Molecular Testing for Gastrointestinal Cancer

Effector Function Characteristics of Exhausted CD8+ T-Cell in Microsatellite Stable and Unstable Gastric Cancer

PURPOSE

Gastric cancer exhibits molecular heterogeneity, with the microsatellite instability-high (MSI-H) subtype drawing attention for its distinct features. Despite a higher survival rate, MSI-H gastric cancer lack significant benefits from conventional chemotherapy. The immune checkpoint inhibitors, presents a potential avenue, but a deeper understanding of the tumor immune microenvironment of MSI-H gastric cancer is essential.

MATERIALS AND METHODS

We explored the molecular characteristics of CD8+ T-cell subtypes in three MSI-H and three microsatellite stable (MSS) gastric cancer samples using single-cell RNA sequencing and spatial transcriptome analysis.

RESULTS

In MSI-H gastric cancer, significantly higher proportions of effector memory T cell (Tem), exhausted T cell (Tex), proliferative exhausted T cell (pTex), and proliferative T cell were observed, while MSS gastric cancer exhibited significantly higher proportions of mucosal-associated invariant T cell and natural killer T cell. In MSI-H gastric cancer, Tex and pTex exhibited a significant upregulation of the exhaustion marker LAG3, as well as elevated expression of effector function markers such as IFNG, GZMB, GZMH, and GZMK, compared to those in MSS gastric cancer. The interferon γ (IFN-γ) signaling pathway of Tex and pTex was retained compared to those of MSS gastric cancer. The spatial transcriptome analysis demonstrates the IFN-γ signaling pathway between neighboring Tex and malignant cell, showcasing a significantly elevated interaction in MSI-H gastric cancer.

CONCLUSION

Our study reveals novel finding indicating that IFN-γ signaling pathway is retained in Tex and pTex of MSI-H gastric cancer, offering a comprehensive perspective for future investigations into immunotherapy for gastric cancer.

Colorectal Cancer: Genetic Underpinning and Molecular Therapeutics for Precision Medicine

Colorectal cancer (CRC) accounts for about 10% of all cancer cases and 9% of cancer-related deaths globally. In the United States alone, CRC represents approximately 12.6% of all cancer cases, with a mortality rate of about 8%. CRC is now the first leading cause of cancer death in men younger than age 50 and second in women younger than age 50. This review delves into the genetic landscape of CRC, highlighting key mutations and their implications in disease progression and treatment. We provide an overview of the current and emerging therapeutic strategies tailored to individual genomic profiles.

Predictive biomarkers and new developments of immunotherapy in gastric cancer: a 2023 update

Gastric cancer is an extremely common digestive tract tumor. The promotion and application of standardized therapy, treatment scheme optimization, and development of new targeted drugs and immunotherapies have improved gastric cancer survival somewhat. However, gastric cancer prognosis generally remains non-optimistic. Immune checkpoint inhibitors (ICI) have gradually become a new choice for gastric cancer treatment and can prolong the survival of some patients. Among them, high-microsatellite instability, Epstein-Barr virus-positive status, or high-tumor mutational burden patients with gastric cancer may be the potential population to benefit from immunotherapy. Nevertheless, there remains a lack of unified and effective predictive markers. Accordingly, this review mainly focused on the possible predictive biomarkers of anti-PD-1/PD-L1 in gastric cancer treatment. Furthermore, the application of anti-PD-1/PD-L1 therapy-related clinical trials on gastric cancer is discussed. The current findings suggest that immunotherapy is a promising application in gastric cancer treatment. Therefore, combining immunotherapy and other therapies may be the trend in the future. Nevertheless, exploring biomarkers to predict ICI response remains a major challenge.

Influence of location-dependent sex difference on PD-L1, MMR/MSI, and EGFR in colorectal carcinogenesis

BACKGROUND

The incidence and mortality rates of colorectal cancer (CRC) has been reported to be strongly associated to sex/gender difference. CRC shows sexual dimorphism, and sex hormones have been shown to affect the tumor immune microenvironment. This study aimed to investigate location-dependent sex differences in tumorigenic molecular characteristics in patients with colorectal tumors, including adenoma and CRC.

METHODS

A total of 231 participants, including 138 patients with CRC, 55 patients with colorectal adenoma, and 38 healthy controls, were recruited between 2015 and 2021 at Seoul National University Bundang Hospital. All patients underwent colonoscopy and acquired tumor lesion samples were further analyzed for programmed death-ligand 1 (PD-L1), epidermal growth factor receptor (EGFR) expression, deficient mismatch repair (dMMR), and microsatellite instability (MSI) status. This study was registered with ClinicalTrial.gov, number NCT05638542.

RESULTS

The average of combined positive score (CPS) was higher in serrated lesions and polyps (lesions/polyps) compared to conventional adenomas (5.73 and 1.41, respectively, P < 0.001). No significant correlation was found between sex and PD-L1 expression within the groups, regardless of histopathological diagnosis. In multivariate analysis where each sex was further stratified by tumor location due to their interaction in CRC, PD-L1 expression was inversely correlated with males having proximal CRC with a CPS cutoff of 1 (Odds ratio (OR) 0.28, P = 0.034). Females with proximal CRC showed a significant association with dMMR/MSI-high (OR 14.93, P = 0.032) and high EGFR expression (OR 4.17, P = 0.017).

CONCLUSION

Sex and tumor location influenced molecular features such as PD-L1, MMR/MSI status and EGFR expression in CRC, suggesting a possible underlying mechanism of sex-specific colorectal carcinogenesis.

A Standardized Pathology Report for Gastric Cancer: 2nd Edition

The first edition of 'A Standardized Pathology Report for Gastric Cancer' was initiated by the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists and published 17 years ago. Since then, significant advances have been made in the pathologic diagnosis, molecular genetics, and management of gastric cancer (GC). To reflect those changes, a committee for publishing a second edition of the report was formed within the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists. This second edition consists of two parts: standard data elements and conditional data elements. The standard data elements contain the basic pathologic findings and items necessary to predict the prognosis of GC patients, and they are adequate for routine surgical pathology service. Other diagnostic and prognostic factors relevant to adjuvant therapy, including molecular biomarkers, are classified as conditional data elements to allow each pathologist to selectively choose items appropriate to the environment in their institution. We trust that the standardized pathology report will be helpful for GC diagnosis and facilitate large-scale multidisciplinary collaborative studies.

Korean Practice Guidelines for Gastric Cancer 2022: An Evidence-based, Multidisciplinary Approach

Gastric cancer is one of the most common cancers in Korea and the world. Since 2004, this is the 4th gastric cancer guideline published in Korea which is the revised version of previous evidence-based approach in 2018. Current guideline is a collaborative work of the interdisciplinary working group including experts in the field of gastric surgery, gastroenterology, endoscopy, medical oncology, abdominal radiology, pathology, nuclear medicine, radiation oncology and guideline development methodology. Total of 33 key questions were updated or proposed after a collaborative review by the working group and 40 statements were developed according to the systematic review using the MEDLINE, Embase, Cochrane Library and KoreaMed database. The level of evidence and the grading of recommendations were categorized according to the Grading of Recommendations, Assessment, Development and Evaluation proposition. Evidence level, benefit, harm, and clinical applicability was considered as the significant factors for recommendation. The working group reviewed recommendations and discussed for consensus. In the earlier part, general consideration discusses screening, diagnosis and staging of endoscopy, pathology, radiology, and nuclear medicine. Flowchart is depicted with statements which is supported by meta-analysis and references. Since clinical trial and systematic review was not suitable for postoperative oncologic and nutritional follow-up, working group agreed to conduct a nationwide survey investigating the clinical practice of all tertiary or general hospitals in Korea. The purpose of this survey was to provide baseline information on follow up. Herein we present a multidisciplinary-evidence based gastric cancer guideline.

A standardized pathology report for gastric cancer: 2nd edition

The first edition of 'A Standardized Pathology Report for Gastric Cancer' was initiated by the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists and published 17 years ago. Since then, significant advances have been made in the pathologic diagnosis, molecular genetics, and management of gastric cancer (GC). To reflect those changes, a committee for publishing a second edition of the report was formed within the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists. This second edition consists of two parts: standard data elements and conditional data elements. The standard data elements contain the basic pathologic findings and items necessary to predict the prognosis of GC patients, and they are adequate for routine surgical pathology service. Other diagnostic and prognostic factors relevant to adjuvant therapy, including molecular biomarkers, are classified as conditional data elements to allow each pathologist to selectively choose items appropriate to the environment in their institution. We trust that the standardized pathology report will be helpful for GC diagnosis and facilitate large-scale multidisciplinary collaborative studies.

