Recent Developments of Systemic Chemotherapy for Gastric Cancer

CBX4 counteracts cellular senescence to desensitize gastric cancer cells to chemotherapy by inducing YAP1 SUMOylation

AIMS

As our comprehension of the intricate relationship between cellular senescence and tumor biology continues to evolve, the therapeutic potential of cellular senescence is gaining increasing recognition. Here, we identify chromobox 4 (CBX4), a Small Ubiquitin-related Modifier (SUMO) E3 ligase, as an antagonist of cellular senescence and elucidate a novel mechanism by which CBX4 promotes drug resistance and malignant progression of gastric cancer (GC).

METHODS

In vitro and in vivo models were conducted to investigate the manifestation and impact of CBX4 on cellular senescence and chemoresistance. High-throughput sequencing, chromatin immunoprecipitation, and co-immunoprecipitation techniques were utilized to identify the upstream regulators and downstream effectors associated with CBX4, revealing its intricate regulatory network.

RESULTS

CBX4 diminishes the sensitivity of GC cells to cellular senescence, facilitating chemoresistance and GC development by deactivating the senescence-related Hippo pathway. Mechanistically, low-dose cisplatin transcriptionally downregulates CBX4 through CEBPB. In addition, CBX4 preserves the stability and cytoplasm-nuclear transport of YAP1, the key player of Hippo pathway, by inducing SUMO1 modification at K97 and K280, which competitively inhibits YAP1-S127 phosphorylation.

CONCLUSIONS

Our study highlights the anti-senescence role of CBX4 and suggests that CBX4 inhibition in combination with low-dose cisplatin has the potential to overcome chemoresistance and effectively restrict GC progression.

Fruquintinib plus paclitaxel versus placebo plus paclitaxel for gastric or gastroesophageal junction adenocarcinoma: the randomized phase 3 FRUTIGA trial

The vascular endothelial growth factor pathway plays a key role in the pathogenesis of gastric cancer. In the multicenter, double-blind phase 3 FRUTIGA trial, 703 patients with advanced gastric or gastroesophageal junction adenocarcinoma who progressed on fluorouracil- and platinum-containing chemotherapy were randomized (1:1) to receive fruquintinib (an inhibitor of vascular endothelial growth factor receptor-1/2/3; 4 mg orally, once daily) or placebo for 3 weeks, followed by 1 week off, plus paclitaxel (80 mg/m2 intravenously on days 1/8/15 per cycle). The study results were positive as one of the dual primary endpoints, progression-free survival (PFS), was met (median PFS, 5.6 months in the fruquintinib arm versus 2.7 months in the placebo arm; hazard ratio 0.57; 95% confidence interval 0.48-0.68; P < 0.0001). The other dual primary endpoint, overall survival (OS), was not met (median OS, 9.6 months versus 8.4 months; hazard ratio 0.96, 95% confidence interval 0.81-1.13; P = 0.6064). The most common grade ≥3 adverse events were neutropenia, leukopenia and anemia. Fruquintinib plus paclitaxel as a second-line treatment significantly improved PFS, but not OS, in Chinese patients with advanced gastric or gastroesophageal junction adenocarcinoma and could potentially be another treatment option for these patients. ClinicalTrials.gov registration: NCT03223376 .

E2F1 Facilitates the Proliferation and Stemness of Gastric Cancer Cells by Activating CDC25B Transcription and Modulating the MAPK Pathway

Gastric cancer (GC) is a health problem that concerns people around the world. CDC25B is an essential cell cycle regulatory factor that is overexpressed in a variety of tumor cells. CDC25B plays a vital part in the progression and proliferation of malignant tumors. However, it is not yet clear that how CDC25B affects the stemness of GC cells. The study used bioinformatics to detect the expression of E2F1 and CDC25B in GC tissues and their correlation, as well as pathways enriched by CDC25B. We detected the expression of E2F1 and CDC25B in GC cell lines using quantitative reverse transcription polymerase chain reaction and tested the combination relationship between E2F1 and CDC25B using chromatin immunoprecipitation (ChIP) and dual-luciferase assays. We measured cell viability using CCK-8 assay, evaluated sphere-forming efficiency using sphere formation assay, and determined cell proliferation ability using colony formation assay. We also analyzed the expression of stemness markers and MAPK pathway-related proteins using western blot. In GC tissues and cells, CDC25B was upregulated. Silencing CDC25B could affect the MAPK pathway, thereby repressing the proliferation and stemness of GC cells. As predicted by bioinformatics, CDC25B had an upstream transcription factor, E2F1, which also had a high expression level in GC. Dual-luciferase and ChIP assays confirmed the combination relationship between the two. Rescue experiments uncovered that overexpression of CDC25B could reverse the impact induced by E2F1 knockdown on proliferation and stemness of cells. In conclusion, E2F1 could activate CDC25B transcription to regulate the MAPK pathway and enhance the proliferation and stemness of GC cells. We revealed a potential regulatory pathway of stemness of GC cells that was mediated by CDC25B, providing new ideas for improving and innovating GC treatment.

Correlation of multiple endpoints in the first-line chemotherapy of advanced gastric cancer: Pooled analysis of individual patient data from Japanese Phase III trials

BACKGROUND

Individual-level surrogates are important for management in patients treated for advanced gastric cancer (AGC). This study aimed to comprehensively investigate the correlation of multiple clinical endpoints in the first-line chemotherapy of AGC.

