An update on gastric cancer

Gastric Cancer Survivorship: Multidisciplinary Management, Best Practices and Opportunities

PURPOSE

Gastric cancer is the 5th most common malignancy worldwide. As early detection increases and treatments for gastric cancer improve, the number of gastric cancer survivors grows.

METHODS

Here, we review the diagnosis and management of gastric cancer and discuss important considerations for gastric cancer survivorship including cancer surveillance, weight loss, malnutrition, fatigue, specific complications related to surgery and radiation, quality of life in gastric cancer survivorship, health behavior, and models of survivorship.

RESULTS

Multimodality therapy with chemotherapy and surgery can result in chronic toxicities in multiple organ systems. This emphasizes the need for a multidisciplinary survivorship care model including cancer surveillance, management of chronic toxicities, and optimization of modifiable risk factors with long-term involvement of appropriate providers.

CONCLUSION

Adequately caring for gastric cancer survivors requires a coordinated, multidisciplinary approach.

Combining Raman spectroscopy and machine learning to assist early diagnosis of gastric cancer

Gastric cancers, with gastric adenocarcinoma (GAC) as the most common histological type, cause quite a few of deaths. In order to improve the survival rate after GAC treatment, it is important to develop a method for early detection and therapy support of GAC. Raman spectroscopy is a potential tool for probing cancer cell due to its real-time and non-destructive measurements without any additional reagents. In this study, we use Raman spectroscopy to examine GAC samples, and distinguish cancerous gastric mucosa from normal gastric mucosa. Average Raman spectra of two groups show differences at 750 cm^-1, 1004 cm^-1, 1449 cm^-1, 1089-1128 cm^-1, 1311-1367 cm^-1 and 1585-1665 cm^-1, These peaks were assigned to cytochrome c, phenylalanine, phospholipid, collagen, lipid, and unsaturated fatty acid respectively. Furthermore, we build a SENet-LSTM model to realize the automatic classification of cancerous gastric mucosa and normal gastric mucosa, with all preprocessed Raman spectra in the range of 400-1800 cm^-1 as input. An accuracy 96.20% was achieved. Besides, by using masking method, we found the Raman spectral features which determine the classification and explore the explainability of the classification model. The results are consistent with the conclusions obtained from the average spectrum. All results indicate it is potential for pre-cancerous screening to combine Raman spectroscopy and machine learning.

Gastric adenocarcinoma: A one-of-a-kind etiology of autoimmune paraneoplastic encephalitis

INTRODUCTION AND IMPORTANCE

Paraneoplastic neurologic syndromes are a group of neurologic disorders that can affect any part of the nervous system and are mediated by immune pathogens produced by cancer. These disorders occur distant to a malignant tumor and are not caused by metastasis, nutritional disorders or side effects of therapy related to the tumor.

CLINICAL FINDINGS

We present the case of a 47-year-old male patient who was admitted to the emergency department due to 1 month of neurological impairment including generalized tonic-clonic movements. He was admitted to the institution and was taken to multiple neurologic tests, all of which were normal, including a negative panel for onconeural antibodies. He persisted with seizures and was taken to a 24-hour video electroencephalogram which showed features consistent with moderate encephalopathy and focal epileptiform activity, which evolved into status epilepticus. Suspecting immune - mediated encephalitis, a therapeutic trial was started with methylprednisolone and plasma exchange, and a positron emission tomography was indicated. The positron emission tomography showed in the brain regions of marked hypometabolism and hypermetabolic thickening of gastric infiltrative aspect fundocorporal topography. Upper gastrointestinal endoscopy revealed in the subcardial region a mass-like lesion with an ulcer-infiltrative appearance, pathology showed an adenocarcinoma.

CONCLUSION

Autoimmune encephalitis as a paraneoplastic neurological syndrome of a gastric adenocarcinoma have been documented in few patients in the literature. It is important to describe and recognize clinical findings in this cases to be able to suspect malignancy and thus have early diagnosis, start treatment promptly and avoid irreversible neurological sequelae.

DOK5 as a Prognostic Biomarker of Gastric Cancer Immunoinvasion: A Bioinformatics Analysis

Background

Docking protein 5 (DOK5) is a member of the docking protein group of membrane proteins and is an adapter protein involved in signal transduction. Nevertheless, the role of DOK5 expression in the prognosis of gastric cancer (GC) remains unclear.

Methods

In this study, clinical prognostic parameters and survival data related to DOK5, in patients with GC, were analyzed using bioinformatics analysis comprising Oncomine and TIMER, UALCAN database, Kaplan-Meier plotter, GEPIA, GSEA, DAVID, and cBioPortal websites.

