-regulated in 5-fluorouracil (5-Fu)-resistant GC biopsies and cell lines. High expression of HMMR significantly correlates with tumor relapse and predicts poorer prognosis in GC patients. Moreover, we observed that HMMR induced epithelial-mesenchymal transition and increased the cancer stem cell properties of GC, thus rendering resistance to chemotherapy. Importantly, silencing of HMMR effectively increased the susceptibility to 5-Fu therapy both in vitro and in vivo. Furthermore, we demonstrated that HMMR activates the TGF-β/Smad2 signaling pathway, which was required for the HMMR-mediated oncogenic effects and exhibited significant clinical relevance with HMMR expression. These findings reveal a critical role for HMMR in the chemoresistance of GC and suggest that HMMR might be a potential prognostic marker or therapeutic target against the disease.-Zhang, H., Ren, L., Ding, Y., Li, F., Chen, X., Ouyang, Y., Zhang, Y., Zhang, D. Hyaluronan-mediated motility receptor confers resistance to chemotherapy via TGFβ/Smad2-induced epithelial-mesenchymal transition in gastric cancer.

GPR177 promotes gastric cancer proliferation by suppressing endoplasmic reticulum stress-induced cell death

Gastric cancer is the fourth most common cancer worldwide. Despite the high incidence of gastric cancer, efficient chemotherapy treatments still need to be developed. In this study, we examined the anticancer effects of endoplasmic reticulum (ER) stress inducer tunicamycin in gastric cancer. Previously, we found that overexpression of WLS1/GPR177 correlated with poor prognosis in patients with gastric cancer. Furthermore, tunicamycin treatment downregulated GPR177 expression in a dose-dependent manner. GPR177 transports WNT ligand from ER to the plasma membrane, mediating its secretion to the extracellular matrix. In gastric cancer cells, GPR177 preferentially localizes to the ER. Small interfering RNA-mediated knockdown of GPR177 leads to sensitization to ER stress and induces apoptosis of cancer cells along with tunicamycin treatment. GPR177 suppression promoted the ER stress-mediated proapoptotic pathway, such as PERK-CHOP cascade. Furthermore, fluorouracil treatment combined with tunicamycin dramatically reduced cancer cell proliferation. Efficacy of tunicamycin chemotherapy treatments depended on GPR177 expression in gastric cancer cell lines. Together, our results indicate that ER stress can potentiate anticancer effects and suggest GPR177 as a potential gastric cancer therapeutic target.

Prognostic value of sorting nexin 10 weak expression in stomach adenocarcinoma revealed by weighted gene co-expression network analysis

AIM

To detect significant clusters of co-expressed genes associated with tumorigenesis that might help to predict stomach adenocarcinoma (SA) prognosis.

METHODS

The Cancer Genome Atlas database was used to obtain RNA sequences as well as complete clinical data of SA and adjacent normal tissues from patients. Weighted gene co-expression network analysis (WGCNA) was used to investigate the meaningful module along with hub genes. Expression of hub genes was analyzed in 362 paraffin-embedded SA biopsy tissues by immunohistochemical staining. Patients were classified into two groups (according to expression of hub genes): Weak expression and over-expression groups. Correlation of biomarkers with clinicopathological factors indicated patient survival.

RESULTS

Whole genome expression level screening identified 6,231 differentially expressed genes. Twenty-four co-expressed gene modules were identified using WGCNA. Pearson’s correlation analysis showed that the tan module was the most relevant to tumor stage (r = 0.24, P = 7 × 10^-6). In addition, we detected sorting nexin (SNX)10 as the hub gene of the tan module. SNX10 expression was linked to T category (P = 0.042, χ² = 8.708), N category (P = 0.000, χ² = 18.778), TNM stage (P = 0.001, χ² = 16.744) as well as tumor differentiation (P = 0.000, χ² = 251.930). Patients with high SNX10 expression tended to have longer disease-free survival (DFS; 44.97 mo vs 33.85 mo, P = 0.000) as well as overall survival (OS; 49.95 vs 40.84 mo, P = 0.000) in univariate analysis. Multivariate analysis showed that dismal prognosis could be precisely predicted clinicopathologically using SNX10 [DFS: P = 0.014, hazard ratio (HR) = 0.698, 95% confidence interval (CI): 0.524-0.930, OS: P = 0.017, HR = 0.704, 95%CI: 0.528-0.940].