METHODS

Individual patient data (IPD) were collected from four Japanese Phase III trials comparing S-1-based first-line chemotherapies (SPIRITS, START, GC0301/TOP-002, and G-SOX trials). Patients without Response Evaluation Criteria in Solid Tumors (RECIST)-based radiological assessments were excluded. Spearman's rank correlation coefficient was tested for correlation among overall survival (OS), progression-free survival (PFS), and postprogression survival (PPS). OS, PFS, and PPS were compared between responders (best response: complete response or partial response) and nonresponders (best response: stable disease or progressive disease).

RESULTS

The study included a total of 1492 patients. Eighty percent of the patients (n = 1190) received subsequent chemotherapies after the failure of each trial's treatment protocol. PFS moderately correlated with OS (Spearman correlation coefficient = 0.66, p < 0.005), whereas the correlation between PPS and OS was strong (Spearman correlation coefficient = 0.87, p < 0.005). Responders had significantly longer OS (median, 17.7 vs. 9.1 months, p < 0.005), PFS (median, 6.9 vs. 2.8 months, p < 0.005), and PPS (median, 10.5 vs. 6.0 months, p < 0.005) than nonresponders.

CONCLUSIONS

Our results reacknowledged the mild surrogacy of PFS and importance of postprogression treatments in patients with AGC receiving first-line chemotherapy. Consistent longer survival outcomes in better RECIST categories suggested that tumor response might be a useful individual-level surrogate.

An immune-related prognostic signature associated with immune landscape and therapeutic responses in gastric cancer

Immune-related genes (IRGs) have attracted attention in recent years as therapeutic targets in various tumors. However, the role of IRGs in gastric cancer (GC) has not been clearly elucidated. This study presents a comprehensive analysis exploring the clinical, molecular, immune, and drug response features characterizing the IRGs in GC. Data were acquired from the TCGA and GEO databases. The Cox regression analyses were performed to develop a prognostic risk signature. The genetic variants, immune infiltration, and drug responses associated with the risk signature were explored using bioinformatics methods. Lastly, the expression of the IRS was verified by qRT-PCR in cell lines. In this manner, an immune-related signature (IRS) was established based on 8 IRGs. According to the IRS, patients were divided into the low-risk group (LRG) and high-risk group (HRG). Compared with the HRG, the LRG was characterized by a better prognosis, high genomic instability, more CD8+ T cell infiltration, greater sensitivity to chemotherapeutic drugs, and greater likelihood of benefiting from the immunotherapy. Moreover, the expression result showed good consistency between the qRT-PCR and TCGA cohort. Our findings provide insights into the specific clinical and immune features underlying the IRS, which may be important for patient treatment.

Piceatannol enhances Beclin-1 activity to suppress tumor progression and its combination therapy strategy with everolimus in gastric cancer

The effects and regulation of Beclin-1-an autophagy-related protein-have not been fully defined, however, a negative correlation has been reported between Beclin-1 expression and carcinogenesis. Meanwhile, no compound has been shown to directly inhibit its activity. Here, we evaluate piceatannol, a naturally occurring polyphenolic compound, as a potential targeting agonist of Beclin-1, to assess its efficacy as an antitumor agent against gastric cancer. More specifically, we determine the effects of piceatannol treatment on cell viability using a monitoring system and colony forming assay. Piceatannol was found to efficiently inhibit the proliferation of several human gastric cancer cell lines. Autophagic flux is increased by piceatannol treatment, and correlates with inhibition of cell proliferation and colony formation. Additionally, microscale thermophoresis and surface plasmon resonance results show a direct interaction between piceatannol and Beclin-1, which reduces the phosphorylation activity of Beclin-1 at the Ser-295 site. Notably, piceatannol impairs the binding of Beclin-1 to Bcl-2 and enhances the recruitment of binding of UV radiation resistance-associated gene protein, which further triggers Beclin-1-dependent autophagy signaling. An increase in autophagic activity via treatment with the mTOR inhibitor, everolimus, effectively sensitizes piceatannol-induced antitumor effects. Xenograft models confirmed that piceatannol inhibits tumor development and elicits a potent synergistic effect with everolimus in vivo. Taken together, the findings of this study strongly support the application of combinatorial piceatannol and everolimus therapy in future clinical trials for gastric cancer patients.

Intratumoral heterogeneity affects tumor regression and Ki67 proliferation index in perioperatively treated gastric carcinoma

BACKGROUND

Intratumoral heterogeneity (ITH) is a major problem in gastric cancer (GC). We tested Ki67 and tumor regression for ITH after neoadjuvant/perioperative chemotherapy.

METHODS

429 paraffin blocks were obtained from 106 neoadjuvantly/perioperatively treated GCs (one to five blocks per case). Serial sections were stained with Masson's trichrome, antibodies directed against cytokeratin and Ki67, and finally digitalized. Tumor regression and three different Ki67 proliferation indices (PI), i.e., maximum PI (KiH), minimum PI (KiL), and the difference between KiH/KiL (KiD) were obtained per block. Statistics were performed in a block-wise (all blocks irrespective of their case-origin) and case-wise manner.

RESULTS

Ki67 and tumor regression showed extensive ITH in our series (maximum ITH within a case: 31% to 85% for KiH; 4.5% to 95.6% for tumor regression). In addition, Ki67 was significantly associated with tumor regression (p < 0.001). Responders (<10% residual tumor, p = 0.016) exhibited prolonged survival. However, there was no significant survival benefit after cut-off values were increased ≥20% residual tumor mass. Ki67 remained without prognostic value.

CONCLUSIONS

Digital image analysis in tumor regression evaluation might help overcome inter- and intraobserver variability and validate classification systems. Ki67 may serve as a sensitivity predictor for chemotherapy and an indicator of ITH.