Exosomal circ_0001190 Regulates the Progression of Gastric Cancer via miR-586/SOSTDC1 Axis

Gastric cancer (GC) is the fifth most common cancer, which has a significant impact on human health. Recent researches have shown that circular RNAs (circRNAs) could affect the progress of GC, but the mechanism still indistinct. In this work, we explored the roles of circ_0001190 in GC. The levels of circ_0001190, microRNA-586 (miR-586) and sclerostin domain containing 1 (SOSTDC1) were detected by quantitative RT-PCR and western blot in GC. The cell functions were scrutinized by cell counting kit-8 assay, 5-Ethynyl-29-deoxyuridine assay, flow cytometry assay, tube formation assay, transwell assay, and western blot. Furthermore, the relationship between miR-586 and circ_0001190 or SOSTDC1 was identified by dual-luciferase reporter assay. Finally, the xenograft model test was implemented to demonstrate the effect of exosomal circ_0001190 in vivo. The levels of circ_0001190 and SOSTDC1 were downregulated, and the miR-586 level was increased in GC. For functional assay, circ _0001190 overexpression inhibited cell vitality, cell proliferation, angiogenesis, cell migration and invasion, whereas stimulated cell apoptosis in GC cells. Circ _0001190 served as a miR-586 sponge to adjust the expression of SOSTDC1. Additionally, miR-586 could promote the advancement of GC by interfering SOSTDC1. Exosomal circ_0001190 overexpression inhibited the development of GC by miR-586/SOSTDC1 axis, which proposed a potential targeted therapy for GC cure.

Case report: Undifferentiated sarcoma with multiple tumors involved in Lynch syndrome: Unexpected favorable outcome to sintilimab combined with chemotherapy

Background

Patients with Lynch syndrome are at an increased risk of developing simultaneous or metachronous tumors, while sarcomas have been occasionally reported. Sarcomas are generally not considered part of the common Lynch syndrome tumor spectrum. However, more and more studies and case reports suggested that sarcoma could be a rare clinical manifestation of Lynch syndrome, leading to new treatment strategies for sarcoma.

Case summary

We report the case of a 74-year-old male patient with Lynch syndrome who had rectal mucinous adenocarcinoma and prostate adenocarcinoma and then developed undifferentiated sarcoma of the left neck two years later. Mismatch repair deficiency (dMMR) was confirmed by immunohistochemical staining for the mismatch repair proteins MSH2, MSH6, MLH1 and PMS2. The result of polymerase chain reaction (PCR) microsatellite instability (MSI) testing of sarcoma showed high-level microsatellite instability (MSI-H). Additionally, a pathogenic germline mutation in MSH2 (c.2459-12A&gt;G) was detected by next-generation sequencing (NGS). Taking into account HE morphology, immunohistochemical phenotype, MSI status, NGS result, medical history and germline MSH2 gene mutation, the pathological diagnosis of left neck biopsy tissue was Lynch syndrome related undifferentiated sarcoma with epithelioid morphology. The patient has been receiving immunotherapy (sintilimab) combined with chemotherapy (tegafur, gimeracil and oteracil potassium capsules) and currently has stable disease. We also reviewed the literature to understand the association between sarcoma and Lynch syndrome.

Conclusion

Sarcoma may now be considered a rare clinical manifestation of Lynch syndrome. Attention and awareness about the association between Lynch syndrome and sarcoma need to be increased. Therefore, timely detection of MMR proteins and validation at the gene level for suspicious patients are the keys to avoiding missed or delayed diagnosis and to identifying patients suited for immunotherapy, which may also help to provide appropriate genetic counseling and follow-up management for patients.

Molecular Pathology of Gastric Cancer

Gastric cancer (GC) is one of the most common lethal malignant neoplasms worldwide, with limited treatment options for both locally advanced and/or metastatic conditions, resulting in a dismal prognosis. Although the widely used morphological classifications may be helpful for endoscopic or surgical treatment choices, they are still insufficient to guide precise and/or personalized therapy for individual patients. Recent advances in genomic technology and high-throughput analysis may improve the understanding of molecular pathways associated with GC pathogenesis and aid in the classification of GC at the molecular level. Advances in next-generation sequencing have enabled the identification of several genetic alterations through single experiments. Thus, understanding the driver alterations involved in gastric carcinogenesis has become increasingly important because it can aid in the discovery of potential biomarkers and therapeutic targets. In this article, we review the molecular classifications of GC, focusing on The Cancer Genome Atlas (TCGA) classification. We further describe the currently available biomarker-targeted therapies and potential biomarker-guided therapies. This review will help clinicians by providing an inclusive understanding of the molecular pathology of GC and may assist in selecting the best treatment approaches for patients with GC.

Optimization of pre-analytical and analytical steps for DNA and RNA analysis of fresh cytology samples

BACKGROUND

Different cytology preparations can be used for molecular diagnostics, however the influence of pre-analytical and analytical steps on the results are not yet well defined. We aimed to determine optimal steps for efficient extraction of DNA and RNA from fresh cells for molecular diagnostics.

METHODS

MCF7 and FaDu human cell lines, were used as a model to determine fresh cells storage conditions (temperature: 25°C, 4°C, -20°C, -80°C; duration: 0 h, 4 h, 12 h, 24 h, 48 h) and optimal nucleic acids extraction method. Besides, the minimal number of total cells and minimal percentage of mutated cells needed for successful extraction of nucleic acids and subsequent determination of present mutation were evaluated.

RESULTS

Extraction of nucleic acids using spin columns yielded the highest quantity and quality of nucleic acids. Isolation of nucleic acids was feasible in all storage conditions, however higher temperature and longer duration of fresh cells storage were associated with lower quality of isolated nucleic acids and similar quantification cycle of housekeeping genes. Successful molecular testing was feasible with least 10⁴ cells, while specific mutation was detected in as low as 5% of mutated cells.

CONCLUSIONS

Our cell line model, mimicking fresh cytology samples, showed that quantity of extracted either DNA or RNA declined with higher temperatures and longer duration of storage but regardless of the storage conditions, we successfully detected both housekeeping genes and mutated gene using qPCR.

Recent Advances in the Diagnosis, Staging, Treatment, and Prognosis of Advanced Gastric Cancer: A Literature Review

Gastric cancer is one of the most common cause of cancer related deaths worldwide which results in malignant tumors in the digestive tract. The only radical treatment option available is surgical resection. Recently, the implementation of neoadjuvant chemotherapy resulted in 5-year survival rates of 95% for early gastric cancer. The main reason of treatment failure is that early diagnosis is minimal, with many patients presenting advanced stages. Hence, the greatest benefit of radical resection is missed. Consequently, the main therapeutic approach for advanced gastric cancer is combined surgery with neoadjuvant chemotherapy, targeted therapy, or immunotherapy. In this review, we will discuss the various treatment options for advanced gastric cancer. Clinical practice and clinical research is the most practical way of reaching new advents in terms of patients' characteristics, optimum drug choice, and better prognosis. With the recent advances in gastric cancer diagnosis, staging, treatment, and prognosis, we are evident that the improvement of survival in this patient population is just a matter of time.

The SUMO E3 ligase CBX4 is identified as a poor prognostic marker of gastric cancer through multipronged OMIC analyses

Gastric cancer (GC) is one of the most common malignancies, with an ever-increasing incidence and high mortality rate. Chromobox4 (CBX4), also named hPC2, is a small ubiquitin-related modifier (SUMO) E3 ligase. Previous studies have found that high CBX4 expression is associated with tumor size, pathologic differentiation and decreased patient survival in hepatocellular carcinoma (HCC). However, the expression and prognostic value of CBX4 in GC have not been clarified. In our study, ONCOMINE, UALCAN, Kaplan-Meier Plotter, cBioPortal, DAVID 6.8 and TIMER were utilized. RT-PCR, immunohistochemistry (IHC), Western blot, CCK-8 assay, cell apoptosis assay, cell cycle assay were used to further verify in GC tissue samples or cell line. The transcriptional and protein level of CBX4 in GC tissues was found significantly elevated and a significant association between the expression of CBX4 and clinicopathological parameters was found in GC patients. Low expression of CBX4 in GC patients were correlated with a significantly improved prognosis. The functions of CBX4 are primarily related to the stem cell pluripotency signaling pathway, Hippo signaling pathway, HTLV-I infection, Notch signaling pathway, and N-glycan biosynthesis. Our results may provide novel insights for the selection of therapeutic targets and prognostic biomarkers for GC.

