High-throughput mutation profiling identifies novel molecular dysregulation in high-grade intraepithelial neoplasia and early gastric cancers

Theranostic Approaches for Gastric Cancer: An Overview of In Vitro and In Vivo Investigations

Gastric cancer (GC) is the second most common cause of cancer-related death worldwide and a serious public health concern. This high death rate is mostly caused by late-stage diagnoses, which lead to poor treatment outcomes. Radiation immunotherapy and targeted therapies are becoming increasingly popular in GC treatment, in addition to surgery and systemic chemotherapy. In this review, we have focused on both in vitro and in vivo research, which presents a summary of recent developments in targeted therapies for gastric cancer. We explore targeted therapy approaches, including integrin receptors, HER2, Claudin 18, and glutathione-responsive systems. For instance, therapies targeting the integrin receptors such as the αvβ3 and αvβ5 integrins have shown promise in enhancing diagnostic precision and treatment efficacy. Furthermore, nanotechnology provides novel approaches to targeted drug delivery and imaging. These include glutathione-responsive nanoplatforms and cyclic RGD peptide-conjugated nanoparticles. These novel strategies seek to reduce systemic toxicity while increasing specificity and efficacy. To sum up, the review addresses the significance of personalized medicine and advancements in gastric cancer-targeted therapies. It explores potential methods for enhancing gastric cancer prognosis and treatment in the future.

Molecular evolution of intestinal-type early gastric cancer according to Correa cascade

Early screening is crucial for the prevention of intestinal-type gastric cancer. The objective of the current study was to ascertain molecular evolution of intestinal-type gastric cancer according to the Correa cascade for the precise gastric cancer screening. We collected sequential lesions of the Correa cascade in the formalin-fixed and paraffin-embedded endoscopic submucosal dissection-resected specimens from 14 Chinese patients by microdissection, and subsequently determined the profiles of somatic aberrations during gastric carcinogenesis using the whole exome sequencing, identifying multiple variants at different Correa stages. The results showed that TP53, PCLO, and PRKDC were the most frequently mutated genes in the early gastric cancer (EGC). A high frequency of TP53 alterations was found in low-grade intraepithelial neoplasia (LGIN), which further increased in high-grade intraepithelial neoplasia (HGIN) and EGC. Intestinal metaplasia (IM) had no significant correlation with EGC in terms of mutational spectra, whereas both LGIN and HGIN showed higher genomic similarities to EGC, compared with IM. Based on Jaccard similarity coefficients, three evolutionary models were further constructed, and most patients showed linear progression from LGIN to HGIN, ultimately resulting in EGC. The ECM-receptor interaction pathway was revealed to be involved in the linear evolution. Additionally, the retrospective validation study of 39 patients diagnosed with LGIN indicated that PRKDC mutations, in addition to TP53 mutations, may drive LGIN progression to HGIN or EGC. In conclusion, the current study unveils the genomic evolution across the Correa cascade of intestinal-type gastric cancer, elucidates the underlying molecular mechanisms of gastric carcinogenesis, and provides some evidence for potential personalized gastric cancer surveillance.

A noninvasive multianalytical approach establishment for risk assessment and gastric cancer screening

Effective screening and early detection are critical to improve the prognosis of gastric cancer (GC). Our study aims to explore noninvasive multianalytical biomarkers and construct integrative models for preliminary risk assessment and GC detection. Whole genomewide methylation marker discovery was conducted with CpG tandems target amplification (CTTA) in cfDNA from large asymptomatic screening participants in a high-risk area of GC. The methylation and mutation candidates were validated simultaneously using one plasma from patients at various gastric lesion stages by multiplex profiling with Mutation Capsule Plus (MCP). Helicobacter pylori specific antibodies were detected with a recomLine assay. Integrated models were constructed and validated by the combination of multianalytical biomarkers. A total of 146 and 120 novel methylation markers were found in CpG islands and promoter regions across the genome with CTTA. The methylation markers together with the candidate mutations were validated with MCP and used to establish a 133-methylation-marker panel for risk assessment of suspicious precancerous lesions and GC cases and a 49-methylation-marker panel as well as a 144-amplicon-mutation panel for GC detection. An integrated model comprising both methylation and specific antibody panels performed better for risk assessment than a traditional model (AUC, 0.83 and 0.63, P < .001). A second model for GC detection integrating methylation and mutation panels also outperformed the traditional model (AUC, 0.82 and 0.68, P = .005). Our study established methylation, mutation and H. pylori-specific antibody panels and constructed two integrated models for risk assessment and GC screening. Our findings provide new insights for a more precise GC screening strategy in the future.

Dynamic variations of the gastric microbiota: Key therapeutic points in the reversal of Correa's cascade

Correa's cascade is a dynamic process in the development of intestinal-type gastric cancer (GC), and its pathological features, gastric microbiota and interactions between microorganisms and their hosts vary at different developmental stages. The characteristics of cells, tissues and gastric microbiota before or after key therapeutic points are critical for monitoring malignant transformation and early tumour reversal. This review summarises the pathological features of gastric mucosa, characteristics of gastric microbiota, specific microbial markers, microbe-microbe interactions and microbe-host interactions at different stages in Correa's cascade. The markers related to each Correa's cascade point were analysed in detail. We attempted to identify key therapeutic points for early cancer reversal and provide a novel approach to reduce the incidence of GC and improve precise treatment.

Confusion and prospects for carcinogenesis of gastric adenoma and dysplasia: What is the correct answer currently?

There are differences in the diagnoses of superficial gastric lesions between Japan and other countries. In Japan, superficial gastric lesions are classified as adenoma or cancer. Conversely, outside Japan, the same lesion is classified as low-grade dysplasia (LGD), high-grade dysplasia, or invasive neoplasia. Gastric carcinogenesis occurs mostly de novo, and the adenoma-carcinoma sequence does not appear to be the main pathway of carcinogenesis. Superficial gastric tumors can be roughly divided into the APC mutation type and the TP53 mutation type, which are mutually exclusive. APC-type tumors have low malignancy and develop into LGD, whereas TP53-type tumors have high malignancy and are considered cancerous even if small. For lesions diagnosed as category 3 or 4 in the Vienna classification, it is desirable to perform complete en bloc resection by endoscopic submucosal dissection followed by staging. If there is lymphovascular or submucosal invasion after mucosal resection, additional surgical treatment of gastrectomy with lymph node dissection is required. In such cases, function-preserving curative gastrectomy guided by sentinel lymph node biopsy may be a good alternative.

Clinicopathological and molecular characterization of early gastric adenocarcinoma in Helicobacter pylori-uninfected patients: emphasis on differentiated gastric adenocarcinoma

BACKGROUND

Recently, Helicobacter pylori (HP)-uninfected gastric mucosal cancer has been reported; however, the clinicopathological and molecular features of HP-uninfected gastric cancer have not been elucidated.

METHODS

We evaluated the clinicopathological, immunohistochemical, and genetic alterations in HP-uninfected early gastric adenocarcinoma using next-generation sequencing (NGS).

RESULTS

Among 968 primary early gastric carcinomas, 64 (6.6%) were HP-uninfected gastric adenocarcinoma and were pathologically classified as gastric adenocarcinoma of fundic-gland type (GA-FG, n = 39), differentiated gastric adenocarcinoma (DGA, n = 16), and signet-ring cell carcinoma (SRCC, n = 9). Based on the expression profile of the mucin core protein, DGAs were classified into a gastrointestinal phenotype showing either MUC5AC or MUC6 expression and MUC2 or CD10 expression simultaneously (n = 5), and a gastric phenotype (n = 11) showing either MUC5AC or MUC6 expression. All DGAs with a gastrointestinal phenotype shared similar endoscopic characteristics, such as reddish depressed lesions in the antrum. In contrast, DGAs with a gastric phenotype exhibited several distinct endoscopic features, including a raspberry-shaped appearance and whitish flat-elevated appearance; the former expressed only MUC5AC and the latter exhibited co-expression of MUC5AC and MUC6. Among 16 HP-uninfected DGAs, seven were subjected to NGS. APC was recurrently mutated in DGA (42.9%) and was enriched in DGAs with a gastrointestinal phenotype (75%).

CONCLUSIONS

Overall, HP-uninfected gastric adenocarcinomas showed distinct clinicopathologic and endoscopic characteristics. Furthermore, HP-uninfected DGAs, especially those with a gastrointestinal phenotype, may be characterized by recurrent APC mutations.

