Molecular classification and prediction in gastric cancer

Cancer-associated fibroblasts: protagonists of the tumor microenvironment in gastric cancer

Enhanced knowledge of the interaction of cancer cells with their environment elucidated the critical role of tumor microenvironment in tumor progression and chemoresistance. Cancer-associated fibroblasts act as the protagonists of the tumor microenvironment, fostering the metastasis, stemness, and chemoresistance of cancer cells and attenuating the anti-cancer immune responses. Gastric cancer is one of the most aggressive cancers in the clinic, refractory to anti-cancer therapies. Growing evidence indicates that cancer-associated fibroblasts are the most prominent risk factors for a poor tumor immune microenvironment and dismal prognosis in gastric cancer. Therefore, targeting cancer-associated fibroblasts may be central to surpassing resistance to conventional chemotherapeutics, molecular-targeted agents, and immunotherapies, improving survival in gastric cancer. However, the heterogeneity in cancer-associated fibroblasts may complicate the development of cancer-associated fibroblast targeting approaches. Although single-cell sequencing studies started dissecting the heterogeneity of cancer-associated fibroblasts, the research community should still answer these questions: "What makes a cancer-associated fibroblast protumorigenic?"; "How do the intracellular signaling and the secretome of different cancer-associated fibroblast subpopulations differ from each other?"; and "Which cancer-associated fibroblast subtypes predominate specific cancer types?". Unveiling these questions can pave the way for discovering efficient cancer-associated fibroblast targeting strategies. Here, we review current knowledge and perspectives on these questions, focusing on how CAFs induce aggressiveness and therapy resistance in gastric cancer. We also review potential therapeutic approaches to prevent the development and activation of cancer-associated fibroblasts via inhibition of CAF inducers and CAF markers in cancer.

Chromosomal Instability in Gastric Cancer: Role in Tumor Development, Progression, and Therapy

According to the Cancer Genome Atlas (TCGA), gastric cancers are classified into four molecular subtypes: Epstein-Barr virus-positive (EBV+), tumors with microsatellite instability (MSI), tumors with chromosomal instability (CIN), and genomically stable (GS) tumors. However, the gastric cancer (GC) with chromosomal instability remains insufficiently described and does not have effective markers for molecular and histological verification and diagnosis. The CIN subtype of GC is characterized by chromosomal instability, which is manifested by an increased frequency of aneuploidies and/or structural chromosomal rearrangements in tumor cells. Structural rearrangements in the CIN subtype of GC are not accidental and are commonly detected in chromosomal loci, being abnormal because of specific structural organization. The causes of CIN are still being discussed; however, according to recent data, aberrations in the TP53 gene may cause CIN development or worsen its phenotype. Clinically, patients with the CIN subtype of GC demonstrate poor survival, but receive the maximum benefit from adjuvant chemotherapy. In the review, we consider the molecular mechanisms and possible causes of chromosomal instability in GC, the common rearrangements of chromosomal loci and their impact on the development and clinical course of the disease, as well as the driver genes, their functions, and perspectives on their targeting in the CIN subtype of GC.

Safety and Efficacy of Neoadjuvant Chemoimmunotherapy in Gastric Cancer Patients with a PD-L1 Positive Status: A Case Report

INTRODUCTION

The landscape of gastric cancer treatment has changed owing to the widespread use of immune checkpoint inhibitors. Autophagy, involved in regulating the immune system, is a potential trigger of immunity in tumors. This study aims to find molecular-based evidence for the effectiveness of FLOT chemotherapy with immune checkpoint inhibitors in gastric cancer patients.

MATERIALS AND METHODS

Three patients with advanced gastric cancer received FLOT neoadjuvant chemotherapy with immunotherapy and surgery. IHC was used to determine the PD-L1 status. Real-time PCR was used to analyze expression patterns of transcriptional growth factors, AKT/mTOR signaling components, PD-1, PD-L1, PD-L2 and LC3B. The LC3B content was measured via Western blotting analysis.

RESULTS

The combination of FLOT neoadjuvant chemotherapy and immunotherapy was found to be efficient in patients with a PD-L1-positive status. Gastric tumors with a PD-L1-positive status exhibited autophagy activation and decreased PD-1 expression.

CONCLUSIONS

FLOT chemotherapy combined with immune checkpoint inhibitors showed high efficacy in gastric cancer patients with a positive PD-L1 status. Autophagy was involved in activating the tumor immunity. Further research is needed to clarify the mechanism of effective anticancer treatment.

Molecular phenotyping of malignant canine mammary tumours: Detection of high-risk group and its relationship with clinicomolecular characteristics

Canine mammary gland tumours (CMTs) constitute the most common cancer in female dogs and comprise approximately 50% of all canine cancers. With the advent of high-throughput technologies such as microarray and next-generation sequencing, the molecular phenotyping (classification) of various cancers has been extensively developed. The present study used a canine RNA-sequencing dataset, namely GSE119810, to classify 113 malignant CMTs and 64 matched normal samples via an unsupervised hierarchical algorithm with a view to evaluating the association between the resulting subtypes (clusters) (n = 4) and clinical and molecular characteristics. Finally, a molecular classifier was developed, and it detected 1 high-risk molecular subtype in the training dataset (GSE119810) and 2 independent validation datasets (GSE20718 and GSE22516). Our results revealed four molecular subtypes (C2-C5) in malignant CMTs. Furthermore, the normal samples constituted a distinct group in the clustering analysis. Marked significant associations were observed between the molecular subtypes (especially C5) and clinical/molecular features, including positive lymphatic invasion, high tumour grades, histopathology diagnoses, short survival and high TP53 mutation rates (ps <.05). The high-risk subtype (C5) was further characterized through the development of a cell cycle-based gene signature, which comprised 37 proliferation-related genes according to the support vector machine algorithm. This signature identified the high-risk group in both training and validation datasets (ps <.001). In the validation analysis, our potential classifier robustly predicted patients with positive lymphatic invasion, metastases and short survival.

Clinicopathological features of PD-L1 protein expression, EBV positivity, and MSI status in patients with advanced gastric and esophagogastric junction adenocarcinoma in Japan

This real-world study examined the prevalence of programmed death ligand-1 (PD-L1) expression and assessed the frequency of microsatellite instability-high (MSI-H) status and Epstein-Barr virus (EBV) positivity in Japanese patients with advanced gastric and gastroesophageal junction (GEJ) adenocarcinoma. This multicenter (5 sites), retrospective, observational study (November 2018–March 2019) evaluated Japanese patients with advanced gastric and GEJ adenocarcinoma after surgical resection (Stage II/III at initial diagnosis) or unresectable advanced cancer (Stage IV). The primary objectives were prevalence of PD-L1 expression (combined positive score [CPS] ≥1), MSI status, and EBV positivity. Tumor specimens of 389/391 patients were analyzed (male, 67.1%; mean age, 67.6 ± 12.2 years); 241/389 (62%) were PD-L1 positive, 24/379 (6.3%) had MSI-H tumors, and 13/389 (3.3%) were EBV positive. PD-L1 expression was higher in tumor-infiltrating immune cells than in tumor cells for lower CPS cutoffs. Among patients with MSI-H tumors and EBV-positive tumors, 19/24 (79.2%) and 9/13 (69.2%), respectively, were PD-L1 positive. A greater proportion of patients with MSI-H tumors (83.3% [20/24]) were PD-L1 positive than those with MSI-low/stable tumors (60.8% [216/355]; p = .0297); similarly, an association was observed between history of H pylori infection and PD-L1 expression. A higher proportion of patients with MSI-H tumors demonstrated PD-L1 expression with a CPS ≥10 (66.7% [16/24]) vs those with MSI-low/stable tumors (24.8% [88/355]; p < .0001). The prevalence of PD-L1 positivity among Japanese patients was comparable to that in previous pembrolizumab clinical trials and studies in gastric cancer. Particularly, higher PD-L1 expression was observed in MSI-H tumors.