Histone Deacetylase Inhibitor Trichostatin A Suppresses Cell Proliferation and Induces Apoptosis by Regulating the PI3K/AKT Signalling Pathway in Gastric Cancer Cells

BACKGROUND

Gastric cancer, a common malignant tumour worldwide, has a relatively poor prognosis and is a serious threat to human health. Histone Deacetylase Inhibitors (HDACi) are anticancer agents that are known to affect the cell growth of different cancer types. Trichostatin A (TSA) selectively inhibits the class I and II mammalian Histone Deacetylase (HDAC) family enzymes and regulates many cell processes. Still, the underlying mechanisms of HDACs are not fully understood in gastric cancer.

OBJECTIVE

This study aims to investigate the antitumor effect and the mechanism of growth modulation of gastric cancer cells by TSA.

METHODS

The cell proliferation of gastric cancer cells was measured by MTT and BrdU immunofluorescence assays. Soft agar assay was used to detect the colony formation ability of gastric cancer cells. Flow cytometry was used to examine cell cycle and apoptosis. Western blot was employed to detect protein expression of target factors.

RESULTS

TSA inhibits the proliferation of MKN-45 and SGC-7901 cells and leads to significant repression of colony number and size. Flow cytometry assays show TSA induces cell cycle arrest at G1 phase and apoptosis, and TSA effects the expression of related factors in the mitochondrial apoptotic signalling and cell cycle-related regulatory pathways. Furthermore, TSA increased histone H3K27 acetylation and downregulated the expression of PI3K and p-AKT.

CONCLUSION

Downregulating PI3K/AKT pathway activation is involved in TSA-mediated proliferation inhibition of gastric cancer.

Kallikrein-11, in Association with Coiled-Coil Domain Containing 25, as a Potential Prognostic Marker for Cholangiocarcinoma with Lymph Node Metastasis

Cholangiocarcinoma (CCA) is a malignancy arising from cholangiocytes. Currently, the treatment and prognosis for CCA are mostly poor. Recently, we have reported that coiled-coil domain containing 25 (CCDC25) protein level in the sera may be a diagnostic marker for CCA. Subsequently, we identified three binding proteins of CCDC25 and found that kallikrein-11 (KLK11) expression was highest among those binding proteins. In this study, we investigated CCDC25 and KLK11 expression in CCA and adjacent normal tissues (n = 18) using immunohistochemistry. The results demonstrated that the expressions of CCDC25 and KLK11 in CCA tissues were both significantly higher than the adjacent tissues (p < 0.001 and p = 0.001, respectively). Then, using GEPIA bioinformatics analysis, KLK11 mRNA was significantly overexpressed in CCA tumor tissues compared with normal tissues (p < 0.05). Moreover, CCDC25 expression was positively correlated with KLK11 expression in CCA with lymph node metastasis (p = 0.028, r = 0.593). An analysis for the interaction of KLK11 with CCDC25 and other proteins, using STRING version 11.0, revealed that CCDC25 and KLK11 correlated with metastasis-related proteins. In addition, Kaplan-Meier survival curve analysis revealed that a high expression of KLK11 was associated with the poor prognosis of CCA. In conclusion, KLK11 is, as a binding protein for CCDC25, possibly involved in the metastatic process of CCA. KLK11 may be used as a prognostic marker for CCA.

Metformin attenuates synergic effect of diabetes mellitus and Helicobacter pylori infection on gastric cancer cells proliferation by suppressing PTEN expression

It has been reported that CagA of Helicobacter pylori reduced PTEN expression by enhancing its promoter methylation. Furthermore, diabetes mellitus (DM) may also promote the methylation status of PTEN, a tumour suppressor gene in gastric cancer (GC). It is intriguing to explore whether DM may strengthen the tumorigenic effect of H pylori (HP) by promoting the methylation of PTEN promoter and whether the administration of metformin may reduce the risk of GC by suppressing the methylation of PTEN promoter. In this study, we enrolled 107 GC patients and grouped them as HP(-)DM(-) group, HP(+)DM(-) group and HP(+)DM(+) group. Bisulphite sequencing PCR evaluated methylation of PTEN promoter. Quantitative real-time PCR, immunohistochemistry and Western blot, immunofluorescence, flow cytometry and MTT assay were performed accordingly. DNA methylation of PTEN promoter was synergistically enhanced in HP(+)DM(+) patients, and the expression of PTEN was suppressed in HP(+)DM(+) patients. Cell apoptosis was decreased in HP(+)DM(+) group. Metformin showed an apparent effect on restoring CagA-induced elevation of PTEN promoter methylation, thus attenuating the PTEN expression. The reduced PTEN level led to increased proliferation and inhibited apoptosis of HGC-27 cells. In this study, we collected GC tumour tissues from GC patients with or without DM/HP to compare their PTEN methylation and expression while testing the effect of metformin on the methylation of PTEN promoter. In summary, our study suggested that DM could strengthen the tumorigenic effect of HP by promoting the PTEN promoter methylation, while metformin reduces GC risk by suppressing PTEN promoter methylation.

Microsatellite Instability in Colorectal Cancer Liquid Biopsy-Current Updates on Its Potential in Non-Invasive Detection, Prognosis and as a Predictive Marker

Colorectal cancer (CRC) is the third most commonly-diagnosed cancer in the world and ranked second for cancer-related mortality in humans. Microsatellite instability (MSI) is an indicator for Lynch syndrome (LS), an inherited cancer predisposition, and a prognostic marker which predicts the response to immunotherapy. A recent trend in immunotherapy has transformed cancer treatment to provide medical alternatives that have not existed before. It is believed that MSI-high (MSI-H) CRC patients would benefit from immunotherapy due to their increased immune infiltration and higher neo-antigenic loads. MSI testing such as immunohistochemistry (IHC) and PCR MSI assay has historically been a tissue-based procedure that involves the testing of adequate tissue with a high concentration of cancer cells, in addition to the requirement for paired normal tissues. The invasive nature and specific prerequisite of such tests might hinder its application when surgery is not an option or when the tissues are insufficient. The application of next-generation sequencing, which is highly sensitive, in combination with liquid biopsy, therefore, presents an interesting possibility worth exploring. This review aimed to discuss the current body of evidence supporting the potential of liquid biopsy as a tool for MSI testing in CRC.

Identification and Analysis of Key Genes Driving Gastric Cancer Through Bioinformatics

Objective: The aim of this study was to use bioinformatic analyses to identify key genes and pathways driving gastric cancer (GC). Materials and Methods: The gene expression profiles, from human gastric tissue samples were downloaded from the Gene Expression Omnibus (GSE)29272 dataset. These data revealed 284 differentially expressed genes (DEGs) that included a group upregulated in cancer tissues (n = 142) and another group that were downregulated in cancer tissues. (n = 142). These DEGs were identified using the GEO2R. We used multiple online analysis tools, including, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), protein-protein interaction networks, gene expression profiling interactive analysis (GEPIA), and the cBio Cancer Genomics Portal (cBioportal) database. Next, we identified the most significant DEGs using the Kaplan-Meier plotter (KM-plotter) database. Multiple bioinformatic platforms were used to identify candidate prognostic marker genes. We then analyzed freshly frozen GC tissues for the expression of these marker genes to validate the informatic findings. Results: We identified three DEGs related to overall survival from our analyses of the GEO data. Next, we analyzed these three DEGs in GEPIA and the cBioportal database and found that the biglycan (BGN) gene was related to invasion and metastases of GCs. This finding of differential gene expression was confirmed in a separate laboratory analysis of normal and GC tissues. In this analysis we found that high levels of BGN expression were correlated with GC clinicopathological characteristics, including microvascular tumor thrombus (p = 0.018), lymph node metastases (p = 0.013), and vessel invasion (p = 0.004). Conclusions: BGN expression levels appear to be an independent prognostic factor for predicting the survival times of GC patients.

[ISH-based HER2 diagnostics]

A prerequisite for all HER2 directed therapies is the demonstration of HER2 receptor protein overexpression and/or gene amplification by in situ hybridization (ISH). ASCO and CAP have published several HER2 test guidelines over the past 15 years for both breast and gastric cancer. The latest version for breast cancer (2018) focuses on special issues of ISH related to the definitions of special diagnostic groups (1-5). The guidelines for gastroesophageal adenocarcinoma (2017), essentially based on ToGA trial data, are now also being used for other tumors such as pancreas, gallbladder, and non-small-cell lung cancer. For colorectal cancer, a modified testing procedure has been proposed. Recently, besides overexpression and amplification, a third type of HER gene alteration, namely mutation, has gained much interest. Next-generation sequencing (NGS) allows detection of both amplification and mutation of the HER2 gene providing new options of therapy especially in the case of activating mutations.

