Sensitivity Of Gastric Cancer Research Articles

New genetic insights into immunotherapy outcomes in gastric cancer via single-cell RNA sequencing and random forest model

ObjectiveThe high mortality rate of gastric cancer, traditionally managed through surgery, underscores the urgent need for advanced therapeutic strategies. Despite advancements in treatment modalities, outcomes remain suboptimal, necessitating the identification of novel biomarkers to predict sensitivity to immunotherapy. This study focuses on utilizing single-cell sequencing for gene identification and developing a random forest model to predict immunotherapy sensitivity in gastric cancer patients.MethodsDifferentially expressed genes were identified using single-cell RNA sequencing (scRNA-seq) and gene set enrichment analysis (GESA). A random forest model was constructed based on these genes, and its effectiveness was validated through prognostic analysis. Further, analyses of immune cell infiltration, immune checkpoints, and the random forest model provided deeper insights.ResultsHigh METTL1 expression was found to correlate with improved survival rates in gastric cancer patients (P = 0.042), and the random forest model, based on METTL1 and associated prognostic genes, achieved a significant predictive performance (AUC = 0.863). It showed associations with various immune cell types and negative correlations with CTLA4 and PDCD1 immune checkpoints. Experiments in vitro and in vivo demonstrated that METTL1 enhances gastric cancer cell activity by suppressing T cell proliferation and upregulating CTLA4 and PDCD1.ConclusionThe random forest model, based on scRNA-seq, shows high predictive value for survival and immunotherapy sensitivity in gastric cancer patients. This study underscores the potential of METTL1 as a biomarker in enhancing the efficacy of gastric cancer immunotherapy.

Abstract 2525: A novel splicing factor, SPF45/RBM17, might influence 5-FU resistance of gastric carcinoma

Abstract Background: SPF45/RBM17 was identified as a factor required for splicing of short introns in mRNA precursors transcribed from DNA. SPF45 is also thought to be related to anti-cancer drug resistance, suggesting that the SPF45 molecule has a different resistance mechanism from the conventional mechanism of anticancer drug resistance. In this study, we investigated the relationship between SPF45 expression and anticancer drug sensitivity in gastric cancer. Materials and Methods: A total of 654 gastric cancer cases were used in this study. SPF45 expression was examined using immunohistochemistry. The correlation between SPF45 expression and clinicopathological factors was evaluated. Results: Of the 654 gastric cancer cases, 240 were positive for SPF45 expression and 414 were negative for expression. There was no significant difference in age and gender between the two groups, but SPF45-positive cases were significantly more frequent in patients with undifferentiation (p = 0.004), lymphatic invasion (p = 0.013) and venous invasion (p < 0.001). As for anticancer drug therapy, 215 of the 654 patients with gastric cancer who underwent radical surgery were treated with adjuvant chemotherapy and 94 patients with advanced recurrent gastric cancer were treated with chemotherapy. 75 SPF45-positive-patients who received 5FU-based adjuvant chemotherapy (S-1, UFT, 5-DFUR) after surgery had significantly worse recurrence-free survival (RFS) than 140 SPF45-negative-patients (p=0.027). 102 SPF45-positive-patients who didn’t receive adjuvant chemotherapy was no significantly different in RFS from 203 SPF45-negative-patients. In the 215 patients who received adjuvant chemotherapy, 81 DPD-positive patients had significantly worse RFS than DPD-negative patients (p=0.043). In the 305 patients who didn’t receive adjuvant chemotherapy, there was no significant difference in RFS between DPD-positive patients and DPD-negative patients (p=0.880). SPF45-positive cases were significantly more frequent in patients with DPD expression (p < 0.001).In 94 patients with advanced recurrent gastric cancer treated with chemotherapy, there were 42 recurrent patients and 52 stage IV patients. 50 of SPF45-positive patients had significantly worse progression-free survival than 44 of SPF45-negative patients (p < 0.001). Regarding overall response, SPF45-positive-patients had worse response rate than SPF45-negative-patients (p=0.016). In SPF45 positive group, 20.0% responded (CR in 0% and PR in 20%) and 80.0% did not respond (SD in 52% and PD in 28%). In SPF45 negative group, 42.6% responded (CR in 0% and PR in 42.6%) and 57.4% did not respond (SD in 46.8% and PD in 10.6%) Conclusion: Our results suggest that the splicing factor SPF45 influences anticancer drugs such as 5-FU resistance in gastric cancer. Acknowledgments: We thank Kazuhiro Fukumura and Akila Mayeda, Fujita Health University. Citation Format: Koji Maruo, Masakazu Yashiro, Takashi Sakuma, Gen Tsujio, Yasuhiro Fukui, Hiroaki Kasashima, Kiyoshi Maeda. A novel splicing factor, SPF45/RBM17, might influence 5-FU resistance of gastric carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2525.

