Guanylate binding protein 5 (GBP5) is a member of the interferon (IFN)-inducible large guanosine triphosphate hydrolases (GTPase) family that regulates cell-autonomous immunity and malignant tumor transformation. However, its specific roles and underlying mechanisms GBP5 in gastric cancer (GC) remain unknown. In this study, we aimed to determine the role GBP5 and underlying mechanism of GBP5 in GC cell progression. Potential oncogenic roles of GBP5 in GC as well as its relationship with the tumor immune microenvironment (TIME) were comprehensively evaluated using bioinformatics analysis. Protein expression levels of GBP5 and their correlation with clinicopathological features of patients were assessed using immunohistochemistry. In addition, diverse in vitro functional experiments were performed to identify the functions of GBP5 in GC. Downstream targets of GBP5 were identified using RNA-sequencing analysis and verified using western blotting or quantitative polymerase chain reaction analysis in different cell lines. GBP5 expression is commonly upregulated and promotes the proliferation and migration of GC cells. Mechanistically, GBP5 was regulated by the IFNγ-Janus kinase (JAK1)-signal transducer and activator of transcription 1 (STAT1) axis and induced CXCL8 expression. Interestingly, GBP5-induced CXCL8 regulated the JAK1-STAT1 signaling pathway to form a positive feedback loop. Moreover, GBP5 is closely related to the TIME and may be used as a biomarker for predicting the efficacy of immunotherapy. Our findings revealed a new JAK1-STAT1/GBP5/CXCL8 pathway and highlighted the value of GBP5 as a predictive biomarker and novel target for GC intervention.
Keywords: CXCL8; GBP5; Gastric cancer; IFNγ-JAK1-STAT1 signaling; positive feedback loop.
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