Results

In our study, GC contained various DOK5 expressions, which forecasted poor survival outcomes. Moreover, our research showed that high DOK5 could predict high-level infiltration of several GC immune cells, as evidenced by M1, TAM, M2, B cell, and T cell failure. Hence, DOK5 might become a new gastric cancer biomarker and therapeutic target. In the following analysis, in order to explore the prognostic value of DOK5 in GC, more clinical trials are needed to validate our results.

Conclusions

Through multiple database verifications, DOK5 was found to be part of the pathogenic genes for GC. Thus, it can change the formation and progression of tumors by acting on human immunity.

Next-Generation Sequencing Analysis of Gastric Cancer Identifies the Leukemia Inhibitory Factor Receptor as a Driving Factor in Gastric Cancer Progression and as a Predictor of Poor Prognosis

Gastric cancer (GC) is the third cause of cancer-related mortality worldwide. Nevertheless, because GC screening programs are not cost-effective, most patients receive diagnosis in the advanced stages, when surgical options are limited. Peritoneal dissemination occurs in approximately one-third of patients with GC at the diagnosis and is a strong predictor of poor outcome. Despite the clinical relevance, biological and molecular mechanisms underlying the development of peritoneal metastasis in GC remain poorly defined. Here, we report results of a high-throughput sequencing of transcriptome expression in paired samples of non-neoplastic and neoplastic gastric samples from 31 patients with GC with or without peritoneal carcinomatosis. The RNA-seq analysis led to the discovery of a group of highly upregulated or downregulated genes, including the leukemia inhibitory factor receptor (LIFR) and one cut domain family member 2 (ONECUT2) that were differentially modulated in patients with peritoneal disease in comparison with patients without peritoneal involvement. Both LIFR and ONECUT2 predicted survival at univariate statistical analysis. LIFR and its major ligand LIF belong to the interleukin-6 (IL-6) cytokine family and have a central role in immune system regulation, carcinogenesis, and dissemination in several human cancers. To confirm the mechanistic role of the LIF/LIFR pathway in promoting GC progression, GC cell lines were challenged in vitro with LIF and a LIFR inhibitor. Among several GC cell lines, MKN45 cells displayed the higher expression of the receptor, and their exposure to LIF promotes a concentration-dependent proliferation and epithelial-mesenchymal transition (EMT), as shown by modulation of relative expression of E-cadherin/vimentin along with JAK and STAT3 phosphorylation and acquisition of a migratory phenotype. Furthermore, exposure to LIF promoted the adhesion of MKN45 cells to the peritoneum in an ex vivo assay. These effects were reversed by the pharmacological blockade of LIFR signaling. Together, these data suggest that LIFR might have a major role in promoting disease progression and peritoneal dissemination in patients with GC and that development of LIF/LIFR inhibitors might have a role in the treatment of GC.

Disruption of Her2-Induced PD-L1 Inhibits Tumor Cell Immune Evasion in Patient-Derived Gastric Cancer Organoids

Simple Summary

HER2 may contribute to immune evasion in gastric cancer that is associated with PD-L1 expression. Autologous organoid/immune cell co-cultures serve as an appropriate in vitro model to study the effects of anti-HER2 targeted therapy in combination with anti-PD1 immune checkpoint inhibition and may be used as an ex vivo tool for precision medicine.

Abstract

(1) Background: The expression of programmed death-ligand 1 (PD-L1), which interacts with programmed cell death protein 1 (PD-1) on cytotoxic T lymphocytes (CTLs), enables tumors to escape immunosurveillance. The PD-1/PD-L1 interaction results in the inhibition of CTL proliferation, and effector function, thus promoting tumor cell evasion from immunosurveillance and cancer persistence. Despite 40% of gastric cancer patients exhibiting PD-L1 expression, only a small subset of patients responds to immunotherapy. Human epidermal growth factor receptor2 (HER2) is one of the critical regulators of several solid tumors, including metastatic gastric cancer. Although half of PD-L1-positive gastric tumors co-express HER2, crosstalk between HER2 and PD-1/PD-L1 in gastric cancer remains undetermined. (2) Methods: Human gastric cancer organoids (huTGOs) were generated from biopsied or resected tissues and co-cultured with CTLs and myeloid-derived suppressor cells (MDSCs). Digital Spatial Profiling (DSP) was performed on FFPE tissue microarrays of numerous gastric cancer patients to examine the protein expression of immune markers. (3) Results: Knockdown of HER2 in PD-L1/HER2-positive huTGOs led to a concomitant decrease in PD-L1 expression. Similarly, in huTGOs/immune cell co-cultures, PD-L1 expression decreased in huTGOs and was correlated with an increase in CTL proliferation which enhanced huTGO death. Treatment with Nivolumab exhibited similar effects. However, a combinatorial treatment with Mubritinib and Nivolumab was unable to inhibit HER2 expression in co-cultures containing MDSCs. (4) Conclusions: Our study suggested that co-expression of HER2 and PD-L1 may contribute to tumor cell immune evasion. In addition, autologous organoid/immune cell co-cultures can be exploited to effectively screen responses to a combination of anti-HER2 and immunotherapy to tailor treatment for gastric cancer patients.