Transcription factor E2F7 activates PKMYT1 to partially suppress adriamycin sensitivity in gastric cancer through the MAPK signaling pathway.

Adriamycin resistance remains an obstacle to gastric cancer chemotherapy treatment. Objective: The objective of this study was to study the role and mechanism of transcription factor E2F7 in sensitivity to ADM chemotherapeutic agents in gastric cancer. Cell viability and cell sensitivity were assessed by CCK-8 and IC50 values of ADM were calculated. The impact of ADM on cellular proliferative capacity was assessed through colony formation assay. The binding relationship between E2F7 and PKMYT1 was then verified by dual luciferase assay and chromatin immunoprecipitation assay. ERK1/ERK2 and p-ERK1/p-ERK2 protein expression levels were detected by western blot. In both gastric cancer tissue and ADM-resistant cells, a conspicuous upregulation of E2F7 and PKMYT1 was observed. Upregulated PKMYT1 was notably enriched in the MAPK signaling pathway. Enhanced levels of E2F7 were shown to not only drive gastric cancer cell proliferation but also engender a reduction in the sensitivity of these cells to ADM. Furthermore, PKMYT1 emerged as a downstream target of E2F7. Activation of E2F7 culminated in the transcriptional upregulation of PKMYT1, and silencing E2F7 reversed the inhibitory impact of PKMYT1 overexpression on ADM sensitivity in gastric cancer cells. E2F7/PKMYT1 axis might promote the proliferation and partially inhibit ADM sensitivity of gastric cancer cells by activating the MAPK pathway.

Mitochondrial dysfunction and cisplatin sensitivity in gastric cancer: GDF15 as a master player.

Gastric cancer, a major global health concern, poses challenges in effective treatment, notably due to chemoresistance. This study investigates the role of growth/differentiation factor-15 (GDF-15) in mitochondrial dysfunction and its impact on cisplatin sensitivity in gastric cancer cells. In this issue of The FEBS Journal, Wang etal. demonstrate that GDF15 upregulation is associated with cisplatin insensitivity, mediated by the ATF4-CHOP pathway and reactive oxygen species-activated general control nonderepressible 2 [Wang S-F etal. (2023) FEBS J, https://doi.org/10.1111/febs.16992]. Connecting these insights, we explore the broader implications of GDF15 expression in the aging-cancer axis, particularly its involvement in cellular senescence and the senescence-associated secretory phenotype (SASP). This study suggests that GDF15 released by senescent cells could contribute to tumor progression, indicating potential avenues for therapeutic intervention by targeting senescent cells and their SASP. While the study provides valuable insights into mitigating cisplatin resistance, further research is crucial to fully understand the role of GDF15 in the tumor microenvironment and its potential feedback loops promoting tumorigenesis.

Bayesian diagnostic test evaluation and true prevalence estimation of malnutrition in gastric cancer patients

Malnutrition is prevalent among gastric cancer (GC) patients, necessitating early assessment of nutritional status to guide monitoring and interventions for improved outcomes. We aim to evaluate the accuracy and prognostic capability of three nutritional tools in GC patients, providing insights for clinical implementation. The present study is an analysis of data from 1308 adult GC patients recruited in a multicenter from July 2013 to July 2018. Nutritional status was assessed using Nutritional Risk Screening 2002 (NRS-2002), Patient-Generated Subjective Global Assessment (PG-SGA) and Global Leadership Initiative on Malnutrition (GLIM) criteria. Bayesian latent class model (LCM) estimated the malnutrition prevalence of GC patients, sensitivity and specificity of nutritional tools. Cox regression model analyzed the relationship between nutritional status and overall survival (OS) in GC patients. Among 1308 GC patients, NRS-2002, PG-SGA, and GLIM identified 50.46%, 76.76%, and 68.81% as positive, respectively. Bayesian LCM analysis revealed that PG-SGA had the highest sensitivity (0.96) for malnutrition assessment, followed by GLIM criteria (0.78) and NRS-2002 (0.65). Malnutrition or being at risk of malnutrition were identified as independent prognostic factors for OS. Use any of these tools improved survival prediction in TNM staging system. PG-SGA is the most reliable tool for diagnosing malnutrition in GC patients, whereas NRS-2002 is suitable for nutritional screening in busy clinical practice. Given the lower sensitivity of NRS-2002, direct utilization of GLIM for nutritional assessment may be necessary. Each nutritional tool should be associated with a specific course of action, although further research is needed.