High DCR and Better Survival in Patients with Advanced or Metastatic Gastric Cancer Receiving Anti-Angiogenic TKI plus Chemotherapy: A Real-World Study

Objectives: This study was carried out to assess the efficacy and drug toxicity of anti-angiogenic tyrosine kinase inhibitor (TKI) plus chemotherapy as second-line or above therapeutic regime in advanced or metastatic gastric cancer patients. Methods: From November 2017 to April 2020, advanced or metastatic gastric cancer patients who have failed from prior treatment and received apatinib combined with irinotecan or irinotecan treatment were analyzed. The primary observed indicator was progression-free survival (PFS). Objective: response rate (ORR), disease control rate (DCR), overall survival (OS), and drug toxicity were also evaluated. Results: 26 patients received apatinib combined with irinotecan and 29 patients received irinotecan. The ORR in the combination therapy and monotherapy population was 26.9% and 17.2%, respectively. The DCR in the apatinib combined with irinotecan group was higher than in irinotecan monotherapy population (80.8% vs 55.2%, P = .043). Median PFS was 4.2 months in the combination group and 3.3 months in the monotherapy group (P = .020). Median OS was 8.0 months in the combination group and 5.9 months in the monotherapy group (P = .048). Except for ECOG PS 2, PFS and OS were generally consistent across subgroups by sex, age, number of metastatic sites and primary tumor site. The incidence of Grade 3-4 adverse events in combination and monotherapy group was 23.1% and 20.7%, respectively. In apatinib combined with irinotecan group, adverse events that were attributed to apatinib were secondary hypertension (in seven patients, 26.9%), hand-foot syndrome (5,19.2%), and proteinuria (5, 19.2%). Univariate analysis demonstrated that secondary hypertension was considered to be a favorable factor (P = .040) for longer OS in combination therapy group. Conclusions: Compared with chemotherapy alone, anti-angiogenic TKI plus chemotherapy showed better PFS, OS and DCR in advanced or metastatic gastric cancer as second-line or above therapy, with a tolerable and manageable safety profile.

Isoquinoline Alkaloids from Coptis chinensis Franch: Focus on Coptisine as a Potential Therapeutic Candidate against Gastric Cancer Cells

Gastric cancer (GC) has high incidence rates and constitutes a common cause of cancer mortality. Despite advances in treatment, GC remains a challenge in cancer therapy which is why novel treatment strategies are needed. The interest in natural compounds has increased significantly in recent years because of their numerous biological activities, including anti-cancer action. The isolation of the bioactive compounds from Coptis chinensis Franch was carried out with the Centrifugal Partition Chromatography (CPC) technique, using a biphasic solvent system composed of chloroform (CHCl₃)—methanol (MeOH)—water (H₂O) (4:3:3, v/v) with an addition of hydrochloric acid and trietylamine. The identity of the isolated alkaloids was confirmed using a high resolution HPLC-MS chromatograph. The phytochemical constituents of Coptis chinensis such as berberine, jatrorrhizine, palmatine and coptisine significantly inhibited the viability and growth of gastric cancer cell lines ACC-201 and NCI-N87 in a dose-dependent manner, with coptisine showing the highest efficacy as revealed using MTT and BrdU assays, respectively. Flow cytometry analysis confirmed the coptisine-induced population of gastric cancer cells in sub-G1 phase and apoptosis. The combination of coptisine with cisplatin at the fixed-ratio of 1:1 exerted synergistic and additive interactions in ACC-201 and NCI-N87, respectively, as determined by means of isobolographic analysis. In in vivo assay, coptisine was safe for developing zebrafish at the dose equivalent to the highest dose active in vitro, but higher doses (greater than 10 times) caused morphological abnormalities in larvae. Our findings provide a theoretical foundation to further studies on more detailed mechanisms of the bioactive compounds from Coptis chinensis Franch anti-cancer action that inhibit GC cell survival in in vitro settings.

Role of Interleukins and New Perspectives in Mechanisms of Resistance to Chemotherapy in Gastric Cancer

Gastric cancer (GC) is the fourth most common cancer in the world in terms of incidence and second in terms of mortality. Chemotherapy is the main treatment for GC. The greatest challenge and major cause of GC treatment failure is resistance to chemotherapy. As such, research is ongoing into molecular evaluation, investigating mechanisms, and screening therapeutic targets. Several mechanisms related to both the tumor cells and the tumor microenvironment (TME) are involved in resistance to chemotherapy. TME promotes the secretion of various inflammatory cytokines. Recent studies have revealed that inflammatory cytokines affect not only tumor growth, but also chemoresistance. Cytokines in TME can be detected in blood circulation and TME cells. Inflammatory cytokines could serve as potential biomarkers in the assessment of chemoresistance and influence the management of therapeutics in GC. This review presents recent data concerning research on inflammatory cytokines involved in the mechanisms of chemoresistance and provides new clues in GC treatment.

Wnt/beta-catenin signaling confers ferroptosis resistance by targeting GPX4 in gastric cancer

The development of chemotherapy resistance is the most vital obstacle to clinical efficacy in gastric cancer (GC). The dysregulation of the Wnt/beta-catenin signaling pathway is critically associated with GC development and chemotherapy resistance. Ferroptosis is a form of regulated cell death, induced by an iron-dependent accumulation of lipid peroxides during chemotherapy. However, whether the Wnt/beta-catenin signaling directly controls resistance to cell death, remains unclear. Here, we show that the activation of the Wnt/beta-catenin signaling attenuates cellular lipid ROS production and subsequently inhibits ferroptosis in GC cells. The beta-catenin/TCF4 transcription complex directly binds to the promoter region of GPX4 and induces its expression, resulting in the suppression of ferroptotic cell death. Concordantly, TCF4 deficiency promotes cisplatin-induced ferroptosis in vitro and in vivo. Thus, we demonstrate that the aberrant activation of the Wnt/beta-catenin signaling confers ferroptosis resistance and suggests a potential therapeutic strategy to enhance chemo-sensitivity for advanced GC patients.