KLF10 Functions as an Independent Prognosis Factor for Gastric Cancer

Background and Objectives: Krűppel-like factor 10 (KLF10) participates in the tumorigenesis of several human cancers by binding to the GC-rich region within the promoter regions of specific genes. KLF10 is downregulated in human cancers. However, the role of KLF10 in gastric cancer formation remains unclear. Materials and Methods: In this study, we performed immunohistochemical staining for KLF10 expression in 121 gastric cancer sections. Results: The loss of KLF10 expression was correlated with advanced stages and T status. Kaplan–Meier analysis revealed that patients with higher KLF10 levels had longer overall survival than those with lower KLF10 levels. Univariate analysis revealed that in patients with gastric cancer, advanced stages and low KLF10 levels were associated with survival. Multivariate analysis indicated that age, gender, advanced stages, and KLF10 expression were independent prognostic factors of the survival of patients with gastric cancer. After adjusting for age, gender, and stage, KLF10 expression was also found to be an independent prognostic factor in the survival of patients with gastric cancer. Conclusion: Our results collectively suggested that KLF10 may play a critical role in gastric cancer formation and is an independent prognosis factor of gastric cancer.

Spatial metabolomics identifies distinct tumor-specific subtypes in gastric cancer patients

PURPOSE

Current systems of gastric cancer (GC) molecular classification include genomic, molecular, and morphological features. GC classification based on tissue metabolomics remains lacking. This study aimed to define metabolically distinct GC subtypes and identify their clinicopathological and molecular characteristics.

EXPERIMENTAL DESIGN

Spatial metabolomics by high mass resolution imaging mass spectrometry was performed in 362 GC patients. K-means clustering was used to define tumor and stroma-related subtypes based on tissue metabolites. The identified subtypes were linked with clinicopathological characteristics, molecular features, and metabolic signatures. Responses to trastuzumab treatment were investigated across the subtypes by introducing an independent patient cohort with HER2-positive GC from a multicenter observational study.

RESULTS

Three tumor- and three stroma-specific subtypes with distinct tissue metabolite patterns were identified. Tumor-specific subtype T1(HER2+MIB+CD3+) positively correlated with HER2, MIB1, DEFA-1, CD3, CD8, FOXP3, but negatively correlated with MMR. Tumor-specific subtype T2(HER2-MIB-CD3-) negatively correlated with HER2, MIB1, CD3, FOXP3, but positively correlated with MMR. Tumor-specific subtype T3(pEGFR+) positively correlated with pEGFR. Patients with tumor subtype T1(HER2+MIB+CD3+) had elevated nucleotide levels, enhanced DNA metabolism, and a better prognosis than T2(HER2-MIB-CD3-) and T3(pEGFR+). An independent validation cohort confirmed that the T1 subtype benefited from trastuzumab therapy. Stroma-specific subtypes had no association with clinicopathological characteristics, however linked to distinct metabolic pathways and molecular features.

CONCLUSIONS

Patient subtypes derived by tissue-based spatial metabolomics are a valuable addition to existing GC molecular classification systems. Metabolic differences between the subtypes and their associations with molecular features could provide a valuable tool to aid in selecting specific treatment approaches.

Enhanced Vasculogenic Capacity Induced by 5-Fluorouracil Chemoresistance in a Gastric Cancer Cell Line

Chemotherapy is still widely used as a coadjutant in gastric cancer when surgery is not possible or in presence of metastasis. During tumor evolution, gatekeeper mutations provide a selective growth advantage to a subpopulation of cancer cells that become resistant to chemotherapy. When this phenomenon happens, patients experience tumor recurrence and treatment failure. Even if many chemoresistance mechanisms are known, such as expression of ATP-binding cassette (ABC) transporters, aldehyde dehydrogenase (ALDH1) activity and activation of peculiar intracellular signaling pathways, a common and universal marker for chemoresistant cancer cells has not been identified yet. In this study we subjected the gastric cancer cell line AGS to chronic exposure of 5-fluorouracil, cisplatin or paclitaxel, thus selecting cell subpopulations showing resistance to the different drugs. Such cells showed biological changes; among them, we observed that the acquired chemoresistance to 5-fluorouracil induced an endothelial-like phenotype and increased the capacity to form vessel-like structures. We identified the upregulation of thymidine phosphorylase (TYMP), which is one of the most commonly reported mutated genes leading to 5-fluorouracil resistance, as the cause of such enhanced vasculogenic ability.

Are Borrmann's Types of Advanced Gastric Cancer Distinct Clinicopathological and Molecular Entities? A Western Study

Most studies on the clinicopathological impact of Borrmann classification for gastric cancer (GC) have been performed in Asian patients with type IV tumors, and immunohistochemical features of Borrmann types have scarcely been analyzed. We assessed the clinicopathological, molecular features and prognostic value of Borrmann types in all patients with advanced GC resected in a Western institution (n = 260). We observed a significant relationship between Borrmann types and age, systemic symptoms, tumor size, Laurén subtype, presence of signet-ring cells, infiltrative growth, high grade, tumor necrosis, HERCEPTEST positivity, microsatellite instability (MSI) and molecular subtypes. Polypoid GC showed systemic symptoms, intestinal-type histology, low grade, expansive growth and HERCEPTEST positivity. Fungating GC occurred in symptomatic older patients. It presented intestinal-type histology, infiltrative growth and necrosis. Ulcerated GC showed smaller size, intestinal-type histology, high grade and infiltrative growth. Most polypoid and ulcerated tumors were stable-p53-not overexpressed or microsatellite unstable. Flat lesions were high-grade diffuse tumors with no MSI, and occurred in younger and less symptomatic patients. No association was found between Borrmann classification and prognosis. According to our results, Borrmann types may represent distinct clinicopathological and biological entities. Further research should be conducted to confirm the role of Borrmann classification in the stratification of patients with advanced GC.

Identification of gastric cancer subtypes based on pathway clustering

Gastric cancer (GC) is highly heterogeneous in the stromal and immune microenvironment, genome instability (GI), and oncogenic signatures. However, a classification of GC by combining these features remains lacking. Using the consensus clustering algorithm, we clustered GCs based on the activities of 15 pathways associated with immune, DNA repair, oncogenic, and stromal signatures in three GC datasets. We identified three GC subtypes: immunity-deprived (ImD), stroma-enriched (StE), and immunity-enriched (ImE). ImD showed low immune infiltration, high DNA damage repair activity, high tumor aneuploidy level, high intratumor heterogeneity (ITH), and frequent TP53 mutations. StE displayed high stromal signatures, low DNA damage repair activity, genomic stability, low ITH, and poor prognosis. ImE had strong immune infiltration, high DNA damage repair activity, high tumor mutation burden, prevalence of microsatellite instability, frequent ARID1A mutations, elevated PD-L1 expression, and favorable prognosis. Based on the expression levels of four genes (TAP2, SERPINB5, LTBP1, and LAMC1) in immune, DNA repair, oncogenic, and stromal pathways, we developed a prognostic model (IDOScore). The IDOScore was an adverse prognostic factor and correlated inversely with immunotherapy response in cancer. Our identification of new GC subtypes provides novel insights into tumor biology and has potential clinical implications for the management of GCs.

[Update on gastric cancer. New molecular classifications]

Gastric cancer (GC) is an aggressive tumor, which is usually diagnosed at an advanced stage and shows high mortality rates. Several GC classifications have been published, based on features such as tumor location, endoscopic features or microscopic architecture. However, TNM stage remains the mainstay of GC management and treatment. In the last years, technical advances have allowed us to investigate the biological heterogeneity of GC and develop new molecular classifications. This knowledge may enhance current classifications, and has the potential to refine GC management and aid in the identification of new molecular targets. In this literature review we have summarized the main findings in epidemiology, screening, classification systems and treatment of GC, focusing on the molecular alterations and new molecular classifications published in the last years.

Characterization and clinical evaluation of microsatellite instability and loss of heterozygosity in tumor-related genes in gastric cancer

Microsatellite instability (MSI) detection is widely used in the diagnosis and prognosis evaluation of colorectal cancer. However, for gastric cancer (GC), there is no standard panel of microsatellites (MSs) used in clinical guidance. The present study aimed to identify useful predictors of the clinical features and for the prognosis of GC, based on an investigation of MSI and loss of heterozygosity (LOH) in tumor-related genes. First, from 20 tumor-related genes which were proven to be important to the development of GC, 91 MSs were identified, and PCR amplification, short tandem repeat scanning analysis and TA clone sequencing were used to analyze MSI and LOH in the first set of 90 GC samples. Subsequently, the same method was used to detect the MSI/LOH of the optimized loci in the second set of 136 GC samples. MSI/LOH in the mismatch repair genes was highly consistent with that in oncogenes and tumor suppressor genes, respectively. The length of the core sequence was a main factor for the MSI/LOH rate. The MSI of 12 single loci was significantly associated with lymph node metastasis. The MSI in TP53-1 and the LOH in MGMT-10 were significantly associated with early stages of tumor infiltration depth. The LOH in MGMT-10, PTN-2 and MCC-17 was significantly associated with TNM stage. The LOH in TP53-1 and ERBB2-12 was associated with adenocarcinoma. The MSI/LOH in 6 single loci of 5 tumor-related genes was associated with poor prognosis of GC. The present study demonstrated that the MSI/LOH of loci in tumor-associated genes was associated with 4 clinicopathological characteristics and outcomes of GC. These results may provide potential specific biomarkers for the clinical prediction and treatment of GC.

