Pharmacological inactivation of Skp2 SCF ubiquitin ligase restricts cancer stem cell traits and cancer progression.

Skp2 E3 ligase is overexpressed in numerous human cancers and plays a critical role in cell-cycle progression, senescence, metabolism, cancer progression, and metastasis. In the present study, we identified a specific Skp2 inhibitor using high-throughput in silico screening of large and diverse chemical libraries. This Skp2 inhibitor selectively suppresses Skp2 E3 ligase activity, but not activity of other SCF complexes. It also phenocopies the effects observed upon genetic Skp2 deficiency, such as suppressing survival and Akt-mediated glycolysis and triggering p53-independent cellular senescence. Strikingly, we discovered a critical function of Skp2 in positively regulating cancer stem cell populations and self-renewal ability through genetic and pharmacological approaches. Notably, Skp2 inhibitor exhibits potent antitumor activities in multiple animal models and cooperates with chemotherapeutic agents to reduce cancer cell survival. Our study thus provides pharmacological evidence that Skp2 is a promising target for restricting cancer stem cell and cancer progression.

SNHG15-mediated feedback loop interplays with HNRNPA1/SLC7A11/GPX4 pathway to promote gastric cancer progression.

Dysregulation of long noncoding RNA (lncRNA) expression plays a pivotal role in the initiation and progression of gastric cancer (GC). However, the regulation of lncRNA SNHG15 in GC has not been well studied. Mechanisms for ferroptosis by SNHG15 have not been revealed. Here, we aimed to explore SNHG15-mediated biological functions and underlying molecular mechanisms in GC. The novel SNHG15 was identified by analyzing RNA-sequencing (RNA-seq) data of GC tissues from our cohort and TCGA dataset, and further validated by qRT-PCR in GC cells and tissues. Gain- and loss-of-function assays were performed to examine the role of SNHG15 on GC both in vitro and in vivo. SNHG15 was highly expressed in GC. The enhanced SNHG15 was positively correlated with malignant stage and poor prognosis in GC patients. Gain- and loss-of-function studies showed that SNHG15 was required to affect GC cell growth, migration and invasion both in vitro and in vivo. Mechanistically, the oncogenic transcription factors E2F1 and MYC could bind to the SNHG15 promoter and enhance its expression. Meanwhile, SNHG15 increased E2F1 and MYC mRNA expression by sponging miR-24-3p. Notably, SNHG15 could also enhance the stability of SLC7A11 in the cytoplasm by competitively binding HNRNPA1. In addition, SNHG15 inhibited ferroptosis through an HNRNPA1-dependent regulation of SLC7A11/GPX4 axis. Our results support a novel model in which E2F1- and MYC-activated SNHG15 regulates ferroptosis via an HNRNPA1-dependent modulation of the SLC7A11/GPX4 axis, which serves as the critical effectors in GC progression, and provides a new therapeutic direction in the treatment of GC.

The E2F1-HOXB9/PBX2-CDK6 axis drives gastric tumorigenesis and serves as a therapeutic target in gastric cancer.

Homeobox genes include HOX and non-HOX genes. HOX proteins play fundamental roles during ontogenesis by interacting with other non-HOX gene-encoded partners and performing transcriptional functions, whereas aberrant activation of HOX family members drives tumorigenesis. In this study, gastric cancer (GC) expression microarray data indicated that HOXB9 is a prominent upregulated HOX member in GC samples significantly associated with clinical outcomes and advanced TNM stages. However, the functional role of HOXB9 in GC remains contradictory in previous reports, and the regulatory mechanisms are elusive. By in silico and experimental analyses, we found that HOXB9 was upregulated by a vital cell cycle-related transcription factor, E2F1. Depleting HOXB9 causes G1-phase cell cycle arrest by downregulating CDK6 and a subset of cell cycle-related genes. Meanwhile, HOXB9 contributes to cell division and maintains the cytoskeleton in GC cells. We verified that HOXB9 interacts with PBX2 to form a heterodimer, which transcriptionally upregulates CDK6. Knocking down CDK6 can phenocopy the tumor-suppressive effects caused by HOXB9 depletion. Blocking HOXB9 can enhance the anti-tumor effect of CDK6 inhibitors. In conclusion, we elucidate the oncogenic role of HOXB9 in GC and reveal CDK6 as its potent downstream effector. The E2F1-HOXB9/PBX2-CDK6 axis represents a novel mechanism driving gastric carcinogenesis and conveys prognostic and therapeutic implications. © 2023 The Pathological Society of Great Britain and Ireland.