Treatment Response Predictors of Neoadjuvant Therapy for Locally Advanced Gastric Cancer: Current Status and Future Perspectives

Neoadjuvant chemotherapy (NAC) for locally advanced gastric cancer (LAGC) has been recognized as an effective therapeutic option because it is expected to improve the curative resection rate by reducing the tumor size and preventing recurrence of micrometastases. However, for patients resistant to NAC, not only will operation timing be delayed, but they will also suffer from side effects. Thus, it is crucial to develop a comprehensive strategy and select patients sensitive to NAC. However, the therapeutic effect of NAC is unpredictable due to tumor heterogeneity and a lack of predictive biomarkers for guiding the choice of optimal preoperative treatment in clinical practice. This article summarizes the related research progress on predictive biomarkers of NAC for gastric cancer. Among the many investigated biomarkers, metabolic enzymes for cytotoxic agents, nucleotide excision repair, and microsatellite instability, have shown promising results and should be assessed in prospective clinical trials. Noninvasive liquid biopsy detection, including miRNA and exosome detection, is also a promising strategy.

Application of next-generation sequencing in the diagnosis of gastric cancer

Objectives: Gastric cancer (GC) is a disease with high mortality, poor prognosis and numerous risk factors. GC has an asymptomatic nature in early stages of the diseases, making timely diagnosis complicated using common conventional approaches, namely pathological examinations and imaging tests. Recently, molecular profiling of GC using next generation sequencing (NGS) has opened new doors to efficient prognostic, diagnostic, and therapeutic strategies. The current review aims to thoroughly discuss and compare the current NGS techniques and commercial platforms utilized for GC diagnosis and treatment, highlighting the most recent NGS-based GC studies. Furthermore, this review addresses the challenges of clinical implementation of NGS in GC.Materials and methods: This review was conducted according to the eligible studies identified via search of Web of Science, PubMed, Scopus, Embase and the Cochrane Library. In the present study, data on gastric cancer patients and NGS methods used to diagnose the disease were reviewed.Conclusion: Given the ever-rising advancements in NGS technologies, bioinformatics, healthcare guidelines and refined classifications, it is hoped that these technologies can actualize their advantages and optimize GC patients' experience.

Molecular Landscapes of Gastric Pre-Neoplastic and Pre-Invasive Lesions

Gastric carcinoma (GC) represents one of the most common and most lethal malignancies worldwide. The histopathological characterization of GC precursor lesions has provided great knowledge about gastric carcinogenesis, with the consequent introduction of effective strategies of primary and secondary prevention. In recent years, a large amount of data about the molecular events in GC development is emerging, flanking the histomorphological descriptions. In this review, we describe the landscape of molecular alterations in gastric pre-invasive lesions with a glance at their potential use in the diagnostic and therapeutic decision-making process.

Molecular Alterations in Gastric Preneoplastic Lesions and Early Gastric Cancer

Prognosis of gastric cancer is dramatically improved by early diagnosis. Correa's cascade correlates the expression of some molecular markers with the progression of preneoplastic lesions toward carcinoma. This article reviews the diagnostic and prognostic values of molecular markers in complete (MUC2) and incomplete (MUC2, MUC5AC, and MUC6) intestinal metaplasia, gastric dysplasia/intra-epithelial neoplasia, and early gastric cancer. In particular, considering preinvasive neoplasia and early gastric cancer, some studies have demonstrated a correlation between molecular alterations and prognosis, for example, mucins phenotype in gastric dysplasia, and GATA6, TP53 mutation/LOH and MUC6 in early gastric cancer. Moreover, this review considers novelties from the literature regarding the (immuno)histochemical characterization of diffuse-type/signet ring cell gastric cancer, with particular attention to clinical outcomes of patients. The aim of this review is the evaluation of the state of the art regarding suitable biomarkers used in the pre-surgical phase, which can distinguish patients with different prognoses and help decide the best therapeutic strategy.

Histomorphological Characteristics and Pathological Types of Hyperproliferation of Gastric Surface Epithelial Cells

Objective

To investigate the histomorphological characteristics and pathological types of hyperproliferation of gastric surface epithelial cells.

Methods

Hematoxylin and Eosin, Periodic acid–Schiff, and immunohistochemical staining were performed on biopsy specimens obtained from 723 patients with hyperproliferation of gastric surface epithelial cells and/or hyperplasia of gastric pits. Follow-up gastroscopic reexaminations were performed on 475 patients included. Improvement probability was analyzed using Kaplan-Meyer as well as Cox proportional hazards models.

Results

Seven different histomorphologies and clinicopathologies of hyperproliferation of gastric surface epithelial cells were identified: (1) common hyperplasia of gastric epithelial cells, which was characterized by focal glandular epithelial hyperplasia of gastric pits with chronic inflammation; (2) drug-induced hyperplasia of gastric epithelial cells, which was characterized by increased hyperplasia of gastric pits and cells arranged in a monolayer; (3) Helicobacter pylori (Hp) infection-induced hyperplasia of gastric epithelial cells, which was characterized by the disappearance of oval, spherical, and bounded membrane-enclosed mucus-containing granules in the cytoplasm and on the nucleus together with cytoplasmic swelling and vacuolation; (4) metaplastic hyperplasia of gastric epithelial cells, which was characterized by the coexistence of intestinal metaplastic cells with hyperplastic gastric epithelial cells; (5) atrophic hyperplasia of gastric epithelial cells, which was characterized by the mucosal atrophy accompanied with hyperplasia of gastric pits; (6) low-grade neoplasia of epithelial cells, which was characterized by the mild to moderate dysplasia of gastric epithelial cells; and (7) high-grade neoplasia of epithelial cells, which was characterized by the evident dysplasia of hyperplastic epithelial cells and losses of cell polarity. The different pathological types are associated with different improvement probabilities.

Conclusions

This study demonstrated the histomorphological characteristics and pathological types, which might guide clinicians to track malignant cell transformation, perform precise treatment, predict the clinical prognosis, and control the development of gastric cancer.

The impact of recent next generation sequencing and the need for a new classification in gastric cancer

The phenotypical and molecular heterogeneity of gastric cancer has hampered the introduction in clinical practice of a unifying classification of the disease. However, as next generation sequencing (NGS) technologies enhanced the comprehension of the molecular landscape of gastric cancer, novel molecular classification systems have been proposed, allowing the dissection of molecular tumor heterogeneity and paving the way for the development of new targeted therapies. Moreover, the use of NGS analyses in the molecular profiling of formalin-fixed paraffin-embedded (FFPE) specimens will improve patient selection for the enrolment in novel clinical trials. In conclusion, the application of NGS in precision oncology will revolutionize the diagnosis and clinical management in gastric cancer patients.

Esophageal squamous cell carcinoma metachronous to head and neck cancers

BACKGROUND

In some HNSCC patients, a metachronous ESCC may develop. No information is available on the HNSCC-associated ESCCs microenvironment and etiology.

METHODS

Among 134 ESCCs surgically treated between 2009 and 2015, a series of 6 HNSCC-associated ESCCs was collected. A series of 12 sex-, age- and stage-matched ESCCs with no previous oncological medical history was selected for comparison. Histologic assessment of intratumoral inflammatory infiltration and immunohistochemistry for CD4, CD8, CD80, PD1, PD-L1 and p53 were performed. HPV detection/genotyping was assessed by PCR single step and reverse line blot.

RESULTS

HPV DNA was negative in all the HNSCC-associated ESCCs. In comparison to non-HNSCC-associated carcinomas, the 6 cases presented a lower lymphomonocytic infiltration, which also corresponded to a lower prevalence of CD4 + T cell infiltration and, 5/6 cases presented a PD-L1 CPS ≥ 1. All the HNSCC-associated ESCCs resulted positive for p53 immunostaining in ≥50 % of cancer cells.

CONCLUSION

Our study suggests that HPV infection is not an etiological factor associated to ESCC after HNSCC. On the other hand, p53 overexpression is a common finding. Moreover, our data suggest that an altered immune microenvironment, conditioned by a dysregulation in lymphomonocytic infiltration, may be a crucial factor allowing the occurrence of a metachronous ESCC.

Role of magnifying endoscopy with narrow-band imaging in the diagnosis of noninvasive gastric neoplasia

Background and Aim

There are no globally approved, distinguishing criteria enabling the classification of gastric adenomas and intramucosal carcinomas for differential diagnosis of noninvasive neoplasia (NIN).