Histological diversity and molecular characteristics in gastric cancer: relation of cancer stem cell-related molecules and receptor tyrosine kinase molecules to mixed histological type and more histological patterns

BACKGROUND

Gastric cancers (GCs) are still one of the leading causes of cancer-related mortality. The histological and molecular features of GC may differ widely from area to area within the same tumor. Intratumoral heterogeneity has been considered a major obstacle to an efficient diagnosis and successful molecular treatment.

METHODS

We selected and reevaluated 842 GC cases and analyzed the relationship between numbers or composites of histological patterns within tumors, and clinicopathological parameters in mucosal and invasive areas. In addition, we searched for the GC-associated molecules or molecular subtypes marking histological diversities.

RESULTS

GC cases with more histological numbers or mixed types in invasive areas showed significantly higher T grade and staging, whereas those in mucosal areas did not show any significant associations. GCs with histological diversities showed poorer prognosis and characteristically expressed cancer stem cell-related molecules (CD44, CD133 or ALDH1) and receptor tyrosine kinase molecules (HER2, EGFR or c-MET) as well as Helicobacter pylori infection. Expressions of CD44, HER2, c-MET, laminin 5·2 or retained E-cadherin in mucosal areas were predictive of more histological numbers and mixed types in invasive areas. In addition, the chromosomal instability subtype of GC showed significant associations with more histological numbers and mixed histological type, whereas the genomic stability subtype of GC showed a significant relationship with pure type.

CONCLUSIONS

We displayed the relationship between histological diversity and molecular features in GC, and we hope that the present data can contribute to the early diagnosis and prevention, and effective treatment of GC.

Procyanidin B2 induces apoptosis and autophagy in gastric cancer cells by inhibiting Akt/mTOR signaling pathway

Background

Procyanidin B2 (PB2), a unique component of the grape seed and other medicinal plants. PB2 has shown wide anticancer activity in various human cancer cells. However, it remains unclear about the biological effects and associated mechanisms of PB2 on gastric cancer cells.

Methods

Cell proliferation was measured by CCK8 assay, and cellular lactate dehydrogenase (LDH) release was measured in the culture medium. Cellular apoptosis was observed via TUNEL staining assay and measured by caspase-3 and -9 activities. Autophagy was observed by LC3 staining. Western blot analysis was performed to verify autophagy-associated proteins (Beclin1 and Atg5) and Akt-mTOR pathway.

Results

PB2 reduced the viability of BGC-823 and SGC-7901 cells in a concentration-dependent manner. Furthermore, PB2 induced increased apoptosis rate of gastric cancer cells and enhanced caspase-3 and -9 activities. Simultaneously, PB2 triggered autophagy in gastric cancer cells, with enhanced LC3 staining and increased expression of Beclin1 and Atg5, while the inhibition of autophagy by 3-MA reversed the PB2-induced suppression on cell viability. In addition, PB2 significantly decreased p-Akt and p-mTOR protein expression of gastric cancer cells.

Conclusion

PB2 exerts anti-proliferative and apoptotic effects and induces autophagy by modulating Akt/mTOR signaling pathway. PB2 may be developed as a potential therapeutic drug for gastric cancer.

Current Achievements and Applications of Transcriptomics in Personalized Cancer Medicine

Over the last decades, transcriptome profiling emerged as one of the most powerful approaches in oncology, providing prognostic and predictive utility for cancer management. The development of novel technologies, such as revolutionary next-generation sequencing, enables the identification of cancer biomarkers, gene signatures, and their aberrant expression affecting oncogenesis, as well as the discovery of molecular targets for anticancer therapies. Transcriptomics contribute to a change in the holistic understanding of cancer, from histopathological and organic to molecular classifications, opening a more personalized perspective for tumor diagnostics and therapy. The further advancement on transcriptome profiling may allow standardization and cost reduction of its analysis, which will be the next step for transcriptomics to become a canon of contemporary cancer medicine.

Identification of key miRNA-gene pairs in gastric cancer through integrated analysis of mRNA and miRNA microarray

Nowadays, the current bioinformatic methods have been increasingly applied in the field of oncological research. In this study, we expect a better understanding of the molecular mechanism of gastric cancer from the bioinformatic methods. By systematically addressing the differential expression of microRNAs (miRNAs) and mRNAs between gastric cancer specimens and normal gastric specimens with the application of bioinformatics tools, A total of 206 DEGs and 38 DEMs were identified. The Gene Ontology (GO) analysis of Annotation, Visualization and Integrated Discovery (DAVID) database revealed that the differentially expressed genes (DEGs) were significantly enriched in biological process, molecular function and cellular component, while Kyoto Encyclopedia of Genes and Genomes (KEGG) database showed DEGs were significantly enriched in 8 signal pathways. The miRNA-gene regulatory network was constructed based on 385 miRNA-gene (DEM-DEG) pairs, consisting of 35 miRNAs and 107 target genes. In the regulatory network, the top 5 up-regulated genes were Transmembrane Protease, Serine 11B (TMPRSS11B), regulator of G protein signaling 1 (RGS1), cysteine rich angiogenic inducer 61 (CYR61), inhibin subunit beta A (INHBA), syntrophin gamma 1 (SNTG1), and the top 5 down-regulated genes were tumor necrosis factor receptor superfamily, member 19 (TNFRSF19), pleckstrin homology domain containing B2 (PLEKHB2), Tax1 binding protein 3 (TAX1BP3), presenilin enhancer, gamma-secretase subunit (PSENEN), NME/NM23 nucleoside diphosphate kinase 3 (NME3). Based on the gastric cancer patient database from Kaplan-Meier Plotter tools, we found that 8 of 10 genes with most significant changes in the miRNA-gene regulatory network possessed a prognostic value for survival time of gastric cancer patients. Patients with higher level of RGS1, PLEKHB2, TAX1BP3 and PSENEN in gastric cancer had a longer survival time compared with the patients with lower level of these genes. On the contrary, patients with higher level of INHBA, SNTG1, TNFRSF19 and NME3 were found associated with a shorter survival time. In conclusion, our findings provided several potential targets regarding gastric cancer, which may result in a new strategy to treat gastric cancer from a system rather than a single-gene perspective.

Partially linear monotone methods with automatic variable selection and monotonicity direction discovery

In many statistical regression and prediction problems, it is reasonable to assume monotone relationships between certain predictor variables and the outcome. Genomic effects on phenotypes are, for instance, often assumed to be monotone. However, in some settings, it may be reasonable to assume a partially linear model, where some of the covariates can be assumed to have a linear effect. One example is a prediction model using both high-dimensional gene expression data, and low-dimensional clinical data, or when combining continuous and categorical covariates. We study methods for fitting the partially linear monotone model, where some covariates are assumed to have a linear effect on the response, and some are assumed to have a monotone (potentially nonlinear) effect. Most existing methods in the literature for fitting such models are subject to the limitation that they have to be provided the monotonicity directions a priori for the different monotone effects. We here present methods for fitting partially linear monotone models which perform both automatic variable selection, and monotonicity direction discovery. The proposed methods perform comparably to, or better than, existing methods, in terms of estimation, prediction, and variable selection performance, in simulation experiments in both classical and high-dimensional data settings.

Systems Biology of Gastric Cancer: Perspectives on the Omics-Based Diagnosis and Treatment

Gastric cancer is the fifth most diagnosed cancer in the world, affecting more than a million people and causing nearly 783,000 deaths each year. The prognosis of advanced gastric cancer remains extremely poor despite the use of surgery and adjuvant therapy. Therefore, understanding the mechanism of gastric cancer development, and the discovery of novel diagnostic biomarkers and therapeutics are major goals in gastric cancer research. Here, we review recent progress in application of omics technologies in gastric cancer research, with special focus on the utilization of systems biology approaches to integrate multi-omics data. In addition, the association between gastrointestinal microbiota and gastric cancer are discussed, which may offer insights in exploring the novel microbiota-targeted therapeutics. Finally, the application of data-driven systems biology and machine learning approaches could provide a predictive understanding of gastric cancer, and pave the way to the development of novel biomarkers and rational design of cancer therapeutics.

