N6-methyadenosine modified SUV39H2 regulates homologous recombination through epigenetic repression of DUSP6 in gastric cancer

Despite many advances in treatment over the past few years, the poor 5-year survival rate and high recurrence rate of gastric cancer (GC) remain unsatisfactory. As the most abundant epigenetic modification in the eukaryotic mRNA, N6-methyladenosine (m⁶A) methylation participates in tumor progression and tissue development. During tumor progression, DNA damage repair mechanisms can be reprogrammed to give new growth advantages on tumor clones whose genomic integrity is disturbed. Here we detected the elevated SUV39H2 expression in GC tissues and cell lines. Functionally, SUV39H2 promoted GC proliferation and inhibited apoptosis in vitro and in vivo. Mechanistically, METTL3-mediated m⁶A modification promotes mRNA stability of SUV39H2 in an IGF2BP2 dependent manner, resulting in upregulated mRNA expression of SUV39H2. As a histone methyltransferase, SUV39H2 was verified to increase the phosphorylation level of ATM through transcriptional repression of DUSP6, thereby promoting HRR and ultimately inhibiting GC chemosensitivity to cisplatin. Collectively, these results indicate the specific mechanism of m⁶A-modified SUV39H2 as a histone methyltransferase promoting HRR to inhibit the chemosensitivity of GC. SUV39H2 is expected to become a key target in the precision targeted therapy of GC.

Risk factors and conservative therapy outcomes of anastomotic leakage after gastrectomy: Experience of 3,926 patients from a single gastric surgical unit

Background

Anastomotic leakage (AL) after gastrectomy is one of the severest postoperative complications and is related to increasing mortality. In addition, no consensus guidelines about strategies of AL treatment have been established. This large cohort study aimed to inspect the risk factors and efficacy of the conservative treatment for AL in patients with gastric cancer.

Methods

We reviewed the clinicopathological data of 3,926 gastric cancer patients undergoing gastrectomy between 2014 and 2021. Results contained the rate, risk factors, and conservative therapy outcomes of AL.

Results

In total, 80 patients (2.03%, 80/3,926) were diagnosed with AL, and esophagojejunostomy was the most frequent AL site (73.8%, 59/80). Among them, one patient (2.5%, 1/80) died. Multivariate analysis indicated that low albumin concentration (P = 0.001), presence of diabetes (P = 0.025), laparoscopic method (P < 0.001), total gastrectomy (P = 0.003), and proximal gastrectomy (P = 0.002) were predicting factors for AL. The closure rate for the conservative treatment of AL in the first month after AL diagnosis was 83.54% (66/79), and the median time from leakage diagnosis to the closure of leakage was 17 days (interquartile range 11–26 days). Low level of plasma albumin (P = 0.004) was associated with late leakage closures. In terms of 5-year overall survival, no significant difference was observed between patients with and without AL.

Conclusion

The incidence of AL after gastrectomy is associated with low albumin concentration, diabetes, the laparoscopic method, and extent of resection. The conservative treatment is relatively safe and effective for the AL management in patients after gastric cancer surgery.

Deubiquitylation of Rab35 by USP32 promotes the transmission of imatinib resistance by enhancing exosome secretion in gastrointestinal stromal tumours

Imatinib is a tyrosine kinase inhibitor that is widely used to combat gastrointestinal stromal tumours (GISTs). However, secondary resistance to imatinib is an important challenge in GIST treatment. Recent studies have demonstrated that cancer-derived nanosized exosomes play a key role in intercellular communication, but little is known about the roles of exosomes in imatinib-resistant GISTs. Here, we reveal that exosomes released from imatinib-resistant GISTs transmit drug resistance to imatinib-sensitive tumours. By using iTRAQ technology, we demonstrate that Ras-related protein Rab-35 (Rab35) is upregulated differentially in imatinib-resistant GISTs. Loss of Rab35 decreases exosome secretion, thereby hampering the transmission of imatinib resistance to sensitive tumours. Mechanistically, we showed that the ubiquitin‒proteasome system is involved in elevated Rab35 expression and that ubiquitin-specific protease 32 (USP32), a deubiquitylating enzyme, is bound to Rab35. Further experiments demonstrate that this protease protects Rab35 from proteasomal degradation by reducing Lys48 (K48)-ubiquitination. Additionally, we found that the transcription factor ETV1, which is a lineage survival factor in GISTs, promotes USP32 expression. Collectively, our results reveal that exosomes transmit imatinib resistance in GISTs and that deubiquitylation plays a key role in regulating the transmission process. The USP32-Rab35 axis provides a potential target for interventions to reduce the occurrence of imatinib resistance in GISTs.

Long non-coding RNA LGALS8-AS1 facilitates PLAGL2-mediated malignant phenotypes in gastric cancer

BACKGROUND

Great progress has been made in studying the function of long non-coding RNA (lncRNA) in various tumors, including gastric cancer (GC). However, there are still numerous lncRNAs that have not yet been studied and explored for their roles in GC, and their important functions need to be further revealed.

METHODS

Through analyzing The Cancer Genome Atlas (TCGA) database combined with bioinformatics survival tools, a novel GC-related lncRNA LGALS8-AS1 was identified. A quantitative real-time polymerase chain reaction and a series of in vitro or in vivo cell functional experiments were performed to determine the expression and the role of LGALS8-AS1/miR-138-5p/PLAGL2 in GC.

RESULTS

LGALS8-AS1 was remarkably upregulated and correlated with the unfavorable prognosis in GC. Higher expression of LGALS8-AS1 was positively associated with higher lymph node metastasis rate, as well as larger tumor size. In addition, a series of cell functional experiments revealed that LGALS8-AS1 could facilitate GC cell proliferation, migration and metastasis in vitro or in vivo. A deeper mechanism exploration revealed that LGALS8-AS1 could function as the miR-138-5p molecular sponge and upregulate the PLAGL2 expression, thereby promoting the cell proliferation, migration and metastasis in GC.

CONCLUSIONS

In brief, we revealed the tumor promoting role of the LGALS8-AS1/miR-138-5p/PLAGL2 molecular signaling axis in GC, and our findings provide enlightenment for further understanding of the mechanism of tumorigenesis and development of GC, making LGALS8-AS1 a possible new diagnostic or therapeutic target for GC.

Serum calcium concentrations and risk of all-cause and cause-specific mortality: results from two prospective cohorts

CONTEXT

Calcium plays a critical role in various physiological activities. However, the association between circulating calcium concentrations and mortality in a general healthy population remains undetermined.

OBJECTIVE

To examine the association of serum calcium concentrations with all-cause and cause-specific mortality.

METHODS

Leveraging data from the UK Biobank (n=361 662) and the US National Health and Nutrition Examination Survey (NHANES, n=36 985), we prospectively examined the association of serum calcium concentrations with all-cause and cause-specific mortality using Cox proportional hazard and restricted-cubic spline models.

RESULTS

During a median follow-up of 12.0 years, UK Biobank documented 18 327 deaths, including 3119 (17.0%) from cardiovascular disease (CVD) and 9599 (52.4%) from cancer. We found a U-shape relationship of albumin-adjusted calcium concentrations with all-cause and CVD mortality. Compared to participants with moderate calcium levels (the third quintile, Q3), those with low and high levels had an increased risk of all-cause (hazard ratio [HR]=1.02 for Q1 vs. Q3; 1.10 for Q5 vs. Q3) and CVD mortality (HR=1.11 for Q1 vs. Q3; 1.25 for Q5 vs. Q3). In contrast, there was a linear positive relationship with cancer mortality (HR=1.09 for Q5 vs. Q1). Similar results for all-cause, CVD, and cancer mortality were observed in US NHANES.

CONCLUSIONS

Our findings provide novel insights into the association between serum calcium concentrations and mortality in the general healthy population.

A Metabolomic Signature of Obesity and Risk of Colorectal Cancer: Two Nested Case-Control Studies

Obesity is a leading contributor to colorectal cancer (CRC) risk, but the metabolic mechanisms linking obesity to CRC are not fully understood. We leveraged untargeted metabolomics data from two 1:1 matched, nested case-control studies for CRC, including 223 pairs from the US Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial and 190 pairs from a prospective Chinese cohort. We explored serum metabolites related to body mass index (BMI), constructed a metabolomic signature of obesity, and examined the association between the signature and CRC risk. In total, 72 of 278 named metabolites were correlated with BMI after multiple testing corrections (p FDR < 0.05). The metabolomic signature was calculated by including 39 metabolites that were independently associated with BMI. There was a linear positive association between the signature and CRC risk in both cohorts (p for linear < 0.05). Per 1-SD increment of the signature was associated with 38% (95% CI: 9-75%) and 28% (95% CI: 2-62%) higher risks of CRC in the US and Chinese cohorts, respectively. In conclusion, we identified a metabolomic signature for obesity and demonstrated the association between the signature and CRC risk. The findings offer new insights into the underlying mechanisms of CRC, which is critical for improved CRC prevention.

N6-methyladenosine-modified USP13 induces pro-survival autophagy and imatinib resistance via regulating the stabilization of autophagy-related protein 5 in gastrointestinal stromal tumors

Secondary resistance to imatinib (IM) represents a major challenge for therapy of gastrointestinal stromal tumors (GISTs). Aberrations in oncogenic pathways, including autophagy, correlate with IM resistance. Regulation of autophagy-related protein 5 (ATG5) by the ubiquitin-proteasome system is critical for autophagic activity, although the molecular mechanisms that underpin reversible deubiquitination of ATG5 have not been deciphered fully. Here, we identified USP13 as an essential deubiquitinase that stabilizes ATG5 in a process that depends on the PAK1 serine/threonine-protein kinase and which enhances autophagy and promotes IM resistance in GIST cells. USP13 preferentially is induced in GIST cells by IM and interacts with ATG5, which leads to stabilization of ATG5 through deubiquitination. Activation of PAK1 promoted phosphorylation of ATG5 thereby enhancing the interaction of ATG5 with USP13. Furthermore, N6-methyladenosine methyltransferase-like 3 (METTL3) mediated stabilization of USP13 mRNA that required the m6A reader IGF2BP2. Moreover, an inhibitor of USP13 caused ATG5 decay and co-administration of this inhibitor with 3-methyladenine boosted treatment efficacy of IM in murine xenograft models derived from GIST cells. Our findings highlight USP13 as an essential regulator of autophagy and IM resistance in GIST cells and reveal USP13 as a novel potential therapeutic target for GIST treatment.

Laparoscopic distal gastrectomy demonstrates acceptable outcomes regarding complications compared to open surgery for gastric cancer patients with pylorus outlet obstruction

Background

For gastric cancer (GC) patients with pylorus outlet obstruction (POO), whether laparoscopic surgery has advantages over open surgery remains unclear. This study aims to investigate the differences between patients with and without POO in open and laparoscopic groups and to determine the differences between laparoscopic distal gastrectomy (LDG) and open distal gastrectomy (ODG) in GC patients with POO.

Methods

A total of 241 GC patients with POO who underwent distal gastrectomy at the Department of Gastric Surgery of the First Affiliated Hospital of Nanjing Medical University between 2016 and 2021 were included in this study. A total of 1,121 non-POO patients who underwent laparoscopic surgery and 948 non-POO patients who underwent open surgery from 2016 to 2021 were also enrolled in the study. We compared complication rates and hospital stays between open and laparoscopic groups.