CONCLUSION

This study provides a new technique for screening prognostic biomarkers of SA. Weak expression of SNX10 is linked to poor prognosis, and is a suitable prognostic biomarker of SA.

Inhibition of Wntless/GPR177 suppresses gastric tumorigenesis

Wntless/GPR177 functions as WNT ligand carrier protein and activator of WNT/β-catenin signaling, however, its molecular role in gastric cancer (GC) has remained elusive. We investigated the role of GPR177 in gastric tumorigenesis and provided the therapeutic potential of a clinical development of anti-GPR177 monoclonal antibodies. GPR177 mRNA expression was assessed in GC transcriptome data sets (GSE15459, n = 184; GSE66229, n = 300); protein expression was assessed in independent patient tumor tissues (Yonsei TMA, n = 909). GPR177 expression were associated with unfavorable prognosis [log-rank test, GSE15459 (P = 0.00736), GSE66229 (P = 0.0142), and Yonsei TMA (P = 0.0334)] and identified as an independent risk predictor of clinical outcomes: GSE15459 [hazard ratio (HR) 1.731 (95% confidence interval; CI; 1.103–2.715), P = 0.017], GSE66229 [HR 1.54 (95% CI, 1.10–2.151), P = 0.011], and Yonsei TMA [HR 1.254 (95% CI, 1.049–1.500), P = 0.013]. Either antibody treatment or GPR177 knockdown suppressed proliferation of GC cells and sensitized cells to apoptosis. And also inhibition of GPR177 suppresses in vitro and in vivo tumorogenesis in GC cells and inhibits WNT/β-catenin signaling. Finally, targeting and inhibition of GPR177 with antibody suppressed tumorigenesis in PDX model. Together, these results suggest GPR177 as a novel candidate for prognostic marker as well as a promising target for treatment of GC patients.

Distinct molecular subtypes of gastric cancer: from Laurén to molecular pathology

In Western countries the majority of gastric cancers (GC) are usually diagnosed in advanced stages reporting a 5-year survival rate of only 26%. The Laurén classification of GC was most widely used in clinical practice since it reflects GC morphology, epidemiology, tumor biology, clinical management and outcome. Despite the initial promise of individualizing antitumor treatment, the management of GC still remains relatively broad and general. Apart from clinical staging, molecular profiling enables targeting of the identified underlying alterations, rather than histology. In contrast to breast carcinoma, molecular classification of GC does not yet imply treatment modality. Molecular classifications of GC and their therapeutic implications are therefore extensively studied. The current proposed molecular divisions of GC come from three different parts of the world where different standard treatment modalities for advanced GC are recommended. Wider use of GC molecular subtyping may solve problems, such as susceptibility to novel systemic therapy regimens or selection of patients for aggressive surgery and targeted adjuvant/conversion therapy. In any case, the rapid entry of novel molecular targeted therapies into routine oncology practice clearly underscores the urgent need for clinicians to be aware of these new possibilities.

Rituximab Treatment Prevents Lymphoma Onset in Gastric Cancer Patient-Derived Xenografts

Patient-Derived Xenografts (PDXs), entailing implantation of cancer specimens in immunocompromised mice, are emerging as a valuable translational model that could help validate biologically relevant targets and assist the clinical development of novel therapeutic strategies for gastric cancer.

More than 30% of PDXs generated from gastric carcinoma samples developed human B-cell lymphomas instead of gastric cancer. These lymphomas were monoclonal, Epstein Barr Virus (EBV) positive, originated tumorigenic cell cultures and displayed a mutational burden and an expression profile distinct from gastric adenocarcinomas. The ability of grafted samples to develop lymphomas did not correlate with patient outcome, nor with the histotype, the lymphocyte infiltration level, or the EBV status of the original gastric tumor, impeding from foreseeing lymphoma onset. Interestingly, lymphoma development was significantly more frequent when primary rather than metastatic samples were grafted.

Notably, the development of such lympho-proliferative disease could be prevented by a short rituximab treatment upon mice implant, without negatively affecting gastric carcinoma engraftment.

Due to the high frequency of human lymphoma onset, our data show that a careful histologic analysis is mandatory when generating gastric cancer PDXs. Such care would avoid misleading results that could occur if testing of putative gastric cancer therapies is performed in lymphoma PDXs. We propose rituximab treatment of mice to prevent lymphoma development in PDX models, averting the loss of human-derived samples.