RPL35A is a key promotor involved in the development and progression of gastric cancer

BACKGROUND

RPL35A has been reported to work as a biomarker in tumor angiogenesis. However, little work has been performed on the expression level and functional importance of RPL35A in gastric cancer (GC).

METHODS

The protein expression level of RPL35A was detected by immunohistochemical staining and western blot analysis. The Celigo cell counting assay was used to assess cell proliferation. Both the wound healing assay and the transwell assay were conducted to evaluate cell migration. Flow cytometric analysis was utilized to detect cell apoptosis and cell cycle. A mouse xenograft model was constructed for in vivo experiments.

RESULTS

The results demonstrated that RPL35A expression was abundantly up-regulated in GC and positively related to tumor infiltrate. In addition, RPL35A knockdown could significantly suppress cell proliferation, migration, enhance apoptosis and arrest cell cycle. The in vivo study also verified the inhibitory effects of RPL35A knockdown on GC tumorigenesis.

CONCLUSIONS

The above mentioned results indicated that the knockdown of RPL35A might be a considerable therapeutic strategy for the treatment of gastric cancer.

Genomic analysis and clinical implications of immune cell infiltration in gastric cancer

The immune infiltration of patients with gastric cancer (GC) is closely associated with clinical prognosis. However, previous studies failed to explain the different subsets of immune cells involved in immune responses and diverse functions. The present study aimed to uncover the differences in immunophenotypes in a tumor microenvironment (TME) between adjacent and tumor tissues and to explore their therapeutic targets. In our study, the relative proportion of immune cells in 229 GC tumor samples and 22 paired matched tissues was evaluated with a Cell type Identification By Estimating Relative Subsets Of known RNA Transcripts (CIBERSORT) algorithm. The correlation between immune cell infiltration and clinical information was analyzed. The proportion of 22 immune cell subsets was assessed to determine the correlation between each immune cell type and clinical features. Three molecular subtypes were identified with ‘CancerSubtypes’ R-package. Functional enrichment was analyzed in each subtype. The profiles of immune infiltration in the GC cohort from The Cancer Genome Atlas (TCGA) varied significantly between the 22 paired tissues. TNM stage was associated with M1 macrophages and eosinophils. Follicular helper T cells were activated at the late stage. Monocytes were associated with radiation therapy. Three clustering processes were obtained via the ‘CancerSubtypes’ R-package. Each cancer subtype had a specific molecular classification and subtype-specific characterization. These findings showed that the CIBERSOFT algorithm could be used to detect differences in the composition of immune-infiltrating cells in GC samples, and these differences might be an important driver of GC progression and treatment response.

Escudo de Blumer: signo diagnóstico de la diseminación a distancia del cáncer gástrico difuso

Introducción. Se conoce como escudo de Blumer al engrosamiento neoplásico del fondo de saco de Douglas,palpable al tacto rectal como una protrusión en forma de resalte, presente en pacientes afectados por carcinomas con infiltración difusa. A pesar de haber sido descrito hace más de un siglo, se trata de un proceso diagnosticado infrecuentemente y con escasa mención en la literatura científica. Es preciso tener un alto nivel de sospecha clínica para correlacionar los síntomas pélvicos con la presencia de un tumor, habitualmente gástrico.Casos clínicos. Presentamos dos pacientes con hallazgo de escudo de Blumer, asociado a cáncer gástrico difuso, uno como diagnóstico primario de enfermedad metastásica y otro como recidiva de la enfermedad, meses después de ser operado. Ambos casos presentan un complejo proceso diagnóstico, en el que prima la sospecha clínica, apoyado sobre pruebas de imagen como tomografía computarizada y resonancia nuclear magnética, ya que tanto las biopsias obtenidas por endoscopia, como las biopsias intraoperatorias fueron negativas. Discusión. En el escudo de Blumer, las células tumorales infiltran el fondo de saco de Douglas de forma difusa por debajo de la serosa, sin necesidad de que existan implantes macroscópicamente visibles en el peritoneo visceral.La infiltración tumoral puede afectar extrínsecamente al recto, causando una estenosis del mismo, lo que produce sintomatología pélvica inespecífica, como tenesmo rectal y proctalgia. Por lo tanto, este ominoso proceso debe ser sospechado en pacientes con sintomatología pélvica, que presenten o hayan presentado cáncer gástrico.

Lack of National Adoption of Evidence-Based Treatment for Resectable Gastric Adenocarcinoma

BACKGROUND

Level 1 evidence for multimodal treatment of resectable gastric adenocarcinoma from the Intergroup 0116 (2001) and MAGIC (2006) trials demonstrated survival benefit of adjuvant chemoradiation (CRT) and perioperative chemotherapy, respectively. We evaluated the adoption of evidence-based treatment in the post-MAGIC era and its impact on survival.

