Objective:This study examines the significance and functions of CLDN9 in gastric cancer(GC),intending to identify novel targets for diagnosis and treatment.Methods:CLDN9 expression in GC tissues and cell lines was inv...Objective:This study examines the significance and functions of CLDN9 in gastric cancer(GC),intending to identify novel targets for diagnosis and treatment.Methods:CLDN9 expression in GC tissues and cell lines was investigated in TCGA data,with analysis with Western blotting,qRT-PCR,and immunohistochemical analyses.Correlations between clinicopathological characteristics,progression-free survival(PFS),and overall survival(OS)were assessed with Cox regression.The effect of CLDN9 knockdown/overexpression on tumorigenic functions(proliferation,migration,and invasion)was assessed using CCK-8,colony formation,and Transwell assays.Tumor-bearing assays were performed to verify the impact of CLDN9 knockdown on the in vivo proliferation of GC cells.Results:Analysis of TCGA data,qRT-PCR,Western blotting,and immunohistochemistry indicated significantly elevated levels of CLDN9 in GC tissues and cell lines(p 0.01).Compared to the group with high CLDN9 expression,<PFS and OS were markedly longer in cases with low CLDN9 levels(p 0.05).Multivariate regression indicated that<CLDN9 levels were independently predictive of GC prognosis.CCK-8,Transwell,and colony formation tests showed that CLDN9 overexpression promoted GC cell proliferation,clonogenicity,and migratory/invasive capabilities,but CLDN9 knockdown markedly reduced these features.Experiments involving tumor-bearing models demonstrated that the suppression of CLDN9 inhibited the in vivo growth of GC cells.Conclusion:In conclusion,this study’s findings suggested that CLDN9 might be a valuable therapeutic target or diagnostic biomarker for GC.展开更多
Background:Gastric cancer(GC)is a common malignancy characterized by the absence of reliable prognostic indicators and effective therapeutic targets.Claudin-9(CLDN9)has been demonstrated to be upregulated in various c...Background:Gastric cancer(GC)is a common malignancy characterized by the absence of reliable prognostic indicators and effective therapeutic targets.Claudin-9(CLDN9)has been demonstrated to be upregulated in various cancers.However,its prognostic value,biological function,and regulatory mechanisms in GC remain unclear.Therefore,this study aimed to elucidate the role of CLDN9 in GC progression and its underlying mechanisms.Methods:We utilized consensus cluster,random survival forest,and multivariate Cox regression analyses to identify CLDN9 in GC.Subsequently,we evaluated the mRNA and protein levels of CLDN9 in GC using quantitative real-time polymerase chain reaction(PCR)(qRT-PCR),Western blotting(WB),and immunohistochemistry(IHC).Furthermore,the role of CLDN9 in GC progression was investigated using a series of functional in vivo and in vitro experiments.Finally,we elucidated the molecular mechanisms of CLDN9 using bioinformatics,molecular biology,animal models,and patient tissue specimens.Results:Two GC subtypes with survival and functional differences were identified based on glycolytic metabolic genes in the Cancer Genome Atlas(TCGA)-Stomach adenocarcinoma(STAD)dataset.A prognostic risk score was calculated using seven genes to assess the overall survival(OS)in GC.Using random survival forest and multivariate Cox analyses,we identified CLDN9 as the key gene linked to the glycolytic subtype and prognosis of GC.CLDN9 expression was significantly upregulated in patients with GC as well as in GC cells.CLDN9 knockdown inhibited tumor proliferation,invasion,and metastasis both in vivo and in vitro.Mechanistically,CLDN9 was found to regulate lactate dehydrogenase A(LDHA)expression and promote glycolytic metabolism by activating the phosphatidylinositol 3-kinase(PI3K)/protein kinase B(AKT)/hypoxia-inducible factor 1-alpha(HIF1α)signaling pathway.Additionally,lactate,a glycolytic metabolite,enhanced programmed cell death ligand 1(PD-L1)lactylation and stability,which suppressed anti-tumor immunity in CD8t T cells,thereby contributing to GC progression.Conclusions:CLDN9 expression is associated with GC development and progression.Mechanistically,CLDN9 enhances the glycolysis pathway and facilitates PD-L1 lactylation through the PI3K/AKT/HIF1αsignaling pathway,thereby suppressing anti-tumor immunity in CD8t T cells.CLDN9 has the potential to serve as a novel prognostic marker and therapeutic target for GC.展开更多
基金supported by the Science and Technology Plan of Suqian City(Grant No.S202117).