Nanomaterials in cancer: Reviewing the combination of hyperthermia and triggered chemotherapy

Nanoparticle mediated hyperthermia has been explored as a method to increase cancer treatment efficacy by heating tumours inside-out. With that purpose, nanoparticles have been designed and their properties tailored to respond to external stimuli and convert the supplied energy into heat, therefore inducing damage to tumour cells. Moreover, the combination of hyperthermia with chemotherapy has been described as a more effective strategy due to the synergy between the high temperature and the drug's effects, also associated with a remote controlled and on-demand drug release. In this review, the methods behind nanoparticle mediated hyperthermia, namely material design, external stimuli response and energy conversion will be discussed and critically analysed. We will address the most relevant studies on hyperthermia and temperature triggered drug release for cancer treatment. Finally, the advantages, difficulties and challenges of this therapeutic strategy will be discussed, while giving insight for future developments.

TULP3 silencing suppresses cell proliferation, migration and invasion in gastric cancer via the PTEN/Akt/Snail pathway

BACKGROUND

Tubby-like protein 3 (TULP3) is a member of the tubby family, has been related to the development of nervous system by gene knockout researches. Nevertheless, the role of TULP3 in the gastric cancer is not clear.

METHODS

Western blotting and real-time polymerase chain reaction (PCR) were employed for the quantitative detection of TULP3 expression in the gastric cancer and consecutive non-cancerous tissues, and gastric cancer cells. The roles of TULP3 in invasion, migration as well as proliferation of the gastric cancer cell in vivo and in vitro through utilizing colony formation, MTT, wound-healing, transwell and mouse xenograft model. Western blotting assay was implemented in order to clarify the potential molecular mechanisms. Furthermore, electron microscopy and western blot were evaluated TULP3 expression in gastric cancer patient extracted serum exosomes.

RESULTS

TULP3 expression levels were remarkably upregulated in the gastric cancer tissues and cells. Subsequent functional assays demonstrated that TULP3 downregulation suppressed invasion, migration as well as the proliferation of the gastric cancer cell. Mechanism assays depicted that the PTEN/Akt/Snail signaling pathway can inhibit invasion, migration as well as the proliferation of the gastric cancer cell via TULP3 silencing. Finally, we found that the expression of TULP3 could be determined in the extracted serum exosomes. The expression of TULP3 in gastric cancer group was higher in comparison with normal group.

CONCLUSIONS

Our results reveal that TULP3 might serve as a potential prognostic biomarker and therapeutic target for the treatment of gastric cancer.

New prognostic model for patients with advanced gastric cancer: Fluoropyrimidine/platinum doublet for first-line chemotherapy

BACKGROUND

New prognostic factors have been reported in patients with metastatic or recurrent gastric cancer (MRGC), necessitating modifications to the previous prognostic model.

AIM

To develop a new model, MRGC patients who received fluoropyrimidines/ platinum doublet chemotherapy between 2008 and 2015 were analyzed.

METHODS

A total of 1883 patients was divided into a training set (n = 937) and an independent validation set (n = 946).

RESULTS

Multivariate analysis showed that the following six factors were associated with poor overall survival (OS) in the training set: Eastern Cooperative Oncology Group performance score ≥ 2 and bone metastasis (2 points each), peritoneal metastasis, high alkaline phosphatase level, low albumin level, and high neutrophil-lymphocyte ratio (1 point each). A prognostic model was developed by stratifying patients into good (0-1 point), moderate (2-3 points), and poor (≥ 4 points) risk groups. In the validation set, the median OS of the three risk groups was 15.8, 10.1, and 5.7 mo, respectively, and those differences were significant (P < 0.001).

CONCLUSION

We identified six factors readily measured in clinical practice that are predictive of poor prognosis in patients with MRGC. The new model is simpler than the old and more easily predicts OS.

Bioinformatics Analysis of Hub Genes and Potential Therapeutic Agents Associated with Gastric Cancer

Purpose

The current treatment methods available for advanced gastric cancer are not very promising. Hence, it is important to explore novel biomarkers and potential therapeutic agents to treat gastric cancer (GC). This study aimed to identify hub genes associated with GC prognosis and explore potential drugs for its treatment.

Materials and Methods

Three gene expression data of GC and normal tissues were downloaded from the Gene Expression Omnibus (GEO) and processed to identify the differentially expressed genes (DEGs). We conducted a comprehensive analysis of DEGs, including functional enrichment analysis, construction of protein-protein interaction (PPI) network, identification of hub genes, survival analysis and expression verification of hub genes. Finally, we constructed the network of miRNA-mRNA, and predicted the drugs that might be effective for GC treatment.