The vicious cycle between ferritinophagy and ROS production triggered EMT inhibition of gastric cancer cells was through p53/AKT/mTor pathway

Cancer metastasis and resistance for chemotherapeutic agent correlate with epithelial-mesenchymal transition (EMT), while ROS production also involves in the EMT process, However, how autophagy mediated ROS production affects EMT remains unclear. Previous study showed that DpdtC (2,2'-di-pyridylketone hydrazone dithiocarbamate) could induce ferritinophagy in HepG2 cell. To insight into more details that how ferritinophagy affects cellular feature, the SGC-7901and BGC-823 gastric cancer cell lines were used. Interestingly DpdtC treatment resulted in EMT inhibition and was ROS dependent. Similar situation occurred in TGF-β1 induced EMT model, supporting that DpdtC was able to inhibit EMT. Next the ability of DpdtC in ferritinophagy induction was further evaluated. As expected, DpdtC induced ferritinophagy in the absence and presence of TGF-β1. The correlation analysis revealed that an enhanced ferritinophagic flux contributed to the EMT inhibition. In addition, ferritinophagy triggers Fenton reaction, resulting in ROS production which give rise of p53 response, thus the role of p53 was further investigated. DpdtC treatment resulted in upregulation of p53, but, the addition of p53 inhibitor, PFT-α could significantly neutralize the action of DpdtC on ferritinophagy induction and EMT inhibition. Furthermore, autophagy inhibitors or NAC could counteract the action of DpdtC, indicating that ferrtinophagy-mediated ROS played an important role in the cellular events. In addition to upregulation of p53, its down-stream targets, AKT/mTor were also downregulated, supporting that DpdtC induced EMT inhibition was achieved through ferritinophagy-ROS vicious cycle mediated p53/AKT/mTor pathway. And the activation of ferritinophagic flux was the dominant driving force in action of DpdtC in gastric cancer cells.

DpdtC-Induced EMT Inhibition in MGC-803 Cells Was Partly through Ferritinophagy-Mediated ROS/p53 Pathway

Epithelial-mesenchymal transition (EMT) is a cellular process in which epithelial cells are partially transformed into stromal cells, which endows the polarized epithelium cells more invasive feature and contributes cancer metastasis and drug resistance. Ferritinophagy is an event of ferritin degradation in lysosomes, which contributes Fenton-mediated ROS production. In addition, some studies have shown that ROS participates in EMT process, but the effect of ROS stemmed from ferritin degradation on EMT has not been fully established. A novel iron chelator, DpdtC (2,2'-di-pyridylketone dithiocarbamate), which could induce ferritinophagy in HepG2 cell in our previous study, was used to investigate its effect on EMT in gastric cancer cells. The proliferation assay showed that DpdtC treatment resulted in growth inhibition and morphologic alteration in MGC-803 cell (IC₅₀ = 3.1 ± 0.3 μM), and its action involved ROS production that was due to the occurrence of ferritinophagy. More interestingly, DpdtC could also inhibit EMT, leading to the upregulation of E-cadherin and the downregulation of vimentin; however, the addition of NAC and 3-MA could attenuate (or neutralize) the action of DpdtC on ferritinophagy induction and EMT inhibition, supporting that the enhanced ferritinophagic flux contributed to the EMT inhibition. Since the degradation of ferritin may trigger the production of ROS and induce the response of p53, we next studied the role of p53 in the above two-cell events. As expected, an upregulation of p53 was observed after DpdtC insulting; however, the addition of a p53 inhibitor, PFT-α, could significantly attenuate the action of DpdtC on ferritinophagy induction and EMT inhibition. In addition, autophagy inhibitors or NAC could counteract the effect of DpdtC and restore the level of p53 to the control group, indicating that the upregulation of p53 was caused by ferritinophagy-mediated ROS production. In conclusion, our data demonstrated that the inhibition of EMT induced by DpdtC was realized through ferritinophagy-mediated ROS/p53 pathway, which supported that the activation of ferritinophagic flux was the main driving force in EMT inhibition in gastric cancer cells, and further strengthening the concept that NCOA4 participates in EMT process.

HER2, NF-κB, and SATB1 Expression Patterns in Gastric Cancer and Their Correlation with Clinical and Pathological Parameters

Gastric cancer (GC) is currently recognized as one of the most common and fatal tumor worldwide. The identification of novel biomarkers in relation to clinical information as well as extending the knowledge on a multiple crosstalk between various oncogenic pathways implicated in GC carcinogenesis seems pivotal to limit the disease-associated mortality. Therefore, we assessed the expression of HER2, NF-κB, and SATB1 in a total of 104 gastric adenocarcinomas and 30 normal gastric samples and correlated the expression patterns with each other and with some clinicopathological variables. Protein expression was examined by immunohistochemistry (IHC) on tissue microarrays (TMAs), and fluorescence in situ hybridization (FISH) was employed to detect HER2 amplification. In the studied group, HER2 and SATB1 were found to be overexpressed in gastric cancer tissue in comparison to normal gastric mucosa. The expression status of the former protein was seen to differ according to some clinicopathological features, but without statistical significance, whereas the expression of the latter was not importantly associated with any of them. In turn, the NF-κB protein level was significantly related to the presence of lymph node metastasis. HER2 expression was not significantly correlated with that of other proteins, but a positive correlation was found between the expression of SATB1 and NF-κB. Further studies with a larger group of patients combined with in vitro mechanistic experiments are required to fully elucidate the role and relationship of HER2, NF-κB, and SATB1 expression in gastric cancer progression. However, to the best of our knowledge, this study is the first look at a simultaneous evaluation of these three markers in the samples of gastric cancer patients.

Multiscale network analysis reveals molecular mechanisms and key regulators of the tumor microenvironment in gastric cancer

Gastric cancer (GC) is the third leading cause of cancer deaths and the fourth most prevalent malignancy worldwide. The high incidence and mortality rates of gastric cancer result from multiple factors such as ineffective screening, diagnosis, and limited treatment options. In our study, we sought to systematically identify predictive molecular networks and key regulators to elucidate complex interacting signaling pathways in GC. We performed an integrative network analysis of the transcriptomic data in The Cancer Genome Atlas (TCGA) gastric cancer cohort and then comprehensively characterized the predictive subnetworks and key regulators by the matched genetic and epigenetic data. We identified 221 gene subnetworks (modules) in GC. The most prognostic subnetworks captured multiple aspects of the tumor microenvironment in GC involving interactions among stromal, epithelial and immune cells. We revealed the genetic and epigenetic underpinnings of those subnetworks and their key transcriptional regulators. We computationally predicted and experimentally validated specific mechanisms of anticancer effects of GKN2 in gastric cancer proliferation and invasion in vitro. The network models and the key regulators of the tumor microenvironment in GC identified here pave a way for developing novel therapeutic strategies for GC.

What's new?

Gene signatures have been identified for diagnosis and classification of gastric cancer (GC) as well as prediction of therapeutic response. However, key molecular mechanisms underlying prognosis remain to be revealed. Our study systematically identifies and characterizes predictive molecular networks and key regulators. The most prognostic subnetworks capture multiple aspects of the tumor microenvironment in GC involving interactions among stromal, epithelial, and immune cells. The authors computationally predicted and experimentally validated specific mechanisms of anti‐cancer effects of GKN2 in GC proliferation and invasion in vitro. These network models and key regulators pave the way for developing novel therapeutic strategies for GC.