CD47-targeted immunotherapy unleashes antitumour immunity in Epstein-Barr virus-associated gastric cancer.

The aims of this study were to enhance the antitumour immunity in Epstein-Barr virus-associated gastric cancer (EBVaGC). We performed RNA-seq analysis to compare the differential expression genes between EBVaGC and EBV-negative gastric cancer (EBVnGC) patients. The expression levels of CD68, CD163 and CD47 were analyzed by immunohistochemistry. Different subsets of macrophages were investigated by a coincubation model. The effects of CD47 blockade were also detected. The expression levels of CD68, CD163 and CD47 were significantly higher in EBVaGC, and were associated with poor prognoses. Macrophages coincubated with EBV+ AGS cells tended to be immunosuppressed, which could be reversed by CD47 deficiency or blocking CD47. EBV resulted in cGAS-STING pathway activation, which stimulated CD47 expression and inhibited macrophage phagocytosis. Anti-CD47 therapy activated cGAS-STING signaling, which was responsible for production of IFN-ß, resulting in activation of antitumour immunity. Our results provide a promising new strategy for CD47-targeted immunotherapy in EBVaGC.

miR-223-3p mediates the diabetic kidney disease progression by targeting IL6ST/STAT3 pathway.

Diabetic kidney disease (DKD), the most pervasive complication in diabetic patients, has become a major health threat to the aging population. Our previous miRNA profiling identified hsa-miR-223-3p as a dysregulated miRNA in the DKD samples, which may serve as a biomarker for DKD diagnosis. However, the specific mechanism of miR-223-3p in the pathogenesis of DKD remains to be elucidated. In this study, we first verified that miR-223-3p level was significantly decreased in the in vitro cell model and in vivo db/db DKD model, accompanied with endothelial cell damage. Importantly, inhibiting the expression of miR-223-3p exacerbated high-glucose induced damages in Human Umbilical Vein Endothelial Cells (HUVECs) and Human Renal Glomerular Endothelial Cells (HRGECs), while miR-223-3p overexpression showed the opposite effect. We further demonstrated that miR-223-3p associated with IL6T mRNA and attenuated the progression of DKD by suppressing the downstream STAT3 activation, indicative of the implication of miR-223-3p/IL6T/STAT3 axis in the pathogenesis of DKD.

Identification of the distinct genomic features in gastroesophageal junction adenocarcinoma and its Siewert subtypes.

Rates of gastroesophageal junction adenocarcinomas (GEJAs) have shown an alarming increase; however, the genetic background of GEJA and its Siewert classification have yet to be uncovered. Here, 60 paired tumor and normal DNA samples from GEJA patients were analyzed by whole-exome sequencing. Among them, 13 were Siewert type I, 14 were type II, and 33 were type III. A predominance of C/G>T/A substitutions was discovered in GEJA, followed by C/G>A/T substitutions. Notably, Siewert type I and type II/III display distinct sets of driver genes, mutational spectrum, and recurrently disrupted pathways. Siewert type I showed similarity to esophageal adenocarcinomas (EACs) and the chromosomal instability subtype of stomach adenocarcinomas, while Siewert type II/III showed similarity to the genomic stable subtype of stomach adenocarcinoma. We also found that mutation of FBXW7, a driver gene of GEJA, was enriched in Siewert type I. Our data identify differences between GEJA and stomach/EACs at the genomic level and provide evidence for differential treatment based on Siewert classification of GEJA. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Meta-analysis of genome-wide association studies and functional assays decipher susceptibility genes for gastric cancer in Chinese populations.