Results

There was no significant difference for LDG between GC patients with and without POO regarding the overall complication rates (P = 0.063), the Grade III-V complication rate (P = 0.673), and the anastomotic complication rate (P = 0.497) from 2016 to 2021. The patients with POO had longer preoperative hospital stay (P = 0.001) and postoperative hospital stay (P=0.007) compared to patients without POO. No significant difference was observed for open patients between POO and non-POO patients regarding the overall complication rate (P = 0.357), grade III-V complication rate (P = 1.000), and anastomosis-related complication rate (P = 0.766). Compared with open surgery in GC patients with POO (n = 111), the total complication rate of the LDG group was 16.2%, which was significantly lower than that of the open group (26.1%, P = 0.041). No significant differences in the Grade III-V complication rate (P = 0.574) and anastomotic complication rate (P = 0.587) were observed between laparoscopic and open groups. Patients receiving laparoscopic surgery had shorter postoperative hospital stay than open surgery (P = 0.001). More resected lymph nodes (LNs) were also observed in the laparoscopic group (P = 0.0145).

Conclusion

The comorbidity of GC with POO does not increase the complication rate after laparoscopic or open distal gastrectomy. In GC patients with POO, laparoscopic surgery shows advantages over open surgery with a lower overall complication rate, shorter postoperative hospital stay, and more harvested lymph nodes. Laparoscopic surgery is a safe, feasible, and effective treatment for GC with POO.

Obesity promotes lipid accumulation in lymph node metastasis of gastric cancer: a retrospective case‒control study

Background

The connection between obesity, lipid accumulation, and lymph node metastasis (LNM) in gastric cancer (GC) is unclear.

Methods

The association of body mass index (BMI) and serum lipid levels with LNM was measured by calculating the odds ratio (OR) and 95% confidence interval (CI) in 1,058 eligible GC patients with a mean age of 61.4 years. Meanwhile, differentially expressed genes (DEGs) were identified between lymph node metastasis-positive (N +) and -negative (N0) groups using public RNA-seq data. Neutral lipids in human GC samples were detected by Oil red O staining. The expression of cluster of differentiation 36 (CD36), fatty acid synthase (FASN), and lipoprotein lipase (LPL) was detected by immunohistochemistry (IHC) and quantitative real-time PCR.

Results

Compared with normal-weight patients, overweight (OR = 2.02, 95% CI = 1.26–3.23) and obese (OR = 1.83, 95% CI = 1.15–2.91) patients showed increased ORs for LNM. However, no significant results were obtained for serum lipids in the multivariable-adjusted model (P > 0.05). Subgroup analysis suggested that increased low-density lipoprotein cholesterol was a risk factor in females (OR = 1.27, 95% CI = 1.02–1.59). Functional enrichment analysis of DEGs revealed a connection between lipid metabolism and LNM. Meanwhile, lipid staining showed a mass of lipids in obese N + tumor samples, and IHC analysis indicated an increase in LPL and CD36 expression in N + cases, implying a crucial role for exogenous lipid supply in LNM.

Conclusions

High BMI significantly increases the risk of LNM in GC and promotes lipid accumulation in GC cells in LNM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01734-7.

Cytosolic TGM2 promotes malignant progression in gastric cancer by suppressing the TRIM21-mediated ubiquitination/degradation of STAT1 in a GTP binding-dependent modality

BACKGROUND

Previous studies have revealed the critical role of transglutaminase 2 (TGM2) as a potential therapeutic target in cancers, but the oncogenic roles and underlying mechanisms of TGM2 in gastric cancer (GC) are not fully understood. In this study, we examined the role and potential mechanism of TGM2 in GC.

METHODS

Western blotting, immunohistochemistry, CCK8, colony formation and transwell assays were used to measure TGM2 expression in the GC cells and tissues and to examine the in vitro role of TGM2 in GC. Xenograft and in vivo metastasis experiments were performed to examine the in vivo role of TGM2 in GC. Gene set enrichment analysis, quantitative PCR and western blotting were conducted to screen for potential TGM2 targets involved in GC. Gain/loss-of-function and rescue experiments were conducted to detect the biological roles of STAT1 in GC cells in the context of TGM2. Co-immunoprecipitation, mass spectrometry, quantitative PCR and western blotting were conducted to identify STAT1-interacting proteins and elucidate their regulatory mechanisms. Mutations in TGM2 and two molecules (ZM39923 and A23187) were used to identify the enzymatic activity of TGM2 involved in the malignant progression of GC and elucidate the underlying mechanism.

RESULTS

In this study, we demonstrated elevated TGM2 expression in the GC tissues, which closely related to pathological grade, and predicted poor survival in patients with GC. TGM2 overexpression or knockdown promoted (and inhibited) cell proliferation, migration, and invasion, which were reversed by STAT1 knockdown or overexpression. Further studies showed that TGM2 promoted GC progression by inhibiting STAT1 ubiquitination/degradation. Then, tripartite motif-containing protein 21 (TRIM21) was identified as a ubiquitin E3 ligase of STAT1 in GC. TGM2 maintained STAT1 stability by facilitating the dissociation of TRIM21 and STAT1 with GTP-binding enzymatic activity. A23187 abolished the role of TGM2 in STAT1 and reversed the pro-tumor role of TGM2 in vitro and in vivo.

CONCLUSIONS

This study revealed a critical role and regulatory mechanism of TGM2 on STAT1 in GC and highlighted the potential of TGM2 as a therapeutic target, which elucidates the development of medicine or strategies by regulating the GTP-binding activity of TGM2 in GC.

A novel risk model construction and immune landscape analysis of gastric cancer based on cuproptosis-related long noncoding RNAs

Recent studies have identified cuproptosis, a new mechanism of regulating cell death. Accumulating evidence suggests that copper homeostasis is associated with tumorigenesis and tumor progression, however, the clinical significance of cuproptosis in gastric cancer (GC) is unclear. In this study, we obtained 26 prognostic cuproptosis-related lncRNAs (CRLs) based on 19 cuproptosis-related genes (CRGs) via Pearson correlation analysis, differential expression analysis, and univariate Cox analysis. A risk model based on 10 CRLs was established with the least absolute shrinkage and selection operator (LASSO) Cox regression analysis and multivariate Cox proportional hazards model to predict the prognosis and immune landscape of GC patients from The Cancer Genome Atlas (TCGA). The risk model has excellent accuracy and efficiency in predicting prognosis of GC patients (Area Under Curve (AUC) = 0.742, 0.803, 0.806 at 1,3,5 years, respectively, P < 0.05). In addition, we found that the risk score was negatively correlated with the infiltration of natural killer (NK) cells and helper T cells, while positively correlated with the infiltration of monocytes, macrophages, mast cells, and neutrophils. Moreover, we evaluated the difference in drug sensitivity of patients with different risk patterns. Furthermore, low-risk patients showed higher tumor mutation burden (TMB) and better immunotherapy response than high-risk patients. In the end, we confirmed the oncogenic role of AL121748.1 which exhibited the highest Hazard Ratio (HR) value among 10 CRLs in GC via cellular functional experiments. In conclusion, our risk model shows a significant role in tumor immunity and could be applied to predict the prognosis of GC patients.

Gastric cancer-derived exosomal miR-519a-3p promotes liver metastasis by inducing intrahepatic M2-like macrophage-mediated angiogenesis

Background

Liver metastasis (LM) is a major obstacle to the prognosis of gastric cancer (GC) patients, but the molecular mechanism underlying gastric cancer liver metastasis (GC-LM) remains unknown. Exosomes have been identified as an important mediator of communication between tumor cells and the microenvironment. Therefore, we sought to investigate the effects of primary GC cells on the liver microenvironment and the role of exosomal microRNAs (exo-miRNA) in GC-LM.

Methods

Sequential differential centrifugation, transmission electron microscopy and NanoSight analysis were used to extract and characterize exosomes. MicroRNA sequencing in GC-derived exosomes and mRNA sequencing in PMA-treated THP-1 cells were used to identify differentially expressed miRNAs in exosomes and the functional targets of exosomal miR-519a-3p (exo-miR-519a-3p) in macrophages, respectively. Tracing and internalization of exosomes and transfer of exo-miR-519a-3p were observed by immunofluorescence. Tubule formation assays, aortic ring assays, and exosome-educated GC-LM model were used to investigate the roles of GC-derived exosomes and exo-miR-519a-3p in angiogenesis and GC-LM. Luciferase reporter assay, qRT-PCR, Western blot, ELISA, flow cytometry and immunofluorescence were used to investigate the regulatory mechanism of exo-miR-519a-3p at GC-LM.

Results

The expression level of miR-519a-3p in serum exosomes was significantly higher in GC-LM patients than in patients without LM, and high expression of exo-miR-519a-3p indicates a worse prognosis. GC-derived exosomes are mainly accumulated in the liver and internalized by intrahepatic macrophages. Mechanistically, exo-miR-519a-3p activates the MAPK/ERK pathway by targeting DUSP2, thereby causing M2-like polarization of macrophages. M2-like polarized macrophages accelerate GC-LM by inducing angiogenesis and promoting intrahepatic premetastatic niche formation.

Conclusions

Our results indicate that exo-miR-519a-3p plays a critical role in mediating crosstalk between primary GC cells and intrahepatic macrophages and is a potential therapeutic target for GC-LM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02499-8.

Multi‑institutional development and validation of a nomogram to predict prognosis of early-onset gastric cancer patients

Background

Early-onset gastric cancer (EOGC, ≤45 years old) is characterized with increasing incidence and more malignant phenotypes compared with late-onset gastric cancer, which exhibits remarkable immune cell infiltration and is potential immunotherapeutic population. Till now, restricted survival information of EOGC is available due to limited case numbers. This study established a novel nomogram to help evaluate cancer-specific survival (CSS) of EOGC patients who underwent gastrectomy, and may provide evidence for predicting patients’ survival.

Methods

We retrospectively enrolled a cohort containing 555 EOGC cases from five independent medical centers in China, among which 388 cases were randomly selected into a training set while the other 167 cases were assigned into the internal validation set. Asian or Pacific Islander (API) patients diagnosed with EOGC during 1975-2016 were retrieved from the SEER database (n=299) and utilized as the external validation cohort. Univariate and multivariate analyses were conducted to test prognostic significances of clinicopathological factors in the training set. Accordingly, two survival nomogram models were established and compared by concordance index (C-index), calibration curve, receiver operating characteristics (ROC) curves and decision curve analyses (DCA).

Results

The 5-year CSS rate of training cohort was 61.3% with a median survival time as 97.2 months. High consistency was observed on calibration curves in all three cohorts. Preferred nomogram was selected due to its better performance on ROC and DCA results. Accordingly, a novel predicative risk model was introduced to better stratify high-risk EOGC patients with low-risk patients. In brief, the 5-year CSS rates for low-risk groups were 92.9% in training set, 83.1% in internal validation set, 89.9% in combined NQSQS cohort, and 85.3% in SEER-API cohort. In contrast, the 5-year CSS rates decreased to 38.5%, 44.3%, 40.5%, and 36.9% in the high-risk groups of the four cohorts above, respectively. The significant survival difference between high-risk group (HRG) and low-risk group (LRG) indicated the precise accuracy of our risk model. Furthermore, the risk model was validated in patients with different TNM stages, respectively. Finally, an EOGC web-based survival calculator was established with public access, which can help predict prognosis.

Conclusions

Our data provided a precise nomogram on predicting CSS of EOGC patients with potential clinical applicability.

Induction of Fibroblast Growth Factor Receptor 4 by Helicobacter pylori via Signal Transducer and Activator of Transcription 3 With a Feedforward Activation Loop Involving SRC Signaling in Gastric Cancer

BACKGROUND & AIMS

Helicobacter pylori (H pylori) infection is the main risk factor for gastric cancer. The role of fibroblast growth factor receptors (FGRFs) in H pylori-mediated gastric tumorigenesis remains largely unknown. This study investigated the molecular and mechanistic links between H pylori, inflammation, and FGFR4 in gastric cancer.

METHODS

Cell lines, human and mouse gastric tissue samples, and gastric organoids models were implemented. Infection with H pylori was performed using in vitro and in vivo models. Western blot, real-time quantitative reverse-transcription polymerase chain reaction, flow cytometry, immunofluorescence, immunohistochemistry, chromatin immunoprecipitation, and luciferase reporter assays were used for molecular, mechanistic, and functional studies.

