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The role of STEAP1 in the biological behavior of gastric cancer


 Background: Six-transmembrane epithelial antigen 1 (STEAP1) is associated with the occurrence and development of cancer. This study aimed to clarify the role of STEAP1 in gastric cancer tumor growth and metastasis, as well as its molecular mechanism of action.Methods: Statistical methods were used for clinical data analysis. Protein expression was detected using immunohistochemistry. The mRNA and protein expression in the cell cultures were detected using reverse transcription-polymerase chain reaction and western blot analysis. Overexpression and silencing models were constructed using plasmid and lentivirus transfection. To detect cell proliferation in vitro, Cell Counting Kit-8, flow cytometry, and colony formation assays were used; transwell and wound healing assays were used to detect cell migration and invasion; RNA sequencing was used for identifying differentially expressed genes; ELISA assay was used to detect the secretory proteins in cells. For in vivo experiments, nude BALB/c mice were used for detecting subcutaneous tumorigenesis and intraperitoneal implantation.Results: STEAP1 was overexpressed in gastric cancer tissues and cell lines. Single factor and Cox analyses showed that STEAP1 gene expression level correlated with poor prognosis. Upregulation of STEAP1 increased cell proliferation, migration, and invasion, which decreased after STEAP1 was knocked down. These changes were achieved via the activation of the AKT/FoxO1 pathway and epithelial-mesenchymal transformation (EMT). The RNA sequencing results indicated that STEAP1 was closely related to inflammatory reactions. STEAP1 can regulate the inflammation-related molecules, IL-1β and IL-6, via the NF-kB and ERK/c-Jun signaling pathways. The in vivo animal experiments showed that STEAP1 knock down, resulted in a decrease in the subcutaneous tumor and peritoneal tumor formation.Conclusion: STEAP1 was overexpressed in gastric cancer and closely associated with OS. STEAP1 can regulate the cell cycle via the Akt/FoxO1 pathway to influence cell proliferation. STEAP1 may affect cell migration and invasion via EMT action. In addition, STEAP1 may mediate the inflammatory response by regulating IL1β and IL6 via the NF-kB and the ERK/c-Jun signaling pathways.