文摘Objective:This study examines the significance and functions of CLDN9 in gastric cancer(GC),intending to identify novel targets for diagnosis and treatment.Methods:CLDN9 expression in GC tissues and cell lines was investigated in TCGA data,with analysis with Western blotting,qRT-PCR,and immunohistochemical analyses.Correlations between clinicopathological characteristics,progression-free survival(PFS),and overall survival(OS)were assessed with Cox regression.The effect of CLDN9 knockdown/overexpression on tumorigenic functions(proliferation,migration,and invasion)was assessed using CCK-8,colony formation,and Transwell assays.Tumor-bearing assays were performed to verify the impact of CLDN9 knockdown on the in vivo proliferation of GC cells.Results:Analysis of TCGA data,qRT-PCR,Western blotting,and immunohistochemistry indicated significantly elevated levels of CLDN9 in GC tissues and cell lines(p 0.01).Compared to the group with high CLDN9 expression,<PFS and OS were markedly longer in cases with low CLDN9 levels(p 0.05).Multivariate regression indicated that<CLDN9 levels were independently predictive of GC prognosis.CCK-8,Transwell,and colony formation tests showed that CLDN9 overexpression promoted GC cell proliferation,clonogenicity,and migratory/invasive capabilities,but CLDN9 knockdown markedly reduced these features.Experiments involving tumor-bearing models demonstrated that the suppression of CLDN9 inhibited the in vivo growth of GC cells.Conclusion:In conclusion,this study’s findings suggested that CLDN9 might be a valuable therapeutic target or diagnostic biomarker for GC.
基金supported by grants from the National Natural Science Foundation of China(Nos.82273204 and 81972471)the Guangdong Medical Science and Technology Program(No.A2023077)+1 种基金Guangdong Basic and Applied Basic Research Foundation(No.2023A1515110952)the China Postdoctoral Science Foundation(Nos.2023M744024 and 2023M734015).
文摘Background:Gastric cancer(GC)is a common malignancy characterized by the absence of reliable prognostic indicators and effective therapeutic targets.Claudin-9(CLDN9)has been demonstrated to be upregulated in various cancers.However,its prognostic value,biological function,and regulatory mechanisms in GC remain unclear.Therefore,this study aimed to elucidate the role of CLDN9 in GC progression and its underlying mechanisms.Methods:We utilized consensus cluster,random survival forest,and multivariate Cox regression analyses to identify CLDN9 in GC.Subsequently,we evaluated the mRNA and protein levels of CLDN9 in GC using quantitative real-time polymerase chain reaction(PCR)(qRT-PCR),Western blotting(WB),and immunohistochemistry(IHC).Furthermore,the role of CLDN9 in GC progression was investigated using a series of functional in vivo and in vitro experiments.Finally,we elucidated the molecular mechanisms of CLDN9 using bioinformatics,molecular biology,animal models,and patient tissue specimens.Results:Two GC subtypes with survival and functional differences were identified based on glycolytic metabolic genes in the Cancer Genome Atlas(TCGA)-Stomach adenocarcinoma(STAD)dataset.A prognostic risk score was calculated using seven genes to assess the overall survival(OS)in GC.Using random survival forest and multivariate Cox analyses,we identified CLDN9 as the key gene linked to the glycolytic subtype and prognosis of GC.CLDN9 expression was significantly upregulated in patients with GC as well as in GC cells.CLDN9 knockdown inhibited tumor proliferation,invasion,and metastasis both in vivo and in vitro.Mechanistically,CLDN9 was found to regulate lactate dehydrogenase A(LDHA)expression and promote glycolytic metabolism by activating the phosphatidylinositol 3-kinase(PI3K)/protein kinase B(AKT)/hypoxia-inducible factor 1-alpha(HIF1α)signaling pathway.Additionally,lactate,a glycolytic metabolite,enhanced programmed cell death ligand 1(PD-L1)lactylation and stability,which suppressed anti-tumor immunity in CD8t T cells,thereby contributing to GC progression.Conclusions:CLDN9 expression is associated with GC development and progression.Mechanistically,CLDN9 enhances the glycolysis pathway and facilitates PD-L1 lactylation through the PI3K/AKT/HIF1αsignaling pathway,thereby suppressing anti-tumor immunity in CD8t T cells.CLDN9 has the potential to serve as a novel prognostic marker and therapeutic target for GC.