Clinical utility of circulating cell-free Epstein-Barr virus DNA in patients with gastric cancer. Oncotarget. 2017;8:28796-28804. [PMID: 28430637 PMCID: PMC5438692 DOI: 10.18632/oncotarget.15675]

Recent comprehensive molecular subtyping of gastric cancer (GC) identified Epstein-Barr virus (EBV)-positive tumors as a subtype with distinct salient molecular and clinical features. In this study, we aimed to determine the potential utility of circulating cell-free EBV DNA as a biomarker for the detection and/or monitoring of therapeutic response in patients with EBV-associated gastric carcinoma (EBVaGC). The EBV genes-to-ribonuclease P RNA component H1 ratios (EBV ratios) in the GC tumors and plasma samples were determined by quantitative real-time polymerase chain reaction in 153 patients with GC, including 14 patients with EBVaGC diagnosed by the conventional method. Circulating cell-free EBV DNA was detected in 14 patients with GC: the sensitivity and specificity of detection were 71.4% (10/14) and 97.1% (135/139), respectively. Plasma EBV ratios were significantly correlated with the size of EBVaGC tumors, and the plasma EBV DNA detected before surgery in EBVaGC cases disappeared after surgery. Patients with EBVaGC may have a better prognosis, but circulating cell-free EBV DNA had no or little impact on prognosis. In addition, repeated assessment of the plasma EBV ratio in EBVaGC showed a decrease and increase in plasma EBV DNA after treatment and during tumor progression/recurrence, respectively. These results suggest the potential utility of circulating cell-free DNA to reveal EBV DNA for the identification of the EBVaGC subtype and/or for real-time monitoring of tumor progression as well as treatment response in patients with EBVaGC.

Identification of COL4A1 as a potential gene conferring trastuzumab resistance in gastric cancer based on bioinformatics analysis

Trastuzumab, the first targeted antibody against human epidermal growth factor receptor 2 (HER2), has been used to treat gastric cancer patients with HER2 overexpression. However, trastuzumab resistance often occurs following an initial period of benefits, and the underlying mechanisms remain largely unclear. The present study revealed that collagen type IV α1 chain (COL4A1), whose expression is upregulated in gastric cancer tissues and trastuzumab-resistant gastric cancer cells, may potentially confer trastuzumab resistance in gastric cancer. By performing bioinformatics analysis of 2 microarray datasets, the present study initially identified COL4A1, overexpressed in gastric cancer tissues and trastuzumab-resistant gastric cancer cells, as a potential candidate for inducing trastuzumab resistance. The drug resistance function of COL4A1 in gastric cancer was then validated by performing protein/gene interactions and biological process annotation analyses, and further validated by analyzing the functionality of microRNAs that target COL4A1 mRNA. Collectively, these data indicated that COL4A1 may confer trastuzumab resistance in gastric cancer.

Gastric cancer biomarkers; A systems biology approach

Gastric cancer is one of the most fatal cancers in the world. Many efforts in recent years have attempted to find effective proteins in gastric cancer. By using a comprehensive list of proteins involved in gastric cancer, scientists were able to retrieve interaction information. The study of protein-protein interaction networks through systems biology based analysis provides appropriate strategies to discover candidate proteins and key biological pathways.

In this study, we investigated dominant functional themes and centrality parameters including betweenness as well as the degree of each topological clusters and expressionally active sub-networks in the resulted network. The results of functional analysis on gene sets showed that neurotrophin signaling pathway, cell cycle and nucleotide excision possess the strongest enrichment signals. According to the computed centrality parameters, HNF4A, TAF1 and TP53 manifested as the most significant nodes in the interaction network of the engaged proteins in gastric cancer. This study also demonstrates pathways and proteins that are applicable as diagnostic markers and therapeutic targets for future attempts to overcome gastric cancer.

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A systematic study of protein-protein interaction networks through comprehensive extracted list of proteins involved in gastric cancer.

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Dominant functional theme and pathways of each topological clusters and expressionally active subnetworks were reported.

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The most effective proteins in gastric cancer formation were proposed according to the computed centrality parameters.

