Molecular Dimensions of Gastric Cancer: Translational and Clinical Perspectives

Establishment and characterization of a new mouse gastric carcinoma cell line, MCC

BACKGROUND

The aim of this study was to establish a primary mouse gastric carcinoma cell line.

METHODS

Gastric adenocarcinoma in the body region was induced in immunocompetent BALB/c mice using N-Methyl-N-nitrosourea and a 2% NaCl solution. Fresh gastric cancer tissue samples were cultured in 1640 medium supplemented with 10% fetal bovine serum for primary culture and subculture. Cellular morphology was assessed via light microscopy, and a cell growth curve was established. Genomic and proteomic analyses were conducted to characterize the molecular features of the cell lines. This cell line demonstrated a 100% success rate in forming subcutaneous tumors in BALB/c mice. By integrating proteomic profiles from clinical gastric cancer patients and the murine subcutaneous tumor model, several molecular targets suitable for preclinical investigation were identified. Trametinib, a MEK inhibitor, was employed as a model compound in our preclinical study.

RESULTS

A novel gastric carcinoma cell line, designated MCC, was established from BALB/c mice. This cell line exhibited a doubling time of approximately 33 h. Genomic and proteomic analyses identified mutations frequently observed in clinical gastric cancer patients, such as Kras, Egfr, and Ccnd3. Additionally, MCC overexpresses proteins, including SLC1A5, MCM6, and ITGA2, which are significantly upregulated in gastric cancer tissues compared to adjacent non-cancerous tissues. The MCC cell line demonstrated stable tumorigenicity in immunocompetent BALB/c mice, forming subcutaneous tumors that closely resemble the proteomic profile of clinical gastric cancer samples. This high concordance facilitated the identification of several potential therapeutic targets for gastric cancer. Preclinical studies with trametinib revealed that treatment effectively inhibited gastric cancer growth, likely mediated through the activation of immune cells, particularly neutrophils and T cells.

CONCLUSIONS

The MCC cell line serves as an indispensable model for gastric cancer research, offering a robust platform for investigating tumor development and progression. Its exceptional tumorigenic capacity and strong concordance with clinical proteomic profiles underscore its significance in translational research, facilitating the discovery of novel therapeutic targets and elucidation of molecular pathways critical for developing effective treatment strategies.

Secondary Primary Cancer after Primary Gastric Cancer: Literature Review and Big Data Analysis Using the Health Insurance Review and Assessment Service (HIRA) Database of Republic of Korea

Advances in cancer screening and early detection, as well as improvements in surgical techniques and therapeutics, have contributed to decreasing gastric cancer mortality. The number of gastric cancer survivors continues to rise; however, long-term follow-up has revealed an increase in the risk of post-gastrectomy symptoms or other health problems, such as extra-gastric secondary primary cancer (SPC), in these survivors. Therefore, evidence-based screening for new primary cancer is needed in these populations; however, the incidence of SPC varies by country or continent and its characteristics have not been clearly reported. The characteristics of SPC are of increasing interest to both treatment providers and gastric cancer survivors; thus, this literature review explores not only the epidemiology and biology of SPC but also clinical and biological factors that influence its prognosis.

Effect of Prognostic Nutrition Index in Gastric or Gastro-oesophageal Junction Cancer Patients Undergoing Nivolumab Monotherapy

BACKGROUND/AIM

We hypothesised that the prognostic nutrition index (PNI) is useful for evaluating host immunity and response to immune checkpoint inhibitors. We investigated the effect of PNI on nivolumab monotherapy efficacy in advanced or recurrent gastric cancer (GC) or gastro-oesophageal junction cancer (GOC) patients.

PATIENTS AND METHODS

We retrospectively examined 110 patients, divided them into a high-PNI group and a low-PNI group, and compared treatment efficacy, adverse events (AEs), and survival between the groups.

RESULTS

Median overall survival (OS) was significantly longer in the high-PNI group than in the low-PNI group (205 vs. 109 days; p<0.001). Multivariate analysis revealed that low PNI was an independent risk factor for OS (hazard ratio=2.398; 95% confidence interval=1.384-4.154; p=0.002). The overall response rate and frequency of AEs were not significantly different between the groups.