Activation of Glycolysis by MCM10 Increases Stemness and Paclitaxel Resistance in Gastric Cancer Cells.

Chemotherapy is an essential avenue for curing malignancies; however, tumor cells acquire resistance to chemotherapeutic agents, eventually leading to chemotherapy failure. At present, paclitaxel (PTX) resistance seriously hinders the therapeutic efficacy of gastric cancer (GC). Investigating the molecular mechanism of PTX resistance in GC is critical. This study attempted to delineate the impact of MCM10 on GC resistance to PTX and its mechanism in GC. The expression of minichromosome maintenance complex component 10 (MCM10) in GC tissues, its enrichment pathways, and its correlation with glycolysis marker genes and stemness index (mRNAsi) were analyzed in a bioinformatics effort. Real-time quantitative polymerase chain reaction was used to assay the expression of MCM10 in cells. Cell counting kit-8 (CCK-8) was used to analyze cell viability and calculate the 50% inhibitor concentration (IC50) value. Western blot was used to measure the expression of MCM10, Hexokinase 2 (HK2) and stemness-related factors in cells. Sphere-forming assay was performed to study cell sphere-forming ability. Seahorse XF 96 was utilized to measure cell extracellular acidification and oxygen consumption rates. The content of glycolysisrelated products was tested with corresponding kits. MCM10 was significantly upregulated in GC and enriched in the glycolysis pathway, and it was positively correlated with both glycolysis-related genes and stemness index. High expression of MCM10 increased sphere-forming ability of drug-resistant cells and GC resistance to PTX. The stimulation of PTX resistance and drug-resistant cell stemness in GC by high MCM10 expression was mediated by the glycolysis pathway. MCM10 was upregulated in GC and drove stemness and PTX resistance in GC cells by activating glycolysis. These findings generated new insights into the development of PTX resistance in GC, implicating that targeting MCM10 may be a novel approach to improve GC sensitivity to PTX chemotherapy.

P70S6K/Akt dual inhibitor DIACC3010 is efficacious in preclinical models of gastric cancer alone and in combination with trastuzumab

The PI3K-Akt-mTOR (PAM) pathway is implicated in tumor progression in many tumor types, including metastatic gastric cancer (GC). The initial promise of PAM inhibitors has been unrealized in the clinic, presumably due, in part, to the up-regulation of Akt signaling that occurs when the pathway is inhibited. Here we present that DIACC3010 (formerly M2698), an inhibitor of two nodes in the PAM pathway, p70S6K and Akt 1/3, blocks the pathway in in vitro and in vivo preclinical models of GC while providing a mechanism that inhibits signaling from subsequent Akt up-regulation. Utilizing GC cell lines and xenograft models, we identified potential markers of DIACC3010-sensitivity in Her2-negative tumors, i.e., PIK3CA mutations, low basal pERK, and a group of differentially expressed genes (DEGs). The combination of DIACC3010 and trastuzumab was evaluated in Her2-positive cell lines and models. Potential biomarkers for the synergistic efficacy of the combination of DIACC3010 + trastuzumab also included DEGs as well as a lack of up-regulation of pERK. Of 27 GC patient-derived xenograft (PDX) models tested in BALB/c nu/nu mice, 59% were sensitive to DIACC3010 + trastuzumab. Of the 21 HER2-negative PDX models, DIACC3010 significantly inhibited the growth of 38%. Altogether, these results provide a path forward to validate the potential biomarkers of DIACC3010 sensitivity in GC and support clinical evaluation of DIACC3010 monotherapy and combination with trastuzumab in patients with HER2- negative and positive advanced GCs, respectively.

LHPP promotes the intracellular reactive oxygen species accumulation and sensitivity of gastric cancer to cisplatin via JNK and p38 MAPK pathways.