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HNF4A, TAF1and TP53 were mentioned as the key proteins in gastric cancer.

c-FLIP is a target of the E3 ligase deltex1 in gastric cancer

The ubiquitin E3 ligase DELTEX1 (DTX1) is specifically downregulated in gastric cancer tissues, and expression of DTX1 is linked to better prognoses and survival in gastric cancer. Cellular FLICE inhibitory protein (c-FLIP) is known for its pivotal role in the resistance of cancer cells to death receptor-induced cell death. Here, we show that DTX1 is an E3 ligase for c-FLIP in gastric cancer cells. DTX1 promoted c-FLIP downregulation. Overexpression of DTX1 sensitized gastric cancer cells to TRAIL-induced apoptosis, whereas DTX1-knockdown attenuated apoptosis induction. DTX1 binds c-FLIP_L and directs it into the endosome-lysosomal pathway for proteasome-independent degradation. Moreover, induction of DTX1 in AGS cells by geldanamycin conferred susceptibility of those cells to TRAIL-induced apoptosis. Our results reveal a tumor-suppressive role for DTX1 and suggest a new approach to increasing TRAIL efficacy by raising DTX1 levels in gastric cancer therapy. DTX1 also enhanced c-FLIP degradation and FasL-induced and TRAIL-induced apoptosis in T cells, suggesting that DTX1 constitutes one of the physiological mechanisms regulating c-FLIP stability.

Wogonin exacerbates the cytotoxic effect of oxaliplatin by inducing nitrosative stress and autophagy in human gastric cancer cells

BACKGROUND

Gastric cancer remains one of the leading cause of death in the world. Drug combinations are potential approaches to provide more efficient treatments that minimize side effects.

PURPOSE

We investigated the pharmacological effects of the combination of wogonin with oxaliplatin on gastric cancer cells in vitro and in vivo.

METHODS AND RESULTS

In the present study, we found that wogonin enhanced the cytotoxicity of oxaliplatin; the drug combination resulted in strong synergistic inhibition of the cell viability in BGC-823 cells and in a zebrafish xenograft model. Interestingly, the combined treatment of wogonin and oxaliplatin modulated the expression of phospho-JNK (Thr183/Tyr185), phospho-ULK1 (Ser555) and the formation of LC3II. Confocal imaging data consistently showed that wogonin exacerbates the oxaliplatin-induced dissipation of the mitochondrial membrane potential (ΔΨm) and formation of peroxynitrite in BGC-823 cells. Moreover, wogonin allows a reduction in oxaliplatin dose when they are combined; therefore, it is a relevant strategy for reducing the side effects of oxaliplatin while achieving the same response.

CONCLUSION

These results suggest that wogonin can be a potential therapeutic candidate for enhancing the efficacy of oxaliplatin in gastric cancer treatment.

The role of pazopanib on tumour angiogenesis and in the management of cancers: A review

Pazopanib is a relatively new compound to be introduced into the chemotherapy field. It is thought to have decent anti-angiogenic properties, which gives an additional hope for the treatment of certain types of cancers. A systematic review solely discussing about pazopanib and its anti-angiogenic effect is yet to be published to date, despite several relevant clinical trials being conducted over the recent years. In this review, we aim to investigate the mechanism of pazopanib's anti-angiogenic effect and its effectiveness in treating several cancers. We have included, in this study, findings from electronically searchable data from randomized clinical trials, clinical studies, cohort studies and other relevant articles. A total of 352 studies were included in this review. From the studies, the effect of pazopanib in various cancers or models was observed and recorded. Study quality is indefinite, with a few decent quality articles. The most elaborately studied cancers include renal cell carcinoma, solid tumors, advanced solid tumors, soft tissue sarcoma, breast cancer and gynecological cancers. In addition, several less commonly studied cancers are included in the studies as well. Pazopanib had demonstrated its anti-angiogenic effect based on favorable results observed in cancers, which are caused by angiogenesis-related mechanisms, such as renal cell carcinoma, solid tumors, advanced solid tumors and soft tissue sarcoma. This review was conducted to study, analyze and review the anti-angiogenic properties of pazopanib in various cancers. The results obtained can provide a decent reference when considering treatment options for angiogenesis-related malignancies. Furthermore, the definite observations of the anti-angiogenic effects of pazopanib could provide newer insights leading to the future development of drugs of the same mechanism with increased efficiency and reduced adverse effects.