Role of Her-2 in Gastrointestinal Tumours beyond Gastric Cancer: A Tool for Precision Medicine

Gastrointestinal (GI) tumors account for a quarter of all the cancer burden and a third of the global cancer-related mortality. Among them, some cancers retain a dismal prognosis; therefore, newer and innovative therapies are urgently needed in priority disease areas of high-unmet medical need. In this context, HER2 could be a relevant prognostic and predictive biomarker acting as a target for specific drugs. However, if the role of HER2 has been object of investigation for several years in gastric cancer, it is not well established in other GI malignancies. The aim of this narrative review was to portray the current landscape of the potential role of HER2 as a predictive biomarker for GI tumors beyond gastric cancer. In colon cancer, the benefit from anti-HER2 therapies is less clear than in gastric neoplasms for the lack of controlled studies. Pancreatic, biliary tract adenocarcinomas and hepatocarcinoma may derive a less clear clinical benefit by using anti-HER2 agents in HER2 positive tumors. Overall, the results are promising and seem to suggest that the integration of multiple modalities of therapies can optimize the cancer care. However, further prospective trials are needed to validate the use of personalized targeted therapies in this field.

ISH-based HER2 diagnostics

A prerequisite for all HER2 directed therapies is the demonstration of HER2 receptor protein overexpression and/or gene amplification by in situ hybridization (ISH). ASCO and CAP have published several HER2 test guidelines over the past 15 years for both breast and gastric cancer. The latest version for breast cancer (2018) focuses on special issues of ISH related to the definitions of special diagnostic groups (1-5). The guidelines for gastroesophageal adenocarcinoma (2017), essentially based on ToGA trial data, are now also being used for other tumors such as pancreas, gallbladder, and non-small-cell lung cancer. For colorectal cancer, a modified testing procedure has been proposed. Recently, besides overexpression and amplification, a third type of HER gene alteration, namely mutation, has gained much interest. Next-generation sequencing (NGS) allows detection of both amplification and mutation of the HER2 gene providing new options of therapy especially in the case of activating mutations.

High-Accuracy Determination of Microsatellite Instability Compatible with Liquid Biopsies

BACKGROUND

Microsatellite instability (MSI) has recently emerged as a predictive pan-tumor biomarker of immunotherapy efficacy, stimulating the development of diagnostic tools compatible with large-scale screening of patients. In this context, noninvasive detection of MSI from circulating tumor DNA stands as a promising diagnostic and posttreatment monitoring tool.

METHODS

We developed drop-off droplet-digital PCR (ddPCR) assays targeting BAT-26, activin A receptor type 2A (ACVR2A), and defensin beta 105A/B (DEFB105A/B) microsatellite markers. Performances of the assays were measured on reconstitution experiments of various mutant allelic fractions, on 185 tumor samples with known MSI status, and on 72 blood samples collected from 42 patients with advanced colorectal or endometrial cancers before and/or during therapy.

RESULTS

The 3 ddPCR assays reached analytical sensitivity <0.1% variant allelic frequency and could reliably detect and quantify MSI in both tumor and body fluid samples. High concordance between MSI status determination by the three-marker ddPCR test and the reference pentaplex method were observed (100% for colorectal tumors and 93% for other tumor types). Moreover, the 3 assays showed correlations with r ≥ 0.99 with other circulating tumor DNA markers and their dynamic during treatment correlated well with clinical response.

CONCLUSIONS

This innovative approach for MSI detection provides a noninvasive, cost-effective, and fast diagnostic tool, well suited for large-scale screening of patients that may benefit from immunotherapy agents, as well as for monitoring treatment responses.

Worldwide variation in lynch syndrome screening: case for universal screening in low colorectal cancer prevalence areas

To perform a systematic assessment of universal Lynch syndrome (LS) screening yield in colorectal cancer (CRC) patients around the world. Universal screening for LS is recommended in all CRC patients. However, the variation in yield of LS screening in the setting of significant global variation in CRC prevalence is unknown. A systematic review of articles in the MEDLINE database was performed to identify studies performing universal screening for LS. All cases with microsatellite instability (MSI-H) or missing one or more proteins on immunohistochemistry (IHC) were considered screening positive. The overall pooled yield of universal LS screening in 97 study arms from 89 identified studies was 11.9% (5649/47545) and the overall pooled percentage of confirmed LS patients was 1.8% (682/37220). LS screening positivity varied significantly based on geographic region (Kruskal Wallis test, p < 0.001) and reported 5-year CRC prevalence in the country (Fisher's exact, p < 0.001). Significant inverse correlation was found between LS screening positivity and 5-year CRC prevalence (Pearson correlation, r =  - 0.56, p < 0.001). The overall yield of LS screening was 15.00% (382/2553) and rate of confirmed LS was 7.7% (113/1475) in LS screening done in patients ≤ 50 years (16 studies). There is significant geographic variation in LS screening positivity with higher yield in countries with lower prevalence of CRC. Our results highlight the importance of universal LS screening in younger patients and low CRC prevalence countries.

Tamoxifen Downregulates the Expression of Notch1 and DLL1 Genes in MKN-45 Gastric Cancer Cells

PURPOSE

Gastric cancer is one of the most prevalent cancers worldwide and the second most common cause for cancer associated mortality. Anti-tumor effects of tamoxifen in breast cancer are well-established. However, no study has so far investigated the effects of tamoxifen on gene expression of Notch1 and DLL1 in gastric cancer cell line. The present study was conducted to explore the effects of tamoxifen, as a repurposed drug, on gene expression of Notch1 and DLL1 in MKN-45, a gastric cancer cell line.

METHODS

MKN-45 cells were cultured in DMEM/F12 medium containing 10% FBS. Cytotoxic effects of tamoxifen on these cells at various concentrations were evaluated by trypan blue exclusion assay. For gene expression analysis, the cells were first incubated with 100 μM tamoxifen followed by total RNA extraction from treated and control cells. Then, cDNA was synthesized. Quantitative real-time PCR using specific primers for Notch1 and DLL1 was performed to assess the effect of tamoxifen on the transcript of them.

RESULTS

Treatment with tamoxifen decreased viability of MKN-45 cells in a dose-dependent manner. CC₅₀ was estimated to be around 200 μM. Also, tamoxifen at the dose of 100 μM could significantly downregulate mRNA levels of both Notch1 and DLL1 genes as compared with untreated cells by 24% and 92%, respectively.

CONCLUSION

Based on these results, tamoxifen interferes with Notch signaling pathway through downregulating the expression of Notch1 and DLL1 genes and this could be regarded as a mechanism for its anti-cancer effects in this malignant disease.

YAP promotes self-renewal of gastric cancer cells by inhibiting expression of L-PTGDS and PTGDR2

INTRODUCTION

Cancer stem cells have been implicated angiogenesis of tumor and invasiveness, drug resistance in tumors. Yes-associated protein 1 (YAP) owns carcinogenic roles in various organs, but the role of YAP in cancer stem cells of gastric cancer (GC) remains unclear. In this study, we explored the function and mechanism of YAP in GC cancer stem cells.

MATERIALS AND METHODS, AND RESULTS

First, we confirmed that the expression of YAP mRNA and protein in GC tissues was higher than in adjacent tissues by RT-PCR, western blot and immunohistochemistry. Immunofluorescence staining of the GC tissues revealed that the region of YAP expression coincided with the region of expression of the cancer stem cell marker SALL4 but did not overlap with that of the epithelial marker cytokeratin 14 (CK14). Additional research revealed that spherical cells expressed relatively high levels of YAP protein, and YAP overexpression reinforced self-renewal and expression of stem cell markers in the GC cells. Knockdown the expression of YAP reversed this phenomenon. Second, we examined the expression patterns of lipocalin-type prostaglandin D2 synthase (L-PTGDS) and prostaglandin D2 receptor 2 (PTGDR2) in GC tissues and proved that there was negatively correlation between the expression of L-PTGDS and PTGDR2 and YAP in GC tissues. Finally, we confirmed that YAP inhibited the expression of L-PTGDS and PTGDR2 by gain- and loss-of-function experiments. Moreover, the overexpression of L-PTGDS and PTGDR2 suppressed the proliferation and self-renewal induced by YAP in vitro and reversed the pro-tumor effect of YAP in vivo.

CONCLUSION

Our results revealed a novel function of YAP and the mechanism underlying cancer stem cell regulation by YAP.