CONCLUSION

PNI could be a useful prognostic factor in GC or GOC patients undergoing nivolumab monotherapy.

Microsatellite instability: a review of what the oncologist should know

The patients with high microsatellite instability (MSI-H)/mismatch repair deficient (dMMR) tumors recently have been reported that can benefit from immunotherapy, and MSI can be used as a genetic instability of a tumor detection index. However, many studies have shown that there are many heterogeneous phenomena in patients with MSI tumors in terms of immunotherapy, prognosis and chemotherapy sensitivity. Here we mainly review the research results of MSI detection methods, the mechanisms of MSI occurrence and its relationship with related tumors, aiming to make a brief analysis of the current research status of MSI and provide comparable reference and guidance value for further research in this field.

Trastuzumab Specific Epitope Evaluation as a Predictive and Prognostic Biomarker in Gastric Cancer Patients

While human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC) antibodies bind to the intracellular domain, trastuzumab binds to the extracellular epitope of HER2 receptor: target of drug action. We aimed to evaluate clinical significance of the new IHC method assessing the target of trastuzumab in gastric cancer (GC) patients and compare with conventional methods. Sixty-nine trastuzumab-treated GC patients were enrolled from two different cohorts. Additionally, we enrolled 528 consecutive GC patients to evaluate prognostic implications of HER2 test methods. HER2 status was assessed by trastuzumab IHC, HER2 IHC (4B5), and HER2 silver in situ hybridization (SISH). HER2 IHC showed 3+ in 48/69 trastuzumab-treated patients (69.6%), however, trastuzumab IHC showed 3+ in 25 (36.2%). Patients with trastuzumab IHC ≥2+ had significantly better progression-free survival (PFS) and overall survival (OS) than their counterpart (p = 0.014). In univariate analysis, trastuzumab IHC ≥2+ and HER2 IHC 3+ were only significant predictive factors for OS in trastuzumab-treated patients. Of the 528 consecutive GCs, patients with trastuzumab IHC ≥2+ had shorter disease-free survival (DFS) and OS (p = 0.008 and 0.031, respectively), while conventional methods failed to reveal any significant survival differences. HER2 assessment by trastuzumab IHC was different from conventional HER2 test results. Trastuzumab IHC was suggested to be a significant predictive factor for trastuzumab responsiveness and prognostic factor for consecutive GCs.

Phosphoproteomics Enables Molecular Subtyping and Nomination of Kinase Candidates for Individual Patients of Diffuse-Type Gastric Cancer

The diffuse-type gastric cancer (DGC) constitutes a subgroup of gastric cancer with poor prognosis and no effective molecular therapies. Here, we report a phosphoproteomic landscape of DGC derived from 83 tumors together with their nearby tissues. Based on phosphorylation, DGC could be classified into three molecular subtypes with distinct overall survival (OS) and chemosensitivity. We identified 16 kinases whose activities were associated with poor OS. These activated kinases covered several cancer hallmark pathways, with the MTOR signaling network being the most frequently activated. We proposed a patient-specific strategy based on the hierarchy of clinically actionable kinases for prioritization of kinases for further clinical evaluation. Our global data analysis indicates that in addition to finding activated kinase pathways in DGC, large-scale phosphoproteomics could be used to classify DGCs into subtypes that are associated with distinct clinical outcomes as well as nomination of kinase targets that may be inhibited for cancer treatments.

Clinicopathologic significance of human leukocyte antigen class I expression in patients with stage II and III gastric cancer