Methods

Next‐generation sequencing of 50 cancer‐related genes was undertaken on 68 pathologically diagnosed microdissected gastric neoplasms (25 adenomas, 27 intramucosal carcinomas, and 16 submucosal carcinomas) obtained during endoscopic submucosal dissection. Findings from magnifying endoscopy with narrow‐band imaging (M‐NBI) of 52 NINs (the 25 adenomas and 27 intramucosal carcinomas) were compared with these data.

Results

Among all 68 neoplasms, the most frequently mutated genes were APC (76% in adenoma, 11.1% in intramucosal carcinoma, and 0% in submucosal carcinoma; P < 0.001) and TP53 in intramucosal and submucosal carcinomas (8% in adenoma, 48.1% in intramucosal carcinoma, and 75% in submucosal carcinoma; P < 0.001). Dividing the NIN neoplasms into five groups according to their mutational status (A1: APC mutation, A2: APC + α mutation, B: APC + TP53 mutation, C: TP53 mutation, D: no mutation in either APC or TP53) resulted in almost identical diagnoses by pathology and M‐NBI for groups A1 (12/13, 92%), C (12/13, 92%), and D (16/17, 94%) but not for groups A2 (3/7, 43%) or B (0/2, 0%). This finding implies that NINs with the APC + α mutation have carcinoma‐like endoscopic features despite most being judged as adenomas by pathology.

Conclusion

A diagnosis of NINs by pathology or M‐NBI in the subset of gastric tumors classified by cancer‐related mutations is not completely identical, suggesting the possible additional role of M‐NBI in diagnosing NINs. Further studies are needed to confirm this.

Genome-wide transcriptional analysis of Aristolochia manshuriensis induced gastric carcinoma

Context: Aristolochia manshuriensis Kom (Aristolochiaceae) (AMK) is known for toxicity and mutagenicity.Objective: The tumorigenic role of AMK has yet to be understood.Materials and methods: AMK extracts were extracted from root crude drug. SD (Sprague Dawley) rats underwent gavage with AMK (0.92 g/kg) every other day for 10 (AMK-10) or 20 (AMK-20) weeks. Stomach samples were gathered for histopathological evaluation, microarray and mRNA analysis.Results: The gastric weight to body weight ratio (GW/BW) is 1.7 in the AMK-10 cohort, and 1.8 in AMK-20 cohort compared to control (CTL) cohort. Liver function was damaged in AMK-10 and AMK-20 rats compared to CTL rats. There were no significant changes of CRE (creatinine) in AMK-10 and AMK-20 rats. Histopathological analysis revealed that rats developed dysplasia in the forestomach in AMK-10 rats, and became gastric carcinoma in AMK-20 rats. Genes including Mapk13, Nme1, Gsta4, Gstm1, Jun, Mgst2, Ggt6, Gpx2, Gpx8, Calml3, Rasgrp2, Cd44, Gsr, Dgkb, Rras, and Amt were found to be critical in AMK-10 and AMK-20 rats. Pik3cb, Plcb3, Tp53, Hras, Myc, Src, Akt1, Gnai3, and Fgfr3 worked in AMK-10 rats, and PDE2a and PDE3a played a pivotal role in AMK-20 rats.Discussion and conclusions: AMK induced benign or malignant gastric tumours depends on the period of AMK administration. Genes including Mapk13, Nme1, Gsta4, Gstm1, Jun, Mgst2, Ggt6, Gpx2, Gpx8, Calml3, Rasgrp2, Cd44, Gsr, Dgkb, Rras, Amt, Pik3cb, Plcb3, Tp53, Hras, Myc, Src, Akt1, Gnai3, Fgfr3, PDE2a, and PDE3a were found to be critical in aristolochic acid-induced gastric tumour process.

Gastrointestinal tissue-based molecular biomarkers: a practical categorisation based on the 2019 World Health Organization classification of epithelial digestive tumours

Molecular biomarkers have come to constitute one of the cornerstones of oncological pathology. The method of classification not only directly affects the manner in which patients are diagnosed and treated, but also guides the development of drugs and of artificial intelligence tools. The aim of this article is to organise and update gastrointestinal molecular biomarkers in order to produce an easy-to-use guide for routine diagnostics. For this purpose, we have extracted and reorganised the molecular information on epithelial neoplasms included in the 2019 World Health Organization classification of tumours. Digestive system tumours, 5th edn.

Molecular Classification of Gastric Cancer among Alaska Native People

Gastric cancer is an aggressive and heterogeneous malignancy that often varies in presentation and disease among racial and ethnic groups. The Alaska Native (AN) people have the highest incidence and mortality rates of gastric cancer in North America. This study examines molecular markers in solid tumor samples from eighty-five AN gastric adenocarcinoma patients using next-generation sequencing, immunohistochemistry, and in situ hybridization analysis. AN patients have a low mutation burden with fewer somatic gene mutations in their tumors compared to other populations, with the most common mutation being TP53. Epstein-Barr virus (EBV) was associated with 20% of AN gastric cancers, which is higher than the world average of 10%. The inflammation marker, cyclooxygenase-2 (COX-2), is highly expressed in patients with the lowest survival rates. Mismatch repair deficiency was present in 10% of AN patients and was associated with patients who were female, 50 years or older, gene mutations, and tumors in the distal stomach. Program death-ligand 1 (PD-L1) was expressed in 14% of AN patients who were more likely to have MMR deficiency, EBV-associated gastric cancers, and mutations in the PIK3CA gene, all of which have been linked to clinical response to PD-1 inhibitors. These studies suggest a portion of AN gastric cancer patients could be candidates for immunotherapy. Overall, this study highlights future avenues of investigation for clinical and translational studies, so that we can improve early detection and develop more effective treatments for AN patients.

Identification of early genetic changes in well-differentiated intramucosal gastric carcinoma by target deep sequencing

BACKGROUND AND AIMS

The recent advancement of next-generation sequencing (NGS) has enabled the identification of cancer-related somatic aberrations in advanced gastric cancer. However, these remain unclear in early gastric cancers, especially in intramucosal gastric cancers.

PATIENTS AND METHODS

Thirty-one well-differentiated (tub1) intramucosal gastric cancers obtained by endoscopic submucosal dissection (ESD) from 29 patients were analyzed. After precise collection of tumors and non-tumors from formalin-fixed paraffin-embedded tissues using laser-captured microdissection (LCM), target sequencing analysis of 50 cancer-related genes was performed using an Ion-Proton sequencer.

RESULTS

The most frequent hotspot mutation was found in TP53 (17 lesions, 54.8%) followed by the Wnt-signaling pathway genes, APC and CTNNB1 (6 lesions, 19.4%). The mutations in TP53 and the Wnt-signaling genes were mutually exclusive (p = 0.004). There was a tendency that H. pylori infection (p = 0.082) and macroscopic protrusion (p = 0.095) was associated with the presence of these mutations. Only 10 lesions (59%) among 17 lesions with proven TP53 mutations were positive for p53 immunostaining demonstrating the superiority of the mutational analysis. In addition, focal gene amplification of ERBB2 (16%) was found frequently in these early stage lesions.

CONCLUSIONS

Using LCM and NGS, mutations in TP53 and the Wnt-signaling pathway were frequently found and were mutually exclusive in the earliest stage of gastric carcinogenesis.

Comprehensive Analysis of Somatic Mutations in Colorectal Cancer With Peritoneal Metastasis

BACKGROUND

To analyze for genetic mutations which may presage peritoneal metastasis by using targeted next-generation sequencing (NGS).

MATERIALS AND METHODS

Formalin-fixed, paraffin-embedded primary tumor specimens were obtained from 10 patients with small obstructing colorectal cancer and peritoneal metastasis (group A) and five with large non-obstructing colorectal cancer and no recurrence (group B). DNA was extracted for the sequencing of 409 cancer genes. The distribution of genetic mutations was compared between the two groups to find genetic mutations related to peritoneal metastasis.

RESULTS

When the samples were sorted based on similarity of gene expression by hierarchical clustering analysis, the samples were well divided between the two study groups. Mutations in AT-rich interactive domain-containing protein 1A (ARID1A), polycystic kidney and hepatic disease 1 (PKHD1), ubiquitin-protein ligase E3 component n-recognin 5 (UBR5), paired box 5 (PAX5), tumor protein p53 (TP53), additional sex combs like 1 (ASXL1) and androgen receptor (AR) genes were detected more frequently in group A.