Farnesoid X receptor antagonizes Wnt/β-catenin signaling in colorectal tumorigenesis

Farnesoid X receptor (FXR, encoded by NR1H4), a critical regulator of bile acid homeostasis, is widely implicated in human tumorigenesis. However, the functional role of FXR in colorectal cancer (CRC) and the precise molecular mechanism remain unclear. In this study, we demonstrated that FXR expression was downregulated in colon cancer tissues and decreased expression of FXR predicted a poor prognosis. Knockdown of FXR promoted colon cancer cell growth and invasion in vitro, and facilitated xenograft tumor formation and distant metastasis in vivo, whereas ectopic expression of FXR had the reserved change. Mechanistic studies indicated that FXR exerted its tumor suppressor functions by antagonizing Wnt/β-catenin signaling. Furthermore, we identified an FXR/β-catenin interaction in colon cancer cells. The FXR/β-catenin interaction impaired β-catenin/TCF4 complex formation. In addition, our study suggested a reciprocal relationship between FXR and β-catenin, since loss of β-catenin increased the transcriptional activation of SHP by FXR. Altogether, these data indicated that FXR functions a tumor-suppressor role in CRC by antagonizing Wnt/β-catenin signaling.

Identification of a Clinical Cutoff Value for Multiplex KRASG12/G13 Mutation Detection in Colorectal Adenocarcinoma Patients Using Digital Droplet PCR, and Comparison with Sanger Sequencing and PNA Clamping Assay

KRAS (Kirsten rat sarcoma 2 viral oncogene homolog) is a major predictive marker for anti-epidermal growth factor receptor treatment, and determination of KRAS mutational status is crucial for successful management of colorectal adenocarcinoma. More standardized and accurate methods for testing KRAS mutation, which is vital for therapeutic decision-making, are required. Digital droplet polymerase chain reaction (ddPCR) is an advanced digital PCR technology developed to provide absolute quantitation of target DNA. In this study, we validated the clinical performance of ddPCR in determination of KRAS mutational status, and compared ddPCR results with those obtained by Sanger sequencing and peptide nucleic acid-clamping. Of 81 colorectal adenocarcinoma tissue samples, three repeated sets of KRAS^G12/G13 mutation were measured by ddPCR, yielding high consistency (ICC = 0.956). Receiver operating characteristic (ROC) curves were constructed to determine KRAS^G12/G13 mutational status based on mutant allele frequency generated by ddPCR. Using the best threshold cutoff (mutant allele frequency of 7.9%), ddPCR had superior diagnostic sensitivity (100%) and specificity (100%) relative to the two other techniques. Thus, ddPCR is effective for detecting the KRAS^G12/G13 mutation in colorectal adenocarcinoma tissue samples. By allowing definition of the optimal cutoff, ddPCR represents a potentially useful diagnostic tool that could improve diagnostic sensitivity and specificity.

Clinical and Molecular Assessment of Patients with Lynch Syndrome and Sarcomas Underpinning the Association with MSH2 Germline Pathogenic Variants

Lynch syndrome (LS) is a hereditary cancer-predisposing syndrome associated most frequently with epithelial tumors, particularly colorectal (CRC) and endometrial carcinomas (EC). The aim of this study was to investigate the relationship between sarcomas and LS by performing clinical and molecular characterization of patients presenting co-occurrence of sarcomas and tumors from the LS spectrum. We identified 27 patients diagnosed with CRC, EC, and other LS-associated tumors who had sarcomas in the same individuals or families. Germline genetic testing, mismatch repair (MMR) protein immunohistochemistry, microsatellite instability (MSI), and other molecular analyses were performed. Five LS patients presenting personal or family history of sarcomas were identified (3 MSH2 carriers and 2 MLH1), with 2 having Muir-Torre phenotypes. For two MSH2 carriers we confirmed the etiology of the sarcomas (one liposarcoma and two osteosarcomas) as LS-related, since the tumors were MSH2/MSH6-deficient, MSI-high, or presented a truncated MSH2 transcript. Additionally, we reviewed 43 previous reports of sarcomas in patients with LS, which revealed a high frequency (58%) of MSH2 alterations. In summary, sarcomas represent a rare clinical manifestation in patients with LS, especially in MSH2 carriers, and the analysis of tumor biological characteristics can be useful for definition of tumor etiology and novel therapeutic options.

Chitosan: A compound for drug delivery system in gastric cancer-a review

Gastric cancer is known as the fourth most common cancer and the second main cause of cancer-related deaths. Gastric cancer has some characteristics including high incidence rates of metastasis and mortality as well as low rates of early diagnosis, radical resection and 5-year survival. Radical surgery and following chemotherapy has been done for patients with early gastric cancer leading to 90 % survival rate in 5-year after operation. Besides, in advanced stage some cases don't have the chance of surgery as well as the risk of metastasis is high in these patients overally leading to poor prognosis. In recent years, finding a suitable drug delivery system for chemotherapeutic drugs in gastric cancer is an considerable subject for researchers. Chitosan is known as an appropriate compound for chemo-drug delivery in cancer treatment due to its high biodegradability and biocompatibility. Moreover, trans-mucosal drug delivery is facilitated by chitosan via its mucoadhesive and cationic features enhancing interaction with mucous membrane. In addition, a large amount of experimental evidence has reported the efficacy of chitosan for drug delivery in gastric cancer. Thus, the aim of this article was to review this evidence as well as new chitosan-based drug delivery systems investigated in gastric cancer.

MSI and EBV Positive Gastric Cancer's Subgroups and Their Link With Novel Immunotherapy

Gastric cancers have been historically classified based on histomorphologic features. The Cancer Genome Atlas network reported the comprehensive identification of genetic alterations associated with gastric cancer, identifying four distinct subtypes- Epstein-Barr virus (EBV)-positive, microsatellite-unstable/instability (MSI), genomically stable and chromosomal instability. In particular, EBV-positive and MSI gastric cancers seem responsive to novel immunotherapies drugs. The aim of this review is to describe MSI and EBV positive gastric cancer's subgroups and their relationship with novel immunotherapy.

Theoretical calculations of molecular descriptors for anticancer activities of 1, 2, 3-triazole-pyrimidine derivatives against gastric cancer cell line (MGC-803): DFT, QSAR and docking approaches

This work used quantum chemical method via DFT to calculate molecular descriptors for the development of QSAR model to predict bioactivity (IC50- 50% inhibition concentration) of the selected 1, 2, 3-triazole-pyrimidine derivatives against receptor (human gastric cancer cell line, MGC-803). The selected molecular parameters were obtained by B3LYP/6-31G∗∗. QSAR model linked the molecular parameters of the studied compounds to their cytotoxicity and reproduced their observed bioactivities against MGC-803. The calculated IC50 tailored the observed IC50 and greater than standard compound, 5-fluorouracil, suggesting that the developed QSAR model reproduced the observed bioactivity. Statistical analyses (including R2, CV. R2 andR a 2 gave 0.950, 0.970 and 0.844 respectively) revealed a very good fitness. Molecular docking studies revealed the hydrogen bonding with the amino acid residues in the binding site, as well as ligand conformations which are essential feature for ligand-receptor interactions. Therefore, the methods used in this study are veritable tools that can be employed in pharmacological and medicinal chemistry researches in designing better drugs with improve potency.

Human epidermal growth factor receptor 2-positive digestive tumors

PURPOSE OF REVIEW

This manuscript aims at providing an update and overview on the role of Human epidermal growth factor receptor 2 (HER2) testing and HER2-directed therapies in digestive tumors.

RECENT FINDINGS

Phase 3 trial data demonstrating a survival benefit of HER2-targeting treatments are limited to gastric cancer. However, HER2 positivity is also found in 5-6% of colorectal, 7% of pancreatic, and 16% of extrahepatic biliary cancers. Although phase 2 trial data support the use of the combination of trastuzumab and lapatinib with chemotherapy in HER2-positive colorectal cancer, the patient's benefit from targeted treatment of HER2-positive biliary or pancreatic neoplasms is currently unclear, and further clinical trials are necessary.

SUMMARY

With the exception of gastric cancer, there are currently no defined guidelines for HER2 testing in other digestive tumors. Various HER2-targeting therapies, which are standard of care in HER2-positive breast cancer, failed in HER2-positive gastric cancers. Thus, the predictive value of HER2 overexpression depends on the tumor type, and results of breast cancer trials cannot a priori be extrapolated to digestive cancers. Next-generation sequencing panel diagnostics may furthermore identify targetable activating mutations in gastric, extrahepatic biliary, and colorectal cancer, particularly if traditional testing (immunohistochemistry/in-situ hybridization) is negative. However, their clinical relevance needs to be determined.