Results

A total of 340 DEGs, including 94 up-regulated and 246 down-regulated genes, were identified. Among the up-regulated DEGs, the enrichment terms were primarily related to tumorigenesis and tumor progression, extracellular matrix organization, and collagen catabolic process. Additionally, 10 hub genes (FN1, COL3A1, COL1A2, BGN, THBS2, COL5A2, THBS1, COL5A1, SPARC, and COL4A1) were identified, out of which 7 genes were significantly associated with poor overall survival (OS) in GC. The expression levels of these 7 hub genes were verified using real-time PCR, immunohistochemistry, and the GEPIA2 (Gene Expression Profiling Interactive Analysis) server. A regulatory network of miRNA-mRNA was also constructed, and the top 4 interactive miRNAs (hsa-miR-29b-3p, hsa-miR-140-3p, hsa-miR-29a-3p, and hsa-miR-29c-3p) that targeted the most hub genes were identified. Finally, fourteen small molecules were predicted to be effective in treating GC.

Conclusion

The identification of the hub genes, miRNA-mRNA network, and potential candidate drugs associated with GC provides new insights into the molecular mechanisms and treatment of GC.

An updated review on the therapeutic, diagnostic, and prognostic value of long non-coding RNAs in gastric cancer

As a novel group of non-coding RNAs, long non-coding RNA (lncRNAs) can substantially regulate various biological processes. Downregulated tumor-suppressive lncRNAs and upregulated oncogenic lncRNAs (onco-lncRNAs) have been implicated in gastric cancer (GC) development. These dysregulations have been associated with decreased chemosensitivity, inhibited apoptosis, and increased tumor migration in GC. Besides, growing evidence indicates that lncRNAs can be a valuable diagnostic and prognostic biomarker, and their expression levels are substantially associated with the clinicopathological features of affected patients. The current study aims to review the recent findings of the tumor-suppressive lncRNAs and onco-lncRNAs in GC development and highlight their therapeutic, diagnostic, and prognostic values in treating GC cells. Besides, it intends to highlight the future direction of lncRNAs in treating GC.

Conversion therapy with tislelizumab for high microsatellite instability, unresectable stage III gastric cancer: a case report

Gastric cancer (GC) is the fifth-highest ranked cancer for incidence and second for mortality from cancer worldwide. Conversion therapy has recently emerged as an alternative therapy for advanced/metastatic GC patients who are unable to undergo surgical resection at the time of diagnosis. Herein, we present the case of a patient with unresectable stage III GC of high microsatellite instability (MSI), high tumor mutation burden (TMB), and Epstein-Barr virus (EBV) positive. The patient received conversion therapy involving a combination of chemotherapy and immunotherapy regimens. After 3 courses of chemotherapy combined with tislelizumab, the patient underwent laparoscopic radical total gastrectomy. The pathological examination demonstrated that there was no cancerous tissue at the proximal or distal end of the tumor and no lymph node metastases in the lesser or greater curvature, indicating a pathologic complete response. Thereafter, the patient continued tislelizumab treatment to prevent postoperative carcinoma recurrence and metastasis, and to improve prognosis. In conclusion, our study confirmed that chemotherapy combined with immunotherapy is a promising conversion therapy for GC patients with locally unresectable lesions or distant lymph node metastasis, and these findings warrant large-scale clinical studies. This report highlights the clinical importance of next-generation sequencing technology in investigating therapeutic strategy to provide the maximal clinical benefit for patients with GC.

Comprehensive Characterization of RNA Processing Factors in Gastric Cancer Identifies a Prognostic Signature for Predicting Clinical Outcomes and Therapeutic Responses

RNA processing converts primary transcript RNA into mature RNA. Altered RNA processing drives tumor initiation and maintenance, and may generate novel therapeutic opportunities. However, the role of RNA processing factors in gastric cancer (GC) has not been clearly elucidated. This study presents a comprehensive analysis exploring the clinical, molecular, immune, and drug response features underlying the RNA processing factors in GC. This study included 1079 GC cases from The Cancer Genome Atlas (TCGA, training set), our hospital cohort, and two other external validation sets (GSE15459, GSE62254). We developed an RNA processing-related prognostic signature using Cox regression with the least absolute shrinkage and selection operator (LASSO) penalty. The prognostic value of the signature was evaluated using a multiple-method approach. The genetic variants, pathway activation, immune heterogeneity, drug response, and splicing features associated with the risk signature were explored using bioinformatics methods. Among the tested 819 RNA processing genes, we identified five distinct RNA processing patterns with specific clinical outcomes and biological features. A 10-gene RNA processing-related prognostic signature, involving ZBTB7A, METTL2B, CACTIN, TRUB2, POLDIP3, TSEN54, SUGP1, RBMS1, TGFB1, and PWP2, was further identified. The signature was a powerful and robust prognosis factor in both the training and validation datasets. Notably, it could stratify the survival of patients with GC in specific tumor-node-metastasis (TNM) classification subgroups. We constructed a composite prognostic nomogram to facilitate clinical practice by integrating this signature with other clinical variables (TNM stage, age). Patients with low-risk scores were characterized with good clinical outcomes, proliferation, and metabolism hallmarks. Conversely, poor clinical outcome, invasion, and metastasis hallmarks were enriched in the high-risk group. The RNA processing signature was also involved in tumor microenvironment reprogramming and regulating alternative splicing, causing different drug response features between the two risk groups. The low-risk subgroup was characterized by high genomic instability, high alternative splicing and might benefit from the immunotherapy. Our findings highlight the prognostic value of RNA processing factors for patients with GC and provide insights into the specific clinical and molecular features underlying the RNA processing-related signature, which may be important for patient management and targeting treatment.

Upregulation of ECT2 Predicts Adverse Clinical Outcomes and Increases 5-Fluorouracil Resistance in Gastric Cancer Patients

Background

The abnormal expression and prognosis prediction of epithelial cell transforming sequence 2 (ECT2) in gastric cancer (GC) has been reported. However, the effect of ECT2 on 5-fluorouracil (5-Fu) resistance in GC is unclear. This research aims to solve the abovementioned problems.