RESULTS

Analysis of FGFR family members using The Cancer Genome Atlas data, followed by validation, indicated that FGFR4 messenger (m)RNA was the most significantly overexpressed member in human gastric cancer tissue samples (P < .001). We also detected high levels of Fgfr4 mRNA and protein in gastric dysplasia and adenocarcinoma lesions in mouse models. Infection with J166, 7.13, and PMSS1 cytotoxin-associated gene A (CagA)+ H pylori strains induced FGFR4 mRNA and protein expression in in vitro and in vivo models. This was associated with a concordant activation of signal transducer and activator of transcription 3 (STAT3). Analysis of the FGFR4 promoter suggested several putative binding sites for STAT3. Using chromatin immunoprecipitation assay and an FGFR-promoter luciferase reporter containing putative STAT3 binding sites and their mutants, we confirmed a direct functional binding of STAT3 on the FGFR4 promoter. Mechanistically, we also discovered a feedforward activation loop between FGFR4 and STAT3 where the fibroblast growth factor 19–FGFR4 axis played an essential role in activating STAT3 in a SRC proto-oncogene non-receptor tyrosine kinase dependent manner. Functionally, we found that FGFR4 protected against H pylori-induced DNA damage and cell death.

CONCLUSIONS

Our findings demonstrated a link between infection, inflammation, and FGFR4 activation, where a feedforward activation loop between FGFR4 and STAT3 is established via SRC proto-oncogene non-receptor tyrosine kinase in response to H pylori infection. Given the relevance of FGFR4 to the etiology and biology of gastric cancer, we propose FGFR4 as a druggable molecular vulnerability that can be tested in patients with gastric cancer.

[Real-world data analysis of 3012 patients undergoing laparoscopic radical gastrectomy in a single center over the past 12 years]

Objective: To Summarize the safety, clinical outcome and technical evolution of laparoscopic gastric cancer surgery. Methods: A retrospective cohort study was carried out. Clinical data of 3012 patients who underwent laparoscopic radical gastrectomy for gastric cancer from January 2010 to March 2022 at Department of General Surgery, the First Affiliated Hospital of Nanjing Medical University were retrospectively collected and analyzed. Case inclusion criteria were gastric malignancies confirmed by pathology, without distant metastasis by examination before operation and exploration during operation, patients undergoing laparoscopic radical gastrectomy, intact function of important organs and with complete data. Exclusion criteria were patients who underwent emergency gastric cancer resection due to gastric bleeding, perforation or obstruction, etc., tumor found to invade adjacent organs such as pancreas or transverse colon during the operation, conversion to open surgery during the operation, those who had other malignant tumors (except thyroid cancer) within 5 years, and those had severe cardiopulmonary, liver, or kidney insufficiency before surgery. Outcomes included: (1) baseline information of patients; (2) trend of the quantity of laparoscopic radical gastrectomy year by year; (3) evolution of the mode of digestive tract reconstruction; (4) periopertive outcome short-term complication was defined as complication occurring within 30 days after operation and classified accordiny to the clavien-Dindo criteria; and (5) 5-year overall survival. SPSS software was used for statistical analysis. Continuous variables that obeyed the normal distribution were expressed in the form of Mean±SD. Days of hospital stay that did not follow a normal distribution were expressed as median (Q₁,Q₃), and the Mann-Whiney U test was used for comparison. Discrete variables were expressed as cases (%), and chi-square test or rank sum test was used for comparison between groups. Linear regression analysis was used to analyze the relationship between the amount of surgery and the year of surgery. Kaplan-Meier method and log-rank test were used for survival analysis. Two-tailed P<0.05 was considered as statistically significant. Results: Among the 3012 cases, 2114 were male and 898 were female. The patients' average age at surgery was (61.1±10.7) years old. According to the number of cumulative cases, the patients were divided into three groups: early, intermediate and late, with 1004 patients in each group. The early group consisted of patients undergoing operation from January 2010 to October 2018, the intermediate group consisted of patients undergoing operation from October 2018 to January 2021, and the late group consisted of patients undergoing operation from January 2021 to March 2022. (1) General information: There were 691 (68.8%), 699 (69.6%) and 724 (72.1%) male patients in early, intermediate and late groups respectively; the average age increased from 56.6 years in 2010 to 62.8 years in March 2022. As for the tumor stage T1, T2, T3, T4, there were 49.0%, 14.4%, 23.9% and 12.6% in the early group; 47.5%, 12.9%, 26.9% and 12.6% in the intermediate group; 39.7%, 14.6%, 30.0%, and 15.6% in the late group, respectively. Patients with N0, N1, N2, N3a, N3b stage were 56.8%, 13.7%, 13.4%, 11.0%, and 5.0% in the early group; 55.7%, 12.9%, 12.8%, 11.6%, and 6.9% in the intermediate group; 51.0%, 16.1%, 12.8%, 12.5%, and 7.5% in the late group, respectively. (2) Year-by-year change in the number of gastric cancer operations: From 19 cases per year in 2010 to 786 per year in 2021, the annual number of gastric cancer operations was proportional to the year of operation (y=47.505x, R²=0.67). The proportion of patients with stage I disease showed a fluctuating downward trend over time, while the proportion of patients with stage III disease increased slightly, accounting for 34% until March 2022. (3) Evolution of digestive tract reconstruction methods: Except in 2010, the digestive tract reconstruction method of distal gastrectomy focused on Billroth-II+Braun anastomosis among patients undergoing laparoscopic gastric cancer surgery in other years, whose proportion had gradually increased from less than 20% in 2016 to about 70% after 2021; the gastrointestinal reconstruction methods after total gastrectomy had gradually increased in π anastomosis and overlap anastomosis since 2016, of which π anastomosis reached about 65% in 2019, and overlap anastomosis reached almost 30% in 2020; the anastomosis methods after proximal gastrectomy had been mainly double-channel anastomosis (54%) and esophagogastric anastomosis (30%) since 2016, and double-channel anastomosis accounted for up to 70% in 2019. (4) Operation time: The operation time of early, intermediate and late group was (193.3±49.8) min, (186.9±44.3) min and (206.7±51.4) min respectively. Intermediate group was significantly shorter than early group (t=3.005, P=0.003), while late group was significantly longer than early group (t=5.875, P<0.001) and intermediate group (t=9.180, P<0.001). (5) Postoperative hospital stay: The median length of hospital stay for gastric cancer patients in early, intermediate and late groups was 9 (8, 11) d, 8 (7, 10) d, and 8 (7.5, 10) d respectively. The postoperative hospital stay of intermediate group and late group was significantly shorter than that of early group (Z=-12.467, Z=-5.981, both P<0.001), but there was no significant difference between intermediate group and late group (Z=0.415,P=0.678). (6) Postoperative complication: The morbidity of short-term complication in early, intermediate and late group was 20.4% (205/1004), 16.2% (163/1004), and 16.2% (162/1004) respectively, and above morbidity of intermediate group and late group was significantly lower than that of early group (χ²=5.869, P=0.015; χ²=6.165, P=0.013), while there was no significant difference between intermediate group and late group (χ²=0.004,P=0.952). The morbidity of short-term complication of grade IIIor higher was 8.0% (80/1004), 7.6% (76/1004), and 4.9% (49/1004) in early, intermediate and late group respectively, and above morbidity of late group was significantly lower than that of early and intermediate group (χ²=7.965, P=0.005; χ²=6.219,P=0.013), while there was no significant difference between intermediate group and early group (χ²=0.111,P=0.739). (7) Survival analysis: The follow-up deadline for survival data was December 31, 2021, and the median follow-up time was 29.5 months. The overall 5-year survival rate of all the patients was 74.7%. The 5-year survival rates of stage I, II and III patients were 92.0%, 77.2%, and 40.3% respectively and 5-year survival rates of patients with stage IA, IB, IIA, IIB, IIIA, IIIB and IIIC were 93.2%, 87.8%, 81.1%, 72.7%, 46.2%, 37.1%, and 34.0% respectively. Conclusions: The number of laparoscopic gastric cancer operation in our center is increasing year by year. With the maturity of laparoscopic technology, the morbidity of complication in laparoscopic gastric cancer surgery is decreasing.

Gastric Microbiome Alterations Are Associated with Decreased CD8+ Tissue-resident Memory T Cells in the Tumor Microenvironment of Gastric Cancer

The host microbiota is tightly associated with tumor initiation and progression in multiple solid tumors including gastric cancer (GC). The aim of this study was to investigate in patients with GC whether there are alterations in gastric microbiota and any potential association these may have with immune dysregulation. 16S rRNA gene sequencing was used to analyze tumor microbiota of 53 patients with GC and gastric mucosal tissue microbiota of 30 patients with chronic gastritis. The effect of microbiota on the tumor microenvironment (TME) was studied by single-cell sequencing, immunohistochemistry, multiplex immunofluorescence staining, and flow cytometry, as well as in a mouse model of primary GC. The GC microbiota was characterized by reduced microbial diversity and enrichment of the Oceanobacter, Methylobacterium and Syntrophomonas genera. Intratumoral Methylobacterium was significantly associated with poor prognoses in GC patients. It also was inversely correlated with the frequency of CD8+ tissue-resident memory T (TRM) cells in the TME. TGFβ was significantly reduced in GC samples with higher abundance of Methylobacterium. Finally, we verified that Methylobacterium can decrease TGFβ expression and CD8+ TRM cells in the tumor by establishing a mouse model of primary GC. The results suggest that tumor microbiota and exhausted CD8+ TRM cells in the TME of GC are significantly correlated, and that Methylobacterium may play a role in gastric carcinogenesis.

Quantification of Tumor Abnormal Proteins in the Diagnosis and Postoperative Prognostic Evaluation of Gastric Cancer

Background:

Abnormal glycosylation of proteins has been identified in almost all types of cancers and is closely related to the cancer progression, metastasis, and survival of cancer patients. This study was to explore the values of serum tumor abnormal protein (TAP), an abnormal glycochain protein, in the diagnosis and prognosis of gastric cancer (GC).

Methods:

A total of 335 GC patients were included as the study group, and another 335 subjects served as the control group. Tumor abnormal protein expression was compared between the 2 groups. Correlation analysis was used to assess the correlations of TAP with clinicopathological factors. Gastric cancer patients were divided into training set and test set at a ratio of 2:1. Univariate and multivariate Cox regression analyses in training set were used to evaluate the prognostic significance of TAP in GC patients and explore the independent risk factors for overall survival (OS) and disease-free survival (DFS) to establish a prognostic model, followed by testing of the model. According to the median of TAP, 335 GC patients were divided into 2 groups to plot the survival curves of OS and DFS.

Results:

Tumor abnormal protein expression in the study group was significantly higher than in the control group. Taking the best cut-off value of TAP (110.128 μm²) as the diagnostic criteria for GC, the sensitivity and specificity of TAP were 83.58% and 97.61%, respectively, and the area under the receiver operating characteristics (ROC) curve was 0.935, which was not inferior to computed tomography (CT). Tumor abnormal protein expression was an independent risk factor for OS and DFS. The prognostic predictive value of TAP was better than that of pathological stage in GC patients. The model with TAP was effective in predicting prognosis.

Conclusion:

Tumor abnormal protein is an effective indicator for early screening and prognostic evaluation of GC and can also assist the clinical diagnosis and treatment of GC.

Abstract 5849: Activation of STAT3 is mediated by FGFR4 induction via SRC signaling after H. pylori infection

Background: Gastric cancer is considered the 5th most common form of cancer and 4th leading cause of cancer-related deaths worldwide. Due to the late stage of diagnosis, gastric cancer carries poor prognosis and poor overall survival. Infection with H. pylori is the strongest known risk factor. Fibroblast Growth Factor Receptor 4 (FGFR4) belongs to a family of highly conserved tyrosine kinases. This study investigated the molecular mechanism of FGFR4 regulation in response to H. pylori infection.

