This study aimed to analyze the functional roles and molecular mechanism of Wilms' tumor 1-associating protein (WTAP) in the tumorigenesis of nonsmall-cell lung cancer (NSCLC).Retrospective analysis was used. Tumor tissues and surrounding nontumor tissues of 150 patients with NSCLS who were surgically resected in the Fourth Hospital of Hebei Medical University from January 2016 to January 2018 were selected. The expression of WTAP in NSCLC tissues was detected by immunohistochemistry. Clinicopathologic parameters were then subjected to univariate and multivariate Cox regression analysis in purpose of uncovering the independent risk factors for overall survival time. MTS (3-[4,5-dimethylthiazol-zyl]-5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]-2H-tetrazoliuzolium, inner salt) assay, colony formation assay, and transwell assays were performed to estimate cell proliferation, migration, and invasion. Meanwhile, the relationship between WTAP and the cell migration and invasion marker-related proteins were evaluated by Western blot analysis and RT-qPCR. WTAP expression was knocked-down in cell lines by shRNA, and RNA-Seq was performed to investigate the pathways regulated by WTAP.In NSCLC patients, WTAP was highly expressed in tumor tissues and the higher expression was significantly associated with poor overall survival (OS) (P<0.01). Compared with the control group in vitro, the overexpression of WTAP could significantly promote cell proliferation, migration, and invasion (P<0.01), while knock-down WTAP significantly reduces the above effects (P<0.01). In a mouse orthotopic implantation model, higher WTAP abundance could significantly promote tumor enlargement compared with the control group (P<0.01). Compared with the control group, the knock-down of WTAP significantly inhibit the expression of carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) in cell lines (P<0.01). Besides, in NSCLC, knocked-down CEACAM5 significantly reduced the impact of WTAP on cell proliferation, migration, and invasion compared with the control group (P<0.05).This study suggests that high expression of WTAP was associated with poor clinical outcomes. CEACAM5 may play a synergistic role with WTAP to jointly promote NSCLC progression by enhancing cell proliferation, invasion, and migration.Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.