Human leukocyte antigen class I (HLA I) molecules composed of alpha (heavy) chain, including HLA-A, -B, or -C encoded by HLA genes, and beta-2-microglobulin (β2M) are membrane proteins on all nucleated cells that display peptide antigens for recognition by CD8-positive cytotoxic T cells. Here, we examined the clinicopathologic signification of HLA I expression in patients with gastric cancer (GC). Immunohistochemistry was performed to detect HLA A/B/C, β2M, CD8, p53, and programmed death-ligand 1 (PD-L1) in the center and invasive margin of the tumor in 395 stage II and III GCs using tissue array method. Additionally, Epstein-Barr virus (EBV) infection and microsatellite instability (MSI) status were investigated. Negative expression of HLA A/B/C and β2M was observed in 258 (65.3%) and 235 (59.5%) of 395 stage II and III GCs, respectively. Negative HLA I expression was significantly associated with aggressive clinicopathologic features. Furthermore, negative expression of HLA A/B/C and β2M was inversely correlated with CD8-positive cytotoxic T cell infiltration, EBV-positivity, and PD-L1 expression (all p < 0.001). Patients with HLA A/B/C-negative GC had worse overall survival (OS) (p = 0.019) and combined analysis with both HLA A/B/C and β2M expression status significantly predicted OS in univariate (p = 0.004) and multivariate survival analysis (p = 0.016). Negative expression of HLA A/B/C and β2M was frequently observed in stage II and III GCs, particularly with the aggressive clinicopathologic features, and correlated with an unfavorable prognosis and host immune response status. These findings contribute to further development of immunotherapy.

Ten Thousand Consecutive Gastrectomies for Gastric Cancer: Perspectives of a Master Surgeon

As radical gastrectomy with lymph node dissection is currently the best strategy to cure gastric cancer, the role of the surgeon remains quite important in conquering it. Dr. Sung Hoon Noh, a surgeon and surgical oncologist specializing in gastric cancer, has treated gastric cancer for 30 years and has conducted over 10000 cases of gastrectomy for gastric cancer. He first adapted an electrocautery device into gastric cancer surgery and has led standardization of surgical procedures, including spleen preserving gastrectomy. His procedures based on patient-oriented insights have become the basis of the concept of enhanced recovery after surgery. He has also contributed to improving patient's survival through adoption of a multidisciplinary approach: he proved the benefit of adjuvant chemotherapy after radical D2 gastrectomy for stage II/III gastric cancer in clinical trials, updating treatment guidelines throughout the world. Dr. Noh also opened the era of precision medicine for treating gastric cancer, as he developed and validated a mRNA expression based algorithm to predict prognosis and response to chemotherapy. This article reviews his contribution and long history of service in the field of gastric cancer. The perspectives of this master surgeon, based on his profound experience and insights, will outline directions for integrative multidisciplinary health care and how can surgeons prepare for the future.

Single Patient Classifier Assay, Microsatellite Instability, and Epstein-Barr Virus Status Predict Clinical Outcomes in Stage II/III Gastric Cancer: Results from CLASSIC Trial

PURPOSE

Clinical implications of single patient classifier (SPC) and microsatellite instability (MSI) in stage II/III gastric cancer have been reported. We investigated SPC and the status of MSI and Epstein-Barr virus (EBV) as combinatory biomarkers to predict the prognosis and responsiveness of adjuvant chemotherapy for stage II/III gastric cancer.

MATERIALS AND METHODS

Tumor specimens and clinical information were collected from patients enrolled in CLASSIC trial, a randomized controlled study of capecitabine plus oxaliplatin-based adjuvant chemotherapy. The results of nine-gene based SPC assay were classified as prognostication (SPC-prognosis) and prediction of chemotherapy benefit (SPC-prediction). Five quasimonomorphic mononucleotide markers were used to assess tumor MSI status. EBV-encoded small RNA in situ hybridization was performed to define EBV status.

RESULTS

There were positive associations among SPC, MSI, and EBV statuses among 586 patients. In multivariate analysis of disease-free survival, SPC-prognosis [hazard ratio (HR): 1.879 (1.101-3.205), 2.399 (1.415-4.067), p=0.003] and MSI status (HR: 0.363, 95% confidence interval: 0.161-0.820, p=0.015) were independent prognostic factors along with age, Lauren classification, TNM stage, and chemotherapy. Patient survival of SPC-prognosis was well stratified regardless of EBV status and in microsatellite stable (MSS) group, but not in MSI-high group. Significant survival benefit from adjuvant chemotherapy was observed by SPC-Prediction in MSS and EBV-negative gastric cancer.

CONCLUSION

SPC, MSI, and EBV statuses could be used in combination to predict the prognosis and responsiveness of adjuvant chemotherapy for stage II/III gastric cancer.