CXXC4 activates apoptosis through up-regulating GDF15 in gastric cancer

Worldwide, gastric cancer is one of the most fatal cancers. Epigenetic alterations in gastric cancer play important roles in silencing of tumor suppressor genes. We previously found that CXXC finger protein 4 (CXXC4) was a novel tumor suppressor in gastric cancer. In this report, we demonstrated that CXXC4 inhibited growth of gastric cancer cells as a pro-apoptotic factor. This inhibition could be reversed by the pan-caspase inhibitor called Z-VAD-FMK. However, CXXC4 with mutations in its DNA binding domain failed to induce apoptosis. Growth differentiation factor 15 (GDF15) was identified as one of potential targets responsible for CXXC4-induced apoptosis. CXXC4 activated GDF15 transcription through enhancing the interaction of transcription factor Sp1 with GDF15 promoter. In summary, the nuclear protein CXXC4 activated apoptosis in gastric cancer through up-regulating its novel potential downstream target GDF15. GDF15 might be a promising target for clinical treatment of gastric cancer with CXXC4 deficiency.

Construction of a combinatorial pipeline using two somatic variant calling methods for whole exome sequence data of gastric cancer

High-throughput next-generation sequencing is a powerful tool to identify the genotypic landscapes of somatic variants and therapeutic targets in various cancers including gastric cancer, forming the basis for personalized medicine in the clinical setting. Although the advent of many computational algorithms leads to higher accuracy in somatic variant calling, no standard method exists due to the limitations of each method. Here, we constructed a new pipeline. We combined two different somatic variant callers with different algorithms, Strelka and VarScan 2, and evaluated performance using whole exome sequencing data obtained from 19 Japanese cases with gastric cancer (GC); then, we characterized these tumors based on identified driver molecular alterations. More single nucleotide variants (SNVs) and small insertions/deletions were detected by Strelka and VarScan 2, respectively. SNVs detected by both tools showed higher accuracy for estimating somatic variants compared with those detected by only one of the two tools and accurately showed the mutation signature and mutations of driver genes reported for GC. Our combinatorial pipeline may have an advantage in detection of somatic mutations in GC and may be useful for further genomic characterization of Japanese patients with GC to improve the efficacy of GC treatments. J. Med. Invest. 64: 233-240, August, 2017.

Profiling cancer-associated genetic alterations and molecular classification of cancer in Korean gastric cancer patients

Recently, the Cancer Genome Atlas (TCGA) Research Network and Asian Cancer Research Group provided a new classification of gastric cancer (GC) to aid the development of biomarkers for targeted therapy and predict prognosis. We studied associations between genetically aberrant profiles of cancer-related genes, environmental factors, and histopathological features in 107 paired gastric tumor-non-tumor tissue GC samples. 6.5% of our GC cases were classified as the EBV subtype, 17.8% as the MSI subtype, 43.0% as the CIN subtype, and 32.7% as the GS subtype. The distribution of four GC subgroups based on the TCGA and our dataset were similar. The MSI subtype showed a hyper-mutated status and the best prognosis among molecular subtype. However, molecular classification based on the four GC subtypes showed no significant survival differences in terms of overall survival (p= 0.548) or relapse-free survival (RFS, p=0.518). The P619fs*43 in ZBTB20 was limited to MSI group (n= 5/19, 26.3%), showing similar trends observed in TCGA dataset.

Genetic alterations of the RTK/RAS/MAPK and PI3K/AKT/mTOR pathways were detected in 34.6% of GC cases (37 individual cases). We also found two cases with likely pathogenic variants (NM_004360.4: c. 2494 G>A, p.V832M) in the CDH1 gene.

Here, we classified molecular subtypes of GC according to the TCGA system and provide a critical starting point for the design of more appropriate clinical trials based on a comprehensive analysis of genetic alterations in Korean GC patients.

Specific antibodies and sensitive immunoassays for the human epidermal growth factor receptors (HER2, HER3, and HER4)