Differential prognostic impact of CD8+ T cells based on human leucocyte antigen I and PD-L1 expression in microsatellite-unstable gastric cancer

BACKGROUND

The aim of the study was to determine the human leucocyte antigen class-I (HLA-I), programmed death-ligand 1 (PD-L1) expression and tumour-infiltrating lymphocytes (TILs) of microsatellite instability-high gastric cancer.

METHODS

The HLA-I expression type was determined by immunohistochemistry of HLA-A, HLA-B, HLA-C and β2-microglobulin in the centre of the tumour (CT) and in the invasive margin (IM) of samples from 293 patients (total loss vs. preserved type). PD-L1 expression and TIL density was examined immunohistochemically. HLA-I genotyping was also performed.

RESULTS

The expression loss of the HLA-I molecules was significantly associated with low TIL density. According to survival analyses, the HLA-I expression type and PD-L1 positivity were not independent prognostic factors. The TIL density had no prognostic implication when survival analysis was performed for the whole patient group; however, high CD8⁺ TIL infiltration was significantly associated with good prognosis in only HLA-I-preserved-type/PD-L1-positive group (p = 0.034). The homozygosity of the HLA-I allele was more frequently observed in the total loss type group.

CONCLUSIONS

We confirmed differential prognostic implication of CD8⁺ TILs according to the HLA-I and PD-L1 expression. Determination of the HLA-I expression could be helpful to select patients who would benefit from anti-PD-1/PD-L1 therapy.

Comparative analysis of HER2 copy number between plasma and tissue samples in gastric cancer using droplet digital PCR

In this study, we measured the human epidermal growth factor receptor 2 (HER2) copy number in both tissue and plasma samples of gastric cancer patients by using droplet digital polymerase chain reaction (ddPCR) method. Eighty gastric cancer patients were enrolled and both formalin-fixed and paraffin-embedded tissue and preoperative plasma samples were collected. HER2 status was determined by HER2 immunohistochemistry (IHC)/silver in situ hybridization (SISH) in tissue samples and ddPCR of the target gene HER2 and the reference gene eukaryotic translation initiation factor 2C, 1 in both tissue and plasma. The concordance rate of tissue HER2 status determined by IHC/SISH and HER2 ddPCR was 90.0% (72/80), and the sensitivity and specificity of tissue ddPCR were 85.0% and 95.0%, respectively. The concordance rate of plasma ddPCR and IHC/SISH was 63.8% (51/80). The sensitivity, specificity, positive predictive value, and negative predictive value of plasma HER2 ddPCR were 37.5%, 90.0%, 79.0%, and 59.0%, respectively. As HER2 measurement by tissue ddPCR showed a high concordance rate with HER2 status by IHC/SISH, it could replace tissue IHC/SISH testing in gastric cancer. These findings may contribute to the development of tissue and plasma HER2 testing that would be useful in daily practice.

PD-L1 Testing in Gastric Cancer by the Combined Positive Score of the 22C3 PharmDx and SP263 Assay with Clinically Relevant Cut-offs

Purpose

We provide a comparison between 22C3 pharmDx and SP263 assay, for evaluating programmed death ligand 1 (PD-L1) expression in advanced gastric cancer (GC) patients.

Materials and Methods

The PD-L1 immunohistochemistry by 22C3 pharmDx and SP263 assays was performed in the center of the tumor (CT) and invasive margin (IM) in 379 GC tissues using tissue microarrays and interpreted as combined positive score (CPS) and tumor proportion score (TPS). Of the total samples, 55 samples were independently reviewed by five pathologists.

Results

The two assays showed a high correlation in both the CPS and TPS. At a CPS ≥ 1 cut-off, 219 (57.8%) and 231 (60.9%) GCs were positive for PD-L1 with the 22C3 and SP263 assays, and at ≥ 10 cut-off, 37 (9.8%) and 36 (9.5%) GCs were positive, respectively. The overall percent agreement (OPA) was greater than 90% with CPS ≥ 1 and ≥ 10 cut-offs, and TPS ≥ 1% and ≥ 10% cut-offs. There was higher OPA between the two assays with a CPS cut-off ≥ 10 (99.2%) than ≥ 1 (94.7%). The percent agreement between the CT and IM was higher with a CPS cut-off ≥ 10 (92.9%) than ≥ 1 (77.6%). Patient with positive expression at CPS ≥ 5 cut-off had a significantly better outcomes in both assays. Interobserver variability among five pathologists was higher than the assay variability.

Conclusion

Two assays for PD-L1 expression in GC showed high agreement. These results provide guidance for selecting eligible patients with GC for pembrolizumab treatment.

Tumor immune response and immunotherapy in gastric cancer

Remarkable developments in immuno-oncology have changed the landscape of gastric cancer (GC) treatment. Because immunotherapy intervenes with tumor immune response rather than directly targeting tumor cells, it is important to develop a greater understanding of tumor immunity. This review paper summarizes the tumor immune reaction and immune escape mechanisms while focusing on the role of T cells and their co-inhibitory signals, such as the immune checkpoint molecules programmed death-1 and programmed deathligand 1 (PD-L1). This paper also describes past clinical trials of immunotherapy for patients with GC and details their clinical implications. Strong predictive markers are essential to improve response to immunotherapy. Microsatellite instability, Epstein-Barr virus, PD-L1 expression, and tumor mutational burden are now regarded as potent predictive markers for immunotherapy in patients with GC. Novel immunotherapy and combination therapy targeting new immune checkpoint molecules such as lymphocyte-activation gene 3, T cell immunoglobulin, and mucin domain containing-3, and indoleamine 2,3-dioxygenase have been suggested, and trials are ongoing to evaluate their safety and efficacy. Immunotherapy is an important treatment option for patients with GC and has great potential for improving patient outcome, and further research in immuno-oncology should be carried out.

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.

Current and future molecular diagnostics of gastric cancer

Introduction: Gastric cancer (GC) is the fifth most common cancer and confers the second-highest mortality among other cancers. Improving the survival rates of GC patients requires prompt and accurate diagnosis and effective treatment which is often preceded by the poorly understood pathogenic mechanisms. Area covered: This literature review aims to summarize current understanding of genetic and molecular alterations that promote carcinogenesis including (1) activation of oncogenes, (2) overexpression of growth factors, receptors and matrix metalloproteinases, (3) inactivation of tumor suppressor genes, DNA repair genes, and cell adhesion molecules and (4) alterations of cell-cycle regulators that regulate biological characteristics of cancer cells. Moreover, the significance of molecular biomarkers such as micro-RNAs (miRNAs) and long non-coding RNAs (lncRNAs) and advanced molecular techniques including droplet digital polymerase chain reaction (ddPCR), quantitative PCR (qPCR) and next-generation sequencing (NGS) are also discussed. Expert opinion: A GC-specific panel of biomarkers based on the NGS or ddPCR has the potential for diagnosis, prognosis, and monitoring treatment response in GC patients. Despite the requirements for validation in larger population in clinical studies, race-specific differences in the gene panel have also to be examined by performing the clinical trials in subjects with different races.

Development and Validation of an Easy-to-Implement, Practical Algorithm for the Identification of Molecular Subtypes of Gastric Cancer: Prognostic and Therapeutic Implications

BACKGROUND

Gastric cancer (GC) is a heterogeneous disease, and substantial efforts have been made to develop a molecular biology-based classification system for GC. Analysis of the genomic signature is not always feasible, and thus, we aimed to (i) develop and validate a practical immunohistochemistry (IHC)- and polymerase chain reaction (PCR)-based molecular classification of GC and (ii) to assess HER2 status according to this classification.

MATERIALS AND METHODS

A total of 894 consecutive patients with GC from two individual cohorts (training, n = 507; validation, n = 387) were classified using Epstein-Barr virus (EBV) in situ hybridization, microsatellite instability (MSI) testing, and IHC for E-cadherin and p53.

RESULTS

We were able to classify patients into five groups in the training cohort: group 1 (MSI⁺), group 2 (EBV^-, MSI^-, non-epithelial-mesenchymal transition [non-EMT]-like, p53^-), group 3 (EBV⁺), group 4 (EBV^-, MSI^-, non-EMT-like, p53⁺), and group 5 (EBV^-, MSI^-, EMT-like). In the training cohort, each group showed different overall survival (OS) after gastrectomy (p < .001); group 1 had the best prognosis, and group 5 showed the worst survival outcome. The significant impact of the classification system on OS was also verified in the validation cohort (p = .004). HER2 positivity was observed in 6.5% of total population, and most of HER2-positive cases (93.1%) were included in groups 2 and 4.