High serum MMP-14 predicts worse survival in gastric cancer

Matrix metalloproteinases (MMPs), endopeptidases with diverse biochemical functions, can promote cancer cell invasion and metastasis by degrading the extracellular matrix. A high matrix metalloproteinase-14 (MMP-14) expression in gastric cancer tissue has been associated with metastasis and poor prognosis. To further understand this association, we investigated serum MMP-14 as a biomarker in gastric cancer patients. The patient cohort consisted of 240 gastric adenocarcinoma patients who underwent surgery at Helsinki University Hospital, Finland, between 2000 and 2009. We determined the soluble MMP-14 serum levels using an enzyme-linked immunosorbent assay. We then calculated the associations between serum levels and clinicopathologic variables using the Mann-Whitney U-test or the Kruskal-Wallis test. We constructed survival curves using the Kaplan-Meier method and calculating the hazard ratios using the Cox proportional hazard model. We revealed a positive association between a high serum MMP-14 level and stages III–IV (p = 0.029), and between a high serum MMP-14 and distant metastasis (p = 0.022). Patients with a low serum MMP-14 had a 5-year disease-specific survival of 49.2% (95% confidence interval [CI] 45.5–52.9), whereas patients with a high serum MMP-14 had a 5-year survival of 22.1% (95% CI 15.2–29.0; p = 0.001). High serum MMP-14 was a statistically significant prognostic factor among patients with an intestinal type of cancer (hazard ratio [HR] 3.54; 95% CI 1.51–8.33; p = 0.004), but not among patients with a diffuse type. The serum MMP-14 level remained an independent prognostic factor in our multivariate survival analysis (HR 1.55; 95% CI 1.02–2.35; p = 0.040). This study indicates for the first time that high serum soluble MMP-14 levels in gastric cancer serves as a marker for a poor prognosis, possibly indicating the presence of distant metastases.

Proposed Molecular and miRNA Classification of Gastric Cancer

Gastric cancer (GC) is a common malignant neoplasm worldwide and one of the main cause of cancer-related deaths. Despite some advances in therapies, long-term survival of patients with advanced disease remains poor. Different types of classification have been used to stratify patients with GC for shaping prognosis and treatment planning. Based on new knowledge of molecular pathways associated with different aspect of GC, new pathogenetic classifications for GC have been and continue to be proposed. These novel classifications create a new paradigm in the definition of cancer biology and allow the identification of relevant GC genomic subsets by using different techniques such as genomic screenings, functional studies and molecular or epigenetic characterization. An improved prognostic classification for GC is essential for the development of a proper therapy for a proper patient population. The aim of this review is to discuss the state-of-the-art on combining histological and molecular classifications of GC to give an overview of the emerging therapeutic possibilities connected to the latest discoveries regarding GC.

New therapeutic options opened by the molecular classification of gastric cancer

Gastric cancer (GC) is one of the most lethal and aggressive cancers, being the third cause of cancer related death worldwide. Even with radical gastrectomy and the latest generation of molecular chemotherapeutics, the numbers of recurrence and mortality remains high. This is due to its biological heterogeneity based on the interaction between multiple factors, from genomic to environmental factors, diet or infections with various pathogens. Therefore, understanding the molecular characteristics at a genomic level is critical to develop new treatment strategies. Recent advances in GC molecular classification provide the unique opportunity to improve GC therapy by exploiting the biomarkers and developing novel targeted therapy specific to each subtype. This article highlights the molecular characteristics of each subtype of gastric cancer that could be considered in shaping a therapeutic decision, and also presents the completed and ongoing clinical trials addressed to those targets. The implementation of the novel molecular classification system will allow a preliminary patient selection for clinical trials, a mandatory issue if it is desired to test the efficacy of a certain inhibitor to the given target. This will represent a substantial advance as well as a powerful tool for targeted therapy. Nevertheless, translating the scientific results into new personalized treatment opportunities is needed in order to improve clinical care, the survival and quality of life of patients with GC.