METHODS

A total of 7058 patients with resectable gastric adenocarcinoma undergoing definitive surgical resection between 2004 and 2015 were analyzed using the National Cancer Database.

RESULTS

Over the study period, the proportion of patients receiving adjuvant CRT decreased from 19.1% to 9.1%, while perioperative chemotherapy increased from 1.9% to 28.6%. Utilization of perioperative chemotherapy surpassed adjuvant CRT in 2011. Evidence-based treatment (either perioperative chemotherapy or adjuvant CRT) had better overall survival (OS) than other treatments for clinical stage II-III patients (p < 0.05). On multivariate analysis of the whole study period, evidence-based treatments were associated with better OS (HR 0.67 [0.60-0.74], p < 0.05). Only 360/1262 (28.5%) patients in the perioperative chemotherapy group completed postoperative therapy, which was associated with improved OS (p < 0.05). For clinical stage III patients (n = 2402), only 806 (33.6%) received evidence-based treatment, while 487 (22.2%) underwent surgery alone. On multivariate analysis of these patients between 2010 and 2015, both perioperative chemotherapy (HR 0.49 [0.35-0.68]) and adjuvant CRT (HR 0.31 [0.21-0.44]) were associated with better OS than surgery alone (p < 0.05).

CONCLUSIONS

Since the INT-0116 and MAGIC trials, utilization of evidence-based treatments for resectable gastric adenocarcinoma has increased, with perioperative chemotherapy surpassing adjuvant CRT as the preferred practice. However, overall utilization of these regimens remains quite low nationally despite association with improved OS.

Overview of Epstein-Barr-Virus-Associated Gastric Cancer Correlated with Prognostic Classification and Development of Therapeutic Options

Gastric cancer (GC) is a deadly disease with poor prognosis that is characterized by heterogeneity. New classifications based on histologic features, genotypes, and molecular phenotypes, for example, the Cancer Genome Atlas subtypes and those by the Asian Cancer Research Group, help understand the carcinogenic differences in GC and have led to the identification of an Epstein–Barr virus (EBV)-related GC subtype (EBVaGC), providing new indications for tailored treatment and prognostic factors. This article provides a review of the features of EBVaGC and an update on the latest insights from EBV-related research with a particular focus on the strict interaction between EBV infection and the gastric tumor environment, including the host immune response. This information may help increase our knowledge of EBVaGC pathogenesis and the mechanisms that sustain the immune response of patients since this mechanism has been demonstrated to offer a survival advantage in a proportion of patients with GC.

Does Roux-en-Y Construction Really Bring Benefit of Type 2 Diabetes Mellitus Remission After Gastrectomy in Patients with Gastric Cancer? A Systematic Review and Meta-Analysis

INTRODUCTION

To evaluate whether the extent of gastrectomy or the reconstruction method brings benefit of type 2 diabetes mellitus (T2DM) remission after gastrectomy in patients with gastric cancer.

METHODS

PUBMED, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library were searched to find eligible studies published from inception to July 31, 2020.

RESULTS

A total of nine studies (1424 patients) were included. At the first year and the end of follow-up time after gastrectomy, the total gastrectomy group had better T2DM remission than the subtotal gastrectomy group, and the Roux-en-Y reconstruction (R-Y) group had better T2DM remission compared with the non-R-Y group. There was no difference between R-Y and non-R-Y in terms of subtotal gastrectomy (OR 1.08, 95% CI 0.63-1.84, P = 0.78). However, total gastrectomy with R-Y had better T2DM remission than subtotal gastrectomy with R-Y (OR 2.75, 95% CI 1.19-6.35, P = 0.02).

CONCLUSION

Total gastrectomy with R-Y had better T2DM remission. The extent of gastrectomy rather than the reconstruction method might play an important role in T2DM remission after gastrectomy in patients with gastric cancer.

MAEL Cancer-Testis Antigen as a Diagnostic Marker in Primary Stages of Gastric Cancer with Helicobacter pylori Infection

PURPOSE

Gastric cancer (GC) is the third leading cause of cancer related deaths in the world. Cancer testis antigens (CTAs) are involved in tumor progression of various cancers. These markers have not any expression or minimally expression in normal tissues, highlighting them as efficient methods for molecular targeted therapy. In the present study, we assessed the role of MAEL as a CTA in biology of GC and risk of Helicobacter Pylori (H pylori) infection.

METHODS

Levels of MAEL mRNA expression in 80 GC tumor tissues were compared to their corresponding normal margins using the real-time polymerase chain reaction.