Reproduction of molecular subtypes of gastric adenocarcinoma by transcriptome sequencing of archival tissue

Gastric cancer (GC) is a heterogeneous disease, so molecular classification is important for selecting the most appropriate treatment strategies for GC patients. To be applicable in the clinic, there is an urgent need for a platform that will allow screening real-life archival tissue specimens. For this purpose, we performed RNA sequencing of 50 samples from our Asian Cancer Research Group (ACRG) GC cohort to reproduce the molecular subtypes of GC using archival tissues with different platforms. We filtered out genes from the epithelial-to-mesenchymal transition (EMT) and microsatellite instability-high (MSI) signatures (coefficient ≤ 0.4) followed by the ACRG molecular subtype strategy. Overall accuracy of reproduction of ACRG subtype was 66% (33/50). Given the importance of EMT subtype in future clinical trials, we further developed the minimum number of genes (10 genes) for EMT signatures correlating highly with the original EMT signatures (correlation ≥ 0.65). Using our 10-gene model, we could classify EMT subtypes with high sensitivity (0.9576) and specificity (0.811). In conclusion, we reproduced ACRG GC subtypes using different platforms and could predict EMT subtypes with 10 genes and are now planning to use them in our prospective clinical study of precision oncology in GC.

miR-125a restrains cell migration and invasion by targeting STAT3 in gastric cancer cells

BACKGROUND

Recently, many microRNAs have been found to be involved in the cancer progression including miR-125a. However, the underlying mechanisms of miR-125a in gastric cancer (GC) remain to be completely elucidated.

OBJECTIVE

The study was to investigate the functional role of miR-125a and the expression relevance of signal transducer and activator of transcription 3 (STAT3) and hyaluronan synthase 1 (HAS1).

METHOD

CCK-8 assay, scratch wound healing and transwell assay were conducted to identify the functional role of miR-125a in GC. In addition, using bioinformatics analysis, the target regulation relationship was found in STAT3 and miR-125a. To confirm the relationship, luciferase reporter assay was performed. More importantly, quantitative polymerase chain reaction and western blot assay were carried out to determine the association among miR-125a, STAT3 and HAS1 in GC cells.

RESULTS

Overexpressed miR-125a inhibited the migration and invasion of GC cells through scratch wound healing and transwell assay, and its knockdown displayed adverse effects, but the viability of GC cells did not show significant difference using CCK-8 assay. In addition, we identified that the knockdown of STAT3 or HAS1 remarkably suppressed the migration and invasion abilities of GC cells. Using bioinformatics analysis, miRTar, in particular, indicated that the 3'-untranslated region of STAT3 binds to miR-125a with a high score. Subsequently, we also verified that STAT3 was a target of miR-125a via luciferase reporter assay. Furthermore, we found that upregulated miR-125a expression could conspicuously constrain STAT3 expression at both protein and mRNA levels in MKN45 and NCI-N87 cells using quantitative polymerase chain reaction and Western blot assay, but no significant difference had been found in SGC 7901 cells. To further identify the regulatory relationship between miR-125a and STAT3, downregulation of miR-125a in MKN45 and NCI-N87 cells was carried out, which showed that the protein and mRNA expression levels of STAT3 were declined in two cell lines. Finally, we observed that upregulated miR-125a could lead to the decrease of HAS1 at protein and mRNA levels, whereas its knockdown revealed opposite effects. Meanwhile, we noticed that overexpression of STAT3 could induce the escalation of HAS1 at protein and mRNA expression levels and its knockdown exhibited the adverse outcomes.

CONCLUSION

These findings indicated that miR-125a may control the HAS1 expression in GC progression by targeting STAT3, which is likely to facilitate a better understanding of the regulation mechanisms of miR-125a in GC.

GeneExpressScore Signature: a robust prognostic and predictive classifier in gastric cancer

Although several prognostic signatures have been developed for gastric cancer (GC), the utility of these tools is limited in clinical practice due to lack of validation with large and multiple independent cohorts, or lack of a statistical test to determine the robustness of the predictive models. Here, a prognostic signature was constructed using a least absolute shrinkage and selection operator (LASSO) Cox regression model and a training dataset with 300 GC patients. The signature was verified in three independent datasets with a total of 658 tumors across multiplatforms. A nomogram based on the signature was built to predict disease-free survival (DFS). Based on the LASSO model, we created a GeneExpressScore signature (GES_GC ) classifier comprised of eight mRNA. With this classifier patients could be divided into two subgroups with distinctive prognoses [hazard ratio (HR) = 4.00, 95% confidence interval (CI) = 2.41-6.66, P < 0.0001]. The prognostic value was consistently validated in three independent datasets. Interestingly, the high-GES_GC group was associated with invasion, microsatellite stable/epithelial-mesenchymal transition (MSS/EMT), and genomically stable (GS) subtypes. The predictive accuracy of GES_GC also outperformed five previously published signatures. Finally, a well-performed nomogram integrating the GES_GC and four clinicopathological factors was generated to predict 3- and 5-year DFS. In summary, we describe an eight-mRNA-based signature, GES_GC , as a predictive model for disease progression in GC. The robustness of this signature was validated across patient series, populations, and multiplatform datasets.

Immunohistochemical classification of gastric cancer based on new molecular biomarkers: a potential predictor of survival

Several classification systems have been described for stratifying patients with gastric carcinoma (GC). However, their prognostic value is low, and there is an urgent need for identification of molecular markers and development of new classifications. Retrospective study of 206 cases of GC diagnosed and surgically resected in our hospital between 2000 and 2017. Clinicopathological features of all cases were assessed and tissue microarrays were constructed for immunohistochemical (IHC) study. Patients were stratified based on IHC results. Mean patient age was 71 years and most patients were male (54.6%). Most tumors were located in the gastric antrum and body, and they were mostly fungoid or ulcerative lesions. GC were mainly intestinal-type tumors and 60.3% were diagnosed at pT3. 56.2% of patients showed recurrences and 29.4% died due to GC. According to our IHC classification, 23.5% of tumors showed microsatellite instability, 6% were E-cadherin negative, 53.5% were stable-p53 not overexpressed, and 17% were stable with p53 overexpression. IHC classification was significantly correlated with patient gender, gross morphology, Laurén classification, tumor necrosis, perineural infiltration, type of leading edge, and patient outcome. Multivariate analysis showed that IHC subtype was significantly and independently associated with overall survival, together with clinical symptoms, signet cell phenotype, tumor grade and vessel invasion. The application of IHC classifications based on molecular biomarkers in clinical practice can aid in the stratification of GC patients. More studies are needed to evaluate the reproducibility and clinical significance of these classifications.

Isoliquiritigenin inhibits proliferation and metastasis of MKN28 gastric cancer cells by suppressing the PI3K/AKT/mTOR signaling pathway

Isoliquiritigenin (ISL) is a flavonoid extracted from licorice root, which is known to serve important antitumor roles in numerous types of cancers; however, its effect on gastric cancer remains to be elucidated. The present study aimed to explore the roles and underlying mechanisms of ISL in MKN28 gastric cancer cells. MKN28 cell proliferation was measured using the Cell Counting Kit‑8 (CCK8) assay. A Transwell assay was used to determine the effects of ISL on the migration and invasion of MKN28 cells. Apoptosis was assessed by flow cytometry, and the expression levels of apoptosis‑, autophagy‑ and signaling pathway‑related proteins were detected by western blot analysis. The results of the CCK8 assay demonstrated that ISL significantly inhibited the proliferation of MKN28 cells (P<0.05). Transwell assays demonstrated that the migration and invasion of MKN28 cells were significantly inhibited following treatment with ISL (P<0.05). Flow cytometric analysis indicated that ISL induced apoptosis of MKN28 cells. In addition, western blot analysis revealed that the ratio of microtubule‑associated proteins 1A/1B light chain 3B (LC3)II/LC3I was upregulated, as was Beclin 1 expression; however, p62 was downregulated following ISL pretreatment, thus suggesting that ISL triggered autophagy in MKN28 cells. In addition, the phosphorylation levels of protein kinase B (AKT) and mammalian target of rapamycin (mTOR) were significantly reduced following ISL treatment. These results indicated that ISL may influence apoptosis and autophagy in MKN28 cells by suppressing the phosphoinositide 3‑kinase/AKT/mTOR signaling pathway. In conclusion, the findings of the present study suggested that ISL may inhibit MKN28 cell proliferation, migration and invasion by inducing apoptosis and autophagy, implying potential as a therapeutic agent for gastric cancer.

Advances in molecular, genetic and immune signatures of gastric cancer: Are we ready to apply them in our patients' decision making?