CONCLUSION

A number of somatic mutations presumed to be relevant to colorectal cancer with peritoneal metastasis were identified in our study by NGS.

Human papillomavirus infection is not involved in esophageal verrucous carcinoma

Verrucous carcinoma of the esophagus (VCE) is a rare variant of squamous cell cancer, with a puzzling clinical, etiological, and molecular profile. The etiological involvement of human papillomavirus (HPV) in the cancer's natural history is controversial. This study considers 9 cases of VCE, focusing on patients' clinical history before surgery, histologic phenotype, immunophenotype (epidermal growth factor receptor [EGFR], E-cadherin, cyclin D1, p16, and p53 expression), HPV infection, and TP53 gene mutational status (exons 5-8). Using 3 different molecular test methods, not one of these cases of VCE featured HPV infection. The only case with synchronous nodal metastasis was characterized by a TP53 missense point mutation in association with high EGFR and low E-cadherin expression levels. In conclusion, HPV infection is probably not involved with VCE, while TP53 gene mutation, EGFR overexpression, and E-cadherin loss might fuel the tumor's proliferation and lend it a metastatic potential.

The oncometabolite d‑2‑hydroxyglutarate induces angiogenic activity through the vascular endothelial growth factor receptor 2 signaling pathway

The mutation of isocitrate dehydrogenase (IDH)1 (R132H) and IDH2 (R172K) and the induction of hypoxia in various solid tumors results in alterations in metabolic profiles, including the production of the d‑ or l‑forms of 2‑hydroxyglutarate (2HG) from α‑ketoglutarate in aerobic metabolism in the tricarboxylic acid (TCA) cycle. However, it is unclear whether the oncometabolite d‑2HG increases angiogenesis in endothelial cells. Therefore, in this study, we analyzed the levels of various metabolites, including d‑2HG, under hypoxic conditions and in IDH2R172K mutant breast cancer cells by mass spectrometry. We then further evaluated the effects of this metabolite on angiogenesis in breast cancer cells. The results revealed that treatment with d‑2HG increased the levels of secreted vascular endothelial growth factor (VEGF) in cancer cells and enhanced endothelial cell proliferation in a concentration‑dependent manner. Wound healing and cell migration (examined by Transwell assay) were significantly increased by d‑2HG to a level similar to that induced by VEGF. Tube formation was significantly stimulated by d‑2HG, and chick chorioallantoic membrane angiogenesis was also enhanced by d‑2HG. d‑2HG activated VEGF receptor (VEGFR)2 and VEGFR2 downstream signaling, extracellular signal‑regulated kinase 1/2, focal adhesion kinase, AKT and matrix metalloproteinase (MMP)2. Taken together, the findings of this study suggested that d‑2HG induced angiogenic activity via VEGFR2 signaling and increased MMP2 activity.

Pulmonary Adenocarcinoma With Enteric Differentiation: Immunohistochemistry and Molecular Morphology

Pulmonary adenocarcinoma with enteric differentiation (PAED) is a rare subtype of lung adenocarcinoma recently recognized in the WHO classification. It is defined as an adenocarcinoma in which the enteric component exceeds 50% and have to show the expression of at least 1 immunohistochemical marker of enteric differentiation. Although the definition of this tumor type is very important, above all in the differential diagnosis between a primary lung tumor and a metastasis of colorectal adenocarcinoma, this cancer still lacks a distinctive immunohistochemical and molecular signature. We recruited the largest series in the literature of PAEDs according to the morphology and the positivity for intestinal markers. Then, we evaluated the immunohistochemical and molecular profile of these adenocarcinomas. In our series, CDX-2 and CK7 were the immunohistochemical markers mostly expressed by PAEDs. There was an inverse relationship between the expression of pnuemocytes markers, such as TTF-1, and intestinal markers. Molecular analysis revealed KRAS as the most frequently mutated gene (>60% of cases), with very few cases harboring abnormalities affecting EGFR, BRAF, and ALK genes. PAEDs are morphologically very heterogenous. The immunohistochemical profile based on CDX-2 and CK7 positivity of PAEDs appears very robust to support this diagnosis, and it is applicable also on small biopsies. KRAS appears as the most important mutated gene in such tumors.

MiR-21 up-regulation in ampullary adenocarcinoma and its pre-invasive lesions

Poor information is available on the molecular landscape characterizing the carcinogenetic process leading to ampullary carcinoma. MiR-21 is one of the most frequently up-regulated miRNAs in pancreatic adenocarcinoma, a tumor sharing similar molecular features with ampullary adenocarcinomas (AVCs), above all with the pancreatic-biliary type. We profiled, by in situ hybridization (ISH), miR-21 expression in a series of 26 AVCs, 50 ampullary dysplastic lesions (35 low-grade [LG-IEN] and 15 high-grade [HG-IEN]) and 10 normal duodenal mucosa samples. The same series was investigated by immunohistochemistry for β-catenin, p53 and HER2 expression. HER2 gene amplification was evaluated by chromogenic in situ hybridization. To validate miR-21 ISH results we performed miR-21 qRT-PCR analysis in a series of 10 AVCs and their matched normal samples. All the normal control samples showed a negative or faint miR-21 expression, whereas a significant miR-21 up-regulation was observed during the carcinogenetic cascade (p < 0.001), with 21/26 (80.8%) of cancer samples showing a miR-21 overexpression. In comparison to control samples, a significant overexpression was found in samples of LG-IEN (p = .0003), HG-IEN (p = .0001), and AVCs (p < 0.0001). No significant difference in miR-21 overexpression was observed between LG-IEN, HG-IEN and AVCs. By qRT-PCR analysis, AVCs showed a 1.7-fold increase over the controls (p = .003). P53 was frequently dysregulated in both dysplastic and carcinoma samples (44 out of 76; 57.9%). A 20% (10/50) of dysplastic lesions and 11% (3/26) of carcinomas were characterized by a nuclear localization of β-catenin. Only 2 AVCs (7.7%; both intestinal-type) showed a HER2 overexpression (both 2+), which corresponded to a HER2 gene amplification at CISH analysis. This is the first study demonstrating a miRNA dysregulation in the whole spectrum of ampullary carcinogenesis. MiR-21 overexpression is an early molecular event during ampullary carcinogenesis and its levels increase with the neoplastic progression.

Molecular profiling and comprehensive genome-wide analysis of somatic copy number alterations in gastric intramucosal neoplasias based on microsatellite status

BACKGROUND

We attempted to identify the molecular profiles of gastric intramucosal neoplasia (IMN; low-grade dysplasia, LGD; high-grade dysplasia, HGD; intramucosal cancer, IMC) by assessing somatic copy number alterations (SCNAs) stratified by microsatellite status (microsatellite stable, MSS; microsatellite instable, MSI). Thus, microsatellite status was determined in 84 tumors with MSS status and 16 tumors with MSI status.

METHODS

One hundred differentiated type IMNs were examined using SCNAs. In addition, genetic mutations (KRAS, BRAF, PIK3CA, and TP53) and DNA methylation status (low, intermediate and high) were also analyzed. Finally, we attempted to identify molecular profiles using a hierarchical clustering analysis.

RESULTS

Three patterns could be categorized according to SCNAs in IMNs with the MSS phenotype: subgroups 1 and 2 showing a high frequency of SCNAs, and subgroup 3 displaying a low frequency of SCNAs (subgroup 1 > 2 > 3 for SCNA). Subgroup 1 could be distinguished from subgroup 2 by the numbers of total SCNAs (gains and losses) and SCN gains (subgroup 1 > 2). The SCNA pattern of LGD was different from that of HGD and IMC. Moreover, IMNs with the MSI phenotype could be categorized into two subtypes: high frequency of SCNAs and low frequency of SCNAs. Genetic mutations and DNA methylation status did not differ among subgroups in IMNs.

CONCLUSION

Molecular profiles stratified by SCNAs based on microsatellite status may be useful for elucidation of the mechanisms of early gastric carcinogenesis.