RESULTS

There was a significant correlation between MAEL expression and tumor stage (p = 0.050). There were also significant correlations between MAEL expression and tumor grade (p = 0.015) and depth of invasion (p = 0.030) among the H pylori negative cases.

CONCLUSIONS

MAEL is probably associated with aggressiveness of primary-stage tumors and can be introduced as an efficient marker for the early detection and also H pylori infected tumors in GC patients.

High expression of miR-135b predicts malignant transformation and poor prognosis of gastric cancer

AIMS

MiR-135b is a downstream effector of oncogenic signaling pathways. This study aimed to reveal the underlying regulation and significance of miR-135b in gastric cancer.

MATERIALS AND METHODS

The influence of Wnt and PI3K/AKT signaling pathways on the transcriptional activation of the miR-135b promoter was determined by dual-luciferase reporter assays. In vitro experiments, including the cell counting kit-8 (CCK8) assay, 5-ethynyl-2'-deoxyuridine (EdU) staining, flow cytometry analysis and malignant phenotype profiles, were conducted to determine the oncogenic role of miR-135b in gastric cancer. To analyze the clinical significance of miR-135b in gastric cancer, the expression profile of miR-135b in tissue specimens and plasma was examined by quantitative real-time PCR (qRT-PCR).

KEY FINDINGS

Oncogenic signaling pathways represented by Wnt and PI3K/AKT promoted the transcriptional activation of the miR-135b promoter in gastric cancer. Downregulation of miR-135b inhibited proliferation, promoted apoptosis, and suppressed the migratory, invasive, and adherent abilities as well as the cancer stem cell phenotype of gastric cancer cells. High expression of miR-135b in gastric cancer tissues was tightly associated with poor prognosis and malignant transformation represented by metastasis of gastric cancer. The miR-135b level in the plasma of gastric cancer patients was significantly higher than that in healthy individuals.

SIGNIFICANCE

MiR-135b is a potential downstream effector of the Wnt and PI3K/AKT signaling pathways in gastric cancer. High expression of miR-135b may predict malignant transformation and poor prognosis of gastric cancer. This study reveals the potential role of miR-135b as a target for the early diagnosis and therapy of gastric cancer.

Short-term outcomes of robotic- versus laparoscopic-assisted Total Gastrectomy for advanced gastric Cancer: a propensity score matching study

BACKGROUND

Few studies have been designed to evaluate the short-term outcomes between robotic-assisted total gastrectomy (RATG) and laparoscopy-assisted total gastrectomy (LATG) for advanced gastric cancer (AGC). The purpose of this study was to assess the short-term outcomes of RATG compared with LATG for AGC.

METHODS

We retrospectively evaluated 126 and 257 patients who underwent RATG or LATG, respectively. In addition, we performed propensity score matching (PSM) analysis between RATG and LATG for clinicopathological characteristics to reduce bias and compared short-term surgical outcomes.

RESULTS

After PSM, the RATG group had a longer mean operation time (291.14 ± 59.18 vs. 270.34 ± 52.22 min, p = 0.003), less intraoperative bleeding (154.37 ± 89.68 vs. 183.77 ± 95.39 ml, p = 0.004) and more N2 tier RLNs (9.07 ± 5.34 vs. 7.56 ± 4.50, p = 0.016) than the LATG group. Additionally, the total RLNs of the RATG group were almost significantly different compared to that of the LATG group (34.90 ± 13.05 vs. 31.91 ± 12.46, p = 0.065). Moreover, no significant differences were found between the two groups in terms of the length of incision, proximal resection margin, distal resection margin, residual disease and postoperative hospital stay. There was no significant difference in the overall complication rate between the RATG and LATG groups after PSM (23.8% vs. 28.6%, p = 0.390). Grade II complications accounted for most of the complications in the two cohorts after PSM. The conversion rates were 4.55 and 8.54% in the RATG and LATG groups, respectively, with no significant difference (p = 0.145), and the ratio of splenectomy were 1.59 and 0.39% (p = 0.253). The mortality rates were 0.8 and 0.4% for the RATG and LATG groups, respectively (p = 1.000).

CONCLUSION

This study demonstrates that RATG is comparable to LATG in terms of short-term surgical outcomes.

Identification of Lesional Tissues and Nonlesional Tissues in Early Gastric Cancer Endoscopic Submucosal Dissection Specimens Using a Fiber Optic Raman System

Aim

To identify lesional and nonlesional tissues from early gastric cancer (EGC) patients by Raman spectroscopy to build a diagnostic model and effectively diagnose EGC.

Method

Specimens were collected by endoscopic submucosal dissection from 13 patients with EGC, and 55 sets of standard Raman spectral data (each integrated 10 times) were obtained using the fiber optic Raman system; there were 33 sets of lesional tissue data, including 18 sets of high-grade intraepithelial neoplasia (HGIN) data and 15 sets of adenocarcinoma data, and 22 sets of nonlesional tissue data. After the preprocessing steps, the average Raman spectrum was obtained.