Cisplatin is the first-line chemotherapy drug for the treatment of gastric cancer (GC) patients. However, GC patients who are resistant to cisplatin often do not benefit from it. Therefore, finding a key molecule that affects cisplatin sensitivity is expected to enhance the efficacy of cisplatin in GC treatment. The human GC cell lines SGC-7901 and BGC-823 were used. The protein chip array was used to screen the cisplatin-resistance genes from the complete response and non-complete response GC patients' tissues, then, the differential gene expression analysis, GO function annotation analysis, and KEGG pathway enrichment analysis were performed. The GC tissue chip in the GEO database was analyzed to screen the target gene. Flow cytometry, Hoechst 33342 staining assay, Western Blot, MTT, tumor sphere formation, cell cycle, and apoptosis assays were performed to explore the effect of Phospholysine Phosphohistidine Inorganic Pyrophosphate Phosphatase (LHPP) on the apoptosis, stemness, and reactive oxygen species (ROS) accumulation of cisplatin-resistant GC cells treated with cisplatin. In vivo, the cisplatin-resistant GC cell lines transfected with pcDNA-LHPP or si-LHPP were injected subcutaneously into mice to construct GC subcutaneous xenograft GC models. Based on protein chip array and bioinformatics analysis, it was found that LHPP is the core molecule in the cisplatin resistance regulatory network in GC, and its expression is down-regulated in GC cisplatin-resistant tissues and cells. In vitro and in vivo experimental results show that the up-regulated expression of LHPP is closely related to the increase in sensitivity of GC to cisplatin. Mechanically, we found that overexpression of LHPP may inhibit the activation of the JNK and p38 MAPK pathways, promote cisplatin-induced ROS accumulation, suppress stemness, and enhance the sensitivity of GC to cisplatin. Up-regulation of LHPP may inhibit the activation of the JNK and p38 MAPK pathways, attenuate stemness, and enhance the accumulation of intracellular ROS, thereby promoting cisplatin-mediated GC cell apoptosis and enhancing cisplatin sensitivity.

Integrated single-cell RNA sequencing analysis reveals a mesenchymal stem cell-associated signature for estimating prognosis and drug sensitivity in gastric cancer.

Mesenchymal stem cells (MSCs) play an important role in regulating all stages of the immune response, angiogenesis, and transformation of matrix components in the tumor microenvironment. The aim of this study was to identify the prognostic value of MSC-related signatures in patients with gastric cancer (GC). MSC marker genes were identified by analyzing single-cell RNA sequencing (scRNA-seq) data for GC from the Gene Expression Omnibus (GEO) database. Using bulk sequencing data from the Cancer Genome Atlas-Stomach adenocarcinoma (TCGA-STAD), as a training cohort, and data from GEO, as a validation cohort, we developed a risk model consisting of MSC prognostic signature genes, and classified GC patients into high- and low-MSC risk subgroups. Multifactorial Cox regression was used to evaluate whether MSC prognostic signature was an independent prognostic factor. An MSC nomogram was constructed combining clinical information and risk grouping. Subsequently, we evaluated the effect of MSC prognostic signature on immune cell infiltration, antitumor drugs and immune checkpoints and verified the expression of MSC prognostic signature by in vitro cellular assays. In this study, 174 MSC marker genes were identified by analyzing scRNA-seq data. We identified seven genes (POSTN, PLOD2, ITGAV, MMP11, SDC2, MARCKS, ANXA5) to construct MSC prognostic signature. MSC prognostic signature was an independent risk factor in the TCGA and GEO cohorts. GC patients in the high-MSC risk group had worse prognoses. In addition, the MSC nomogram has a high clinical application value. Notably, the MSC signature can induce the development of a poor immune microenvironment. GC patients in the high MSC-risk group were more sensitive to anticancer drugs and tended to have higher levels of immune checkpoint markers. In qRT-PCR assays, the MSC signature was more highly expressed in GC cell lines. The MSC marker gene-based risk signature developed in this study can not only be used to predict the prognosis of GC patients, but also has the potential to reflect the efficacy of antitumor therapies.

Integrin-based prognostic model predicts survival, immunotherapy response, and drug sensitivity in gastric cancer

BackgroundExtracellular matrix (ECM) acts as a physical barrier to tumors, resulting in the lysis or delay of drug delivery. Integrins (ITGs) are essential for tumor cell-ECM interactions. Thus, we established a novel prognostic model to predict overall survival, immunotherapy benefits, and therapeutic agents in gastric cancer (GC) based on ITGs-related ECM landscape. MethodsUsing the TCGA-STAD dataset, we studied the genetic and transcriptional changes of ITGs. We used a merged cohort for ITGs survival analysis and determined molecular pattern clusters using consensus unsupervised clustering methodology. We confirmed the distinct ECM landscape between constructed clusters by performing gene set variation and Kaplan-Meier analysis. We utilized prognostic differentially expressed genes between clusters to develop a prognostic model utilizing logistic least absolute shrinkage and selection operator cox regression analysis, followed by stepwise multivariate Cox analysis in the training dataset. The model was validated by receiver operating characteristic curves and Kaplan-Meier analysis in the testing dataset and seven validation datasets. We compared our model to 35 previously published models. To analyze immune infiltration, we used multiple algorithms, which were further confirmed by single-cell RNA-sequencing and fluorescent multiplex immunohistochemistry. We explored tumor mutation burden (TMB), microsatellite instability-high (MSI-H) grade, immunotherapy response, chemotherapy sensitivity, and clinical significance between the low-risk and high-risk groups. Finally, we assessed the risk score in five reported molecular subtypes. ResultsThe two ITGs-related clusters were identified, and their ECM landscapes were distinct. The prognostic model was constructed and had shown stable performance in internal and external validation. In addition, our model outperformed 35 previously published models. High-risk patients had a bad prognostic ECM landscape, high stromal cell inflammation, a lower TMB, a lower MSI-H grade, a worse tumor stage, a worse response to immunotherapy, and less sensitivity to chemotherapy. In five reported molecular subtypes, the worse subtypes showed a higher risk score. ConclusionsThe prognostic model could be an effective and promising tool for predicting prognosis and therapy response in GC patients.