The use of trastuzumab in patients with breast cancer that overexpresses human epidermal growth factor receptor 2 has significantly improved treatment outcomes. However, a substantial proportion of this patient group still experiences progression of the disease after receiving the drug. Evaluation of the changes in expression of the human epidermal growth factor receptors could be of interest. Monoclonal antibodies against the extracellular domain of the human growth factor receptors, 2, 3, and 4, have been raised, and specific and sensitive immunoassays have been established. Sera from healthy individuals (Nordic Reference Interval Project and Database) were analyzed in the human epidermal growth factor receptor 2 assay (N = 805) and the human epidermal growth factor receptor 3 and 4 assays (N = 114), and reference limits were calculated. In addition, sera from 208 individual patients with breast cancer were tested in all three assays. Finally, the human epidermal growth factor receptor 2 assay was compared with a chemiluminescent immunoassay for serum human epidermal growth factor receptor 2/neu. Reference values were as follows: human epidermal growth factor receptor 2, <2.5 µg/L; human epidermal growth factor receptor 3, <2.8 µg/L; and human epidermal growth factor receptor 4, <1.8 µg/L. There were significant differences in human epidermal growth factor receptor 2 and human epidermal growth factor receptor 3 serum levels between the patients with tissue human epidermal growth factor receptor 2-positive and tissue human epidermal growth factor receptor 2-negative ( p = 0.0026, p = 0.000011) tumors, but not in the serum levels of human epidermal growth factor receptor 4 ( p = 0.054). There was good agreement between the in-house human epidermal growth factor receptor 2 assay and the chemiluminescent immunoassay. Our new specific antibodies for all the three human epidermal growth factor receptors may prove valuable in the development of novel anti-human epidermal growth factor receptor targeted therapies with sensitive immunoassays for measuring serum levels of the respective targets and in monitoring established treatment.

The significance of a nineteenth century definition in the era of genomics: linitis plastica

Background

Linitis plastica due to gastric adenocarcinoma is a condition with a long history, but still lacks a standardized definition and is commonly confused with Borrmann type IV, Lauren diffuse, and signet-cell type gastric cancer. The absence of a clear definition is a problem when investigating its biological characteristics and role as a possible independent factor for prognosis. Nevertheless, the biological behavior for linitis plastica, which is unique, may be valuable in risk stratification and have implications for treatment. A definition of linitis plastica based on molecular or genomic criteria could represent a useful starting point for investigating new targeted therapies.

Main body

This literature review of linitis plastica will focus on the current classifications for gastric cancer, illustrating how the concept of linitis plastica relates to them in most cases and identifying a clear and reproducible definition. Moreover, the review will highlight the diagnostic challenges associated with linitis plastica, its prognostic implications, and the therapeutic options available. Future perspectives for its management are also addressed.

Conclusion

Linitis plastica is a carcinoma with a scirrhous stroma, involving the submucosal and muscular layers of the stomach even in the absence of mucosal alteration. In most cases, the primary cancer cells are signet-ring cells or scattered cells in the context of a poorly differentiated carcinoma. Diagnosis is challenging. Staging should be thorough, including diagnostic laparoscopy in all cases due to the high incidence of peritoneal involvement. The prognostic significance of linitis plastica is still controversial. Curative-intent surgery, when feasible, should be performed, with a multimodality treatment approach. Cancer-stroma interactions are important features of this disease, and represent attaining potential target for future therapies. Future pathologic assessments of gastric cancer should report the stromal reaction in order to allow better characterization of the tumor.

P21 activated kinase 4 binds translation elongation factor eEF1A1 to promote gastric cancer cell migration and invasion

P21 activated kinase 4 (PAK4), as an effector of Cdc42, playing important roles in regulating the processes of cytoskeleton organization. PAK4 has been considered to be an oncogenic protein, which has strong relationship with gastric cancer metastasis. However, the mechanism of PAK4 in regulating gastric cancer metastasis is still not fully understood. In this study, using yeast two-hybrid system, we identified that the eukaryotic elongation factor 1 α1 (eEF1A1) is a new binding partner of PAK4. The interaction between PAK4 and eEF1A1 was confirmed by GST pull-down and co-immunoprecipitation. PAK4 co-localized with eEF1A1 in the cytoplasm of gastric cancer cells. Overexpression of PAK4 enhanced the expression level of eEF1A1 and vice versa. PAK4 and eEF1A1 could cooperate to promote gastric cancer cell migration and invasion. Furthermore, the expression of PAK4 and eEF1A1 in clinical gastric cancer samples were examined by western blotting and immunohistochemistry. Statistical analysis indicated that there was positive correlation between the expression of PAK4 and eEF1A1. This study demonstrated for the first time that PAK4 interacted with eEF1A1 to promote migration and invasion of gastric cancer cells, thereby providing new insights into the function of PAK4 and eEF1A1 in the progression of gastric cancer.