Methods and Results: Among all the FGFRs, FGFR4 mRNA expression level was the most significantly elevated in human gastric cancer samples as compared to normal samples, using Real-time qPCR. These results were confirmed using the TCGA and Geo database analysis, confirming that FGFR4 is highly expressed in gastric cancer. Using western blot, we found that FGFR4 is significantly expressed in dysplasia and adenocarcinoma lesions in the TFF1-KO gastric cancer mouse model. Following infection with H. pylori in in-vitro (J166, 7.13) and in-vivo (PMSS1) models, we detected a significant increase in the expression of FGFR4 at the protein and mRNA levels. We also detected activation of STAT3 in human gastric cell lines and mice gastric tissues. Furthermore, analysis of FGFR4 promoter revealed several putative binding sites for STAT3. To confirm that FGFR4 expression is dependent upon STAT3 activation, we performed ChIP assay and confirmed direct functional binding of STAT3 on FGFR4 promoter. Using the FGF19, the ligand for FGFR4, we found that FGF19-FGFR4 axis played a vital role in activating STAT3 through an SRC-dependent mechanism and discovered that there is a feedforward activation loop between FGFR4 and STAT3. Functionally, we found that FGFR4 protected against H. pylori-induced DNA damage and cell death.

Conclusion: Our study established a feedforward activation loop between FGFR4 and STAT3 in response to H. pylori infection and FGFR4 could be a possible druggable moiety for future therapies in gastric cancer.

Citation Format: Nadeem S. Bhat, Mohammed Soutto, Xing Zhang, Zheng Chen, Shoumin Zhu, Heng Lu, Dunfa Peng, Zekuan Xu, Wael El-Rifai. Activation of STAT3 is mediated by FGFR4 induction via SRC signaling after H. pylori infection [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5849.

[Anti-reflux gastrointestinal reconstruction techniques after laparoscopic proximal gastrectomy]

Laparoscopic techniques are more and more poplular in proximal gastrectomy. The traditional esophagogastric anastomosis may lead to severe reflux esophagitis after surgery, affecting patient's quality of life. In recent years, multiple methods of digestive tract reconstruction after laparoscopic proximal gastrectomy capable of resisting reflux have been applied to the clinic. Combining the results of the latest clinical studies and our clinical experience, we elaborate the views on digestive tract reconstruction after laparoscopic proximal gastrectomy. Esophagogastric anastomosis (posterior esophagogastric anastomosis, anterior esophagogastric anastomosis, gastric tube reconstruction, lateral esophagogastric anastomosis, Kamikawa anastomosis and modified Kamikawa anastomosis, etc.) and esophagojejunal anastomosis (interposition jejunum, interposition jejunum with pouch, and double-channel anastomosis, etc.) are mainly discussed. Of course, the anti-reflux mechanisms of different surgical procedures are not the same, the anti-reflux effects are variable, and the surgical difficulties under laparoscopy are also different. Therefore, how to choose a rational reconstruction method after proximal gastrectomy needs to be comprehensively considered based on patient's own situation and technical level of the surgeons.

CircTHBS1 drives gastric cancer progression by increasing INHBA mRNA expression and stability in a ceRNA- and RBP-dependent manner

Circular RNAs (circRNAs) play vital regulatory roles in the progression of multiple cancers. In our study, transcriptome analysis and self-organizing maps (SOM) were applied to screen backbone circRNAs in gastric cancer (GC). Upon validation of the expression patterns of screened circRNAs, gain- and loss-of-function assays were performed in vitro and in vivo. Underlying mechanisms were investigated using RNA pull-down, luciferase reporter assay and RNA immunoprecipitation. The expression of circTHBS1 was significantly increased in GC and associated with poor prognosis. CircTHBS1 facilitated the malignant behavior and epithelial-to-mesenchymal transition of GC cells. Mechanistically, circTHBS1 sponged miR-204-5p to promote the expression of Inhibin Subunit Beta A (INHBA). Moreover, circTHBS1 could enhance the HuR-mediated mRNA stability of INHBA, which subsequently activated the TGF-β pathway. Our research identified circTHBS1 as an oncogenic circRNA that enhances GC malignancy by elevating INHBA expression, providing new insight and a feasible target for the diagnosis and treatment of GC.

Comparison of Deep and Moderate Neuromuscular Blockade on Intestinal Mucosal Barrier in Laparoscopic Gastrectomy: A Prospective, Randomized, Double-Blind Clinical Trial

Deep neuromuscular blockade (NMB) improves the surgical conditions and is benefit for the postoperative recovery after laparoscopic surgery. However, the mechanisms of deep NMB in promoting the recovery of intestinal function have not been completely investigated. The objective of our study was to determine the impact of the deep NMB and moderate NMB strategy on the intestinal barrier function after laparoscopic gastrectomy. We collected patients undergoing elective laparoscopic gastrectomy. Patients were randomized to deep NMB (post-tetanic count 1–2) vs. moderate NMB (train-of-four count 1–2) during the surgery. Primary outcomes were time to flatus, serum diamine oxidase (DAO) and D-lactate, and gut microbiota. Other outcomes were surgical condition scores, postoperative visual analog pain scores, and length of hospital stay. Ninety patients in deep NMB group and sixty patients in moderate NMB group completed the study. Main results showed that the time to flatus was decreased in deep NMB group (74 ± 32 h) than that in moderate NMB group (93 ± 52 h, P = 0.006). The level of serum D-lactate was statistically increased in the moderate NMB group than that in the deep NMB group (1,209 ± 224 vs. 1,164 ± 185 ng/ml, p < 0.001). But no significant differences could be detected in the level of DAO between the groups. Additionally, the 16s rRNA analysis indicated that gut microbiota were similar in Alpha diversity but distinct in Beta diversity. Furthermore, the beneficial bacteria, such as genus Lactobacillus and Bifidobacterium, were more abundant in the deep NMB group, while the potentially harmful bacteria were more abundant in the moderate NMB group. Our findings suggested that the intestinal mucosal barrier and gut microbiota were better preserved in deep NMB, which greatly improved the postoperative recovery of intestinal function after laparoscopic gastrectomy.

Exploration of drug resistance in advanced gastrointestinal stromal tumor

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Background: Gastrointestinal stromal tumors (GISTs) are prone to multi-drug resistance after drug treatment, but tissue samples from advanced patients with drug resistance are hard to obtain, impeding the study of the mechanism of drug resistance. In this study, plasma samples from TKI-resistant GIST patients were collected for next generation sequencing (NGS) to detect circulating tumor DNA (ctDNA), which were then used to generate mutation profiles leading to TKI resistance. Methods: A total of 82 GIST patients who acquired TKI resistance were enrolled from Apr. 2016 to Jun. 2021. Plasma ctDNA samples after drug resistance were collected for NGS analysis of 425 genes. Results: Among 82 patients, 54 received monotherapy with imatinib, 24 with 2 TKIs (21 with imatinib and subsequent sunitinib, 2 with imatinib subsequent regorafenib, and 1 with imatinib subsequent anlotinib), and 4 with 3 TKIs (imatinib subsequent sunitinib and regorafenib). Fifty patients (61%) were ctDNA-positive and their mutation profiles were further analyzed. Detection rate of ctDNA in imatinib-resistant patients was 57% (31/54). Among these 31 patients, 12 (39%) showed KIT gene mutation (8 with the known drug-resistant KIT mutations, 6 of these patients exhibited single-drug resistance while 2 showed multi-drug resistance due to KIT mutations mainly in Exon 13 V654A, Exons 17 Y823D, D820Y, N822Y, and N822K). The remaining 19/31 cases (61%) could be attributed to other gene mutations, with 47% due to cancer-associated mutations or other downstream signaling pathways (such as, cell cycle, TP53, RAS and PI3K). Among patients resistant to imatinib followed by other TKIs, ctDNA detection rate was 68% (19/28). Among these 19 patients, 10 (53%) showed KIT gene mutation (including 5 with the known drug-resistant KIT mutations, 4 of these patients exhibited single-drug resistance, while 1 showed multi-drug resistance due to mutations mainly in Exon 13 V654A, Exons 17 D820A, and D820G). The remaining 9/19 cases (47%) could be attributed to other gene mutations, with 44% due to cancer-associated mutations or other in downstream signaling pathways (such as Wnt, cell cycle, TP53, RAS and PI3K). Results indicated a growing trend of mutations leading to resistance among GIST patients treated with multiple TKIs (baseline vs. imatinib resistance vs. multiple TKIs resistance, 3.95% vs. 25.81% vs. 26.32%). Conclusions: Advanced GIST patients who received one or more TKI(s) may be resistant to single or multiple drugs due to complex mutations. NGS can be used to detect ctDNA without the need to obtain tumor tissue samples. This approach facilitates the monitoring of drug resistance in patients with advanced tumors, especially those with multiple metastases. NGS allows detection of mutations at multiple secondary sites and helps to overcome tumor heterogeneity, ctDNA-based NGS analysis will play an increasingly important role in assessment of drug resistance in GIST patients.

Effect of S-1 Plus Oxaliplatin Compared With Fluorouracil, Leucovorin Plus Oxaliplatin as Perioperative Chemotherapy for Locally Advanced, Resectable Gastric Cancer: A Randomized Clinical Trial

IMPORTANCE

Perioperative chemotherapy is a potential treatment for locally advanced gastric cancer. However, the optimal chemotherapy regimen remains unknown.

OBJECTIVE

To investigate the safety and efficacy of S-1 plus oxaliplatin (SOX) vs fluorouracil, leucovorin, and oxaliplatin (FOLFOX) as a perioperative chemotherapy regimen for patients with locally advanced gastric cancer.

DESIGN, SETTING, AND PARTICIPANTS

In this phase 3, open-label, multicenter, randomized clinical trial, patients from 12 Chinese hospitals were enrolled between June 2011 and August 2016, with a last follow-up date of September 2019. The primary tumor was evaluated as either invading the serosa or the adjacent structures with or without metastatic lymph nodes, and with no evidence of distant metastases. Data were analyzed from December 2019 to June 2020.

INTERVENTIONS

Patients were randomly assigned (1:1) to receive either 6 perioperative (2-4 preoperative and 2-4 postoperative) 3-week cycles of 130 mg/m2 oxaliplatin on day 1 and 80 to 120 mg/d S-1 orally daily for 2 weeks (SOX) or 130 mg/m2 oxaliplatin, 400 mg/m2 fluorouracil, 400 mg/m2 leucovorin, and 2400 mg/m2 fluorouracil as 46-hour infusion on day 1 (FOLFOX).

MAIN OUTCOMES AND MEASURES

The primary end point was 3-year overall survival (OS). An absolute noninferiority margin of -8% was chosen.

RESULTS

A total of 583 patients were enrolled; 293 were randomized to the SOX group and 290 were randomized to the FOLFOX group. Twelve patients (2.1%) refused preoperative chemotherapy (5 patients in the SOX group and 7 patients in the FOLFOX group), leaving a total of 288 patients in the SOX group (median [range] age, 61 [24 to 78] years; 197 men [68.4%]) and 283 patients in the FOLFOX group (median [range] age, 62 [24 to 80] years; 209 men [73.9%]) who received preoperative chemotherapy. The 3-year OS rate was 75.2% (95% CI, 70.3% to 80.5%) in the SOX group and 67.8% (95% CI, 62.5% to 73.5%) in the FOLFOX group. The absolute difference of 3-year OS rate between the 2 groups was 7.4% (95% CI, -0.1% to 14.9%), which was greater than the prespecified noninferiority margin (-8%) and showed the noninferiority of perioperative chemotherapy with SOX compared with FOLFOX.