In the last few years we have witnessed a vast expansion of our knowledge regarding the molecular and genetic profile of gastric cancer. The molecular subtypes described have shed light on the pathogenesis of the disease, thus prompting the development of new therapeutic strategies and favoring a more individualized approach for treatment. Most of the clinical trials for so called targeted therapies could be considered, at best, partially successful. In addition, checkpoint inhibitors have recently been added to our armamentarium in later stages of the disease, and combinations with chemotherapy and targeted agents are currently under development. In view of the rapid advances of molecular oncology, a new challenge for the clinical oncologist arises: The appropriate patient selection for each new therapy, which can be made possible only through the implementation of predictive biomarkers in our therapy decision making.

Diagnostic utility of glycosyltransferase mRNA expression in gastric cancer

OBJECTIVE/BACKGROUND

Posttranslational modification of proteins, including glycosylation, is known to differ between normal and tumor cells. Altered glycosyltransferase levels have been observed in tumor tissues and their role in tumor metastasis and invasion has been implicated. In this study the role of altered glycosyltransferase messenger RNA (mRNA) levels in serum of gastric cancer patients as early markers of gastric cancer was evaluated.

METHODS

In this case control study the expression profile of ppGalNAc-T6, GlcNAcT-V, ST3Gal I, ST3 Gal IV, and ST6GalNAc-I in normal healthy control and gastric cancer patients was compared. Serum was isolated from blood samples of gastric cancer patients (n = 200) and controls (n = 200). Following RNA extraction, reverse transcription was carried out and transcript levels of glycosyltransferases were determined using real-time quantitative polymerase chain reaction and normalized against glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression. The amount of target gene, normalized to an endogenous reference gene relative to calibrator was calculated by using ΔΔCT method. Transcript levels in the serum samples of gastric cancer patients were compared with those of controls; also the same was correlated within sex and different stages of disease.

RESULTS

The mRNA expression of ppGalNAc-T6 and ST6GalNAc-I was significantly higher in serum samples of gastric cancer patients on comparison with controls (p = .008), however, there was no significant difference in mRNA expression of GlcNAcT-V, ST3Gal I, and ST3 Gal IV in serum samples of gastric cancer patients and controls (p = .097). In addition, no significant association of mRNA expression of these glycosyltransferases was found within sex and stages in this study.

CONCLUSION

This study revealed the potential of ppGalNAc-T6 and ST6GalNAc-I mRNA transcript levels in serum as markers of gastric cancer. Further studies on the wider range of glycosyltransferases in various cancers are needed to establish signature mRNA batteries as minimally invasive markers of gastric cancer.

Di-2-pyridylhydrazone Dithiocarbamate Butyric Acid Ester Exerted Its Proliferative Inhibition against Gastric Cell via ROS-Mediated Apoptosis and Autophagy

Diversified biological activities of dithiocarbamates have attracted widespread attention; improving their feature or exploring their potent action of mechanism is a hot topic in medicinal research. Herein, we presented a study on synthesis and investigation of a novel dithiocarbamate, DpdtbA (di-2-pyridylhydrazone dithiocarbamate butyric acid ester), on antitumor activity. The growth inhibition assay revealed that DpdtbA had important antitumor activity for gastric cancer (GC) cell lines (IC₅₀ = 4.2 ± 0.52 μM for SGC-7901, 3.80 ± 0.40 μM for MGC-803). The next study indicated that growth inhibition is involved in ROS generation in mechanism; accordingly, the changes in mitochondrial membrane permeability, apoptotic genes, cytochrome c, bax, and bcl-2 were observed, implying that the growth inhibition of DpdtbA is involved in ROS-mediated apoptosis. On the other hand, the upregulated p53 upon DpdtbA treatment implied that p53 could also mediate the apoptosis. Yet the excess generation of ROS induced by DpdtbA led to cathepsin D translocation and increase of autophagic vacuoles and LC3-II, demonstrating that autophagy was also a contributor to growth inhibition. Further investigation showed that DpdtbA could induce cell cycle arrest at the G1 phase. This clearly indicated the growth inhibition of DpdtbA was via triggering ROS formation and evoking p53 response, consequently leading to alteration in gene expressions that are related to cell survival.

NDRG4 hypermethylation is a potential biomarker for diagnosis and prognosis of gastric cancer in Chinese population

In order to assess whether N-Myc downstream regulated gene 4 (NDRG4) methylation was associated with the diagnosis and prognosis of gastric cancer, we measured the methylation of NDRG4 promoter and gene body regions among 110 gastric cancer patients using quantitative methods (MethyLight and pyrosequencing). Both NDRG4 promoter and gene body methylation levels were increased in tumor tissues than paired adjacent normal tissues (P < 0.001). NDRG4 gene body methylation was found to be significantly associated with age and tumor differentiation. NDRG4 promoter hypermethylation was proved to be a predictor of poor overall survival. However, opposite result was observed among The Cancer Genome Atlas (TCGA) cohort. The findings from gastric cell lines and public databases have suggested that NDRG4 methylation level was inversely associated with NDRG4 transcription level. Subsequent luciferase reporter gene assay showed that promoter CpG island but not gene body CpG island was able to upregulate gene expression. Collectively, NDRG4 promoter hypermethylation contributed to the risk of gastric cancer and predicted a poor prognosis in Chinese gastric cancer patients. Moreover, the combined methylation levels of NDRG4 promoter and gene body served as diagnostic biomarkers in gastric cancer.

Prognostic significance of mucinous component in gastric adenocarcinoma after radical D2 gastrectomy

BACKGROUND

The mucinous component is a special histologic factor in gastric adenocarcinoma. The aim of this study was to assess the prognostic significance of mucinous component in gastric adenocarcinoma according to proportion.

PATIENTS AND METHODS

Candidate patients with gastric adenocarcinoma were given radical D2 gastrectomies from September 2008 to May 2015 in our division. Clinicopathologic data and prognosis were monitored and analyzed among gastric adenocarcinoma patients with various proportions of mucinous component.

RESULTS

A total of 690 gastric adenocarcinomas with various proportions of mucinous component from 6,025 gastric adenocarcinoma patients were included. Higher numbers of patients with mucinous component came from: young patients, females, those with drinking history, at lower locations, Borrmann type III and IV, T4 stage, and positive for dissected lymph nodes. Tumors and pathological molecular markers showed more positivity in CEA, CA19-9, S100, and CD34. As the various proportions increased, more mucinous component seemed to be accompanied by more Borrmann type III and IV, T4 stage, and more positive expression of CEA and CA19-9. However, no significant difference in 5-year overall survival rate was observed among various proportions or existence of mucinous component. Also, proportion or existence of mucinous component was not an independent prognostic factor in multivariate analysis.

CONCLUSION

Mucinous component was not a prognostic factor for gastric adenocarcinoma after radical D2 gastrectomy, no matter what proportion the component comprised. However, gastric adenocarcinoma with mucinous component showed specific clinicopathological characteristics, such as more advanced tumor stage, different age and sex, and more positive rate of molecular markers, which might provide a new strategy for optimal individual diagnosis and therapies.

QKI5-mediated alternative splicing of the histone variant macroH2A1 regulates gastric carcinogenesis

Alternative pre-mRNA splicing is a key mechanism for increasing proteomic diversity and modulating gene expression. Emerging evidence indicated that the splicing program is frequently dysregulated during tumorigenesis. Cancer cells produce protein isoforms that can promote growth and survival. The RNA-binding protein QKI5 is a critical regulator of alternative splicing in expanding lists of primary human tumors and tumor cell lines. However, its biological role and regulatory mechanism are poorly defined in gastric cancer (GC) development and progression. In this study, we demonstrated that the downregulation of QKI5 was associated with pTNM stage and pM state of GC patients. Re-introduction of QKI5 could inhibit GC cell proliferation, migration, and invasion in vitro and in vivo, which might be due to the altered splicing pattern of macroH2A1 pre-mRNA, leading to the accumulation of macroH2A1.1 isoform. Furthermore, QKI5 could inhibit cyclin L1 expression via promoting macroH2A1.1 production. Thus, this study identified a novel regulatory axis involved in gastric tumorigenesis and provided a new strategy for GC therapy.

Is the signet ring cell histological type a positive prognostic factor for gastric adenocarcinoma after D2 radical gastrectomy?

BACKGROUND

Previous studies indicated the histological type might have prognostic value in gastric adenocarcinoma patients. The aim of this study was to clarify whether the signet ring cell (SRC) histological type of gastric adenocarcinoma is associated with worse prognosis than pure gastric adenocarcinoma without any mixed histological component (PGA) for patients underwent D2 radical gastrectomy.