OBJECTIVE: Although a subset of genetic loci have been associated with gastric cancer (GC) risk, the underlying mechanisms are largely unknown. We aimed to identify new susceptibility genes and elucidate their mechanisms in GC development. DESIGN: We conducted a meta-analysis of four genome-wide association studies (GWASs) encompassing 3771 cases and 5426 controls. After targeted sequencing and functional annotation, we performed in vitro and in vivo experiments to confirm the functions of genetic variants and candidate genes. Moreover, we selected 33 promising variants for two-stage replication in 7035 cases and 8323 controls from other five studies. RESULTS: The meta-analysis of GWASs identified three loci at 1q22, 5p13.1 and 10q23.33 associated with GC risk at p<5×10-8 and replicated seven known loci at p<0.05. At 5p13.1, the risk rs59133000[C] allele enhanced the binding affinity of NF-κB1 (nuclear factor kappa B subunit 1) to the promoter of PRKAA1, resulting in a reduced promoter activity and lower expression. The knockout of PRKAA1 promoted both GC cell proliferation and xenograft tumour growth in nude mice. At 10q23.33, the rs3781266[C] and rs3740365[T] risk alleles in complete linkage disequilibrium disrupted and created, respectively, the binding motifs of POU2F1 and PAX3, resulting in an increased enhancer activity and expression of NOC3L, while the NOC3L knockdown suppressed GC cell growth. Moreover, two new loci at 3q11.2 (OR=1.21, p=4.56×10-9) and 4q28.1 (OR=1.14, p=3.33×10-11) were associated with GC risk. CONCLUSION: We identified 12 loci to be associated with GC risk in Chinese populations and deciphered the mechanisms of PRKAA1 at 5p13.1 and NOC3L at 10q23.33 in gastric tumourigenesis.

Genetic risk, incident gastric cancer, and healthy lifestyle: a meta-analysis of genome-wide association studies and prospective cohort study.

BACKGROUND: Genetic variants and lifestyle factors have been associated with gastric cancer risk, but the extent to which an increased genetic risk can be offset by a healthy lifestyle remains unknown. We aimed to establish a genetic risk model for gastric cancer and assess the benefits of adhering to a healthy lifestyle in individuals with a high genetic risk. METHODS: In this meta-analysis and prospective cohort study, we first did a fixed-effects meta-analysis of the association between genetic variants and gastric cancer in six independent genome-wide association studies (GWAS) with a case-control study design. These GWAS comprised 21 168 Han Chinese individuals, of whom 10 254 had gastric cancer and 10 914 geographically matched controls did not. Using summary statistics from the meta-analysis, we constructed five polygenic risk scores in a range of thresholds (p=5 × 10-4 p=5 × 10-5 p=5 × 10-6 p=5 × 10-7, and p=5 × 10-8) for gastric cancer. We then applied these scores to an independent, prospective, nationwide cohort of 100 220 individuals from the China Kadoorie Biobank (CKB), with more than 10 years of follow-up. The relative and absolute risk of incident gastric cancer associated with healthy lifestyle factors (defined as not smoking, never consuming alcohol, the low consumption of preserved foods, and the frequent intake of fresh fruits and vegetables), was assessed and stratified by genetic risk (low [quintile 1 of the polygenic risk score], intermediate [quintile 2-4 of the polygenic risk score], and high [quintile 5 of the polygenic risk score]). Individuals with a favourable lifestyle were considered as those who adopted all four healthy lifestyle factors, those with an intermediate lifestyle adopted two or three factors, and those with an unfavourable lifestyle adopted none or one factor. FINDINGS: The polygenic risk score derived from 112 single-nucleotide polymorphisms (p<5 × 10-5) showed the strongest association with gastric cancer risk (p=7·56 × 10-10). When this polygenic risk score was applied to the CKB cohort, we found that there was a significant increase in the relative risk of incident gastric cancer across the quintiles of the polygenic risk score (ptrend<0·0001). Compared with individuals who had a low genetic risk, those with an intermediate genetic risk (hazard ratio [HR] 1·54 [95% CI 1·22-1·94], p=2·67 × 10-4) and a high genetic risk (2·08 [1·61-2·69], p<0·0001) had a greater risk of gastric cancer. A similar increase in the relative risk of incident gastric cancer was observed across the lifestyle categories (ptrend<0·0001), with a higher risk of gastric cancer in those with an unfavourable lifestyle than those with a favourable lifestyle (2·03 [1·46-2·83], p<0·0001). Participants with a high genetic risk and a favourable lifestyle had a lower risk of gastric cancer than those with a high genetic risk and an unfavourable lifestyle (0·53 [0·29-0·99], p=0·048), with an absolute risk reduction of 1·12% (95% CI 0·62-1·56). INTERPRETATION: Chinese individuals at an increased risk of incident gastric cancer could be identified by use of our newly developed polygenic risk score. Compared with individuals at a high genetic risk who adopt an unhealthy lifestyle, those who adopt a healthy lifestyle could substantially reduce their risk of incident gastric cancer. FUNDING: National Key R&D Program of China, National Natural Science Foundation of China, 333 High-Level Talents Cultivation Project of Jiangsu Province, and China Postdoctoral Science Foundation.