Gastric Cancer as Preventable Disease

Gastric cancer, 1 of the 5 most common causes of cancer death, is associated with a 5-year overall survival rate less than 30%. A minority of cancers occurs as part of syndromic diseases; more than 90% of adenocarcinomas are considered as the ultimate consequence of a longstanding mucosal inflammation. Helicobacter pylori infection is the leading etiology of non-self-limiting gastritis, which may result in atrophy of the gastric mucosa and impaired acid secretion. Gastric atrophy establishes a field of cancerization prone to further molecular and phenotypic changes, possibly resulting in cancer growth. This well-understood natural history provides the clinicopathologic rationale for primary and secondary cancer prevention strategies. A large body of evidence demonstrates that combined primary (H pylori eradication) and secondary (mainly endoscopy) prevention efforts may prevent or limit the progression of gastric oncogenesis. This approach, which is tailored to different country-specific gastric cancer incidence, socioeconomic, and cultural factors, requires that the complementary competences of gastroenterologists, oncologists, and pathologists be amalgamated into a common strategy of health policy.

Pancreatic undifferentiated carcinoma with osteoclast-like giant cells is genetically similar to, but clinically distinct from, conventional ductal adenocarcinoma

Undifferentiated carcinoma of the pancreas with osteoclast-like giant cells (UCOGC) is currently considered a morphologically and clinically distinct variant of pancreatic ductal adenocarcinoma (PDAC). In this study, we report clinical and pathological features of a series of 22 UCOGCs, including the whole exome sequencing of eight UCOGCs. We observed that 60% of the UCOGCs contained a well-defined epithelial component and that patients with pure UCOGC had a significantly better prognosis than did those with an UCOGC with an associated epithelial neoplasm. The genetic alterations in UCOGC are strikingly similar to those known to drive conventional PDAC, including activating mutations in the oncogene KRAS and inactivating mutations in the tumor suppressor genes CDKN2A, TP53, and SMAD4. These results further support the classification of UCOGC as a PDAC variant and suggest that somatic mutations are not the determinants of the unique phenotype of UCOGC. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Oncofetal gene SALL4 and prognosis in cancer: A systematic review with meta-analysis

The Spalt-Like Transcription Factor 4 (SALL4) oncogene plays a central function in embryo-fetal development and is absent in differentiated tissues. Evidence suggests that it can be reactivated in several cancers worsening the prognosis. We aimed at investigating the risk associated with SALL4 reactivation for all-cause mortality and recurrence in cancer using the current literature. A PubMed and SCOPUS search until 1st September 2016 was performed, focusing on perspective studies reporting prognostic parameters in cancer data. In addition, 17 datasets of different cancer types from The Cancer Genome Atlas were considered. A total of 9,947 participants across 40 cohorts, followed-up for about 5 years on average, were analyzed comparing patients showing SALL4 presence (SALL4+, n = 1,811) or absence (SALL4-, n = 8,136). All data were summarised using risk ratios (RRs) for the number of deaths/recurrences and hazard ratios (HRs) for the time-dependent risk related to SALL4+, adjusted for potential confounders. SALL4+ significantly increased overall mortality (RR = 1.34, 95% confidence intervals (CI)=1.21-1.48, p<0.0001, I2=66%; HR=1.4; 95%CI: 1.19-1.65; p<0.0001; I2=63%) and recurrence of disease (RR = 1.25, 95% CI = 1.1-1.42, p=0.0006, I2=62%); HR=1.52; 95% CI: 1.22-1.89, p=0.0002; I2=69%) compared to SALL4-. Moreover, SALL4 remained significantly associated with poor prognosis even using HRs adjusted for potential confounders (overall mortality: HR=1.4; 95%CI: 1.19-1.65; p<0.0001; I2=63%; recurrence of disease: HR=1.52; 95% CI: 1.22-1.89, p=0.0002; I2=69%). These results suggest that SALL4 expression increases both mortality and recurrence of cancer, confirming this gene as an important prognostic marker and a potential target for personalized medicine.

Next-Generation Sequencing in Oncology: Genetic Diagnosis, Risk Prediction and Cancer Classification

Next-generation sequencing (NGS) technology has expanded in the last decades with significant improvements in the reliability, sequencing chemistry, pipeline analyses, data interpretation and costs. Such advances make the use of NGS feasible in clinical practice today. This review describes the recent technological developments in NGS applied to the field of oncology. A number of clinical applications are reviewed, i.e., mutation detection in inherited cancer syndromes based on DNA-sequencing, detection of spliceogenic variants based on RNA-sequencing, DNA-sequencing to identify risk modifiers and application for pre-implantation genetic diagnosis, cancer somatic mutation analysis, pharmacogenetics and liquid biopsy. Conclusive remarks, clinical limitations, implications and ethical considerations that relate to the different applications are provided.

Poorly Differentiated Medullary Phenotype Predicts Poor Survival in Early Lymph Node-Negative Gastro-Esophageal Adenocarcinomas

BACKGROUND

5-year survival rate in patients with early adenocarcinoma of the gastro-esophageal junction or stomach (AGE/S) in Caucasian patients is reported to be 60-80%. We aimed to identify prognostic markers for patients with UICC-I without lymph-node involvement (N0).

METHODS

Clinical data and tissue specimen from patients with AGE/S stage UICC-I-N0, treated by surgery only, were collected retrospectively. Tumor size, lymphatic vessel or vein invasion, grading, classification systems (WHO, Lauren, Ming), expression of BAX, BCL-2, CDX2, Cyclin E, E-cadherin, Ki-67, TP53, TP21, SHH, Survivin, HIF1A, TROP2 and mismatch repair deficiency were analyzed using tissue microarrays and correlated with overall and tumor related survival.

RESULTS

129 patients (48 female) with a mean follow-up of 129.1 months were identified. 5-year overall survival was 83.9%, 5-year tumor related survival was 95.1%. Poorly differentiated medullary cancer subtypes (p<0.001) and positive vein invasion (p<0.001) were identified as risk factors for decreased overall-and tumor related survival. Ki-67 (p = 0.012) and TP53 mutation (p = 0.044) were the only immunohistochemical markers associated with worse overall survival but did not reach significance for decreased tumor related survival.

CONCLUSION

In the presented study patients with AGE/S in stage UICC-I-N0 had a better prognosis as previously reported for Caucasian patients. Poorly differentiated medullary subtype was associated with reduced survival and should be considered when studying prognosis in these patients.

Gastric cancer related genes

Gastric cancer is one of the most common malignant tumors. In addition to environmental, socioeconomic, and dietary factors, hereditary factors also play an important role in the development of gastric cancer. Although some driver genes have been identified in gastric cancer, the molecular compositions of gastric cancer have not been fully understood. Genome-wide association studies, copy number variations and next-generation sequencing provide systematic methods to identify all genetic alterations in the cancer genome, especially in the field of mutation detection. Here we make a brief review of the current status of research on gastric cancer genetics.

Comparison between two amplicon-based sequencing panels of different scales in the detection of somatic mutations associated with gastric cancer

BACKGROUND

Sequencing data from The Cancer Genome Atlas (TGCA), the International Cancer Genome Consortium and other research institutes have revealed the presence of genetic alterations in several tumor types, including gastric cancer. These data have been combined into a catalog of significantly mutated genes for each cancer type. However, it is unclear to what extent significantly mutated genes need to be examined for detecting genetic alterations in gastric cancer patients. Here, we constructed two custom-made sequencing panels of different scales, the Selective hotspot Panel and the Comprehensive Panel, to analyze genetic alterations in 21 resected specimens endoscopically obtained from 20 gastric cancer patients, and we assessed how many mutations were detectable using these different panels.

RESULTS

A total of 21 somatic mutations were identified by the Selective hotspot Panel and 70 mutations were detected by the Comprehensive Panel. All mutations identified by the Selective hotspot Panel were detected by the Comprehensive Panel, with high concordant values of the variant allelic fraction of each mutation (correlation coefficient, R = 0.92). At least one mutation was identified in 13 patients (65 %) by the Selective hotspot Panel, whereas the Comprehensive Panel detected mutations in 19 (95 %) patients. Library preparation and sequencing costs were comparable between the two panels.

CONCLUSIONS

Our results indicate the utility of comprehensive panel-based targeted sequencing in gastric cancer.

Clinicopathological Significance of Elevated PIK3CA Expression in Gastric Cancer

Purpose

PIK3CA is often mutated in a variety of malignancies, including colon, gastric, ovary, breast, and brain tumors. We investigated PIK3CA expression in gastric cancer and explored the relationships between the PIK3CA expression level and clinicopathological features as well as survival of the patients.

Materials and Methods

We examined PIK3CA expression in a tissue microarray of 178 gastric adenocarcinomas by immunohisto-chemistry and reviewed patients' medical records.