METHOD

By the database of 6205 surgical patients with gastric adenocarcinoma at our department between September 2008 and May 2015, we investigated 133 SRC patients and 2847 PGA patients who underwent D2 radical gastrectomy. The clinic and pathologic data, especially tumor and pathology molecular markers, and 5-year overall survival rate were compared between SRC and PGA. The univariate and multivariate analysis were used to testify the prognosis significance of SRC.

RESULTS

SRC was more frequently found in younger (<50), female patients, lower part of stomach and easy to metastasize lymph nodes. And more positive CA19-9 and less positive EGFR were obtained in SRC. The 5-year survival rate was not different between SRC and PGA after D2 radical gastrectomy, even assessed by T stage. Multivariate analysis showed age, T and N stage, CEA, CA19-9 and CA125 were the independent prognostic factors, not included the SRC histological type.

CONCLUSION

Although SRC histological type of gastric adenocarcinoma after D2 radical gastrectomy had its own clinic-pathologic characters, especially in molecular tumor and pathological markers, the histological type of SRC was a negative prognostic factor in gastric adenocarcinoma patients after D2 radical gastrectomy.

Omics-based molecular techniques in oral pathology centred cancer: prospect and challenges in Africa

BACKGROUND

The completion of the human genome project and the accomplished milestones in the human proteome project; as well as the progress made so far in computational bioinformatics and "big data" processing have contributed immensely to individualized/personalized medicine in the developed world.

MAIN BODY

At the dawn of precision medicine, various omics-based therapies and bioengineering can now be applied accurately for the diagnosis, prognosis, treatment, and risk stratification of cancer in a manner that was hitherto not thought possible. The widespread introduction of genomics and other omics-based approaches into the postgraduate training curriculum of diverse medical and dental specialties, including pathology has improved the proficiency of practitioners in the use of novel molecular signatures in patient management. In addition, intricate details about disease disparity among different human populations are beginning to emerge. This would facilitate the use of tailor-made novel theranostic methods based on emerging molecular evidences.

CONCLUSION

In this review, we examined the challenges and prospects of using currently available omics-based technologies vis-à-vis oral pathology as well as prompt cancer diagnosis and treatment in a resource limited setting.

Identification and validation of a prognostic 9-genes expression signature for gastric cancer

Gastric cancer (GC) is a common malignant tumor with high incidence and mortality. Reasonable assessment of prognosis is essential to improve the outcomes of patients. In this study, we constructed and validated a prognostic gene model to evaluate the risks of GC patients. To identify the differentially expressed genes between GC patients and controls, we extracted Gene expression profiles of GC patients (N=432) from Gene Expression Omnibus database and then stable signature genes by using Robust likelihood-based modeling with 1000 iterations. Unsupervised hierarchical clustering of all samples was performed basing on the characteristics of gene expressions. Meanwhile, the differences between the clusters were analyzed by Kaplan Meier survival analysis. A 9-genes model was obtained (frequency = 999; p=1.333628e^-18), including two negative impact factors (NR1I2 and LGALSL) and 7 positive ones (C1ORF198, CST2, LAMP5, FOXS1, CES1P1, MMP7 and COL8A1). This model was verified in single factor survival analysis (p=0.004447558) and significant analysis with recurrence time (p=0.001474831) by using independent datasets from TCGA. The constructed 9-genes model was stable and effective, which might serve as prognostic signature to predict the survival of GC patients and monitor the long-term treatment of GC.

TGR5, Not Only a Metabolic Regulator

G-protein-coupled bile acid receptor, Gpbar1 (TGR5), is a member of G-protein-coupled receptor (GPCR) superfamily. High levels of TGR5 mRNA were detected in several tissues such as small intestine, stomach, liver, lung, especially in placenta and spleen. TGR5 is not only the receptor for bile acids, but also the receptor for multiple selective synthetic agonists such as 6α-ethyl-23(S)-methyl-cholic acid (6-EMCA, INT-777) and a series of 4-benzofuranyloxynicotinamde derivatives to regulate different signaling pathways such as nuclear factor κB (NF-κB), AKT, and extracellular signal-regulated kinases (ERK). TGR5, as a metabolic regulator, is involved in energy homeostasis, bile acid homeostasis, as well as glucose metabolism. More recently, our group and others have extended the functions of TGR5 to more than metabolic regulation, which include inflammatory response, cancer and liver regeneration. These findings highlight TGR5 as a potential drug target for different diseases. This review summarizes the basic information of TGR5 and its new functions.

Chromoendoscopy in combination with random biopsies does not improve detection of gastric cancer foci in CDH1 mutation positive patients

Background and study aims: Hereditary diffuse gastric cancer (HGGC), an autosomal dominant tumor-syndrome, accounts for 1 % to 3 % of gastric cancers worldwide. Presumably 30 % to 40 % of all patients fulfilling the clinical guidelines for HDGC are carriers of a pathogenic mutation in the CDH1 gene. Patients often show multiple foci of signet ring cell carcinoma at early age and are advised to undergo prophylactic total gastrectomy (PTG). Our aim was to improve the endoscopic detection of HDGC by using an enhanced endoscopic protocol. Patient and methods: Patients with a proven CDH1 germline mutation identified in our institute were prospectively included. Patients were advised to undergo PTG and offered a baseline endoscopic examination prior surgery. Examination was performed by using high-resolution white-light endoscopy and pan-gastric chromoendoscopy with indigo carmine as dye combined with targeted and multiple random biopsies assessed by an expert histopathologist. Postoperative histopathology was compared with results from endoscopic biopsies. Results: Between September 2012 and November 2014 8 patients with a proven CDH1 germline mutation were included. We conducted 44 targeted (6.3/patient) and 225 random (32.1/patient) biopsies in 7 patients. We detected 1 gastric cancer by random biopsy (14 %). All other examinations showed no signs of cancer. Histopathology of gastrectomy specimen revealed multiple foci of gastric carcinoma in 6 patients (86 %) with a total number of 27 cancer foci. Conclusions: Examination with targeted and random biopsies combined with chromoendoscopy is not able to detect small foci of gastric cancer in CDH1 mutation carriers. Therefore PTG is advocated in these patients.

Antitumor activity of TY-011 against gastric cancer by inhibiting Aurora A, Aurora B and VEGFR2 kinases

Background

Overexpression of Aurora A and B has been reported in a wide range of tumor types, including gastric cancer. Anti-angiogenesis has been considered as an important therapeutic modality in advanced gastric cancer. Here we identified a novel compound TY-011 with promising antitumor activity by targeting mitotic kinases (Aurora A and B) and angiogenic receptor tyrosine kinase (VEGFR2).

Methods

HTRF® KinEASE™ assay was used to detect the effect of TY-011 against Aurora A, Aurora B and VEGFR2 activities. Docking simulation study was performed to predict the binding mode of TY-011 with Aurora A and B kinases. CCK-8 assay was used to test cell growth. Cell cycle and cell apoptosis was analyzed by flow cytometry. Gastric cancer cell xenograft mouse models were used for in vivo study. TUNEL kit was used to determine the apoptosis of tumor tissues. Immunohistochemistry analysis and HUVEC tube formation assay were performed to determine the anti-angiogenesis ability. Immunofluorescence and western blot were used to test protein expression.

Results

TY-011 was identified as a potential Aurora A and B inhibitor by HTRF® KinEASE™ assay. It effectively inhibited cellular Aurora A and B activities in a concentration-dependent manner. TY-011 occupied the ATP-binding site of both Aurora A and B kinases. TY-011 demonstrated prominent inhibitory effects on proliferation of gastric cancer cells. TY-011 treatment induced an obvious accumulation of cells at G2/M phase and a modest increase of cells with >4 N DNA content, which then underwent apoptosis. Meaningfully, orally administration of TY-011 demonstrated superior efficacy against the tumor growth in gastric cancer cell xenograft, with ~90% inhibition rate and 100% tumor regression at 9 mg/kg dose, and TY-011 did not affect the body weight of mice. Interestingly, we observed that TY-011 also antagonized tumor angiogenesis by targeting VEGFR2 kinase.

Conclusions

These results indicate that TY-011 is a well-tolerated, orally active compound that targets mitosis and angiogenesis in tumor growth, and provides strong preclinical support for use as a therapeutic for human gastric cancers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0464-2) contains supplementary material, which is available to authorized users.