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial, SOX was noninferior to FOLFOX as perioperative chemotherapy for patients with locally advanced gastric cancer and could be recommended as an alternative treatment for these patients in Asia.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01364376.

N6-methyladenosine modification regulates imatinib resistance of gastrointestinal stromal tumor by enhancing the expression of multidrug transporter MRP1

N⁶-methyladenosine (m⁶A) is a frequently occurring mRNA modification, which regulates mRNA stability, splicing, and translation. However, its role in drug resistance of gastrointestinal stromal tumor (GIST) is not known. Here, we report that m⁶A modification levels are elevated in imatinib-resistant GIST cells and tissues, and that methyltransferase METTL3 is one of the main protein responsible for this aberrant modification. Increased METTL3 levels contributed to imatinib resistance and worse progression-free survival of GIST patients. Mechanistic studies revealed that METTL3-mediated m⁶A modification of the 5'UTR of the multidrug transporter MRP1 mRNA promoted drug resistance of GIST by stimulating MRP1 mRNA translation, via binding with YTHDF1 and eEF-1. Further, METTL3 transcription in Imatinib resistant GIST cells was activated by ETV1, leading to the increased m⁶A methylation of MRP1 mRNA. This is the first report showing a novel regulatory mechanism whereby ETV1, METTL3, and the YTHDF1/eEF-1 complex mediate the translation of MRP1 mRNA in an m⁶A-dependent manner to regulate the intracellular concentration of imatinib and drug resistance of GIST. These findings highlight MRP1 as a new potential therapeutic target for imatinib resistance of GIST.

[Role of crenel lateral lumbar interbody fusion in the precise selection of fusion level in posterior correction for adult degenerative scoliosis]

Objective: To investigate the role of minimally invasive crenel lateral lumbar interbody fusion (CLIF) in the decision of fusion level in posterior correction for severe adult degenerative scoliosis. Methods: This is prospective study.Patients with level Ⅴ and Ⅵ of Lenke-Silva classification who were treated in department of spine surgery,orthopedics center,the Second Affiliated Hospital, School of Medicine, Zhejiang University from June 2016 to March 2019 were included.First,the enrolled patients completed the preoperative clinical and imaging examination,the Lenke-Silva classification was evaluated,the surgical segments in first-stage CLIF was determined and the fusion segments required for single-stage posterior correction was predicted.After the first-stage CLIF,patients received reassessment of Lenke-Silva classification and global coronal and sagittal balance.Patients were divided into two groups:the effective group (level of Lenke-Silva classification decreased) and the ineffective group (level of Lenke-Silva classification unchanged).Second-stage posterior surgery was performed based on the results of reassessments.The fusion segment,Cobb angle,parameters of global coronal and sagittal plane,visual analogue pain score (VAS) and Oswestry disability index (ODI) were compared between the two groups preoperatively,after first-stage CLIF,second-stage posterior fixation and at the final follow-up.The potential factors associated with the decrease of the level of Lenke-Silva classification were recorded and compared between the two groups.Independent sample t test,repeated measure analysis of variance,rank sum test,χ² test or Fisher exact method were used to compare the difference among groups. Results: Fifty-four patients were enrolled,including 8 males and 46 females,aged (68.8±5.8) years (range:56 to 77 years).Preoperatively,26 patients were classified as level Ⅴ by Lenke-Silva classification,28 cases were grade Ⅵ.CLIF was performed in 194 segments,with 114 (58.8%) segments receiving anterior column realignment (ACR) and 15 (7.7%) segments using hyperlordotic cages.After first-stage CLIF,22 patients with level Ⅴ and 10 patients with Ⅵ of Lenke-Silva classification decreased and were classified into effective group.The level of the remaining 4 patients with level Ⅴ and 18 patients with grade Ⅵ unchanged and were classified into ineffective group.Preoperatively,the apical vertebrae was below L₁ in all 32 patients of effective group and 18 (81.8%,18/22) patients of ineffective group.The difference was statistically significant (P=0.023).There were 7 (31.8%,7/22) patients had continuous osteophyte in front of the intervertebral space in ineffective group,while none patient had continuous osteophyte in front of the intervertebral space in effective group,and the difference was statistically significant (P=0.001).In first-stage CLIF,more intraoperative ACR(71.2% vs.39.5%,χ²=20.66,P<0.01)and hyperlordotic cage (12.7$ vs.0,P=0.001)were used in the effective group,while there was less severe cage subsidence after the operation (5.9% vs.15.8%,χ²=4.793,P=0.029) in effective group.After first-stage CLIF,there was no difference in the Cobb angle between the two groups.While,lumbar lordosis (LL) in effective group (34.0±8.3)° was greater than that of the ineffective group (25.5±9.7)° (t=3.478,P=0.001),and the difference between the pelvic incidence (PI) and LL in effective group (15.7±4.6)°was significantly smaller than ineffective group(20.0±10.8)° (t=-2.129,P=0.038).The posterior fusion levels was less,the rate of fusion to thoracic spine region and the actual fusion segment was less than that of single-stage posterior correction in effective group (all P<0.01).All patients were follow-up for 24 to 45 months.There was no significant difference in radiological and clinical results between the two groups after first-,second-stage surgery and at the final follow-up (all P>0.05). Conclusions: First-stage CLIF decreased the Lenke-Silva classification of some patients with severe degenerative scoliosis.Combined with the reassessment of Lenke-Silva classification and global coronal and sagittal plane,it helps to accurately determine the fusion segment.Decrease of Lenke-Silva classification was associated with the preoperative level of apical vertebrae,continuous osteophytes in front of the intervertebral space,intraoperative use of ACR and hyperlordotic cage and the degree of cage subsidence postoperatively.

Circular CPM promotes chemoresistance of gastric cancer via activating PRKAA2-mediated autophagy

BACKGROUND

Chemotherapy can significantly improve the disease-free survival and overall survival of patients with advanced gastric cancer (GC). 5-fluorouracil (5-FU) is frequently applied in the clinic, acting as a first-line chemotherapy drug of advanced GC, which could be used alone or combining platinum drugs. However, its efficacy is significantly attenuated by chemoresistance, which is associated with patients' poor survival. Recently, there is evidence suggesting that dysregulation of autophagy may contribute to drug resistance in cancer, and circular RNAs (circRNAs) also take part in chemoresistance. However, whether circRNAs participate in 5-FU chemoresistance through autophagy remains largely unknown.

METHODS

RNA sequencing technologies and bioinformatics analysis were performed in GC. Sanger sequencing, Actinomycin D assay and RNase R assay confirmed the circular structure of circular CPM (circCPM). Various cell line models and animal models were used to explore related functions in vitro and in vivo. Quantitative Real-time PCR (qRT-PCR), fluorescence in situ hybridization, ribonucleic acid; (RNA) pulldown assays, RNA binding protein immunoprecipitation assays and Luciferase reporter assays were applied to explore involved pathways.

RESULTS

circCPM was up-regulated in 5-FU resistant GC cell lines and tissue. Moreover, high circCPM expression is positively associated with poor survival. Silencing circCPM greatly improved chemosensitivity in vitro and in vivo. Mechanistically, it directly binds to miR-21-3p in the cytoplasm and therefore increases the expression of PRKAA2, contributing to the activation of autophagy and chemoresistance.

CONCLUSION

Our results reveal that circCPM has a crucial role in regulating GC autophagy and 5-FU resistance by targeting PRKAA2. It may function as a new theory basis for assessing the curative effect of GC and reversing 5-FU chemoresistance.

The novel role of circular RNA ST3GAL6 on blocking gastric cancer malignant behaviours through autophagy regulated by the FOXP2/MET/mTOR axis

Gastric cancer (GC) ranks third in mortality among all cancers worldwide. Circular RNAs (circRNAs) play an important role in the occurrence and development of gastric cancer. Forkhead box P2 (FOXP2), as a transcription factor, is closely associated with the development of many types of tumours. However, the regulatory network between FOXP2 and circRNAs remains to be explored. In our study, circST3GAL6 was significantly downregulated in GC and was associated with poor prognosis in GC patients. Overexpression of circST3GAL6 inhibited the malignant behaviours of GC cells, which was mediated by inducing apoptosis and autophagy. In addition, we demonstrated that circST3GAL6 regulated FOXP2 through the mir-300 sponge. We further found that FOXP2 inhibited MET Proto-Oncogene (MET), which was the initiating factor that regulated the classic AKT/mTOR pathway of autophagy. In conclusion, our results suggested that circST3GAL6 played a tumour suppressive role in gastric cancer through miR-300/FOXP2 axis and regulated apoptosis and autophagy through FOXP2-mediated transcriptional inhibition of the MET axis, which may become a potential target for GC therapy.

Outcomes of Laparoscopic Total Gastrectomy Combined With Spleen-Preserving Hilar Lymphadenectomy for Locally Advanced Proximal Gastric Cancer: A Nonrandomized Clinical Trial

IMPORTANCE

The long-term survival of patients with laparoscopic total gastrectomy combined with spleen-preserving splenic hilar lymphadenectomy (LSTG) for advanced upper-third gastric cancer (AUTGC) and the association of splenic hilar lymph node (LN-10) metastasis with survival remain controversial.

OBJECTIVE

To evaluate the long-term outcomes of LSTG and the value index of LN-10 metastasis for patients with AUTGC.

DESIGN, SETTING, AND PARTICIPANTS

The Chinese Laparoscopic Gastrointestinal Surgery Study 4 (CLASS-04) was a prospective, multicenter, single-arm trial that involved 19 centers in China. A total of 251 eligible patients with clinical stage T2, T3, or T4a upper-third gastric cancer without distant metastases were enrolled from September 1, 2016, to October 31, 2017. The final follow-up was on December 31, 2020.

INTERVENTIONS

All patients were enrolled to undergo LSTG.

MAIN OUTCOMES AND MEASURES

The main outcomes were the 3-year overall survival (OS) and disease-free survival (DFS). Multivariate analyses were used to explore the association of LN-10 metastasis with survival.

RESULTS

Among the 251 patients, 246 (98.0%; mean [SD] age, 60.1 [9.4] years; 197 [80.1%] male) underwent LSTG and completed the study. The 3-year OS was 79.1% (95% CI, 74.0%-84.2%), and the 3-year DFS was 73.1% (95% CI, 67.4%-78.8%). In addition, the 3-year therapeutic value index of LN-10 dissection was 4.5, exceeding the indexes for the partial D2 LN group (including LNs 5, 6, 11d, and 12a). Nineteen patients (7.7%) with LN-10 metastasis had significantly worse survival than the nonmetastasis group, and multivariate analysis revealed that splenic LN-10 metastasis was an independent risk factor (OS: hazard ratio [HR], 2.38; 95% CI, 1.08-5.26; P = .03; DFS: HR, 2.28; 95% CI, 1.12-4.63; P = .02). Moreover, patients with LN-10 metastasis were more likely to have recurrence (42.1% vs 20.7%, P = .03), especially when multiple site metastasis was present (21.1% vs 4.4%, P = .01). However, patients with LN-10 metastasis who received adjuvant chemotherapy had significantly better OS and DFS than those without adjuvant chemotherapy and achieved the same oncologic effect as those without LN-10 metastasis.

CONCLUSIONS AND RELEVANCE

This results of this study suggest that LSTG for AUTGC has feasible long-term outcomes. In addition, patients with LN-10 metastasis may have worse survival and may be more prone to recurrence.