Clinicopathologic implications of immune classification by PD-L1 expression and CD8-positive tumor-infiltrating lymphocytes in stage II and III gastric cancer patients

We co-assessed PD-L1 expression and CD8⁺ tumor-infiltrating lymphocytes in gastric cancer (GC), and categorized into 4 microenvironment immune types. Immunohistochemistry (PD-L1, CD8, Foxp3, E-cadherin, and p53), PD-L1 mRNA in situ hybridization (ISH), microsatellite instability (MSI), and EBV ISH were performed in 392 stage II/III GCs treated with curative surgery and fluoropyrimidine-based adjuvant chemotherapy, and two public genome databases were analyzed for validation. PD-L1⁺ was found in 98/392 GCs (25.0%). The proportions of immune types are as follows: PD-L1⁺/CD8^High, 22.7%; PD-L1⁻/CD8^Low, 22.7%; PD-L1⁺/CD8^Low, 2.3%; PD-L1⁻/CD8^High, 52.3%. PD-L1⁺/CD8^High type accounted for majority of EBV⁺ and MSI-high (MSI-H) GCs (92.0% and 66.7%, respectively), and genome analysis from public datasets demonstrated similar pattern. PD-L1⁻/CD8^High showed the best overall survival (OS) and PD-L1⁻/CD8^Low the worst (P < 0.001). PD-L1 expression alone was not associated with OS, however, PD-L1⁻/CD8^High type compared to PD-L1⁺/CD8^High was independent favorable prognostic factor of OS by multivariate analysis (P = 0.042). Adaptation of recent molecular classification based on EBV, MSI, E-cadherin, and p53 showed no significant survival differences. These findings support the close relationship between PD-L1/CD8 status based immune types and EBV⁺, MSI-H GCs, and their prognostic significance in stage II/III GCs.

GRAM domain-containing protein 1B (GRAMD1B), a novel component of the JAK/STAT signaling pathway, functions in gastric carcinogenesis

Dysregulated JAK/STAT signaling has been implicated in the molecular pathogenesis of gastric cancer. However, downstream effectors of STAT signaling that facilitate gastric carcinogenesis remain to be explored. We previously identified the Drosophila ortholog of human GRAMD1B in our genome-wide RNAi screen to identify novel components of the JAK/STAT signaling pathway in Drosophila. Here, we examined the involvement of GRAMD1B in JAK/STAT-associated gastric carcinogenesis. We found that GRAMD1B expression is positively regulated by JAK/STAT signaling and GRAMD1B inhibition decreases STAT3 levels, suggesting the existence of a positive feedback loop. Consistently, GRAMD1B and JAK/STAT signaling acted synergistically to promote gastric cancer cell survival by upregulating the expression of the anti-apoptotic molecule Bcl-xL. Interestingly, our immunohistochemical analysis for GRAMD1B revealed a gradual loss of cytoplasmic staining but an increase in the nuclear accumulation of GRAMD1B, as gastric tissue becomes malignant. GRAMD1B expression levels were also found to be significantly associated with clinicopathological features of the gastric cancer patients, particularly the tumor grades and lymph node status. Moreover, GRAMD1B and pSTAT3 (Tyr705) showed a positive correlation in gastric tissues, thereby confirming the existence of a close link between these two signaling molecules in vivo. This new knowledge about JAK/STAT-GRAMD1B regulation deepens our understanding of JAK/STAT signaling in gastric carcinogenesis and provides a foundation for the development of novel biomarkers in gastric cancer.

Perioperative chemotherapy for resectable gastric cancer - what is the evidence?

The UK MAGIC trial published in 2006 was the first RCT to identify improved long-term survival rates using preoperative chemotherapy for resectable gastric or gastroesophageal cancer. Overnight, the treatment regimen impacted European guidelines. However, the majority of patients underwent limited lymph node dissection, and analyses of the rates of curative resection, downsizing and downstaging were not by intention to treat, rightfully raising concerns about their validity. For the subset of true gastric cancers, meta-analyses may even question the claims of improved long-term survival rates by present-day regimens. A rhetorical question can be posed as to whether downstaging and improved survival rates by preoperative (radio)-chemotherapy for cancers of the distal esophagus or gastric cardia, has confounded our conclusions on the (lack of) effect of present-day regimens of perioperative chemotherapy for true gastric cancers, let alone in a situation with proper lymph node dissection. At present, a plea can be made to move one step back and revert to an RCT with a surgery alone arm. Inclusion criteria and analyses of future RCTs must stratify on tumor location and the Lauren type and embrace the newly developed scheme of sub-classification of gastric cancers based on extensive molecular profiling as reported in the seminal Cancer Genome Atlas Study.