CONCLUSION

We developed and validated a modified IHC- and PCR-based molecular classification system in GC, which showed significant impact on survival, irrespective of stage or other clinical variables. We also found close association between HER2 status and non-EMT phenotype in our classification system.

IMPLICATIONS FOR PRACTICE

Molecular classification of gastric cancer suggested by previous studies mostly relies on extensive genomic data analysis, which is not always available in daily practice. The authors developed a simplified immunohistochemistry- and polymerase chain reaction-based molecular classification of gastric cancer and proved the prognostic significance of this classification, as well as the close association between HER2 status and certain groups of the classification, in the largest consecutive cohort of gastric cancer. Results of this study suggest that this scheme is a cost-effective, easy-to-implement, and feasible way of classifying gastric cancer in daily clinical practice, also serving as a practical tool for aiding therapeutic decisions and predicting prognosis.

Assessing molecular subtypes of gastric cancer: microsatellite unstable and Epstein-Barr virus subtypes. Methods for detection and clinical and pathological implications

Background

The molecular classification of gastric cancer recognises two subtypes prone to immune checkpoint blockade: the microsatellite unstable and the Epstein-Barr virus (EBV)-related tumours. We aim to assess the concordance between immunohistochemistry and PCR for microsatellite status evaluation, and explore the value of microsatellite instability (MSI) and EBV as predictive survival factors.

Material and methods

We collected 246 consecutively diagnosed gastric cancer cases in all stages and evaluated the microsatellite status using immunohistochemistry for mismatched repair (MMR) proteins and PCR. EBV expression was studied through in situ hybridisation.

Results

Forty-five (18%) cases presented MSI and 13 (6%) were positive for EBV. MSI was associated with female sex, older age, distal location and distal non-diffuse type of the modified Lauren classification. EBV expression was most frequent in proximal location and proximal non-diffuse type. The sensitivity, specificity, positive predictive value and negative predictive value of immunohistochemistry for the microsatellite study were 91%, 98%, 91% and 98%, respectively. In the multivariate analysis, MSI was an independent predictor of favourable tumour-specific survival (TSS) in stages I–III (MSI: HR: 0.37, 95% CI 0.12 to 0.95, p=0.04).

Conclusions

The MSI status and the EBV expression should be incorporated in routine pathological report for two reasons. First, MSI defines a different pathological entity with a better outcome. Second, MSI and EBV may be useful biomarkers to identify patients who will respond to immune checkpoint blockade inhibitors. For this purpose, immunohistochemical study for MMR proteins and in situ hybridisation study for EBV evaluation are feasible and cost-effective methods.

Molecular profile in Paraguayan colorectal cancer patients, towards to a precision medicine strategy

Somatic mutation analysis and evaluation of microsatellite instability (MSI) have become mandatory for selecting personalized therapy strategies for advanced colorectal cancer and are not available as routine methods in Paraguay. The aims of this study were to analyze the molecular profile as well as the microsatellite status in a series of advanced colorectal patients from two public hospitals from Paraguay, to introduce these methodologies in the routine practice to guide the therapeutic decisions. Thirty‐six patients diagnosed with advanced colorectal cancer from two referent public hospitals from Paraguay were recruited from May 2017 to February 2018. Sequenom Mass spectrometry, Oncocarta Panel V.1 was applied to analyze the mutational profile from formalin‐fixed paraffin‐embedded samples. The microsatellite status was tested by immunohistochemistry (IHC). The mean age of the patients was 52 years with a range from 20 to 74 years. Eighty‐three percent of the patients included in the study have advanced‐stage tumors at the moment of the diagnosis. Sixteen patients (44.4%) were wild‐type for all the oncogene regions analyzed with the Oncocarta panel. Thirty‐two hot‐spot pathogenic variants on seven oncogenes, among 20 patients (55.6%), were identified, including KRAS, NRAS, BRAF, PI3KCA, FGFR, epidermal growth factor receptor, and PDGFRA. Moreover, 14 (38.8%) of these patients presented pathogenic variants in KRAS/NRAS or BRAF genes that have implications in the clinical practice decisions. Five patients (14%) presented MSI. The IHC study for microsatellite status and the molecular profile analysis through Sequenom mass spectrometry are feasible and useful methods, due to identify those patient candidates for targeted therapies and for the budgetary calculations of the National Health Plans.

Next-generation Sequencing in the Management of Gastric and Esophageal Cancers

Next-generation sequencing has enabled genome-wide molecular profiling of gastric and esophageal malignancies at single-nucleotide resolution. The resultant genomic profiles provide information about the specific oncogenic pathways that are the likely driving forces behind tumorigenesis and progression. The abundance of available genomic data has immense potential to redefine management paradigms for these difficult disease processes. The ability to capitalize on the information provided through high-throughput sequencing technologies will define cancer care in the coming decades and could shift the paradigm from current stage-based, organ-specific treatments toward tailored regimens that target the specific culprit pathways driving individual tumors.

A 25-year trend in gastrointestinal cancers in northern Iran (1991-2016)

BACKGROUND

Identifying the incidence of cancer helps in planning and prioritizing resources for its screening, prevention, treatment and diagnosis. This study aimed at investigating a 25-year trend in gastrointestinal cancer in northern Iran during 1991-2016.

METHODS

This research was a trend analysis. The study population was one thousand five hundred and thirty-five cancer patients referring to Shahid Rajai Hospital in Babolsar, northern Iran, as the only center for radiotherapy in the North of Iran, during 1991-2016. SPSS version 22 was used for entering data and t-test, ᵡ2 and ANOVA were used for analyzing data in the significant level of ≤0.05.

RESULTS

The highest incidence of stomach cancer was 111 (35%) in 2011 and the lowest incidence was 44 (16.3%) in 1996, The highest frequency of esophageal cancer was reported 137(56.1%) cases in 1991 and the lowest frequency was 78 (26.3%) cases in 2016, while the highest incidence of colorectal cancer was 109 (36.7%) cases in 2016 and its lowest frequency was 32 (16.3%) in 1996. There was also a significant difference in the frequency of gastrointestinal cancers in different studied years (p <0.001).

CONCLUSION

The trends in the incidence of stomach and colorectal cancers in northern Iran were increasing while esophageal cancer was decreasing.

Status of programmed death-ligand 1 expression in sarcomas

Background

Sarcomas are challenging to study because of their rarity and histomorphological complexity. PD1 and PD-L1 inhibitors showed a promising anti-tumor effect in solid tumors, where a relationship between PD-L1 expression and the objective response has been evidenced.

Methods

In this study, we examined PD-L1 expression in 16 bone and soft tissue sarcoma cell lines of 11 different subtypes by means of western blot, flow cytometry and immunocytochemistry, and in 230 FFPE patient-derived tumor tissues by means of immunohistochemistry using three different antibody clones. The association between PD-L1 expression and clinicopathological features was evaluated.

Results

We demonstrated that PD-L1 protein is highly expressed in pleomorphic rhabdomyosarcoma, fibrosarcoma, and dedifferentiated liposarcoma (DDLPS) cell lines. From the tissue microarray, undifferentiated pleomorphic sarcoma showed ≥ 1% immunoreactivity in 20%, 17.6%, and 16.3% of the cases with PD-L1 22C3, SP263, and SP142 antibodies, respectively. In whole sections stained with a PD-L1 22C3 antibody, DDLPS showed ≥ 1% immunoreactivity in 21.9% of the cases. In DDLPS group, cases with ≥ 1% PD-L1 expression showed statistically significantly worse recurrence-free survival (P = 0.027) and overall survival (P = 0.017) rates. Upon interferon–gamma treatment, the mRNA expression levels of PD-L1 were elevated in the HS-RMS-1, LIPO-224B, MLS1765, RH30, and RH41 cell lines.

Conclusions

We found that the expression of PD-L1 in sarcoma differs depending on the histologic subtype and the PD-L1 antibody clones. These results may serve as primary data for the selection of appropriate patients when applying PD1/PD-L1 inhibitor therapy in sarcoma.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1658-5) contains supplementary material, which is available to authorized users.