Depletion of circPDSS1 inhibits ITGA11 production to confer cisplatin sensitivity through miR-515-5p in gastric cancer

Chemoresistance limits cisplatin (DDP)-mediated treatment for gastric cancer (GC). Circular RNA (circRNA) acts an important role in chemoresistance. However, the underlying mechanism of circPDSS1 regulating DDP sensitivity in GC remains unclear. The expression patterns of circPDSS1, miR-515-5p and integrin subunit alpha 11 (ITGA11) were analyzed by qRT-PCR. Protein expression was checked by Western blotting analysis. Cell viability was investigated by 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell proliferation was evaluated by colony formation assay and 5-ethynyl-2′-deoxyuridine (EdU) assay. The analysis of cell apoptosis, migration and invasion was performed by flow cytometry analysis and transwell assays. Dual-luciferase reporter assay and RNA immunoprecipitation assay were conducted to identify the associations among circPDSS1, miR-515-5p and ITGA11. In vivo assay was implemented using a xenograft mouse model assay. CircPDSS1 and ITGA11 expression were significantly upregulated, whereas miR-515-5p was downregulated in DDP-resistant GC tissues and cells in comparison with controls. CircPDSS1 depletion reduced DDP resistance, cell proliferation, migration and invasion but induced cell apoptosis in DDP-resistant GC cells. CircPDSS1 directly bound to miR-515-5p. CircPDSS1-mediated actions were dependent on the regulation of miR-515-5p. Besides, miR-515-5p was associated with ITGA11, and circPDSS1 regulated ITGA11 expression by binding to miR-515-5p. Overexpression of miR-515-5p improved DDP sensitivity owing to the downregulation of ITGA11. Further, circPDSS1 mediated DDP sensitivity by regulating miR-515-5p and ITGA11 in vivo. CircPDSS1 conferred DDP resistance through the miR-515-5p/ITGA11 axis in GC cells.

Utility of serum interleukin-18 (IL-18) as a tumour marker in gastric cancer

Introduction: Gastric cancer (GC) is the fourth most prevailing cancer globally, attributing to more than 70% of cases in developing countries. Protein cancer biomarkers, such as CEA, CA- 125, AFP and PSA, are clinically helpful diagnostic tools, but they have low sensitivity and specificity for GC. Hence, it is essential to discover better markers for GC diagnosis. Interleukin-18 (IL-18) is the member of Interleukin-1 family. It is hypothesized to be a potent inhibitor of gastric acid secretion, leading to gastric atrophy and causing an increased risk of GC. This study was to evaluate the association between the serum IL-18 in GC. Methodology: We included cases who underwent UGI Scopy and were proven to have GC histopathologically. The patients who presented to the out-patient who underwent UGI scopy and was found to have no growth were selected as controls. Twenty-eight cases and 84 control sample sizes were derived from nMaster V2. Blood samples from patients and controls were collected, and serum IL-18 levels were estimated using a solid-phase sandwich ELISA method. Results: We found that the cut-off value of serum IL-18 was 85.59 pg/ml, had a sensitivity of 63.1% and specificity of 57.1%, with a positive predictive value of 81.5% and a negative predictive value of 34% in diagnosing GC. The study plotted the receiver operating characteristic curve against IL-18 for sensitivity and specificity. Statistically, we found through the Area Under the Curve (AUC) that the rise in serum IL-18 levels was a poor indicator of GC with a p-value of 0.078. Conclusion: Statistically, a cut-off of 85.59pg/ml showed good sensitivity and specificity; however, the probability was insignificant, suggesting that IL-18 may not be of diagnostic importance. Studies with a larger sample size are required to further probe into the usefulness of estimating IL-18 in GC.

Identification and Validation of METTL3-Related Molecules for Predicting Prognosis and Efficacy of Immunotherapy in Gastric Cancer Based on m6A Methylome and Transcriptome Sequencing Analysis.