c-Met-dependent phosphorylation of RhoA plays a key role in gastric cancer tumorigenesis.

RhoA has been identified as having a gain-of-function mutation in approximately 20% of diffuse gastric cancer patients. However, the carcinogenic role of RhoA mutations in gastric cancer (GC) is unclear. In the present study, we report that RhoA directly interacts with c-Met and can be phosphorylated by c-Met at Y42 before subsequent K48-linked polyubiquitination and proteasome-mediated protein degradation. Y42C-mutated RhoA exhibits higher protein levels and promotes the proliferation and motility of GC cells. Interestingly, a c-Met inhibitor significantly repressed the growth of GC cells transfected with WT RhoA but not RhoA mutated at Y42 in vivo and in vitro. Analyses of human GC tissues showed that the combined levels of p-c-Met and p-RhoA are a better predictor for prognosis than either factor alone. Taken together, our findings unravel the mechanism by which the RhoA Y42 mutant is linked to poor prognosis in GC. Moreover, this study helps to identify a strategy for patient stratification and optimization of targeted c-Met therapy. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Pile-up effect in an infrared single-pixel compressive LiDAR system.

Compressive sensing (CS) has been used in LiDAR systems utilizing one single-photon-counting avalanche diode. We demonstrate an unexpected grayscale inversed image of an object at an unchosen depth, which appears in the reconstruction of the infrared single-pixel LiDAR system due to the pile-up effect. A correction algorithm and the sparse measurement are proposed and experimentally verified to effectively reduce the photon pile-up influence, so that the negative images can be completely removed. The correction methods in this research can improve the accuracy and the flexibility of the single-pixel LiDAR systems employing detectors with a low maximum light count.

The microRNA-423-3p-Bim Axis Promotes Cancer Progression and Activates Oncogenic Autophagy in Gastric Cancer.

Human serum microRNAs (miRNAs) have been shown to serve as disease fingerprints for predicting survival of cancer patients. However, the roles of specific miRNAs involved in gastric cancer (GC) are largely unknown. In this study, miRNA profiling was performed on sera obtained from six patients in good- and poor-survival groups. Expression of miR-423-3p was validated by quantitative RT-PCR in another 67 GC serum samples and paired normal and cancerous gastric tissues. Luciferase reporter assays were used to identify the target gene Bcl-2-interacting mediator of cell death (Bim). As a result, between the good-survival and poor-survival groups, the expression of nine serum miRNAs was altered more than two-fold. Among these, miR-423-3p was significantly increased in the poor-survival group, and its overexpression in GC tissues predicted poor survival in 119 patients with GC. miR-423-3p was found to promote cell proliferation, migration, and invasion in cell lines and animal models. Mechanistically, knockdown of the autophagy-related gene (Atg) 7 rescued the GC-promoting effect of miR-423-3p. In conclusion, miR-423-3p activates oncogenic and Beclin-1-dependent autophagy and promotes GC progression by reducing the expression of Bim. The newly identified miR-423-3p-Bim axis might be a potential therapeutic target in GC.

Phosphorylation by mTORC1 stablizes Skp2 and regulates its oncogenic function in gastric cancer.