Results

The nonlesional tissues showed peaks at 891 cm⁻¹, 1103 cm⁻¹, 1417 cm⁻¹, 1206 cm⁻¹, 1234 cm⁻¹, 1479 cm⁻¹, 1560 cm⁻¹, and 1678 cm⁻¹. Compared with the peaks corresponding to nonlesional tissues, the peaks of the lesional tissues shifted by different magnitudes, and a new characteristic peak at 1324 cm⁻¹ was observed. Comparing the peak intensity ratio and the integral energy ratio of the lesional tissues with those of the nonlesional tissues revealed a significant difference between the two groups (independent-samplest-test, P < 0.05). Considering the peak intensity ratio of I1560 cm⁻¹/I1103 cm⁻¹ as a diagnostic indicator, the accuracy, sensitivity, and specificity of diagnosing EGC were 98.8%, 93.9%, and 91.9%, respectively. Considering the integral energy ratio (noncontinuous frequency band and continuous frequency band) as a diagnostic indicator, the accuracy, sensitivity, and specificity of diagnosing EGC were 99.2-99.6%, 93.9-97.0%, and 95.5%, respectively.

Conclusions

The integral energy ratio of the Raman spectrum could be considered an effective indicator for the diagnosis of EGC.

A novel circular RNA circFN1 enhances cisplatin resistance in gastric cancer via sponging miR-182-5p

Cisplatin (CDDP) is commonly used for gastric cancer (GC) chemotherapy. However, after several CDDP-based treatment cycles, patients always acquire chemotherapy resistance, which limits the overall clinical efficacy of the treatment. Clarification of the mechanisms responsible for CDDP resistance is required to improve therapeutic outcomes for patients. Circular RNAs (circRNAs) are noncoding RNAs involved in the pathogenesis of cancer, although their role in the mechanism underlying CDDP resistance in GC remains unknown. In the present study, we explored the underlying roles of circRNAs in the modulation of CDDP resistance in CDDP-sensitive and CDDP-resistant human GC cells. Using RNA sequencing and quantitative reverse transcription polymerase chain reaction, expression of circFN1 (originating from exons 10, 11, and 12 of the FN1 gene hsa_circ_0058147) was higher in CDDP-resistant GC cells and tissues. CircFN1 upregulation in GC patients treated by CDDP was significantly correlated with aggressive biological behavior. CircFN1 promoted viability and inhibited apoptosis of GC cells exposed to CDDP in vivo and in vitro. Furthermore, circFN1 suppressed GC cell apoptosis by "sponging" miR-182-5p. These findings demonstrate the involvement of circFN1 in CDDP resistance of GC and implicate circFN1 as a therapeutic target for GC patients treated with CDDP. It provides novel evidence of the function of circRNAs as microRNA sponges and highlight a potential therapeutic target for extinguishing CDDP resistance in patients with GC.

Hedgehog signaling induces PD-L1 expression and tumor cell proliferation in gastric cancer

Tumor cells expressing programmed cell death ligand 1 (PD-L1) interact with PD-1 on CD8+ cytotoxic T lymphocytes (CTLs) to inhibit CTL effector function. In gastric cancer, the mechanism regulating PD-L1 is unclear. The Hedgehog (Hh) signaling pathway is reactivated in various cancers including gastric. Here we tested the hypothesis that Hh-induced PD-L1 inactivates effector T cell function and allows gastric cancer cell proliferation. Mouse organoids were generated from tumors of a triple-transgenic mouse model engineered to express an activated GLI2 allele, GLI2A, in Lgr5-expressing stem cells, (mTGOs) or normal mouse stomachs (mGOs). Bone marrow-derived dendritic cells (DCs) were pulsed with conditioned media collected from normal (mGOCM) or cancer (mTGOCM) organoids. Pulsed DCs and CTLs were then co-cultured with either mGOs or mTGOs in the presence of PD-L1 neutralizing antibody (PD-L1Ab). Human-derived gastric cancer organoids (huTGOs) were used in drug and xenograft assays. Hh/Gli inhibitor, GANT-61 significantly reduced the expression of PD-L1 and tumor cell proliferation both in vivo and in vitro. PD-L1Ab treatment induced tumor cell apoptosis in mTGO/immune cell co-cultures. GANT-61 treatment sensitized huTGOs to standard-of-care chemotherapeutic drugs both in vivo and in vitro. Thus, Hh signaling mediates PD-L1 expression in gastric cancer cells and subsequently promotes tumor proliferation.