Beyond precision surgery: Molecularly motivated precision care for gastric cancer

Gastric cancer is one of the leading causes of cancer-related deaths worldwide. Despite the high disease prevalence, gastric cancer research has not gained much attention. Recently, genome-scale technology has made it possible to explore the characteristics of gastric cancer at the molecular level. Accordingly, gastric cancer can be classified into molecular subtypes that convey more detailed information of tumor than histopathological characteristics, and these subtypes are associated with clinical outcomes. Furthermore, this molecular knowledge helps to identify new actionable targets and develop novel therapeutic strategies. To advance the concept of precision patient care in the clinic, patient-derived xenograft (PDX) models have recently been developed. PDX models not only represent histology and genomic features, but also predict responsiveness to investigational drugs in patient tumors. Molecularly curated PDX cohorts will be instrumental in hypothesis generation, biomarker discovery, and drug screening and testing in proof-of-concept preclinical trials for precision therapy. In the era of precision medicine, molecularly tailored therapeutic strategies should be individualized for cancer patients. To improve the overall clinical outcome, a multimodal approach is indispensable for advanced cancer patients. Careful, oncological principle-based surgery, combined with a molecularly guided multidisciplinary approach, will open new horizons in surgical oncology.

[Immunohistochemical assessment of HER2 expression in gastric cancer. A clinicopathologic study of 93 cases]

BACKGROUND

Gastric cancer in Mexico is ranked third in both males and females. Most patients present clinically with advanced disease and treatment options are sparse. HER2 overexpression in gastric cancer is related to poor outcome. Immunohistochemical testing for HER2 is becoming the standard of care for guiding adjuvant treatment of gastric cancer with trastuzumab.

OBJECTIVES

To determine the frequency of HER2 overexpression in patients with gastric cancer in the Hospital de Oncología del Centro Médico Nacional, Siglo XXI and its association with other histopathological findings.

MATERIAL AND METHODS

Patients with gastric cancer who underwent surgery between March 12, 2006-August 31, 2011, were enrolled in this retrospective study. Diagnosis was confirmed by review of slides and immunohistochemistry with anti-HER2 antibody was performed. Scoring was done by Hoffman scoring system. Medical records were evaluated.

RESULTS

Ninety-three patients were included in the study, with 43 (46.2%) male and 50 (53.7%) female patients. The median age was 64 years. HER2-positive tumours were identified in 6 patients (6.45%) and located most frequently in the proximal stomach. There was no difference in HER2 overexpression in relation to age, gender or histologic type.

CONCLUSION

In our study, about 7% of patients with gastric cancer were HER2-positive on immunohistochemistry.

Targeted Treatment of Esophagogastric Cancer

Adenocarcinoma of the esophagogastric junction (EGJ) and stomach remains one of the most common causes of cancer-related death worldwide. Although there is increasing data on the mutational landscape of esophagogastric cancer, phase III trials often yield negative results, and there is a paucity of approved targeted agents. For the time being, the subset of patients carrying HER2-positive metastatic tumors can receive trastuzumab in addition to chemotherapy. Furthermore, ramucirumab has been found to be active both as a single agent and in combination with paclitaxel. Herein, we give an overview of currently approved targeted treatments for locally advanced/resectable as well as unresectable/metastatic EGJ/gastric adenocarcinoma, summarizing the underlying clinical studies. Moreover, further potential targets still under investigation are presented.

Gastric cancer: somatic genetics as a guide to therapy

Gastric cancer is the leading cause of cancer-related mortality across the world, with poor prognosis and a median overall survival of ≤12 months for advanced stage gastric cancer. Environmental, genetic and other predisposing factors contribute to the development of gastric cancer and a predominant factor was found to be infection of Helicobacter pylori Advances in understanding the deranged signalling pathways that are critical for normal cellular homeostasis helped in the development of novel drugs that target specific proteins and pathways to curtail the growth of gastric cancer. Genetic studies revealed several single nucleotide polymorphisms, chromosomal aberrations and epigenetic alterations that likely play a major role in elevating the susceptibility to develop gastric cancer. Methylation pattern of specific genes may likely prove to be a valid biomarker for early detection of gastric cancer, but much progress is needed to establish specific markers. Important developments have been made in targeting human epidermal growth factor receptor-2 and vascular endothelial growth factor receptor 2 for treating advanced gastro-oesophageal junction cancer, using specific monoclonal antibodies. Lack of efficacy with regard to targeting other signalling pathways including mesenchymal-epithelial transition/hepatocyte growth factor and mammalian target of rapamycin is probably due to suboptimal patient selection for these clinical trials, which is probably due to the lack of appropriate biomarkers, to decide on responsive patient population. Besides the development of antagonists for the cell growth-related signalling pathways, advances are also being made to tackle gastric cancer by immunotherapies, targeting immune check-points, which may hold promise for better treatment options in future.