Methods

Gene expression was detected by RT-qPCR and Western blot analysis. Cell viability was evaluated by the colony formation assay, MTT assay, and flow cytometric analysis. Transwell and wound healing assays were used to detect cell metastasis.

Results

Upregulation of ECT2 was found in stomach adenocarcinoma (STAD) and GC tissues. In addition, high ECT2 expression can predict adverse clinical outcomes in GC patients. More importantly, ECT2 knockdown weakened the resistance of 5-FU in GC cells. ECT2 silencing reduced the cell migratory and invasive abilities of GC cells treated with 5-FU. We also found that downregulation of ECT2 increased 5-FU sensitivity in GC cells by downregulating P-gp, MRP1, and Bcl-2.

Conclusion

Upregulation of ECT2 can predict adverse clinical outcomes and increase 5-FU resistance in GC patients.

A novel protein encoded by circMAPK1 inhibits progression of gastric cancer by suppressing activation of MAPK signaling

BACKGROUND

A novel type of noncoding RNA, circRNA has been reported to participate in the occurrence and development of diseases through many mechanisms. The MAPK pathway is a common signal transduction pathway involved in cell proliferation, inflammation and apoptosis and plays a particularly important role in cancers. However, the role of circRNAs related to the MAPK pathway in gastric cancer has not been explored.

METHODS

A bioinformatics analysis was performed to profile and identify the circRNAs involved in the MAPK pathway in gastric cancer. The tumor-suppressive role of circMAPK1 was confirmed both in vitro and in vivo. Mass spectrometry, Western blot and immunofluorescence staining assays were used to validate the existence and expression of MAPK1-109aa. The molecular mechanism of circMAPK1 was investigated by mass spectrometry and immunoprecipitation analyses.

RESULTS

In this study, we identified that circMAPK1 (hsa_circ_0004872) was downregulated in gastric cancer tissues compared with adjacent normal tissues. Importantly, lower circMAPK1 expression predicted poor survival in GC patients. CircMAPK1 inhibited the proliferation and invasion of gastric cancer cells in vitro and in vivo. Next, we found that circMAPK1 encoded a novel protein with 109 amino acids in length. Through a series of functional experiments, we confirmed that circMAPK1 exerted a tumor-suppressing effect via the encoded protein MAPK1-109aa. Mechanistically, the tumor suppressor MAPK1-109aa inhibited the phosphorylation of MAPK1 by competitively binding to MEK1, thereby suppressing the activation of MAPK1 and its downstream factors in MAPK pathway.

CONCLUSIONS

Our study revealed that circMAPK1 inhibits the malignant biological behavior of gastric cancer cells through its encoded protein MAPK1-109aa. More importantly, circMAPK1 is a favorable predictor for gastric cancer patients and may provide a new therapeutic target in the treatment of gastric cancer.

NUPR1 participates in YAP-mediate gastric cancer malignancy and drug resistance via AKT and p21 activation

OBJECTIVES

To assess nuclear protein 1 (NUPR1) level in human gastric cancer (GC) cells, explore the effects of NUPR1 on GC progression, and investigate the possible regulatory mechanism.

METHODS

Immunohistochemistry (IHC), Immunoblot and quantitative PCR assays were conducted to detect the NUPR1 level in human GC tissues and corresponding normal tissues. Also, NUPR1 expression level correlates with clinical features of GC patients. 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (MTT), transwell assays, Immunoblot assays, and flow cytometry (FCM) assays were used to evaluate the effects of NUPR1 on the proliferation, invasion, epithelial-mesenchymal transformation (EMT) and apoptosis of GC cells in vitro. Immunoblot assays were performed to detect the potential mechanism in NUPR1-mediated drug resistance.

KEY FINDINGS

We found the expression of NUPR1 was upregulated in human gastric cancer tissues and correlated with the clinical features including tumour size, tumour stage and, lymph node metastasis. We further noticed that the depletion of NUPR1 inhibited the invasion and EMT of gastric cancer cells and stimulated the apoptosis. In doxorubicin-resistant gastric cancer cells, yes-associated protein (YAP) activation was up-regulated, and YAP could regulate the expression of NUPR1 to affect drug-resistance. We further provided the evidence that overexpression of NUPR1 reversed the effect of YAP knockdown on cell malignancy and drug resistance via regulating AKT and p21 pathway.

CONCLUSIONS

Our findings indicated the involvement of NUPR1 in the progression of gastric cancer and elucidated its molecular mechanism in regulating drug resistance.

Identification of Cyclophilin A as a Potential Anticancer Target of Novel Nargenicin A1 Analog in AGS Gastric Cancer Cells