BACKGROUND: Both mTOR and Skp2 play critical roles in gastric cancer (GC) tumorigenesis. However, potential mechanisms for the association between these two proteins remains unidentified. METHODS: The regulatory role for mTORC1 in Skp2 stability was tested using ubiquitination assay. The functions of p-Skp2 (phosphorylation of Skp2) were studied in vitro and in vivo. Expression of p-Skp2 and p-mTOR (phosphorylation of mTOR) were shown in GC lines and in 169 human primary GC tissues. RESULTS: mTORC1 can directly interact with Skp2 and phosphorylated Skp2 at Ser64, which sequentially protect Skp2 from ubiquitination and degradation. Furthermore, the phospho-deficient p-Skp2 (S64) mutant significantly suppresses GC cell proliferation and tumorigenesis. The expression of p-Skp2 was associated with p-mTOR in GC cell lines and tissues. Interestingly, the combination of p-Skp2 and p-mTOR was a better predictor of survival than either factor alone. CONCLUSION: The mTORC1 function to regulate Skp2 by Ser64 phosphorylation may represent an oncogenic event in GC tumorigenesis. Moreover, our study also indicates that Skp2 Ser64 expression is a potential indicator in the treatment of GC patients using mTORC1 inhibitor.

Prognostic Significance of Carcinoembryonic Antigen Staining in Cancer Tissues of Gastric Cancer Patients.

PURPOSE: The aim of this study was to assess the significance of the correlation among tissue carcinoembryonic antigen (CEA) expression with serum CEA (sCEA) levels and long-term survival to highlight the clinical prognostic significance of tissue CEA expression in gastric cancer patients. METHODS: Immunohistological method and radioimmunoassay were used to assess tissue and sCEA expression, respectively. Univariate and multivariate analyses were performed to determine correlations, and the Kaplan-Meier method was used to investigate the prognostic significance. RESULTS: Our results demonstrate that tissue CEA in gastric cancer is significantly correlated with preoperative sCEA levels (p = 0.031), depth of invasion (p = 0.001), lymph node metastasis (p < 0.001), distant metastasis (p = 0.001), and TNM staging (p < 0.001). The 5-year survival rates were 67.6, 53.9, and 40.1 % for negatively, moderately, and intensely positively stained tissues (p < 0.001), and 57.0 and 37.9 % for serum with normal and elevated CEA expression (p = 0.031). Multivariate analysis revealed that tissue CEA can be considered an independent prognostic factor. Further analysis illustrated that patients with negative expression in both tissue and serum had better prognosis compared with those positively expressing CEA in both tissue and serum and/or those positively expressing CEA in either tissue or serum (p < 0.001). Our results also demonstrated that patients with negative tissue CEA staining and elevated sCEA expression had a better 5-year survival. CONCLUSION: Tissue CEA expression in gastric cancer is directly correlated with sCEA levels and long-term prognosis. Thus, tissue CEA expression can be considered as a useful biomarker to improve the interpretation of sCEA levels in predicting long-term survival.

Prognostic significance of Epstein-Barr virus infection in gastric cancer: a meta-analysis.

BACKGROUND: The prognostic significance of Epstein-Barr virus (EBV) infection in gastric cancer (GC) remains unclear. Recently, a number of studies have investigated the association between EBV infection and the prognosis of GC with controversial results. We therefore conducted a meta-analysis to assess its prognostic significance. METHODS: PubMed and EMBASE were searched for studies up to October 1, 2014. We investigated the association between EBV infection with survival in patients with GC. The pooled hazard ratio (HR) and its 95% confidence interval (CI) were calculated to evaluate risk. RESULTS: A final analysis of 8,336 patients with GC from 24 studies was performed. Our analysis results indicated that the pooled HR was 0.67 (95% CI: 0.55-0.79; Z = 11.18, P < 0.001). Subgroup analyses stratified by region revealed that the protective role of EBV infection only remained in the Asian population (HR: 0.62, 95% CI: 0.48-0.75; P < 0.001). When stratified by study quality and statistical methodology, the protective role could also be identified in high quality studies (HR: 0.67, 95% CI: 0.55-0.79) and in univariate analysis studies (HR: 0.62, 95% CI: 0.50-0.74). There was no evidence of significant heterogeneity and publication bias. CONCLUSIONS: The presence of EBV has a favorable impact on GC patient's survival, especially in an Asian population. Future updated studies, especially large-scale randomized controlled studies stratified by region, are warranted as validation studies.