Results

In our study, 112 of the 178 gastric cancer patients displayed positive PIK3CA expression. Overexpression of PIK3CA was correlated with low grade differentiation (P=0.001), frequent lymphatic invasion (P=0.032), and high T stage (P=0.040). Patients with positive PIK3CA staining were more likely to display worse overall survival rate than those with negative PIK3CA staining, as determined by Kaplan-Meier survival analysis with log-rank test (P=0.047) and a univariate analysis using the Cox proportional hazard model (hazard ratio=1.832, P=0.051).

Conclusions

Elevated PIK3CA expression was significantly correlated with tumor invasiveness, tumor phenotypes, and poor patient survival.

LKB1 inhibits the proliferation of gastric cancer cells by suppressing the nuclear translocation of Yap and β-catenin

Liver kinase B1 (LKB1) is known to suppress the proliferation, energy metabolism and mesenchymal transition of various cancer cells, and is involved in the regulation of Hippo-Yes-associated protein (Yap) and the Wnt/β-catenin signaling pathways. However, the role of LKB1 in gastric cancer (GC) was not fully understood. Thus, in the present study, we studied LKB1 and found that protein expression (0.37±0.061 vs. 0.59±0.108, P=0.006) and the protein ratio of p-Yap/Yap (0.179±0.085 vs. 0.8±0.126, P=0.001) were reduced in 54 gastric adenocarcinoma (GAC) tissues compared with the matched adjacent non-cancerous tissues, using western blotting and RT-qPCR assays. LKB1 expression was also observed decreased in 109 GAC tissues compared with 54 adjacent non-cancerous tissues (χ2=4.678, P=0.0306), and negatively correlated with the nuclear expression of Yap (r=-0.6997) and β-catenin (r=-0.3510), using immunohistochemical analysis. In GC patients, LKB1 expression was negatively associated with tumor size, tumor infiltration, lymph node metastasis and the TNM stage. LKB1 expression was determined to be positively correlated with longer overall survival of GC patients using Kaplan-Meier analysis (P=0.001). Subsequently, LKB1 expression in human GAC AGS cells was enhanced with a full‑length LKB1 transfection. In vitro and in vivo proliferation was inhibited in LKB1-overexpressing GC cells compared with the control cells. Yap and β-catenin expression were assessed by western blotting and RT-qPCR, and were found to be increased in the cytoplasm but decreased in the nucleus in LKB1-overexpressing GC cells compared with the control cells. The increase in cytoplasmic β-catenin was reversed by the silencing of LKB1 or Yap with shRNAs in LKB1-overexpressing GC cells. Moreover, Yap and β-catenin mRNA were barely altered by LKB1 overexpression. Thus, we concluded that LKB1 expression was reduced in GAC tissues but that it correlated positively with better prognosis for GC patients. LKB1 inhibits the proliferation of GC cells by suppressing the nuclear translocation of Yap and β-catenin.

Prognostic role and implications of mutation status of tumor suppressor gene ARID1A in cancer: a systematic review and meta-analysis

Loss of the tumor suppressor gene AT-rich interactive domain-containing protein 1A (ARID1A) has been demonstrated in several cancers, but its prognostic role is unknown. We aimed to investigate the risk associated with loss of ARID1A (ARID1A-) for all-cause mortality, cancer-specific mortality and recurrence of disease in subjects with cancer. PubMed and SCOPUS search from database inception until 01/31/2015 without language restriction was conducted, contacting authors for unpublished data. Eligible were prospective studies reporting data on prognostic parameters in subjects with cancer, comparing participants with presence of ARID1A (ARID1A+) vs. ARID1A-, assessed either via immunohistochemistry (loss of expression) or with genetic testing (presence of mutation). Data were summarized using risk ratios (RR) for number of deaths/recurrences and hazard ratios (HR) for time-dependent risk related to ARID1A- adjusted for potential confounders. Of 136 hits, 25 studies with 5,651 participants (28 cohorts; ARID1A-: n = 1,701; ARID1A+: n = 3,950), with a mean follow-up period of 4.7 ± 1.8 years, were meta-analyzed. Compared to ARID1A+, ARID1A- significantly increased cancer-specific mortality (studies = 3; RR = 1.55, 95% confidence interval (CI) = 1.19-2.00, I(2) = 31%). Using HRs adjusted for potential confounders, ARID1A- was associated with a greater risk of cancer-specific mortality (studies = 2; HR = 2.55, 95%CI = 1.19-5.45, I(2) = 19%) and cancer recurrence (studies = 10; HR = 1.93, 95%CI = 1.22-3.05, I(2) = 76%). On the basis of these results, we have demonstrated that loss of ARID1A shortened time to cancer-specific mortality, and to recurrence of cancer when adjusting for potential confounders. For its role, this gene should be considered as an important potential target for personalized medicine in cancer treatment.

Epithelial dysplasia of the stomach with gastric immunophenotype shows features of biological aggressiveness

BACKGROUND

Gastric dysplasia is classified as adenomatous/type I (intestinal phenotype) and foveolar or pyloric/type II (gastric phenotype) according to morphological (architectural and cytological) features. The immunophenotypic classification of dysplasia, based on the expression of the mucins, CD10 and CDX2, recognizes the following immunophenotypes: intestinal (MUC2, CD10, and CDX2); gastric (MUC5AC and/or MUC6, absence of CD10, and absent or low expression of CDX2); hybrid (gastric and intestinal markers); and null.

METHODS

Sixty-six cases of nonpolypoid epithelial dysplasia of the stomach were classified according to morphological features (histotype and grade) and immunophenotype. Immunohistochemical staining was performed with antibodies against MUC2, MUC5AC, MUC6, CD10, CDX2, chromogranin, synaptophysin, Ki-67, and TP53. HER2 alterations were analyzed by immunohistochemistry and silver-enhanced in situ hybridization.

RESULTS

By conventional histology, dysplasia was classified as adenomatous/intestinal (n = 42; 64 %) and foveolar or pyloric/gastric (n = 24; 36 %) and graded as low grade (n = 37; 56 %) or high grade (n = 29; 44 %). Immunophenotypic classification showed intestinal (n = 22; 33.3 %), gastric (n = 25; 37.9 %), hybrid (n = 17; 25.8 %), or null (n = 2; 3.0 %) phenotypes. In 20 cases a coexistent intramucosal carcinoma was identified. The intestinal immunophenotype was shown to be significantly associated with low-grade dysplasia (p = 0.001), high expression of CDX2 (p = 0.015), TP53 (p = 0.034), synaptophysin (p = 0.003), and chromogranin (p < 0.0001); the gastric immunophenotype was significantly associated with high-grade dysplasia (p = 0.001), high Ki-67 proliferative index (p = 0.05), and coexistence of intramucosal carcinoma (p = 0.013). HER2 amplification was observed in 3 cases, typed as gastric or hybrid.

CONCLUSIONS

Epithelial nonpolypoid dysplasia of the stomach with gastric immunophenotype shows features of biological aggressiveness and may represent the putative precursor lesion in a pathway of gastric carcinogenesis originated de novo from the native gastric mucosa, leading to gastric-type adenocarcinoma.

Performance characteristics of the AmpliSeq Cancer Hotspot panel v2 in combination with the Ion Torrent Next Generation Sequencing Personal Genome Machine

Next-Generation Sequencing is a rapidly advancing technology that has research and clinical applications. For many cancers, it is important to know the precise mutation(s) present, as specific mutations could indicate or contra-indicate certain treatments as well as be indicative of prognosis. Using the Ion Torrent Personal Genome Machine and the AmpliSeq Cancer Hotspot panel v2, we sequenced two pancreatic cancer cell lines, BxPC-3 and HPAF-II, alone or in mixtures, to determine the error rate, sensitivity, and reproducibility of this system. The system resulted in coverage averaging 2000× across the various amplicons and was able to reliably and reproducibly identify mutations present at a rate of 5%. Identification of mutations present at a lower rate was possible by altering the parameters by which calls were made, but with an increase in erroneous, low-level calls. The panel was able to identify known mutations in these cell lines that are present in the COSMIC database. In addition, other, novel mutations were also identified that may prove clinically useful. The system was assessed for systematic errors such as homopolymer effects, end of amplicon effects and patterns in NO CALL sequence. Overall, the system is adequate at identifying the known, targeted mutations in the panel.