We recently discovered a novel nargenicin A1 analog, 23-demethyl 8,13-deoxynargenicin (compound 9), with potential anti-cancer and anti-angiogenic activities against human gastric adenocarcinoma (AGS) cells. To identify the key molecular targets of compound 9, that are responsible for its biological activities, the changes in proteome expression in AGS cells following compound 9 treatment were analyzed using two-dimensional gel electrophoresis (2-DE), followed by MALDI/TOF/MS. Analyses using chemical proteomics and western blotting revealed that compound 9 treatment significantly suppressed the expression of cyclophilin A (CypA), a member of the immunophilin family. Furthermore, compound 9 downregulated CD147-mediated mitogen-activated protein kinase (MAPK) signaling pathway, including c-Jun N-terminal kinase (JNK) and extracellular signal-regulated protein kinase 1/2 (ERK1/2) by inhibiting the expression of CD147, the cellular receptor of CypA. Notably, the responses of AGS cells to CypA knockdown were significantly correlated with the anticancer and antiangiogenic effects of compound 9. CypA siRNAs reduced the expression of CD147 and phosphorylation of JNK and ERK1/2. In addition, the suppressive effects of CypA siRNAs on proliferation, migration, invasion, and angiogenesis induction of AGS cells were associated with G2/M cell cycle arrest, caspase-mediated apoptosis, inhibition of MMP-9 and MMP-2 expression, inactivation of PI3K/AKT/mTOR pathway, and inhibition of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) expression. The specific interaction between compound 9 and CypA was also confirmed using the drug affinity responsive target stability (DARTS) and cellular thermal shift assay (CETSA) approaches. Moreover, in silico docking analysis revealed that the structure of compound 9 was a good fit for the cyclosporin A binding cavity of CypA. Collectively, these findings provide a novel molecular basis for compound 9-mediated suppression of gastric cancer progression through the targeting of CypA.

PolG Inhibits Gastric Cancer Glycolysis and Viability by Suppressing PKM2 Phosphorylation

Purpose

Gastric cancer (GC) is the fifth most frequently diagnosed cancer and the third leading cause of cancer-related death. There is a critical need for the development of novel therapies in GC. DNA polymerase gamma (PolG) has been implicated in mitochondrial homeostasis and affects the development of numerous types of cancer, however, its effects on GC and molecular mechanisms remain to be fully determined. The aim of the present research was to clarify the effects of PolG on GC and its possible molecular mechanism of action.

Methods

The GSE62254 dataset was used to predict the effect of PolG on prognostic value in GC patients. Lentivirus-mediated transduction was used to silence PolG expression. Western blot analysis evinced the silencing effect. Co-immunoprecipitation (Co-IP) analysis was performed to explore the potential molecular mechanism of action. Analysis of the glycolysis process in GC cells was also undertaken. Cell proliferation was determined using a CCK-8 (Cell Counting Kit-8) proliferation assay. Cell migration was detected using the Transwell device. Animal experiments were used to measure in vivo xenograft tumor growth.

Results

GC patients with low PolG expression have worse overall survival (OS) and progression-free survival (PFS). PolG binds to PKM2 and affects the activation of Tyr105-site phosphorylation, thus interfering with the glycolysis of GC cells. In vitro tumor formation experiments in mice also confirmed that PolG silencing of GC has a stronger proliferation ability. PolG can suppress GC cell growth both in vivo and in vitro.

Conclusion

Our study reveals a potential molecular mechanism between PolG and the energy metabolic process of GC tumor cells for the first time, suggesting PolG as an independent novel potential therapeutic target for tumor therapy, and providing new ideas for clinical GC treatment.

Roles of E3 ubiquitin ligases in gastric cancer carcinogenesis and their effects on cisplatin resistance

Although gastric cancer (GC) is one of the most common cancers with high incidence and mortality rates, its pathogenesis is still not elucidated. GC carcinogenesis is complicated and involved in the activation of oncoproteins and inactivation of tumor suppressors. The ubiquitin-proteasome system (UPS) is crucial for protein degradation and regulation of physiological and pathological processes. E3 ubiquitin ligases are pivotal enzymes in UPS, containing various subfamily proteins. Previous studies report that some E3 ligases, including SKP2, CUL1, and MDM2, act as oncoproteins in GC carcinogenesis. On the other hand, FBXW7, FBXL5, FBXO31, RNF43, and RNF180 exert as tumor suppressors in GC carcinogenesis. Moreover, E3 ligases modulate cell growth, cell apoptosis, and cell cycle; thus, it is complicated to confer cisplatin resistance/sensitivity in GC cells. The intrinsic and acquired cisplatin resistance limits its clinical application against GC. In this review, we explore oncogenic and tumor suppressive roles of E3 ligases in GC carcinogenesis and focus on the effects of E3 ligases on cisplatin resistance in GC cells, which will provide novel therapeutic targets for GC therapy, especially for cisplatin-resistant patients.

Identification of Core Prognosis-Related Candidate Genes in Chinese Gastric Cancer Population Based on Integrated Bioinformatics

Background

Gastric cancer (GC) is one of the leading causes of cancer-related mortality worldwide. There are great geographical differences in the incidence of GC, and somatic mutation rates of driver genes are also different. The present study is aimed at screening core prognosis-related candidate genes in Chinese gastric cancer population based on integrated bioinformatics for the early diagnosis and prognosis of GC.

Methods

In the present study, the differentially expressed genes (DEGs) in GC were identified using four microarray datasets from the Gene Expression Omnibus (GEO) database. The samples of these datasets were all from China. Functional enrichment analysis of DEGs was conducted to evaluate the underlying molecular mechanisms involved in GC. Protein-protein interaction (PPI) network and cytoHubba were performed to determine hub genes associated with GC. Gene Expression Profiling Interactive Analysis (GEPIA) and Human Protein Atlas (HPA) were performed to validate the hub genes.

Results

A total of 240 DEGs were obtained through the RRA method, including 80 upregulated genes and 160 downregulated genes. Upregulated genes were mainly enriched in extracellular matrix organization, extracellular matrix, and extracellular matrix structural constituent. The downregulated genes were mainly enriched in digestion, extracellular space, and oxidoreductase activity. The KEGG pathway enrichment analysis showed that the upregulated genes were mainly associated with ECM-receptor interaction, focal adhesion, and PI3K-Akt signaling pathway. And downregulated genes were mainly associated with the metabolism of xenobiotics by cytochrome P450, metabolic pathways, and gastric acid secretion. The transcriptional and translational expression levels of the genes including COL1A1, COL5A2, COL12A1, and VCAN were higher in GC tissues than normal tissues.