Etiologic and Clinicopathological Correlates of Gastric Carcinoma in the Egyptian Delta

We aimed at evaluation of the clinicoepidemiologic data of patients with gastric carcinoma in the Egyptian Delta as regards the etiologic factors, behavior, presenting symptoms, and tumor location, grade, and stage with highlighting of the treatment modalities, survival, and prognostic factors. Three hundred cases with gastric carcinoma were enrolled, diagnosed, and treated in a tertiary oncology center in the Egyptian Delta. Data were collected as regards the etiology, presenting symptoms, family history, comorbid conditions, treatment modalities, responses, recurrences, and survival outcomes. Univariate and multivariate analyses were done to correlate the different clinicopathologic factors with the overall and disease-free survivals. Male to female ratio was 2:1. The median age was 43 years. The main tumor location was in the gastric body. Pain was the commonest presenting symptom (36%). Most of the cases were stage IV (42.0%). Only 49% of cases were operable. On multivariate analysis, age more than 60 years, performance status 3-4, high grade, diffuse type, T4 lesions, N2 and N3, and the presence of metastasis were independently associated with worse OS. We report a clinic-epidemiologic study of gastric carcinoma in the Egyptian delta; the age at presentation was a decade earlier than that recorded in the USA and Europe; most of the cases were sporadic, located mostly at the body. Most of the cases were presented at stage IV with poor response to neoadjuvant therapy with a poorer overall survival than that recorded in the USA and Europe.

An Organoid-Based Preclinical Model of Human Gastric Cancer

BACKGROUND & AIMS

Our goal was to develop an initial study for the proof of concept whereby gastric cancer organoids are used as an approach to predict the tumor response in individual patients.

METHODS

Organoids were derived from resected gastric cancer tumors (huTGOs) or normal stomach tissue collected from sleeve gastrectomies (huFGOs). Organoid cultures were treated with standard-of-care chemotherapeutic drugs corresponding to patient treatment: epirubicin, oxaliplatin, and 5-fluorouracil. Organoid response to chemotherapeutic treatment was correlated with the tumor response in each patient from whom the huTGOs were derived. HuTGOs were orthotopically transplanted into the gastric mucosa of NOD scid gamma mice.

RESULTS

Whereas huFGOs exhibited a half maximal inhibitory concentration that was similar among organoid lines, divergent responses and varying half maximal inhibitory concentration values among the huTGO lines were observed in response to chemotherapeutic drugs. HuTGOs that were sensitive to treatment were derived from a patient with a near complete tumor response to chemotherapy. However, organoids resistant to treatment were derived from patients who exhibited no response to chemotherapy. Orthotropic transplantation of organoids resulted in the engraftment and development of human adenocarcinoma. RNA sequencing revealed that huTGOs closely resembled the patient's native tumor tissue and not commonly used gastric cancer cell lines and cell lines derived from the organoid cultures.

CONCLUSIONS

The treatment of patient-derived organoids alongside patients from whom cultures were derived will ultimately test their usefulness to predict individual therapy response and patient outcome.

Mouse-Derived Gastric Organoid and Immune Cell Co-culture for the Study of the Tumor Microenvironment

The interaction between the receptor, programmed cell death protein 1 (PD-1) and ligand, programmed cell death 1 (PD-L1) is known to inhibit CD8+ cytotoxic T lymphocyte proliferation, survival, and effector function. The result of this interaction leads to evasion of immune surveillance by tumors and subsequently cancer cell proliferation. Immunotherapy via PD-L1 blockade is used for a variety of malignancies, yet the prognostic value of immune checkpoint inhibition for the treatment of gastric cancer remains controversial. Thus, preclinical models that would predict the efficacy of such therapy in a subgroup of gastric cancer patients would be an advancement in the personalized treatment of this disease. Three-dimensional organoid cultures have not only been used to investigate the mechanisms regulating development and disease, but have also been used for high-throughput drug screening for targeted personalized therapy. Here we present the methodology for the co-culture of mouse-derived gastric cancer organoids with autologous immune cells specifically for the study of PD-L1/PD-1 interactions within the tumor microenvironment in vitro.

MAEL contributes to gastric cancer progression by promoting ILKAP degradation

The cancer-testis gene MAEL is involved in the development and progression of bladder, liver and colorectal cancers. However, its role in other cancers is unclear. By systematically analyzing transcriptomics and genomics data from various cancer databases, we identified that the MAEL gene is aberrantly elevated in gastric cancer (GC) tissues and that its expression is strongly negatively correlated with DNA methylation (Pearson's correlation coefficient = −0.675). Survival analysis revealed that MAEL expression may serve as a prognostic marker for GC patients (overall survival: hazard ratio [HR] = 1.54, p = 1.2E-4; first progression: HR = 1.51, p = 8.7E-4). In vitro and in vivo experiments demonstrated that silencing MAEL expression in the GC cell lines HGC-27 and AGS inhibits proliferation, colony formation, migration, invasion and growth of xenograft tumors, whereas MAEL overexpression exerts the opposite effects in the normal gastric cell line GES-1. Mechanistically, MAEL promotes the lysosome-dependent degradation of the protein phosphatase ILKAP, leading to increased phosphorylation of its substrates (p38, CHK1 and RSK2). Moreover, adenovirus-mediated ILKAP overexpression reversed the oncogenic effects of MAEL in vitro and in vivo. Taken together, these results indicate that MAEL exerts its oncogenic function by promoting ILKAP degradation in the GC.