Gene mutations in gastric cancer: a review of recent next-generation sequencing studies

Gastric cancer (GC) is one of the most common malignancies worldwide. Although some driver genes have been identified in GC, the molecular compositions of GC have not been fully understood. The development of next-generation sequencing (NGS) provides a high-throughput and systematic method to identify all genetic alterations in the cancer genome, especially in the field of mutation detection. NGS studies in GC have discovered some novel driver mutations. In this review, we focused on novel gene mutations discovered by NGS studies, along with some well-known driver genes in GC. We organized mutated genes from the perspective of related biological pathways. Mutations in genes relating to genome integrity (TP53, BRCA2), chromatin remodeling (ARID1A), cell adhesion (CDH1, FAT4, CTNNA1), cytoskeleton and cell motility (RHOA), Wnt pathway (CTNNB1, APC, RNF43), and RTK pathway (RTKs, RAS family, MAPK pathway, PIK pathway) are discussed. Efforts to establish a molecular classification based on NGS data which is valuable for future targeted therapy for GC are introduced. Comprehensive dissection of the molecular profile of GC cannot only unveil the molecular basis for GC but also identify genes of clinical utility, especially potential and specific therapeutic targets for GC.

Next-generation sequencing for genetic testing of familial colorectal cancer syndromes

BACKGROUND

Genetic screening in families with high risk to develop colorectal cancer (CRC) prevents incurable disease and permits personalized therapeutic and follow-up strategies. The advancement of next-generation sequencing (NGS) technologies has revolutionized the throughput of DNA sequencing.

METHODS

A series of 16 probands for either familial adenomatous polyposis (FAP; 8 cases) or hereditary nonpolyposis colorectal cancer (HNPCC; 8 cases) were investigated for intragenic mutations in five CRC familial syndromes-associated genes (APC, MUTYH, MLH1, MSH2, MSH6) applying both a custom multigene Ion AmpliSeq NGS panel and conventional Sanger sequencing.

RESULTS

Fourteen pathogenic variants were detected in 13/16 FAP/HNPCC probands (81.3 %); one FAP proband presented two co-existing pathogenic variants, one in APC and one in MUTYH. Thirteen of these 14 pathogenic variants were detected by both NGS and Sanger, while one MSH2 mutation (L280FfsX3) was identified only by Sanger sequencing. This is due to a limitation of the NGS approach in resolving sequences close or within homopolymeric stretches of DNA. To evaluate the performance of our NGS custom panel we assessed its capability to resolve the DNA sequences corresponding to 2225 pathogenic variants reported in the COSMIC database for APC, MUTYH, MLH1, MSH2, MSH6. Our NGS custom panel resolves the sequences where 2108 (94.7 %) of these variants occur. The remaining 117 mutations reside inside or in close proximity to homopolymer stretches; of these 27 (1.2 %) are imprecisely identified by the software but can be resolved by visual inspection of the region, while the remaining 90 variants (4.0 %) are blind spots. In summary, our custom panel would miss 4 % (90/2225) of pathogenic variants that would need a small set of Sanger sequencing reactions to be solved.

CONCLUSIONS

The multiplex NGS approach has the advantage of analyzing multiple genes in multiple samples simultaneously, requiring only a reduced number of Sanger sequences to resolve homopolymeric DNA regions not adequately assessed by NGS. The implementation of NGS approaches in routine diagnostics of familial CRC is cost-effective and significantly reduces diagnostic turnaround times.

Gastric cancer and gene copy number variation: emerging cancer drivers for targeted therapy

Gastric cancer (GC) is among the most common malignancy in the world with poor prognosis and limited treatment options. It has been established that gastric carcinogenesis is caused by a complex interaction between host and environmental factors. Copy number variation (CNV) refers to a form of genomic structural variation that results in abnormal gene copy numbers, including gene amplification, gain, loss and deletion. DNA CNV is an important influential factor for the expression of both protein-coding and non-coding genes, affecting the activity of various signaling pathways. CNV arises as a result of preferential selection that favors cancer development, and thus, targeting the amplified 'driver genes' in GC may provide novel opportunities for personalized therapy. The detection of CNVs in chromosomal or mitochondrial DNA from tissue or blood samples may assist the diagnosis, prognosis and targeted therapy of GC. In this review, we discuss the recent CNV discoveries that shed light on the molecular pathogenesis of GC, with a specific emphasis on CNVs that display diagnostic, prognostic or therapeutic significances in GC.

α-Fetoprotein-Producing Hepatoid Gastric Adenocarcinoma With Osteoclast-Like Giant Cells and Neuroendocrine Differentiation: A Case Study With Molecular Profiling

Here we present the case of a 73-year-old woman with an ulcerated, advanced, hepatoid, and α-fetoprotein-producing poorly differentiated (G3) primary gastric adenocarcinoma pT3 N3a M1 with multinucleated cells and evident neuroendocrine component. This tumor was consistent with giant cell tumor type gastric carcinoma with osteoclast-like giant cells (OGCs). The cancer was HER2 and E-cadherin negative, chromogranin A dispersedly and moderately positive, and strongly α-fetoprotein-positive with evident CK AE1/AE3 immunoreactivity, while OGCs expressed CD68. To provide an insight into the molecular background of this peculiar neoplasm, next-generation sequencing (NGS) was performed to analyze the 50 most frequently mutated oncogenes and tumor suppressors. We detected mutations in the primary tumor in the following genes: KIT, EGFR, PTEN, ATM, and RB1. In the liver metastasis, we revealed mutations in 3 genes: PIK3CA, KIT, and CDKN2A.

Role of the Wnt/β-catenin pathway in gastric cancer: An in-depth literature review

Gastric cancer remains one of the most common cancers worldwide and one of the leading cause for cancer-related deaths. Gastric adenocarcinoma is a multifactorial disease that is genetically, cytologically and architecturally more heterogeneous than other gastrointestinal carcinomas. The aberrant activation of the Wnt/β-catenin signaling pathway is involved in the development and progression of a significant proportion of gastric cancer cases. This review focuses on the participation of the Wnt/β-catenin pathway in gastric cancer by offering an analysis of the relevant literature published in this field. Indeed, it is discussed the role of key factors in Wnt/β-catenin signaling and their downstream effectors regulating processes involved in tumor initiation, tumor growth, metastasis and resistance to therapy. Available data indicate that constitutive Wnt signalling resulting from Helicobacter pylori infection and inactivation of Wnt inhibitors (mainly by inactivating mutations and promoter hypermethylation) play an important role in gastric cancer. Moreover, a number of recent studies confirmed CTNNB1 and APC as driver genes in gastric cancer. The identification of specific membrane, intracellular, and extracellular components of the Wnt pathway has revealed potential targets for gastric cancer therapy. High-throughput “omics” approaches will help in the search for Wnt pathway antagonist in the near future.

Progress in research of gastric intraepithelial neoplasia

Gastric carcinoma is one of the most common malignant tumors in the world, and the accurate diagnosis of precancerous lesions plays an important role in gastric cancer prevention. Intraepithelial neoplasia is a form of precancerous lesion of gastric cancer, and many efforts have been done to explore the relationship between gastric cancer and dysplasia. Recently, there has been much progress in the research of intraepithelial neoplasia, including genetic changes at the molecular level, the eradication of Helicobacter pylori (H. pylori), regular follow-up and endoscopic therapy. All of these will play an important role in clinical management of this condition. However, the etiological mechanism, influencing factors and malignant transformation of GIN are still unclear. Hence, further multi-center and long-term prospective studies are needed to solve these problems.

Retrospective review using targeted deep sequencing reveals mutational differences between gastroesophageal junction and gastric carcinomas

BACKGROUND

Adenocarcinomas of both the gastroesophageal junction and stomach are molecularly complex, but differ with respect to epidemiology, etiology and survival. There are few data directly comparing the frequencies of single nucleotide mutations in cancer-related genes between the two sites. Sequencing of targeted gene panels may be useful in uncovering multiple genomic aberrations using a single test.

METHODS

DNA from 92 gastroesophageal junction and 75 gastric adenocarcinoma resection specimens was extracted from formalin-fixed paraffin-embedded tissue. Targeted deep sequencing of 46 cancer-related genes was performed through emulsion PCR followed by semiconductor-based sequencing. Gastroesophageal junction and gastric carcinomas were contrasted with respect to mutational profiles, immunohistochemistry and in situ hybridization, as well as corresponding clinicopathologic data.