Conclusion

A total of four genes including COL1A1, COL5A2, COL12A1, and VCAN were considered potential GC biomarkers in the Chinese population. And ECM-receptor interaction, focal adhesion, and PI3K-Akt signaling pathway were revealed to be important mechanisms of GC. Our findings provide novel insights into the occurrence and progression of GC in the Chinese population.

Update, validation and comparison of three different clinicopathological scores for patients with resected gastric cancer: A western experience

INTRODUCTION

Gastric cancer (GC) is a multifactorial disease. Several prognostic scores have been proposed for refining the prognostic information provided by the TNM classification. Our aim is to validate and compare the prognostic performance of different clinicopathological scores in a western cohort of patients (Marubini, Haraguchi and Kologlu scores).

MATERIAL AND METHODS

Retrospective study of all cases of GC resected in a western tertiary center (N = 377). Clinicopathological features were collected, scores were applied and statistical analyses were performed.

RESULTS

315 cases were finally included. According to Marubini, Haraguchi and Kologlu scores, patients were stage I (18.5%, 13.3% and 49%), II (29.3%, 47.2% and 29.5%) and III (52.2%, 39.5% and 21.5%, respectively). All classifications were significantly associated with lymphovascular invasion, perineural infiltration, lymph node involvement, patient progression and death due to GC. All scores showed good patient stratification by Kaplan-Meier analyses, but OS and DFS curves depending on Haraguchi score were less evenly spaced. Kologlu classification showed prognostic superiority over Haraguchi and Marubini classifications by ROC analysis. AUC values for OS and DFS were 0.654 and 0.647 (Marubini), 0.626 and 0.618 (Haraguchi) and 0.724 and 0.709 (Kologlu). Kologlu and Marubini classifications were independent factors for both OS and DFS, but Haraguchi classification was independently associated only with DFS.

CONCLUSIONS

Clinicopathological scores can be easily validated and are cost-effective. Kologlu score is the most thorough classification, and it showed the best prognostic performance for both DFS and OS in our study. More studies are needed to validate its value in other populations.

From Interconnection between Genes and Microenvironment to Novel Immunotherapeutic Approaches in Upper Gastro-Intestinal Cancers-A Multidisciplinary Perspective

Despite the progress during the last decade, patients with advanced gastric and esophageal cancers still have poor prognosis. Finding optimal therapeutic strategies represents an unmet need in this field. Several prognostic and predictive factors have been evaluated and may guide clinicians in choosing a tailored treatment. Data from large studies investigating the role of immunotherapy in gastrointestinal cancers are promising but further investigations are necessary to better select those patients who can mostly benefit from these novel therapies. This review will focus on the treatment of metastatic esophageal and gastric cancer. We will review the standard of care and the role of novel therapies such as immunotherapies and CAR-T. Moreover, we will focus on the analysis of potential predictive biomarkers such as Modify as: Microsatellite Instability (MSI) and PD-L1, which may lead to treatment personalization and improved treatment outcomes. A multidisciplinary point of view is mandatory to generate an integrated approach to properly exploit these novel antiproliferative agents.

Circular RNAs in Gastric Cancer: Potential Biomarkers and Therapeutic Targets

Circular RNAs (circRNAs), as a recently established group of endogenous noncoding RNAs, have been involved in the occurrence and development of different malignancies. Gastric cancer (GC) remains a globally significant contributor to death in cancer patients due to insufficient early diagnosis, limited treatment measures, and poor prognosis. An increasing number of studies have found that many circRNAs are dysregulated in GC and are closely associated with its tumorigenesis and metastasis. Thus, circRNAs have the potential to serve as diagnostic and prognostic biomarkers and even therapeutic targets. This review comprehensively summarizes the most recent findings on how circRNAs influence GC progression and their clinical value. In addition, we present several methological deficiencies in the studies and provide some promising ideas for future research.

STAT3 Pathway in Gastric Cancer: Signaling, Therapeutic Targeting and Future Prospects

Molecular signaling pathways play a significant role in the regulation of biological mechanisms, and their abnormal expression can provide the conditions for cancer development. The signal transducer and activator of transcription 3 (STAT3) is a key member of the STAT proteins and its oncogene role in cancer has been shown. STAT3 is able to promote the proliferation and invasion of cancer cells and induces chemoresistance. Different downstream targets of STAT3 have been identified in cancer and it has also been shown that microRNA (miR), long non-coding RNA (lncRNA) and other molecular pathways are able to function as upstream mediators of STAT3 in cancer. In the present review, we focus on the role and regulation of STAT3 in gastric cancer (GC). miRs and lncRNAs are considered as potential upstream mediators of STAT3 and they are able to affect STAT3 expression in exerting their oncogene or onco-suppressor role in GC cells. Anti-tumor compounds suppress the STAT3 signaling pathway to restrict the proliferation and malignant behavior of GC cells. Other molecular pathways, such as sirtuin, stathmin and so on, can act as upstream mediators of STAT3 in GC. Notably, the components of the tumor microenvironment that are capable of targeting STAT3 in GC, such as fibroblasts and macrophages, are discussed in this review. Finally, we demonstrate that STAT3 can target oncogene factors to enhance the proliferation and metastasis of GC cells.