E3-ligase Skp2 regulates ß-catenin expression and maintains hematopoietic stem cell homing.

The homing ability of hematopoietic stem cells (HSCs) was a critical step for transplantation and subsequent hematopoiesis. Although the HSC transplantation was widely used for many diseases, the mechanism by which HSC homing was regulated remained poorly understood. F-box protein S-phase kinase associated protein2 (Skp2), a component of the Skp2-SCF E3 ligase complex, was regarded as a cell cycle regulator by controlling the level of p21 and p27 through ubiquitination. We recently reported an important role of Skp2 in maintaining HSC pool size, quiescent stage and self-renewal ability. In this current study, we showed that Skp2 was a novel and critical regulator for maintaining the homing of HSCs as well as their residence in the endosteal niche. Microarray analysis together with biochemical validations revealed that Skp2 deficiency profoundly reduced the expression of ß-catenin and its target genes. Knockdown of ß-catenin mimicked the decline of HSC homing upon Skp2 deficiency, suggesting that Skp2 may regulate ß-catenin and its target gene expression to orchestrate HSC homing. Our study not only identified Skp2 as a new regulator for maintaining ß-catenin expression and HSC homing, but also suggested that Skp2 may serve as a predictive marker for monitoring the transplantation efficiency.

Clinical comparison of total gastrectomy with single-vessel transection Roux-en-Y(SR-Y) reconstruction versus total gastrectomy with conventional Roux-en-Y reconstruction for proximal gastric cancer.

PURPOSE: The aim of this study was to investigate the clinical benefits of single-vessel transection Roux-en-Y reconstruction following total gastrectomy. METHODS: A total of 194 patients with proximal gastric cancer were prospectively collected at Fudan University Shanghai Cancer Center between January 2021 and September 2022. This included 97 patients who underwent conventional Roux-en-Y reconstruction and 97 patients who underwent single-vessel transection Roux-en-Y reconstruction. Clinicopathological characteristics, surgical outcomes, and postoperative complications were compared between the conventional and single-vessel transection groups. RESULTS: There were no significant differences in baseline characteristics between the two groups in terms of age(p=0.882), sex (p=0.595), BMI(p=0.683), tumor location (p=0.568), TNM stage(p=0.122), tumor size(p=0.927), anemia (p=0.756), neoadjuvant chemotherapy(p=0.730) and surgical approach (p=0.592). However, in comparion with the conventional group, the single-vessel transection group had a shorter operation time (162.5±37.6min vs 178.5±48.3min; p=0.011) and less intraoperative bleeding (167.2±91.8ml vs 207.8±167.5ml; p=0.037) after complete reservation of the terminal jejunal vascular archs. Nevertheless, there were no significant differences in tensions of jejunal mesentery, durations of peritoneal drainage, postoperative hospital stay durations or the number of lymph node dissections and early complications between the two groups. CONCLUSIONS: The single-vessel transection Roux-en-Y reconstruction could simplify surgical procedures, reduce operating time, and minimize intraoperative bleeding without increasing tensions of jejunal mesentery or short-term complications. It is feasible and safe and worth further promotion in clinical practice.

STAT3-mediated up-regulation of DAB2 via SRC-YAP1 signaling axis promotes Helicobacter pylori-driven gastric tumorigenesis.

