| Summary: | Background: Recently, increasing evidence has indicated that platelet-activating factor acetylhydrolase 1b catalytic subunit 3 (PAFAH1B3) plays an important role in several cancers. However, its role in lung adenocarcinoma (LUAD) has not been reported until now. Methods: The expression of PAFAH1B3 in LUAD was determined by using the Gene Expression Profiling Interactive Analysis (GEPIA) database and real-time PCR (RT–PCR), western blot and immunohistochemical (IHC) analyses. A chi-square test was used to investigate the correlation between PAFAH1B3 expression and clinical parameters. Cox regression and Kaplan–Meier analysis were performed to analyze the prognostic value of PAFAH1B3. The CCK-8 assay, clone formation assay, transwell invasion assay and flow cytometry were conducted to detect cell proliferation, clone formation, invasion and the cell cycle. The xenograft tumor model was constructed to explore the function of PAFAH1B3 in vivo. Western blot and IHC analyses were performed to detect epithelial-to-mesenchymal transition (EMT)-related markers. Immune Cell Abundance Identifier (ImmuneCellAI) and IHC analyses were used to analyze the effect of PAFAH1B3 on immune cell infiltration. Results: Our study showed that the expression of PAFAH1B3 was upregulated in LUAD tissues and cells compared with noncancerous tissues and cells. Additionally, the results indicated that the expression of PAFAH1B3 was positively correlated with distant metastasis, TNM stage and poor clinical outcome and it was an independent prognostic risk factor for LUAD. In addition, silencing PAFAH1B3 suppressed cell proliferation, colony formation, and invasion and increased the cell population in the G0-G1 phases in vitro. Furthermore, our results showed that knockdown of PAFAH1B3 increased the epithelial marker E-cadherin level and decreased the mesenchymal marker N-cadherin level in vitro and in vivo. We also proved that PAFAH1B3 downregulation inhibited tumorigenesis and neutrophil infiltration in the xenograft tumor model. Conclusion: Our studies indicate that PAFAH1B3, a prognostic risk factor, promotes proliferation, invasion and EMT and affects immune infiltrates in LUAD. © 2022, The Author(s).
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