Molecular classifications of gastric cancers: Novel insights and possible future applications

Despite some notable advances in the systemic management of gastric cancer (GC), the prognosis of patients with advanced disease remains overall poor and their chance of cure is anecdotic. In a molecularly selected population, a median overall survival of 13.8 mo has been reached with the use of human epidermal growth factor 2 (HER2) inhibitors in combination with chemotherapy, which has soon after become the standard of care for patients with HER2-overexpressing GC. Moreover, oncologists have recognized the clinical utility of conceiving cancers as a collection of different molecularly-driven entities rather than a single disease. Several molecular drivers have been identified as having crucial roles in other tumors and new molecular classifications have been recently proposed for gastric cancer as well. Not only these classifications allow the identification of different tumor subtypes with unique features, but also they serve as springboard for the development of different therapeutic strategies. Hopefully, the application of standard systemic chemotherapy, specific targeted agents, immunotherapy or even surgery in specific cancer subgroups will help maximizing treatment outcomes and will avoid treating patients with minimal chance to respond, therefore diluting the average benefit. In this review, we aim at elucidating the aspects of GC molecular subtypes, and the possible future applications of such molecular analyses.

Clinicopathologic implication of meticulous pathologic examination of regional lymph nodes in gastric cancer patients

BACKGROUND

We aimed to investigate effect of increased number of examined lymph nodes (LNs) to pN category, and compare various N categories in gastric cancer: American Joint Committee on Cancer (AJCC) 7th edition, metastatic LN ratio (MLR), and log odds of positive LNs (LODDS).

METHODS

Four cohorts with a total of 2,309 gastric cancer patients were enrolled. For cohort 1 and 2, prognostic significance of each method by disease-specific survival was analyzed using Akaike and Bayesian information criterion (AIC and BIC).

RESULTS

The total LNs in four cohorts significantly differed [median (range), 28 (6-97) in cohort 1, 37 (8-120) in cohort 2, 48 (7-122) in cohort 3, and 54 (4-221) in cohort 4; p<0.001]. The numbers of negative LNs increased with increase of total LN (p<0.001), but the numbers of metastatic LNs did not increase from cohort 1 to 4. MLR and LODDS in four cohorts had decreasing tendency with increase of total LNs in each pT3 and pT4 category (p<0.001), while the numbers of metastatic LNs did not differ significantly in any pT category (p>0.05). The AIC and BIC varied according to different cut-off values for MLR; model by cut-offs of 0.2 and 0.5 being better for cohort 1, while cut-offs 0.1 and 0.25 was better for cohort 2.

CONCLUSION

Our study showed that the number of metastatic LNs did not increase with maximal pathologic examination of regional LNs. AJCC 7th system is suggested as the simplest method with single cut-off value, but prognostic significance of MLR may be influenced by various cut-offs.

miR-30 functions as an oncomiR in gastric cancer cells through regulation of P53-mediated mitochondrial apoptotic pathway

The present study was designed to investigate the role of miR-30 in the development of Gastric cancer (GC). miR-30 expression was increased in GC tissues and cell lines. Downregulation of miR-30 inhibited cell proliferation and promoted apoptosis in HGC-27 cells. Upregulation of miR-30 enhanced the proliferation and inhibited apoptosis. P53 expression was decreased in GC tissues. P53 expression was correlated with miR-30 expression. Downregulation of miR-30 increased P53 expression. Knockdown of P53 inhibited miR-30-inhibitor-induced suppression of cell proliferation and increase of apoptosis. Downregulation of miR-30 increased ROS generation which was inhibited by shP53. miR-30 inhibitors induced a decrease in mitochondrial oxygen consumption, cytoplasmic release of cytochrome c, and activation of Caspase 3 and 9, activating mitochondrial apoptotic pathway. Downregulation of P53 and N-acetyl-cysteine suppressed miR-30 inhibitors-activated mitochondrial dysfunction and apoptotic events. In conclusion, we identified that miR-30 functioned as a potential oncomiR through P53/ROS-mediated regulation of mitochondrial apoptotic pathway.