Natriuretic peptide receptor a promotes gastric malignancy through angiogenesis process

Gastric cancer (GC) ranks the third among global cancer-related mortality, especially in East Asia. Angiogenesis plays an important role in promoting tumor progression, and clinical trials have demonstrated that anti-angiogenesis therapy is effective in GC management. Natriuretic peptide receptor A (NPRA) functions significantly in promoting GC development and progression. Whether NPRA can promote angiogenesis of GC remains unclear. Tumor samples collection and immunohistochemical experiment showed that the expression of NPRA was positively correlated with the expression of CD31 and vessel density. In vivo and in vitro analysis showed that NPRA could promote GC-associated angiogenesis and tumor metastasis. Results of Co-IP/MS showed that NPRA could prevent HIF-1α from being degraded by binding to HIF-1α. Protection of HIF-1α improved VEGF levels and thus promoted angiogenesis. In summary, NPRA protected HIF-1α from proteolysis by binding to HIF-1α, increased the expression of HIF-1α, and promoted GC angiogenesis. This study has discovered a new mechanism for NPRA to promote gastric cancer development and a new regulatory mechanism for HIF-1α.

Circular RNA UBE2Q2 promotes malignant progression of gastric cancer by regulating signal transducer and activator of transcription 3-mediated autophagy and glycolysis

Gastric cancer remains the third leading cause of cancer-related mortality worldwide. Emerging evidence has shown that circular RNAs (circRNAs) play a critical regulatory role in the occurrence and development of various cancers through sponging miRNAs or acting as RNA-binding protein (RBP) sponges. We found that circUBE2Q2 was significantly upregulated in GC tissues and cell lines. Knockdown of circUBE2Q2 inhibited proliferation, migration, invasion, and glycolysis, and increased autophagy in vitro. In addition, knockdown of circUBE2Q2 inhibited GC tumorigenicity and metastasis potential in vivo. A series of experiments were performed to confirm that circUBE2Q2 regulates GC progression via the circUBE2Q2-miR-370-3p-STAT3 axis and promotes tumor metastasis through exosomal communication. Further in vivo experiments confirmed that, combination treatment of circUBE2Q2 knocking down and STAT3 inhibitor has synergistic effects on the gastric cancer growth inhibition, which provides a possibility to enhance the sensitivity of targeted drugs to gastric cancer through targeting circUBE2Q2. Our findings revealed that circUBE2Q2 may serve as a new proliferation-promoting factor and prognostic marker in gastric cancer.

miR-151a-3p-rich small extracellular vesicles derived from gastric cancer accelerate liver metastasis via initiating a hepatic stemness-enhancing niche

Liver metastasis (LM) severely affects gastric cancer (GC) patients' prognosis. Small extracellular vesicles (sEVs) play key roles in intercellular communication. Specific sEV-miRNAs from several types of cancer were found to induce a premetastatic niche in target organs before tumor cell arrive. However, whether the primary GC affects hepatic microenvironment or the role of sEV-miRNAs in GC-LM is yet unclear. We report that GC-derived sEVs are primarily absorbed by Kupffer cells (KCs). sEV-miR-151a-3p is highly expressed in GC-LM patients' plasma and presents poor prognosis. Treating mice with sEVs-enriched in miR-151a-3p promotes GC-LM, whereas has no influence on the proliferation of GC cells in situ. Mechanistically, sEV-miR-151a-3p inhibits SP3 in KCs. Simultaneously, sEV-miR-151a-3p targets YTHDF3 to decrease the transcriptional inhibitory activity of SP3 by reducing SUMO1 translation in a N6-methyladenosine-dependent manner. These factors contribute to TGF-β1 transactivation in KCs, subsequently activating the SMAD2/3 pathway and enhancing the stem cell-like properties of incoming GC cells. Furthermore, sEV-miR-151a-3p induces miR-151a-3p transcription in KCs to form a positive feedback loop. In summary, our results reveal a previously unidentified regulatory axis initiated by sEV-miR-151a-3p that establishes a hepatic stemness-permissive niche to support GC-LM. sEV-miR-151a-3p could be a promising diagnostic biomarker and preventive treatment candidate for GC-LM.

Heritable Variants in the Chromosome 1q22 Locus Increase Gastric Cancer Risk via Altered Chromatin Looping and Increased UBAP2L Expression

Genome-wide association studies (GWAS) have implicated the 1q22 gastric cancer risk locus in disease, but little is known about its underlying oncogenic functions. This study represents a systematic investigation of the biological significance and potential mechanism associated with the gastric cancer risk of SNP rs2075570(C>T) in 1q22. We identified two functional germline variations (rs2049805-C and rs2974931-G) in an active enhancer in a 64.8 kb high-linkage disequilibrium block of rs2075570. The enhancer upregulated ubiquitin associated protein 2 like (UBAP2L) gene expression over a 960 kb distance by chromatin looping. Gastric cancer tissues expressed significantly higher levels of UBAP2L than was observed in the matched noncancerous tissues, and the UBAP2L expression was negatively correlated with patient survival. Downregulation of UBAP2L inhibited the proliferation and invasion of human gastric cancer cells in vitro and in a xenograft mouse model. Notably, the two mutant variations significantly enforced the enhancer activity and UBAP2L expression. In conclusion, this study revealed two causal variations in the 1q22 region using tag-SNP rs2075570 as a genetic marker. These variations may affect the occurrence and progression of gastric cancer by reinforcing the expression of the 1q22-Enh enhancer-regulated UBAP2L target gene. IMPLICATIONS: Our study provides an important clue of how noncoding germline variations contribute to gastric cancer, which gives a novel insight into understanding the genetic mechanism of gastric cancer.

Comparison of Survival and Patterns of Recurrence in Gastric Neuroendocrine Carcinoma, Mixed Adenoneuroendocrine Carcinoma, and Adenocarcinoma

IMPORTANCE

Gastric neuroendocrine carcinoma and mixed adenoneuroendocrine carcinoma are rare pathological types of gastric cancer, and there is a lack of multicenter studies comparing the prognosis and recurrence patterns of gastric neuroendocrine carcinoma, gastric mixed adenoneuroendocrine carcinoma, and gastric adenocarcinoma.

OBJECTIVE

To compare the differences in long-term survival and patterns of recurrence among gastric neuroendocrine carcinoma, gastric mixed adenoneuroendocrine carcinoma, and gastric adenocarcinoma.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included patients with resectable gastric neuroendocrine carcinoma and gastric mixed adenoneuroendocrine carcinoma at 23 hospitals in China from January 2006 to December 2016. In addition, patients with gastric adenocarcinoma were selected as controls. Propensity score-matched analysis was used to match pathological stage among the different pathological types, and disease-free survival (DFS), postrecurrence survival (PRS), and patterns of recurrence were examined. Data analysis was conducted from July 15, 2020, to October 21, 2020.

EXPOSURES

Curative resection for gastric neuroendocrine carcinoma, gastric mixed adenoneuroendocrine carcinoma, and gastric adenocarcinoma.

MAIN OUTCOMES AND MEASURES

The main outcomes were DFS and patterns of recurrence.

RESULTS

A total of 3689 patients were analyzed (median [interquartile range] age, 62 [55-69] years; 2748 [74.5%] men), including 503 patients (13.6%) with gastric neuroendocrine carcinoma, 401 patients (10.9%) with gastric mixed adenoneuroendocrine carcinoma, and 2785 patients (75.5%) with gastric adenocarcinoma. After propensity score matching, 5-year DFS was 47.6% (95% CI, 42.7%-52.5%) for patients with gastric neuroendocrine carcinoma, compared with 57.6% (95% CI, 55.1%-60.1%) with gastric adenocarcinoma (P < .001) and 51.1% (95% CI, 46.0%-56.2%) for patients with gastric mixed adenoneuroendocrine carcinoma, compared with 57.8% (95% CI, 55.1%-60.5%) patients with gastric adenocarcinoma (P = .02). Multivariable analyses found that, compared with gastric adenocarcinoma, gastric neuroendocrine carcinoma (hazard ratio [HR], 1.64; 95% CI, 1.40-1.93) and gastric mixed adenoneuroendocrine carcinoma (HR, 1.25; 95% CI, 1.05-1.49) were independent risk factors associated with worse DFS. Compared with matched patients with gastric adenocarcinoma, patients with gastric neuroendocrine carcinoma were more likely to have distant recurrence (268 patients [17.2%] vs 101 patients [23.7%]; P = .002), as were patients with gastric mixed adenoneuroendocrine carcinoma (232 patients [17.3%] vs 76 patients [22.8%]; P = .02). In multivariate analysis, gastric neuroendocrine carcinoma (HR, 2.22; 95% CI, 1.66-2.98) and gastric mixed adenoneuroendocrine carcinoma (HR, 1.70; 95% CI, 1.24-2.34) were independent risk factors associated with distant recurrence. Additionally, T3 to T4 stage (odds ratio, 2.84; 95% CI, 1.57-5.14; P = .001) and lymph node metastasis (odds ratio, 2.01; 95% CI, 1.31-3.10; P = .002) were independent risk factors associated with distant recurrence of gastric neuroendocrine carcinoma and gastric mixed adenoneuroendocrine carcinoma.

CONCLUSIONS AND RELEVANCE

This cohort study found that patients with gastric neuroendocrine carcinoma or gastric mixed adenoneuroendocrine carcinoma had worse prognoses and were more prone to distant recurrence than those with gastric adenocarcinoma. Thus, different follow-up and treatment strategies should be developed to improve the long-term survival of patients with gastric neuroendocrine carcinoma or gastric mixed adenoneuroendocrine carcinoma, especially patients with tumors penetrating into the subserosa or deeper layers or with lymph node metastasis.

Genetic polymorphisms of Cathepsin B are associated with gastric cancer risk and prognosis in a Chinese population

BACKGROUND

Genetic polymorphisms are believed to represent a key aspect of predisposition to gastric cancer (GC). Therefore, considering the important role of Cathepsin B (CTSB) in promoting cancer onset and development, it could be very worthful to explore the function of CTSB-related genetic polymorphisms in GC.

OBJECTIVE

In this study, we investigated the correlation of CTSB-related polymorphisms (rs9009A>T, rs6731T>C, rs1293303G>C, rs1874547C>T, rs3779659C>T, rs17814426C>T and rs148669985C>T) with GC risk and prognosis in a case-control study of 994 cases and 1000 controls.

METHODS

All tag single nucleotide polymorphisms (SNPs) were genotyped by polymerase chain reaction-ligase detection reaction (PCR-LDR) sequencing technology.

RESULTS

The results indicated rs9009, rs6731 and rs17814426 correlated with decreased risks of GC (HR = 0.97, p< 0.001; HR = 0.86, P= 0.019; HR = 0.85, P= 0.017; respectively). Stratification analysis further showed rs17814426 variant genotypes correlated with earlier T stage (p= 0.044). In addition, GC patients carrying the C allele of rs6371 had better overall prognosis (HR = 0.62, 95%CI = 0.44-0.88).

CONCLUSION

Our results firstly suggested the importance of CTSB-related polymorphisms on GC which could predict GC risk and prognosis.

miR-1301-3p Promotes Cell Proliferation and Facilitates Cell Cycle Progression via Targeting SIRT1 in Gastric Cancer

So far, many existing evidences indicate that microRNAs (miRNA) are closely associated with the tumorigenesis and progression of various tumors. It has been reported that miR-1301-3p is abnormally expressed in several malignant tumors. However, the role of miR-1301-3p in gastric cancer (GC) remains unclear and is worth studying. Through qRT-PCR, the expression of miR-1301-3p and SIRT1 were detected in GC tissues and cells. The cell proliferation and cell cycle were measured through CCK-8 assay and clone formation assay. Dual luciferase reporter assay was used to determine the target of miR-1301-3p. Though tumorigenesis assay, we monitored the effect of miR-1301-3p on GC cell growth in vivo. miR-1301-3p was upregulated in GC tissues and cells in our study. Overexpression of miR-1301-3p accelerated GC cell proliferation, cell cycle progression and tumorigenesis. Notably, altering the expression miR-1301-3p caused deregulation of Cyclin D1, CDK4, c-Myc and P21. Furthermore, SIRT1 was the direct target of miR-1301-3p by luciferase reporter assay. After transfecting with miR-1301-3p inhibitor, we found that knockdown of SIRT1 could enhance the ability of proliferation. Our results identify miR-1301-3p as a novel potential therapeutic target that is associated with the tumorigenesis and progression of gastric cancer.