Evolving role of FDG-PET/CT in prognostic evaluation of resectable gastric cancer

Gastric cancer (GC) remains a leading cause of cancer death worldwide. Radical gastrectomy is the only potentially curative treatment, and perioperative adjuvant therapies may improve the prognosis after curative resection. Prognosis largely depends on the tumour stage and histology, but the host systemic inflammatory response (SIR) to GC may contribute as well, as has been determined for other malignancies. In GC patients, the potential utility of positron emission tomography/computed tomography (PET/CT) with the imaging radiopharmaceutical ¹⁸F-fluorodeoxyglucose (FDG) is still debated, due to its lower sensitivity in diagnosing and staging GC compared to other imaging modalities. There is, however, growing evidence that FDG uptake in the primary tumour and regional lymph nodes may be efficient for predicting prognosis of resected patients and for monitoring tumour response to perioperative treatments, having prognostic value in that it can change therapeutic strategies. Moreover, FDG uptake in bone marrow seems to be significantly associated with SIR to GC and to represent an efficient prognostic factor after curative surgery. In conclusion, PET/CT technology is efficient in GC patients, since it is useful to integrate other imaging modalities in staging tumours and may have prognostic value that can change therapeutic strategies. With ongoing improvements, PET/CT imaging may gain further importance in the management of GC patients.

LncRNA ZEB1-AS1 predicts unfavorable prognosis in gastric cancer

OBJECTIVES

LncRNA ZEB1 Antisense 1 (ZEB1-AS1) has been suggested to be an oncogenic role in human hepatocellular carcinoma, osteosarcoma, glioma and esophageal carcinoma progression. However, the clinical significance and biological function of ZEB1-AS1 in gastric cancer is poorly understood.

METHODS

Levels of ZEB1-AS1 expression in gastric cancer tissues and cell lines were detected by qRT-PCR. Loss-of-function and gain-of-function studies were conducted to explore the biological function of ZEB1-AS1 in gastric cancer cells migration, invasion and EMT process. Rescued-function studies were performed to explore the association between ZEB1-AS1 and ZEB1 in gastric cancer cells migration, invasion and EMT process.

RESULTS

ZEB1-AS1 was overexpressed in gastric cancer tissues and cell lines, and correlated with malignant status and prognosis in gastric cancer patients. ZEB1-AS1 regulated gastric cancer cells migration, invasion and EMT process. ZEB1-AS1 positively regulated ZEB1 expression in gastric cancer cells, and had a strongly positive correlation with ZEB1 expression in gastric cancer tissues. Rescued-function studies showed ZEB1 was critical for ZEB1-AS1 induced gastric cancer cells migration, invasion and EMT process.

CONCLUSIONS

ZEB1-AS1 served as oncogenic roles in the regulation of gastric cancer cells migration, invasion and EMT process through modulating ZEB1.

Initiation and Maintenance of Gastric Cancer: A Focus on CD44 Variant Isoforms and Cancer Stem Cells

Gastric cancer is the third most common cause of cancer-related death. Although the incidence of gastric cancer in the United States is relatively low, it remains significantly higher in some countries, including Japan and Korea. Interactions between cancer stem cells and the tumor microenvironment can have a substantial impact on tumor characteristics and contribute to heterogeneity. The mechanisms responsible for maintaining malignant cancer stem cells within the tumor microenvironment in human gastric cancer are largely unknown. Tumor cell and genetic heterogeneity contribute to either de novo intrinsic or the therapy-induced emergence of drug-resistant clones and eventual tumor recurrence. Although chemotherapy often is capable of inducing cell death in tumors, many cancer patients experience recurrence because of failure to effectively target the cancer stem cells, which are believed to be key tumor-initiating cells. Among the population of stem cells within the stomach that may be targeted during chronic Helicobacter pylori infection and altered into tumor-initiating cells are those cells marked by the cluster-of-differentiation (CD)44 cell surface receptor. CD44 variable isoforms (CD44v) have been implicated as key players in malignant transformation whereby their expression is highly restricted and specific, unlike the canonical CD44 standard isoform. Overall, CD44v, in particular CD44v9, are believed to mark the gastric cancer cells that contribute to increased resistance for chemotherapy- or radiation-induced cell death. This review focuses on the following: the alteration of the gastric stem cell during bacterial infection, and the role of CD44v in the initiation, maintenance, and growth of tumors associated with gastric cancer.