Abnormal N6-methyladenosine (m6A) modification levels caused by METTL3 have been identified to be a critical regulator in human cancers, and its roles in the immune microenvironment and the relationship between targeted therapy and immunotherapy sensitivity in gastric cancer (GC) remain poorly understood. In this study, we assessed the transcriptome-wide m6A methylation profile after METTL3 overexpression by m6A sequencing and RNA sequencing in BGC-823 cells. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to analyze the function of core targets of METTL3. Eighteen methylation core molecules were identified in GC patients by combining transcriptome and methylome sequencing. GC patients can be separated into two subtypes based on the expression of 18 methylation core molecules. Furthermore, subgroup analysis showed that patients with different subtypes had a different OS, PFS, stage, grade, and TMB. Gene set enrichment analysis (GSEA) showed that immune-related pathways were enriched among subtype A. The ESTIMATE analysis suggested that the extent of infiltration of immune cells was different in two subtypes of GC patients. Tumor Immune Dysfunction and Exclusion (TIDE) and The Cancer Immunome Atlas (TCIA) database also showed that there were significant differences in the efficacy of immunotherapy among different types of GC patients. Altogether, our results reveal that METTL3-mediated m6A methylation modification is associated with the immune microenvironment and the effects of immunotherapy in GC patients. Our findings provide novel insights for clinicians in the diagnosis and optimal treatment of GC patients.

Integrative Analysis Identifies a TNFα-Derived Gene Signature for Predicting Prognosis, Tumor Immunity, and Treatment Sensitivity in Gastric Cancer.

Objective: TNF-α is an essential pro-inflammatory cytokine in the tumor microenvironment of gastric cancer (GC), possessing a key biological and clinical impact. Here, we conducted an integrative analysis of the role of TNFα-derived genes in GC prognosis and precision medicine. Methods: We pooled transcriptome and clinical features of GC patients from TCGA and GSE15459 projects. TNFα signaling was quantified through the ssGSEA algorithm, and TNFα-derived genes were screened with WGCNA. Thereafter, a LASSO model was established. The somatic mutation was analyzed across GC specimens. Immune cell infiltrations were inferred through ESTIMATE and ssGSEA algorithms, followed by measuring the immune checkpoint expression. AKR1B1, CPVL, and CTSL expressions were measured in gastric mucosal cells GES-1 and GC cells (HGC-27, MKN-28, and AGS) through RT-qPCR and Western blotting. Results: A TNFα-derived gene signature (containing AKR1B1, CPVL, and CTSL) was developed for GC. A high-risk score indicated more undesirable OS, DFS, DSS, and PFS outcomes. Time-independent ROC curves and multivariate cox regression models confirmed that the signature reliably and independently predicted GC prognosis. Additionally, risk scores displayed significant correlations to more severe histological grades and pathological stages. A low-risk score was characterized by increased somatic mutation, while a high-risk score was characterized by immune and stromal activation, enhanced immune cell infiltrations, and increased expression of immune checkpoint molecules. Experimental results confirmed the significant upregulation of AKR1B1, CPVL, and CTSL in GC cells. Conclusion: Collectively, stratification based on the TNFα-derived gene signature might enable GC patients to predict prognosis, benefit from immunotherapy, and assist in formulating novel therapeutic regimens.

Characterization of RNA modifications in gastric cancer to identify prognosis-relevant gene signatures.

Most human genes have diverse transcript isoforms, which mainly arise from alternative cleavage and polyadenylation (APA) at 3' ends. N7-methylguanosine (m7 G) is also an essential epigenetic modification at the 5' end. However, the contribution of these two RNA modifications to the development, prognosis, regulation mechanisms, and drug sensitivity of gastric cancer (GC) is unclear. The expression data of 2412 patients were extracted from 12 cohorts and the RNA modification patterns of 20 marker genes were systematically identified into phenotypic clusters using the unsupervised clustering approach. Following that, we developed an RNA modification model (RMscore) to quantify each GC patient's RNA modification index. Finally, we examined the correlation between RMscore and clinical features such as survival outcomes, molecular subtypes identified by the Asian Cancer Research Group (ACRG), posttranscriptional regulation, and chemotherapeutic sensitivity in GC. The samples were categorized into two groups on the basis of their RMscore: high and low. The group with a low RMscore had a bad prognosis. Moreover, the low RMscore was associated with KRAS, Hedgehog, EMT, and TGF-β signaling, whereas a high RMscore was related to abnormal cell cycle signaling pathway activation. The findings also revealed that the RMscore contributes to the regulation of the miRNA-mRNA network. Drug sensitivity analysis revealed that RMscore is associated with the response to some anticancer drugs. The RMscore model has the potential to be a useful tool for prognosis prediction in patients with GC. A comprehensive investigation of APA-RNA and m7 G-RNA modifications may reveal novel insights into the epigenetics of GC and aid in the development of more effective treatment strategies.