Correlations of SNHG5 genetic polymorphisms with susceptibility and prognosis to gastric cancer in a Chinese population

The most studied genetic polymorphisms associated with gastric cancer (GC) risk are located in protein-coding genes. However, these sited in long noncoding RNA (lncRNA) are not adequately explored yet. Here, we designed a case-control study of 848 cases and 880 controls to investigate the associations of polymorphisms (rs61396151, rs1059307, rs11961028, rs9351065) in lncRNA SNHG5 with the risk and prognosis of GC. The results indicate rs61396151 associated with decreased risk of GC (OR = 0.78, 95% CI = 0.62-0.96), but there were no correlations observed with the clinicopathological features of GC (P > 0.05). However, the CA genotype of rs61396151 was correlated with poor overall survival rate in a multivariate cox regression model (HR = 1.91, P = 0.040), but it was reversed with adjustment for age, gender and TNM stage (HR = 1.35, P = 0.213). Collectively, our results highlight the importance of SNHG5-related polymorphisms to GC susceptibility and prognosis.

MicroRNA-653-5p Promotes Gastric Cancer Proliferation and Metastasis by Targeting the SOCS6-STAT3 Pathway

MicroRNAs (miRNAs) are emerging as significant regulators of the tumorigenesis of gastric cancer (GC), and may be effective biomarkers for diagnosis, prognosis, and therapeutic targeting for GC. In this study, miR-653-5p was found to be significantly upregulated in GC tissues, serum, and cell lines and was strongly associated with poor prognosis in patients with GC. Furthermore, miR-653-5p promoted GC cell proliferation and metastasis in vivo and in vitro. Suppressor of cytokine signaling 6 (SOCS6) was directly targeted by miR-653-5p, and SOCS6 attenuated miR-653-5p-mediated GC cell growth, migration, and invasion. In addition, SOCS6-mediated inactivation of the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway was also reversed by the administration of miR-653-5p. The findings from this study support a novel regulatory axis between miR-653-5p, SOCS6, and JAK2/STAT3 that may be a target for diagnosis and therapeutic intervention for GC.

Involvement of APRIL in Helicobacter pylori-related gastric cancer

BACKGROUND/AIMS

A proliferation-inducing ligand (APRIL, also known as TNFSF13, CD256) is a member of the tumor necrosis factor (TNF) superfamily and involved in a diverse set of diseases. In this work, we explored the potential associations and underlying mechanism in patients suffered from gastric cancer between the expression of APRIL and H. pylori infection.

METHODS

We analyzed APRIL expression levels in 200 GC tissue samples by immunohistochemistry staining. H. pylori infection was detected by modified Giemsa staining. The biological effects of APRIL on human GC cells in vitro and in vivo were tested by CCK-8 assay, colony formation, flow cytometry detection, transwell migration assay, matrigel invasion assay, and tumor xenograft assay in animals.

RESULTS

APRIL reactivity was positively correlated with H. pylori infection in vitro and vivo. It turned out that the decrease of miR-145 expression was dose-dependent and time-dependent on H. pylori infection and in consistent with APRIL expression. MiR-145 significantly attenuated the effect of H. pylori infection on APRIL gene expression in SGC7901 and BGC823 cell lines. Furthermore, APRIL overexpression promoted the proliferation, migration, invasion, and transfer of GC cells and decreased apoptosis, while APRIL knockdown suppressed these effects. We confirmed that APRIL activated the canonical NF-κB pathway through phosphorylation of AKT.

CONCLUSION

The expression of APRIL, which promoted the proliferation, migration, invasion, viability, and metastasis of GC cells, was upregulated in human H. pylori-infected GC through miR-145. Besides, APRIL-induced gastric tumorigenicity via activating NF-κB pathway. These results may provide a framework for the deeper analysis of APRIL in GC risk and prognosis.

CircFAM73A promotes the cancer stem cell-like properties of gastric cancer through the miR-490-3p/HMGA2 positive feedback loop and HNRNPK-mediated β-catenin stabilization

Background

Circular RNAs (circRNAs) have emerged as a new subclass of regulatory RNAs that play critical roles in various cancers. Cancer stem cells (CSCs), a small subset of cancer cells, are believed to possess the capacities to initiate tumorigenesis and promote progression. Although accumulating evidence has suggested that cells with CSC-like properties are crucial for the malignancy of gastric cancer (GC), it remains unclear whether circRNAs are related to the acquisition of CSC-like properties in GC.

Methods

CircFAM73A expression was analyzed by GEO datasets and verified in GC samples. The roles of circFAM73A in GC cell proliferation, migration, cisplatin resistance, and CSC-like properties were determined by a series of functional experiments both in vitro and in vivo. RNA pulldown was used to explore the miRNAs and proteins binding to circFAM73A. Bioinformatic analysis and experimental verification confirmed the downstream targets of circFAM73A. The regulation of circFAM73A by HMGA2 was verified by ChIP and RIP assays.

Results

Elevated circFAM73A expression was confirmed in GC tissues, and higher circFAM73A predicted poor prognosis in GC patients. The upregulation of circFAM73A enhanced CSC-like properties in GC, thus facilitating cell proliferation, migration, and cisplatin resistance. Mechanistically, circFAM73A promoted GC malignancy by regulating miR-490-3p/HMGA2 in a positive feedback loop and recruiting HNRNPK to facilitate β-catenin stabilization. Moreover, HMGA2 further enhanced E2F1 and HNRNPL activity, which in turn promoted circFAM73A expression.

Conclusions

Our work demonstrates the crucial role of circFAM73A in the CSC-like properties of GC and uncovers a positive feedback loop in circFAM73A regulation that leads to the progression of gastric cancer, which may provide new insights into circRNA-based diagnostic and therapeutic strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01896-9.

Multi-institutional development and validation of a nomogram to predict recurrence after curative resection of gastric neuroendocrine/mixed adenoneuroendocrine carcinoma

OBJECTIVE

To establish a novel nomogram to predict individual 1, 3, and 5 years disease-free survival (DFS) of patients with gastric neuroendocrine carcinoma/mixed adenoneuroendocrine carcinoma [(MA)NEC].

BACKGROUND

Among patients undergoing radical resection of gastric (MA)NEC, there is still a high tendency for relapse.

METHODS

A retrospective analysis of 777 patients with gastric (MA)NEC at 23 centers in China from 2004 to 2015 was performed. Based on the established nomogram, which included age, ASA, pT, pN and Ki67, the overall patients were divided into low-risk group (LRG) and high-risk group (HRG).

RESULTS

The median follow-up time was 40 months (1-169 months). The C-index, AUC and time-ROC of the nomogram were significantly higher than that of the 8th edition AJCC and ENETS TNM staging systems. The 3-year DFS of patients in HRG generated by the nomogram was significantly lower than that in LRG (all patients: 35% vs 66.9%, p < 0.001), and there were still significant differences in stratified analysis of the TNM staging systems. The local recurrence rate (10.5% vs 2.6%) and distant recurrence rate (45.1% vs 22.6%) in HRG were significantly higher than those in LRG, especially in anastomotic recurrence (6.3% vs 2%), liver recurrence (20.7% vs 13.4%) and peritoneal metastasis (12.7% vs 2.6%).

CONCLUSIONS

Compared with AJCC and ENETS TNM staging systems, the established novel validated nomogram had a significantly better prediction ability for DFS and recurrence patterns in patients with gastric (MA)NEC. It can also compensate for the shortcomings of existing AJCC and ENETS TNM staging in predicting individual recurrence risk.

SRPK1/2 and PP1α exert opposite functions by modulating SRSF1-guided MKNK2 alternative splicing in colon adenocarcinoma

BACKGROUND

The Mnk2 kinase, encoded by MKNK2 gene, plays critical roles in MAPK signaling and was involved in oncogenesis. Human MKNK2 pre-mRNA can be alternatively spliced into two splicing isoforms, the MKNK2a and MKNK2b, thus yielding Mnk2a and Mnk2b proteins with different domains. The involvement of Mnk2 alternative splicing in colon cancer has been implicated based on RNA-sequencing data from TCGA database. This study aimed at investigating the upstream modulators and clinical relevance of Mnk2 alternative splicing in colon adenocarcinoma (CAC).

METHODS

PCR, western blotting and immunohistochemistry (IHC) were performed to assess the expression of Mnk2 and upstream proteins in CAC. The function of Mnk2 and its regulators were demonstrated in different CAC cell lines as well as in xenograft models. Two independent cohorts of CAC patients were used to reveal the clinical significance of MKNK2 alternative splicing.

RESULTS

Comparing with adjacent nontumorous tissue, CAC specimen showed a decreased MKNK2a level and an increased MKNK2b level, which were correlated with KRAS mutation and tumor size. The SRSF1 (serine/arginine-rich splicing factor 1) was further confirmed to be the major splicing factor targeting MKNK2 in CAC cells. Higher expression of SRPK1/2 or decreased activity of PP1α were responsible for enhancing SRSF1 phosphorylation and nucleus translocation, subsequently resulted in a switch of MKNK2 alternative splicing.

CONCLUSIONS

Our data showed that phosphorylation and subcellular localization of SRSF1 were balanced by SRPK1/2 and PP1α in CAC cells. High nucleus SRSF1 promoted MKNK2 splicing into MKNK2b instead of MNK2a, consequently enhanced tumor proliferation.

Morbidity and Mortality of Laparoscopic vs Open Total Gastrectomy for Clinical Stage I Gastric Cancer: The CLASS02 Multicenter Randomized Clinical Trial

Importance

The safety of laparoscopic total gastrectomy (LTG) for the treatment of gastric cancer remains uncertain given the lack of high-level clinical evidence.

Objective

To compare the safety of LTG for clinical stage I gastric cancer with that of conventional open total gastrectomy (OTG).

Design, Setting, and Participants

The Chinese Laparoscopic Gastrointestinal Surgery Study (CLASS) Group CLASS02 study was a prospective, multicenter, open-label, noninferiority, randomized clinical trial that compared the safety of LTG vs OTG with lymphadenectomy for patients with clinical stage I gastric cancer. From January 2017 to September 2018, a total of 227 patients were enrolled. Final follow-up was in October 2018.

Interventions

Eligible patients were randomized to LTG (n = 113) or OTG (n = 114) by an interactive web response system.

Main Outcomes and Measures

The primary outcome was the morbidity and mortality within 30 days following surgeries between LTG and OTG with a noninferiority margin of 10%. The secondary outcomes were recovery courses and postoperative hospital stays.

Results

A total of 214 patients were analyzed for morbidity and mortality (105 patients in the LTG group and 109 patients in the OTG group). The mean (SD) age was 59.8 (9.4) years in the LTG group and 59.4 (9.2) years in the OTG group, and most were male (LTG group, 75 of 105 [71.4%]; OTG group, 80 of 109 [73.4%]). The overall morbidity and mortality rates were not significantly different between the groups (rate difference, -1.1%; 95% CI, -11.8% to 9.6%). Intraoperative complications occurred in 3 patients (2.9%) in the LTG group and 4 patients (3.7%) in the OTG group (rate difference, -0.8%; 95% CI, -6.5% to 4.9%). In addition, there was no significant difference in the overall postoperative complication rate of 18.1% in the LTG group and 17.4% in the OTG group (rate difference, 0.7%; 95% CI, -9.6% to 11.0%). One patient in the LTG group died from intra-abdominal bleeding secondary to splenic artery hemorrhage. However, there was no significant difference in mortality between the LTG group and the OTG group (rate difference, 1.0%; 95% CI, -2.5% to 5.2%), and the distribution of complication severity was similar between the 2 groups.