JD enhances the anti-tumour effects of low-dose paclitaxel on gastric cancer MKN45 cells both in vitro and in vivo

BACKGROUND

Gastric cancer is the third most common cause of cancer mortality worldwide, and paclitaxel (PTX) is one of the most widely used traditional drugs in gastric cancer therapy. However, the response to traditional therapy is limited by acquired chemo-resistance and side effects. Here, we establish a newly designed combination therapy consisting of a compound that is a structural variant of oridonin, i.e. Jesridonin (JD), and low-dose PTX for gastric cancer cells (MKN45) to investigate whether the anti-tumour activity of low-dose PTX could be enhanced when combined with JD.

METHODS

The interaction of JD and low-dose PTX was detected in MKN45 cells using the median-effect analysis method. The synergistic effect on cell viability and apoptosis was measured by MTT assay, colony formation assay, transient transfection, flow cytometry and Western blotting. The synergistic in vivo effect of JD plus low-dose PTX was evaluated in nude mouse xenograft models using H&E and TUNEL staining and Western blotting.

RESULTS

JD plus low-dose PTX showed a synergistic effect, as the combination indexes were less than 1. Additionally, a synergistic anti-proliferative and pro-apoptotic effect was detected for the combination of JD and low-dose PTX. The apoptotic mechanism induced by JD plus PTX revealed that the combination therapy synergistically activated the mitochondrial pathway.

CONCLUSION

Our findings suggest that JD enhances the anti-tumour effect of low-dose PTX on gastric carcinoma cancer cells in both vitro and in vivo, accompanied by activation of the mitochondrial pathway, which may present a more effective therapeutic strategy in gastric cancer treatment.

Emerging power of proteomics for delineation of intrinsic tumor subtypes and resistance mechanisms to anti-cancer therapies

INTRODUCTION

Despite extreme genetic heterogeneity, tumors often show similar alterations in the expression, stability, and activation of proteins important in oncogenic signaling pathways. Thus, classifying tumor samples according to shared proteomic features may help facilitate the identification of cancer subtypes predictive of therapeutic responses and prognostic for patient outcomes. Meanwhile, understanding mechanisms of intrinsic and acquired resistance to anti-cancer therapies at the protein level may prove crucial to devising reversal strategies. Areas covered: Herein, we review recent advances in quantitative proteomic technology and their applications in studies to identify intrinsic tumor subtypes of various tumors, to illuminate mechanistic aspects of pharmacological and oncogenic adaptations, and to highlight interaction targets for anti-cancer compounds and cancer-addicted proteins. Expert commentary: Quantitative proteomic technologies are being successfully employed to classify tumor samples into distinct intrinsic subtypes, to improve existing DNA/RNA based classification methods, and to evaluate the activation status of key signaling pathways.

Exploring the role of molecular biomarkers as a potential weapon against gastric cancer: A review of the literature

Gastric cancer (GC) is a global health problem and a major cause of cancer-related death with high recurrence rates ranging from 25% to 40% for GC patients staging II-IV. Unfortunately, while the majority of GC patients usually present with advanced tumor stage; there is still limited evidence-based therapeutic options. Current approach to GC management consists mainly of; endoscopy followed by, gastrectomy and chemotherapy or chemo-radiotherapy. Recent studies in GC have confirmed that it is a heterogeneous disease. Many molecular characterization studies have been performed in GC. Recent discoveries of the molecular pathways underlying the disease have opened the door to more personalized treatment and better predictable outcome. The identification of molecular markers is a useful tool for clinical managementin GC patients, assisting in diagnosis, evaluation of response to treatment and development of novel therapeutic modalities. While chemotherapeutic agents have certain physiological effects on the tumor cells, the prediction of the response is different from one type of tumor to the other. The specificity of molecular biomarkers is a principal feature driving their application in anticancer therapies. Here we are trying to focus on the role of molecular pathways of GC and well-established molecular markers that can guide the therapeutic management.

Emerging molecular classifications and therapeutic implications for gastric cancer

Gastric cancer (GC) is a highly aggressive and life-threatening malignancy. Even with radical surgical removal and front-line chemotherapy, more than half of GCs locally relapse and metastasize at a distant site. The dismal outcomes reflect the ineffectiveness of a one-size-fits-all approach for a highly heterogeneous disease with diverse etiological causes and complex molecular underpinnings. The recent comprehensive genomic and molecular profiling has led to our deepened understanding of GC. The emerging molecular classification schemes based on the genetic, epigenetic, and molecular signatures are providing great promise for the development of more effective therapeutic strategies in a more personalized and precise manner. To this end, the Cancer Genome Atlas (TCGA) research network conducted a comprehensive molecular evaluation of primary GCs and proposed a new molecular classification dividing GCs into four subtypes: Epstein-Barr virus-associated tumors, microsatellite unstable tumors, genomically stable tumors, and tumors with chromosomal instability. This review primarily focuses on the TCGA molecular classification of GCs and discusses the implications on novel targeted therapy strategies. We believe that these fundamental findings will support the future application of targeted therapies and will guide our efforts to develop more efficacious drugs to treat human GCs.

Effect of First Line Gastric Cancer Chemotherapy Regime on the AGS Cell Line - MTT Assay Results

BACKGROUND

Combination chemotherapy regimes are common treatments for cancer. The aim of this study was to evaluation the effect of individual chemotherapeutic agents in comparison with a first line chemotherapy regime treatment in the AGS gastric cancer cell line by MTT assay.

MATERIALS AND METHODS

In this experimental study, AGS cells were grown in RPMI-1640 supplemented with 10% fetal calf serum and 100 IU/ml penicillin, and 10 μg/ml streptomycinin, under a humidified condition at 37° with 5% CO2. All cells were washed with PBS and detached with trypsin, centrifuged and 8000 cells re-plated on to 96- well plates. LD50 doses of Epirubicin, Cisplatin and 5-fluorouracil were added to each well in mono or triple therapy. Anti-proliferative activities were determined by MTT assay after 24, 48 or 72 h.

RESULTS

Results of MTT assays showed that there were no significant differences among 3 drugs in monotherapy (p=0.088), but there was significant difference between combination therapy with epirubicin (P=0.031) and 5FU (p=0.013) on cell survival at 24 h. After 48 and 72 hours, cell viability showed significant differences between the 3 drugs (p=0.048 and P=0.000 for 48 and 72 h, respectively) and there was significant difference between combination therapy with epirubicin (P=0.035 and P=0.002 for 48 and 72 h, respectively).

CONCLUSIONS

The results showed no significant differences between these chemotherapy drugs each given alone, but combination therapy with 3 drugs had significant effects on cell viability in comparison with epirubicin alone.

DAG/PKCδ and IP3/Ca²⁺/CaMK IIβ Operate in Parallel to Each Other in PLCγ1-Driven Cell Proliferation and Migration of Human Gastric Adenocarcinoma Cells, through Akt/mTOR/S6 Pathway

Phosphoinositide specific phospholipase Cγ (PLCγ) activates diacylglycerol (DAG)/protein kinase C (PKC) and inositol 1,4,5-trisphosphate (IP3)/Ca²⁺/calmodulin-dependent protein kinase II (CaMK II) axes to regulate import events in some cancer cells, including gastric adenocarcinoma cells. However, whether DAG/PKCδ and IP3/Ca²⁺/CaMK IIβ axes are simultaneously involved in PLCγ1-driven cell proliferation and migration of human gastric adenocarcinoma cells and the underlying mechanism are not elucidated. Here, we investigated the role of DAG/PKCδ or CaMK IIβ in PLCγ1-driven cell proliferation and migration of human gastric adenocarcinoma cells, using the BGC-823 cell line. The results indicated that the inhibition of PKCδ and CaMK IIβ could block cell proliferation and migration of BGC-823 cells as well as the effect of inhibiting PLCγ1, including the decrease of cell viability, the increase of apoptotic index, the down-regulation of matrix metalloproteinase (MMP) 9 expression level, and the decrease of cell migration rate. Both DAG/PKCδ and CaMK IIβ triggered protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/S6 pathway to regulate protein synthesis. The data indicate that DAG/PKCδ and IP3/Ca²⁺/CaMK IIβ operate in parallel to each other in PLCγ1-driven cell proliferation and migration of human gastric adenocarcinoma cells through Akt/mTOR/S6 pathway, with important implication for validating PLCγ1 as a molecular biomarker in early gastric cancer diagnosis and disease surveillance.