Curcumol enhances cisplatin sensitivity of gastric cancer: involvement of microRNA-7 and the nuclear factor-kappa B/snail family transcriptional repressor 1 axis

ABSTRACT Cisplatin is a primary chemotherapeutic drug for gastric cancer (GC) patients, but the drug resistance remains the leading cause of treatment failure and high mortality. Curcumol is a bioactive sesquiterpenoid that has reportedly been linked to cisplatin sensitivity in GC. This study focuses on the exact functions of curcumol in the cisplatin sensitivity of GC cells and the molecules of action. The curcumol treatment reduced the viability and migration and enhanced cisplatin sensitivity of GC cells in a dose-dependent manner. Microarray analysis suggested that microRNA-7 (miR-7) was the most upregulated miRNA in GC cells after curcumol treatment. The Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that the curcumol-affected genes, including the target genes of miR-7, were enriched in the nuclear factor-kappa B (NF-κB) pathway, whose activity was suppressed after curcumol treatment. miR-7 was found to target and suppress RELA proto-oncogene (RELA, also known as p65), a NF-κB subunit. Downregulation of miR-7 blocked the sensitizing effects of curcumol on cells to cisplatin and led to increased expression of NF-κB p65 and snail family transcriptional repressor 1 (SNAIL). Further downregulation of RELA enhanced, whereas upregulation of SNAIL suppressed the sensitivity again. In summary, this study suggests that curcumol sensitizes GC cells to cisplatin via miR-7 and the suppression of the NF-κB/SNAIL axis. The findings may offer new thoughts that curcumol in combination with cisplatin might be a useful strategy for GC management.

Circular RNA mitochondrial translation optimization 1 correlates with less lymph node metastasis, longer disease-free survival, and higher chemotherapy sensitivity in gastric cancer.

ObjectiveCircular‐mitochondrial translation optimization 1 (circ‐MTO1) inhibits the progression of gastric cancer by regulating the growth, apoptosis, and invasion of tumor cells. However, its clinical potential as a biomarker for gastric cancer remains to be further evaluated. This study aimed to assess circ‐MTO1 expression and its correlation with clinical features and prognosis in gastric cancer patients, as well as the effect of circ‐MTO1 on the sensitivity to chemotherapy in gastric cancer cells.MethodsCirc‐MTO1 in tumor and adjacent tissues of 97 gastric cancer patients undergoing resection was examined by reverse transcription‐quantitative polymerase chain reaction. HGC‐27 and NCI‐N87 cells transfected by circ‐MOT1 overexpression plasmid (OE‐circ‐MOT1) and negative control (OE‐NC) were treated with 0‒6.4 μM oxaliplatin. Relative cell viability was detected using Cell Counting Kit‐8.ResultsCirc‐MTO1 was insufficiently expressed in gastric tumor tissue (median (interquartile range): 0.403 (0.288‒0.518)) compared with adjacent tissue (median (interquartile range): 1.000 (0.715‒1.524)) (p < 0.001). Besides, tumor circ‐MTO1 was correlated with less lymph node metastasis (p = 0.014) and low TNM stage (p = 0.039), while was not correlated with demographic features or other clinical characteristics (all p > 0.05). Furthermore, tumor circ‐MTO1 high expression was independently correlated with prolonged disease‐free survival (DFS) (p = 0.013, adjusted hazard ratio (95% confidential interval): 0.314 (0.126‒0.782)), but was not correlated with overall survival (p > 0.05). Lastly, in gastric cancer cells, OE‐circ‐MTO1 apparently decreased relative cell viabilities at oxaliplatin concentrations of 0.4, 0.8, 1.6, and 3.2 μM (all p < 0.05).ConclusionCirc‐MTO1 correlates with less lymph node metastasis, prolonged DFS, and improved chemotherapy sensitivity in gastric cancer.

MiR-874-3p represses the migration and invasion yet promotes the apoptosis and cisplatin sensitivity via being sponged by long intergenic non-coding RNA 00922 (LINC00922) and targeting Glycerophosphodiester Phosphodiesterase Domain Containing 5 (GDPD5) in gastric cancer cells