Conclusions and Relevance

The results of the CLASS02 trial showed that the safety of LTG with lymphadenectomy by experienced surgeons for clinical stage I gastric cancer was comparable to that of OTG.

Trial Registration

ClinicalTrials.gov Identifier: NCT03007550.

Circular RNA TMEM87A promotes cell proliferation and metastasis of gastric cancer by elevating ULK1 via sponging miR-142-5p

BACKGROUND

Circular RNAs (circRNAs) act as vital regulators of gene expression in a variety of cancers. However, the role of circRNAs in gastric cancer (GC) remains largely unexplored. Herein, we identified that circTMEM87A sponges miR-142-5p to promote GC progression through up-regulating ULK1 expression.

METHODS

The expression of circTMEM87A in GC was determined by RNA sequencing and quantitative real-time PCR (qRT-PCR). The effects of knockdown or exogenous expression of circTMEM87A on GC cell phenotypes were evaluated both in vitro and in vivo. The interacting miRNA of circTMEM87A was predicted by bioinformatics and confirmed by RNA pull-down, dual-luciferase reporter assay and fluorescence in situ hybridization (FISH). The mechanism by which circTMEM87A/miR-142-5p/ULK1 axis promotes GC was determined by western blot, GFP/mRFP-LC3 puncta analysis, transmission electron microscope (TEM).

RESULTS

CircTMEM87A was dramatically elevated in GC tissues and cell lines, and high circTMEM87A expression was closely correlated with poor prognosis of GC patients. Knockdown of circTMEM87A suppressed cell growth, migration, invasion and induced apoptosis in vitro, as well as inhibited GC tumorigenicity and lung metastasis potential in vivo. Meanwhile, circTMEM87A overexpression had the opposite effects. Furthermore, we demonstrated that circTMEM87A could act as a sponge of miR-142-5p to regulate ULK1 expression and GC progression.

CONCLUSIONS

Our findings suggest that circTMEM87A functions as an oncogene through the miR-142-5p/ULK1 axis in GC. CircTMEM87A might be a prognostic biomarker as well as a promising therapeutic target for GC.

Circular RNA circLMO7 acts as a microRNA-30a-3p sponge to promote gastric cancer progression via the WNT2/β-catenin pathway

Background

Gastric cancer (GC) is one of the most common malignant tumors worldwide. Currently, the overall survival rate of GC is still unsatisfactory despite progress in diagnosis and treatment. Therefore, studying the molecular mechanisms involved in GC is vital for diagnosis and treatment. CircRNAs, a type of noncoding RNA, have been proven to act as miRNA sponges that can widely regulate various cancers. By this mechanism, circRNA can regulate tumors at the genetic level by releasing miRNA from inhibiting its target genes. The WNT2/β-Catenin regulatory pathway is one of the canonical signaling pathways in tumors. It can not only promote the development of tumors but also provide energy for tumor growth through cell metabolism (such as glutamine metabolism).

Methods

Through RNA sequencing, we found that hsa_circ_0008259 (circLMO7) was highly expressed in GC tissues. After verifying the circular characteristics of circLMO7, we determined the downstream miRNA (miR-30a-3p) of circLMO7 by RNA pull-down and luciferase reporter assays. We verified the effect of circLMO7 and miR-30a-3p on GC cells through a series of functional experiments, including colony formation, 5-ethynyl-2′-deoxyuridine and Transwell assays. Through Western blot and immunofluorescence analyses, we found that WNT2 was the downstream target gene of miR-30a-3p and further confirmed that the circLMO7-miR-30a-3p-WNT2 axis could promote the development of GC. In addition, measurement of related metabolites confirmed that this axis could also provide energy for the growth of GC cells through glutamine metabolism. We found that circLMO7 could promote the growth and metastasis of GC in vivo by the establishment of nude mouse models. Finally, we also demonstrated that HNRNPL could bind to the flanking introns of the circLMO7 exons to promote circLMO7 cyclization.

Results

CircLMO7 acted as a miR-30a-3p sponge affecting the WNT2/β-Catenin pathway to promote the proliferation, migration and invasion of GC cells. Moreover, animal results also showed that circLMO7 could promote GC growth and metastasis in vivo. CircLMO7 could also affect the glutamine metabolism of GC cells through the WNT2/β-Catenin pathway to promote its malignant biological function. In addition, we proved that HNRNPL could promote the self-cyclization of circLMO7.

Conclusions

CircLMO7 promotes the development of GC by releasing the inhibitory effect of miR-30a-3p on its target gene WNT2.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-020-01791-9.

The protocol of a prospective, multicenter, randomized, controlled phase III study evaluating different cycles of oxaliplatin combined with S-1 (SOX) as neoadjuvant chemotherapy for patients with locally advanced gastric cancer: RESONANCE-II trial

Background

Curing locally advanced gastric cancer through surgery alone is difficult. Adjuvant and neoadjuvant chemotherapy bring potential benefits to more patients with gastric cancer based on several clinical trials. According to phase II studies and guidelines, SOX regimen as neoadjuvant chemotherapy is efficient. However, the optimal duration of neoadjuvant chemotherapy has not been established. In this study, we will evaluate the efficacy and safety of different cycles of SOX as neoadjuvant chemotherapy for patients with locally advanced gastric cancer.

Methods

RESONANCE-II trial is a prospective, multicenter, randomized, controlled phase III study which will enroll 524 patients in total. Eligible patients will be registered, pre-enrolled and receive three cycles of SOX, after which tumor response evaluations will be carried out. Those who show stable disease or progressive disease will be excluded. Patients showing complete response or partial response will be enrolled and assigned into either group A for another three cycles of SOX (six cycles in total) followed by D2 surgery; or group B for D2 surgery (three cycles in total). The primary endpoint is the rate of pathological complete response and the secondary endpoints are R0 resection rate, three-year disease-free survival, five-year overall survival, and safety.

Discussion

This study is the first phase III randomized trial to compare the cycles of neoadjuvant chemotherapy using SOX for resectable locally advanced cancer. Based on a total of six to eight cycles of perioperative chemotherapy usually applied in locally advanced gastric cancer, patients in group A can be considered to have completed all perioperative chemotherapy, the results of which may suggest the feasibility of using chemotherapy only before surgery in gastric cancer.

Trial registration

Registered prospectively in the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) with registration number ChiCTR1900023293 on May 21st, 2019.

Which Staging System Is More Suitable for Gastric Neuroendocrine Cancer and Mixed Adenoneuroendocrine Carcinomas? A Multicenter Cohort Study

PURPOSE

To evaluate whether the European Neuroendocrine Tumor Society (ENETS) system or the 8th American Joint Committee on Cancer (AJCC) staging manual are suitable for gastric neuroendocrine carcinomas and/or mixed adenoneuroendocrine carcinomas (G-NECs/MANECs).

METHODS

Patients in a multicentric series with G-NEC/MANEC who underwent curative-intent surgical resection for a primary tumor were included. An optimal staging system was proposed base on analysis of the T and N status and validated by the SEER database.

RESULTS

Compared with the ENETS system, the survival curves of the T category and N category in the 8th AJCC system were better separated and distributed in a more balanced way, but the survival curves of T2 vs. T3, N0 vs. N1, and N3a vs. N3b overlapped. For the T category, the 8th AJCC T category was modified by combining T2 and T3, which was consistent with the T category in the 6th AJCC manual for GC. For the N category, the optimal cut-off values of metastatic lymph nodes using X-tile were also similar to those of the N category in the 6th AJCC system. The Kaplan-Meier plots of the 6th AJCC system showed statistically significant differences between individual substages. Compared with the other 2 classifications, the 6th AJCC system also showed superior prognostic stratification. Similar results were obtained in both multicentric and SEER validation sets.

CONCLUSIONS

Compared to the 8th AJCC and ENETS systems, the 6th AJCC staging system for GC is more suitable for G-NEC/MANEC and can be adopted in clinical practice.

Circular RNA MCTP2 inhibits cisplatin resistance in gastric cancer by miR-99a-5p-mediated induction of MTMR3 expression

Background

Cisplatin (CDDP) is the first-line chemotherapy for gastric cancer (GC). The poor prognosis of GC patients is partially due to the development of CDDP resistance. Circular RNAs (circRNAs) are a subclass of noncoding RNAs that function as microRNA (miRNA) sponges. The role of circRNAs in CDDP resistance in GC has not been evaluated.

Methods

RNA sequencing was used to identify the differentially expressed circRNAs between CDDP-resistant and CDDP-sensitive GC cells. qRT-PCR was used to detect the expression of circMCTP2 in GC tissues. The effects of circMCTP2 on CDDP resistance were investigated in vitro and in vivo. Pull-down assays and luciferase reporter assays were performed to confirm the interactions among circMCTP2, miR-99a-5p, and myotubularin-related protein 3 (MTMR3). The protein expression levels of MTMR3 were detected by western blotting. Autophagy was evaluated by confocal microscopy and transmission electron microscopy (TEM).

Results

CircMCTP2 was downregulated in CDDP-resistant GC cells and tissues compared to CDDP-sensitive GC cells and tissues. A high level of circMCTP2 was found to be a favorable factor for the prognosis of patients with GC. CircMCTP2 inhibited proliferation while promoting apoptosis of CDDP-resistant GC cells in response to CDDP treatment. CircMCTP2 was also found to reduce autophagy in CDDP-resistant GC cells. MiR-99a-5p was verified to be sponged by circMCTP2. Inhibition of miR-99a-5p could sensitize GC cells to CDDP. MTMR3 was confirmed to be a direct target of miR-99a-5p. Knockdown of MTMR3 reversed the effects of circMCTP2 on the proliferation, apoptosis and autophagy of CDDP-resistant GC cells. CircMCTP2 was also confirmed to inhibit CDDP resistance in vivo in a nude mouse xenograft model.

Conclusions

CircMCTP2 sensitizes GC to CDDP through the upregulation of MTMR3 by sponging miR-99a-5p. Overexpression of CircMCTP2 could be a new therapeutic strategy for counteracting CDDP resistance in GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-020-01758-w.

Cimetidine promotes STUB1-mediated degradation of tumoral FOXP3 by activating PI3K-Akt pathway in gastric cancer

Background

Previous studies have confirmed the antitumor effects of cimetidine, while the therapeutic targets and the mechanisms are not yet fully understood. We previously reported the protumoral role of endogenous FOXP3 in gastric cancer (GC), but whether cimetidine plays an antitumor role by targeting FOXP3 is still unknown.

Methods

A series of assays were used to examine the role of cimetidine on the malignant behaviors and the expression of endogenous FOXP3 in GC cells. The role of cimetidine on ligase E3-STUB1and the role of STUB1 on FOXP3 level were examined, with the signaling pathway involved in these processes also being explored.

Results

Cimetidine inhibited the malignant behaviors of GC cells, and led to the ubiquitination/degradation of FOXP3. Moreover, cimetidine promoted STUB1 expression, STUB1 knockdown rescued the decline of FOXP3 in cimetidine-treated GC cells, and reduced the turnover effect of cimetidine on GC cells, but had minimal effect in untreated cells. Immunoprecipitation (IP) assay confirmed the formation of the STUB1-FOXP3 complex in cimetidine-treated GC cells. Furthermore, Cimetidine promoted STUB1 expression by activating PI3K/Akt pathway, and the inhibition of PI3K/Akt pathway rescued the decline of FOXP3 by suppressing the upregulation of STUB1.

Conclusions

Cimetidine suppressed GC development by promoting STUB1-mediated ubiquitination/degradation of endogenous FOXP3 through the activation of the PI3K/Akt pathway.