BACKGROUND: Helicobacter pylori (H pylori) infection is the primary cause of gastric cancer (GC). The role of Disabled-2 (DAB2) in GC remains largely unclear. This study aimed to investigate the role of DAB2 in H pylori-mediated gastric tumorigenesis. METHODS: We screened various datasets of GC to analyze DAB2 expression and cell signaling pathways. DAB2 expression was assessed in human GC tissue microarrays. H pylori infection in vivo and in vitro models were further explored. Immunostaining, immunofluorescence, chromatin immunoprecipitation, co-immunoprecipitation, Western blot, quantitative polymerase chain reaction, and luciferase reporter assays were performed in the current study. RESULTS: The bioinformatic analysis verified that DAB2 was 1 of the 8 genes contributed to tumorigenesis and associated with poor prognosis in GC. The median overall survival and disease-free survival rates in DAB2high group were significantly less than those in DAB2low group. These findings demonstrated that H pylori transcriptionally activated DAB2 expression via signal transducer and activator of transcription 3 (STAT3)-dependent pathway. By bioinformatics analysis and knockdown or overexpression of DAB2, we found that DAB2 upregulated Yes-associated protein 1 (YAP1) transcriptional activity. Mechanistically, DAB2 served as a scaffold protein for integrin beta 3 (ITGB3) and SRC proto-oncogene non-receptor tyrosine kinase (SRC), facilitated the phosphorylation of SRC, promoted the small GTPase ras homolog family member A (RHOA) activation and phosphorylation of YAP1, and ultimately enhanced the YAP1 transcriptional activity. CONCLUSIONS: Altogether, these findings indicated that DAB2 is a key mediator in STAT3-regulated translation of YAP1 and plays crucial roles in H pylori-mediated GC development. DAB2 might serve as a novel therapeutic target for GC.

The epigenetic modifier lysine methyltransferase 2C is frequently mutated in gastric remnant carcinoma.

Gastric remnant carcinoma (GRC), which occurs in the stomach after partial gastrectomy, is a rare and aggressive form of gastric adenocarcinoma (GAC). Comprehensive profiling of genomic mutations in GRC could provide the basis for elucidating the origin and characteristics of this cancer. Herein, whole-exome sequencing (WES) was performed on 36 matched tumor-normal samples from patients with GRC and identified recurrent mutations in epigenetic modifiers, notably KMT2C, ARID1A, NSD1, and KMT2D, in 61.11% of cases. Mutational signature analysis revealed a low frequency of microsatellite instability (MSI) in GRC, which was further identified by MSIsensor, MSI-polymerase chain reaction, and immunohistochemistry analysis. Comparative analysis demonstrated that GRC had a distinct mutation spectrum compared to that of GAC in The Cancer Genome Atlas samples, with a significantly higher mutation rate of KMT2C. Targeted deep sequencing (Target-seq) of an additional 25 paired tumor-normal samples verified the high mutation frequency (48%) of KMT2C in GRC. KMT2C mutations correlated with poor overall survival in both WES and Target-seq cohorts and were independent prognosticators in GRC. In addition, KMT2C mutations were positively correlated with favorable outcomes in immune checkpoint inhibitor-treated pan-cancer patients and associated with higher intratumoral CD3+ , CD8+ tumor-infiltrating lymphocyte counts, and PD-L1 expression in GRC samples (p = 0.018, 0.092, 0.047, 0.010, and 0.034, respectively). Our dataset provides a platform for information and knowledge mining of the genomic characteristics of GRC and helps to frame new therapeutic approaches for this disease.

SDC2 Stabilization by USP14 Promotes Gastric Cancer Progression through Co-option of PDK1.

Gastric cancer (GC) is a common malignancy and remains the fourth-leading cause of cancer-related deaths worldwide. Oncogenic potential of SDC2 has been implicated in multiple types of cancers, yet its role and underlying molecular mechanisms in GC remain unknown. Here, we found that SDC2 was highly expressed in GC and its upregulation correlated with poor prognosis in GC patients. Depletion of SDC2 significantly suppressed the growth and invasive capability of GC cells, while overexpressing SDC2 exerts opposite effects. Combined bioinformatics and experimental analyses substantiated that overexpression of SDC2 activated the AKT signaling pathway in GC, mechanistically through the interaction between SDC2 and PDK1-PH domain, thereby facilitating PDK1 membrane translocation to promote AKT activation. Moreover, SDC2 could also function as a co-receptor for FGF2 and was profoundly involved in the FGF2-AKT signaling axis in GC. Lastly, we revealed a mechanism on the USP14-mediated stabilization of SDC2 that is likely to contribute to SDC2 upregulation in GC tissues. Furthermore, we showed that IU1, a potent USP14 inhibitor, decreased the abundance of SDC2 in GC cells. Our findings indicate that SDC2 functions as a novel GC oncogene and has potential utility as a diagnostic marker and therapeutic target for GC.