ABSTRACT Our study mainly reports the specific mechanisms of microRNA (miR)-874-3p on drug resistance in gastric cancer (GC). Clinical specimen was collected. The upstream long non-coding RNA (lncRNA) and the downstream gene of miR-874-3p were predicted using bioinformatic analysis with the results being ascertained with dual-luciferase reporter assay. The viability, apoptosis, migration and invasion of transfected GC cells with or without cisplatin (DDP) treatment were evaluated by Cell Counting Kit-8 (CCK-8), flow cytometric, Scratch, and Transwell assays. An animal xenograft model was constructed. Expressions of long intergenic non-coding RNA 00922 (LINC00922), miR-874-3p and potential target genes were quantified by quantitative real-time polymerase-chain reaction (qRT-PCR) and Western blot. MiR-874-3p, which was lower-expressed in drug-resistant GC tissues and cells, was upregulated to repress the viability, migration and invasion but enhance the apoptosis and sensitivity in GC cells with or without DDP resistance. Downregulation of miR-874-3p eliminated the effects of silenced LINC00922, a upstream lncRNA of miR-874-3p, on cell viability, apoptosis, migration and invasion, as well as the expressions of Glycerophosphodiester Phosphodiesterase Domain Containing 5 (GDPD5) and the downstream gene of miR-874-3p in DDP-resistant GC cells. GDPD5 silencing diminished the effects of miR-874-3p downregulation on GDPD5 expression, viability, migration and invasion of DDP-resistant GC cells. Additionally, LINC00922 silencing enhanced the inhibitory effect of DDP on tumor growth, whereas reversing the effects of DDP on LINC00922, miR-874-3p and GDPD5 expressions in tumors. MiR-874-3p, an miRNA, which is sponged by LINC00922 and targets GDPD5, inhibits the GC progression yet enhances the DDP sensitivity in GC.

Ubiquitylation of cyclin C by HACE1 regulates cisplatin-associated sensitivity in gastric cancer.

BackgroundCyclin C (CCNC) was reported to take part in regulating mitochondria‐derived oxidative stress under cisplatin stimulation. However, its effect in gastric cancer is unknown. This study aimed to investigate the role of cyclin C and its ubiquitylation in regulating cisplatin resistance in gastric cancer.MethodsThe interaction between HECT domain and ankyrin repeat‐containing E3 ubiquitin‐protein ligase 1 (HACE1) and cyclin C was investigated by GST pull‐down assay, co‐immunoprecipitation and ubiquitylation assay. Mitochondria‐derived oxidative stress was studied by MitoSOX Red assay, seahorse assay and mitochondrial membrane potential measurement. Cyclin C‐associated cisplatin resistance was studied in vivo via xenograft.ResultsHACE1 catalysed the ubiquitylation of cyclin C by adding Lys11‐linked ubiquitin chains when cyclin C translocates to cytoplasm induced by cisplatin treatment. The ubiquitin‐modified cyclin C then anchor at mitochondira, which induced mitochondrial fission and ROS synthesis. Depleting CCNC or mutation on the ubiquitylation sites decreased mitochondrial ROS production and reduced cell apoptosis under cisplatin treatment. Xenograft study showed that disrupting cyclin C ubiquitylation by HACE1 conferred impairing cell apoptosis response upon cisplatin administration.ConclusionsCyclin C is a newly identified substrate of HACE1 E3 ligase. HACE1‐mediated ubiquitylation of cyclin C sheds light on a better understanding of cisplatin‐associated resistance in gastric cancer patients. Ubiquitylation of cyclin C by HACE1 regulates cisplatin‐associated sensitivity in gastric cancer. With cisplatin‐induced nuclear–mitochondrial translocation of cyclin C, its ubiquitylation by HACE1 increased mitochondrial fission and mitochondrial‐derived oxidative stress, leading to cell apoptosis.

Identification and Comprehensive Prognostic Analysis of a Novel Chemokine-Related lncRNA Signature and Immune Landscape in Gastric Cancer.

Gastric cancer (GC) is a malignant tumor with poor survival outcomes. Immunotherapy can improve the prognosis of many cancers, including GC. However, in clinical practice, not all cancer patients are sensitive to immunotherapy. Therefore, it is essential to identify effective biomarkers for predicting the prognosis and immunotherapy sensitivity of GC. In recent years, chemokines have been widely reported to regulate the tumor microenvironment, especially the immune landscape. However, whether chemokine-related lncRNAs are associated with the prognosis and immune landscape of GC remains unclear. In this study, we first constructed a novel chemokine-related lncRNA risk model to predict the prognosis and immune landscape of GC patients. By using various algorithms, we identified 10 chemokine-related lncRNAs to construct the risk model. Then, we determined the prognostic efficiency and accuracy of the risk model. The effectiveness and accuracy of the risk model were further validated in the testing set and the entire set. In addition, our risk model exerted a crucial role in predicting the infiltration of immune cells, immune checkpoint genes expression, immunotherapy scores and tumor mutation burden of GC patients. In conclusion, our risk model has preferable prognostic performance and may provide crucial clues to formulate immunotherapy strategies for GC.