RESULTS

Gastroesophageal junction carcinomas were associated with younger age, more frequent intestinal-type histology, more frequent p53 overexpression, and worse disease-free survival on multivariable analysis. Among all cases, 145 mutations were detected in 31 genes. TP53 mutations were the most common abnormality detected, and were more common in gastroesophageal junction carcinomas (42% vs. 27%, p = 0.036). Mutations in the Wnt pathway components APC and CTNNB1 were more common among gastric carcinomas (16% vs. 3%, p = 0.006), and gastric carcinomas were more likely to have ≥3 driver mutations detected (11% vs. 2%, p = 0.044). Twenty percent of cases had potentially actionable mutations identified. R132H and R132C missense mutations in the IDH1 gene were observed, and are the first reported mutations of their kind in gastric carcinoma.

CONCLUSIONS

Panel sequencing of routine pathology material can yield mutational information on several driver genes, including some for which targeted therapies are available. Differing rates of mutations and clinicopathologic differences support a distinction between adenocarcinomas that arise in the gastroesophageal junction and those that arise in the stomach proper.

Genomic assays for Epstein-Barr virus-positive gastric adenocarcinoma

A small set of gastric adenocarcinomas (9%) harbor Epstein–Barr virus (EBV) DNA within malignant cells, and the virus is not an innocent bystander but rather is intimately linked to pathogenesis and tumor maintenance. Evidence comes from unique genomic features of host DNA, mRNA, microRNA and CpG methylation profiles as revealed by recent comprehensive genomic analysis by The Cancer Genome Atlas Network. Their data show that gastric cancer is not one disease but rather comprises four major classes: EBV-positive, microsatellite instability (MSI), genomically stable and chromosome instability. The EBV-positive class has even more marked CpG methylation than does the MSI class, and viral cancers have a unique pattern of methylation linked to the downregulation of CDKN2A (p16) but not MLH1. EBV-positive cancers often have mutated PIK3CA and ARID1A and an amplified 9p24.1 locus linked to overexpression of JAK2, CD274 (PD-L1) and PDCD1LG2 (PD-L2). Multiple noncoding viral RNAs are highly expressed. Patients who fail standard therapy may qualify for enrollment in clinical trials targeting cancer-related human gene pathways or promoting destruction of infected cells through lytic induction of EBV genes. Genomic tests such as the GastroGenus Gastric Cancer Classifier are available to identify actionable variants in formalin-fixed cancer tissue of affected patients.

Individual risk stratification of gastric cancer: evolving concepts and their impact on clinical practice

Gastric cancer (GC) is the third leading cause of cancer-related death worldwide and it mostly develops in long-standing inflammatory conditions, and Helicobacter pylori-gastritis, in particular. Despite the increasing understanding of both the phenotypic alterations and the molecular mechanisms occurring during GC multi-step carcinogenesis, no reliable biomarker is available to be reliably implemented into GC secondary prevention strategies. Multidisciplinary diagnostic approaches integrating endoscopy, serology, histology and molecular profiling currently appears as the most appropriate approach for patients' stratification into different GC risk classes.

Mixed adenoneuroendocrine carcinomas of the gastrointestinal tract: targeted next-generation sequencing suggests a monoclonal origin of the two components

BACKGROUND

Mixed adenoneuroendocrine carcinomas (MANECs) of the gastrointestinal tract are rare neoplasms characterized by coexisting exocrine and neuroendocrine neoplastic components. MANECs' histogenetic classification and molecular characterization remain unclear, significantly affecting the identification of innovative therapeutic options for these tumors.

METHODS

The exocrine and neuroendocrine components of 6 gastrointestinal MANECs were microdissected and subjected to the simultaneous mutation assessment in selected regions of 54 cancer-associated genes using Ion Torrent semiconductor-based next-generation sequencing. Sanger sequencing and immunohistochemistry were used as validation of the mutational status.

RESULTS

A total of 20 driver gene somatic mutations were observed among the 12 neoplastic components investigated. In 11 of 12 (91.7%) samples, at least one mutation was detected; 7 samples (58.3%) were found to have multiple mutations. TP53 gene mutations were the most frequent genetic alterations observed in the series, occurring in 11/12 samples (91.7%). Somatic mutations in other genes were detected at lower frequencies: ATM, CTNNB1, ERBB4, JAK3, KDR, KRAS, RB1.

CONCLUSIONS

Five of the 6 MANECs presented an overlapping mutational profile in both components, suggesting a monoclonal origin of the two MANEC components.

Reporting tumor molecular heterogeneity in histopathological diagnosis

BACKGROUND

Detection of molecular tumor heterogeneity has become of paramount importance with the advent of targeted therapies. Analysis for detection should be comprehensive, timely and based on routinely available tumor samples.

AIM

To evaluate the diagnostic potential of targeted multigene next-generation sequencing (TM-NGS) in characterizing gastrointestinal cancer molecular heterogeneity.

METHODS

35 gastrointestinal tract tumors, five of each intestinal type gastric carcinomas, pancreatic ductal adenocarcinomas, pancreatic intraductal papillary mucinous neoplasms, ampulla of Vater carcinomas, hepatocellular carcinomas, cholangiocarcinomas, pancreatic solid pseudopapillary tumors were assessed for mutations in 46 cancer-associated genes, using Ion Torrent semiconductor-based TM-NGS. One ampulla of Vater carcinoma cell line and one hepatic carcinosarcoma served to assess assay sensitivity. TP53, PIK3CA, KRAS, and BRAF mutations were validated by conventional Sanger sequencing.

RESULTS

TM-NGS yielded overlapping results on matched fresh-frozen and formalin-fixed paraffin-embedded (FFPE) tissues, with a mutation detection limit of 1% for fresh-frozen high molecular weight DNA and 2% for FFPE partially degraded DNA. At least one somatic mutation was observed in all tumors tested; multiple alterations were detected in 20/35 (57%) tumors. Seven cancers displayed significant differences in allelic frequencies for distinct mutations, indicating the presence of intratumor molecular heterogeneity; this was confirmed on selected samples by immunohistochemistry of p53 and Smad4, showing concordance with mutational analysis.

CONCLUSIONS

TM-NGS is able to detect and quantitate multiple gene alterations from limited amounts of DNA, moving one step closer to a next-generation histopathologic diagnosis that integrates morphologic, immunophenotypic, and multigene mutational analysis on routinely processed tissues, essential for personalized cancer therapy.

Targeted next-generation sequencing of cancer genes dissects the molecular profiles of intraductal papillary neoplasms of the pancreas

Intraductal neoplasms are important precursors to invasive pancreatic cancer and provide an opportunity to detect and treat pancreatic neoplasia before an invasive carcinoma develops. The diagnostic evaluation of these lesions is challenging, as diagnostic imaging and cytological sampling do not provide accurate information on lesion classification, the grade of dysplasia or the presence of invasion. Moreover, the molecular driver gene mutations of these precursor lesions have yet to be fully characterized. Fifty-two intraductal papillary neoplasms, including 48 intraductal papillary mucinous neoplasms (IPMNs) and four intraductal tubulopapillary neoplasms (ITPNs), were subjected to the mutation assessment in 51 cancer-associated genes, using ion torrent semiconductor-based next-generation sequencing. P16 and Smad4 immunohistochemistry was performed on 34 IPMNs and 17 IPMN-associated carcinomas. At least one somatic mutation was observed in 46/48 (96%) IPMNs; 29 (60%) had multiple gene alterations. GNAS and/or KRAS mutations were found in 44/48 (92%) of IPMNs. GNAS was mutated in 38/48 (79%) IPMNs, KRAS in 24/48 (50%) and these mutations coexisted in 18/48 (37.5%) of IPMNs. RNF43 was the third most commonly mutated gene and was always associated with GNAS and/or KRAS mutations, as were virtually all the low-frequency mutations found in other genes. Mutations in TP53 and BRAF genes (10% and 6%) were only observed in high-grade IPMNs. P16 was lost in 7/34 IPMNs and 9/17 IPMN-associated carcinomas; Smad4 was lost in 1/34 IPMNs and 5/17 IPMN-associated carcinomas. In contrast to IPMNs, only one of four ITPNs had detectable driver gene (GNAS and NRAS) mutations. Deep sequencing DNA from seven cyst fluid aspirates identified 10 of the 13 mutations detected in their associated IPMN. Using next-generation sequencing to detect cyst fluid mutations has the potential to improve the diagnostic and prognostic stratification of pancreatic cystic neoplasms.