DUSP1 induces apatinib resistance by activating the MAPK pathway in gastric cancer

Dual-specificity phosphatase-1 (DUSP1) is an oncogene that is associated with cancer progression following drug resistance. In order to investigate the potential relationship between DUSP1 and apatinib resistance in gastric cancer cells, we preformed many assays to study this problem. DUSP1 gene was detected by RT-qPCR assay, proteins in MAPK pathway were quantified by western blot assay, and CCK-8 assay, flow cytometry and Hoechest 33342 stain were performed to detect the resistance of cells, cell cycles and apoptosis, respectively. Immunohistochemical staining was used to discover the expression of DUSP1 protein in patients' tumor or paratumor tissues. It was found that apatinib (Apa)-resistant gastric cancer (GC) cells showed increased expression of DUSP1, whereas the knockdown of DUSP1 in resistant cells resensitized these cells to Apa. The restored sensitivity to Apa was the result of inactivation of mitogen-activated protein kinase (MAPK) signaling and the induction of apoptosis. The in vitro use of Apa in combination with a DUSP1 inhibitor, triptolide, exerted significant effects on inhibiting the expression of DUSP1, growth inhibition, and apoptosis via the inactivation of MAPK signaling. In patients who did not undergo chemotherapy or targeted therapy, the expression of DUSP1 in adjacent tissues was higher when compared with that observed in tumor tissues. In addition, the expression of DUSP1 was higher in the early stages of GC than in the advanced stages. The expression of DUSP1 in tumor tissues was not associated with the survival rate of the patients. Therefore, increased expression of DUSP1 may be responsible for Apa resistance, and DUSP1 may serve as a biomarker for Apa efficacy. In conclusion, inducing the downregulation of DUSP1 may be a promising strategy to overcome Apa resistance.

Mechanisms and Therapy for Cancer Metastasis to the Brain

Advances in chemotherapy and targeted therapies have improved survival in cancer patients with an increase of the incidence of newly diagnosed brain metastases (BMs). Intracranial metastases are symptomatic in 60–70% of patients. Magnetic resonance imaging (MRI) with gadolinium is more sensitive than computed tomography and advanced neuroimaging techniques have been increasingly used in the detection, treatment planning, and follow-up of BM. Apart from the morphological analysis, the most effective tool for characterizing BM is immunohistochemistry. Molecular alterations not always reflect those of the primary tumor. More sophisticated methods of tumor analysis detecting circulating biomarkers in fluids (liquid biopsy), including circulating DNA, circulating tumor cells, and extracellular vesicles, containing tumor DNA and macromolecules (microRNA), have shown promise regarding tumor treatment response and progression. The choice of therapeutic approaches is guided by prognostic scores (Recursive Partitioning Analysis and diagnostic-specific Graded Prognostic Assessment-DS-GPA). The survival benefit of surgical resection seems limited to the subgroup of patients with controlled systemic disease and good performance status. Leptomeningeal disease (LMD) can be a complication, especially in posterior fossa metastases undergoing a “piecemeal” resection. Radiosurgery of the resection cavity may offer comparable survival and local control as postoperative whole-brain radiotherapy (WBRT). WBRT alone is now the treatment of choice only for patients with single or multiple BMs not amenable to surgery or radiosurgery, or with poor prognostic factors. To reduce the neurocognitive sequelae of WBRT intensity modulated radiotherapy with hippocampal sparing, and pharmacological approaches (memantine and donepezil) have been investigated. In the last decade, a multitude of molecular abnormalities have been discovered. Approximately 33% of patients with non-small cell lung cancer (NSCLC) tumors and epidermal growth factor receptor mutations develop BMs, which are targetable with different generations of tyrosine kinase inhibitors (TKIs: gefitinib, erlotinib, afatinib, icotinib, and osimertinib). Other “druggable” alterations seen in up to 5% of NSCLC patients are the rearrangements of the “anaplastic lymphoma kinase” gene TKI (crizotinib, ceritinib, alectinib, brigatinib, and lorlatinib). In human epidermal growth factor receptor 2-positive, breast cancer targeted therapies have been widely used (trastuzumab, trastuzumab-emtansine, lapatinib-capecitabine, and neratinib). Novel targeted and immunotherapeutic agents have also revolutionized the systemic management of melanoma (ipilimumab, nivolumab, pembrolizumab, and BRAF inhibitors dabrafenib and vemurafenib).

High Expression of Retinoic Acid Induced 14 (RAI14) in Gastric Cancer and Its Prognostic Value

Background

To explore the expression level of retinoic acid induced 14 (RAI14) in gastric cancer (GC) patients and its potentially clinical prognostic value.

Material/Methods

Initially, The Cancer Genome Atlas (TCGA) and Oncomine databases were mined to examine the differential expression levels and clinical prognostic significance of RAI14 mRNA in GC patients. Subsequently, 68 cases of GC and paired adjacent normal tissues were collected retrospectively, and the expression level of RAI14 protein was detected by immunohistochemical staining. In addition, Kaplan-Meier univariate and Cox multivariate survival analyses were used to verify the correlation between RAI14 expression and clinicopathological parameters in GC patients and its clinical prognostic significance.

Results

TCGA and GEO (from Oncomine database) data mining results found that RAI14 mRNA level was remarkably higher in GC than normal gastric tissues (All P<0.05). Besides, immunohistochemical results detected that RAI14 protein level in GC was dramatically higher (P=0.004) compared to that in the matched normal tissues. Moreover, TCGA database and Kaplan-Meier Plotter mining results showed that compared to those with RAI14 low mRNA expression levels, GC patients with RAI14 high mRNA expression levels had remarkably lower time of both overall survival and disease-free survival (All P<0.05). Additionally, based on the immunohistochemical results, Kaplan-Meier univariate and Cox multivariate survival analyses indicated that high expression of RAI14 was the only independent predictor of unfavorable prognosis in patients with gastric cancer (P=0.000).

Conclusions

RAI14 was highly expressed in GC, and the high expression of RAI14 could be an independent predictor of poor prognosis in GC patients.

NR4A1-induced increase in the sensitivity of a human gastric cancer line to TNFα-mediated apoptosis is associated with the inhibition of JNK/Parkin-dependent mitophagy

Tumor necrosis factor α (TNFα)-based immunotherapy is the vital host defense system against the progression of gastric cancer (GC) as a pro-inflammatory and pro-apoptotic cytokine. However, resistance limits its therapeutic efficiency. Therefore, an increasing number of studies are focusing on the development of drugs or methods with which to enhance the treatment efficacy of TNFα. Nuclear receptor subfamily 4 group A member 1 (NR4A1) has been shown to exert antitumor effects through several mechanisms, such as by inhibiting proliferation, as well as pro-apoptotic and potent pro-oxidant effects. In this study, we examined the effects and mechanisms of action of NR4A1 on the apoptosis of GC cells treated with TNFα, with particular focus on mitochondrial homeostasis. We found that TNFα treatment decreased NR4A1 expression. Moreover, the overexpression of NR4A1 in the presence of TNFα further increased GC cell apoptosis. Mechanistically, the overexpression of NR4A1 augmented caspase-9-dependent mitochondrial apoptosis, as evidenced by reduced mitochondrial membrane potential, reactive oxygen species (ROS) overproduction, mitochondrial permeability transition pore (mPTP) opening and the leakage of cytochrome c (Cyt-c) leakage. Moreover, NR4A1 overexpression also evoked mitochondrial energy disorder via the suppression of mitochondrial respiratory complex expression. Furthermore, we found that TNFα treatment activated Parkin-dependent mitophagy. Excessive Parkin-dependent mitophagy blocked mitochondrial apoptosis, undermining the toxic effects of TNFα on cells. However, NR4A1 overexpression suppressed Parkin-dependent mitophagy via the inhibition of c-Jun N-terminal kinase (JNK). Re-activation of the JNK/Parkin pathway abrogated the inhibitory effects of NR4A1 on mitophagy, eventually limiting cell apoptosis. Collectively, this study confirmed that NR4A1 sensitizes GC cells to TNFα-induced apoptosis through the inhibition of JNK/Parkin-dependent mitophagy.

Progress in the treatment of advanced gastric cancer

Gastric cancer is one of the most common malignant tumors in the digestive system. Surgery is currently considered to be the only radical treatment. As surgical techniques improve and progress is made in traditional radiotherapy, chemotherapy, and the implementation of neoadjuvant therapy, the 5-year survival rate of early gastric cancer can reach >95%. However, the low rate of early diagnosis means that most patients have advanced-stage disease at diagnosis and so the best surgical window is missed. Therefore, the main treatment for advanced gastric cancer is the combination of neoadjuvant chemoradiotherapy, molecular-targeted therapy, and immunotherapy. In this article, we summarize several common methods used to treat advanced gastric cancer and discuss the progress made in the treatment of gastric cancer in detail. Only clinical practice and clinical research will allow us to prolong the survival time of patients and allow the patients to truly benefit by paying attention to the individual patient characteristics, drug choice, and developing a reasonable and comprehensive treatment plan.