NCKAP1 as a prognostic and immunological biomarker: pan-cancer analysis and validation in renal clear cell carcinoma.

Objectives: To systematically investigate the expression, prognostic value, genetic alterations, immune infiltration, and molecular function of Nck-associated protein 1 (NCKAP1) in a pan-cancer analysis, with a specific focus on its association with kidney renal cell carcinoma (KIRC).

Methods: We analyzed the role of NCKAP1 across various tumor types using data from The Cancer Genome Atlas (TCGA). The Gene Expression Profiling Interactive Analysis version 2 (GEPIA2) database was used to assess the correlation between NCKAP1 expression levels and overall survival (OS) and disease-free survival (DFS) across different cancers, as well as its association with cancer stage. Genetic alterations of NCKAP1 were explored using CBioPortal, and their prognostic implications were assessed. NCKAP1 was further analyzed through Gene Ontology and protein interaction network analyses. Immunohistochemistry (IHC) staining from the Human Protein Atlas (HPA) database evaluated NCKAP1 levels in KIRC tissues. Functional assays, including Cell Counting Kit-8 (CCK-8), colony formation, transwell, and wound healing assays, were conducted to determine the effects of NCKAP1 overexpression on cell growth rate and their ability to invade, proliferate, migrate in a KIRC (786-O) cell line. The relationship between NCKAP1 expression and immune infiltration in KIRC was systematically examined using the Tumor Immune Estimation Resource.

Results: NCKAP1 expression was significantly altered in most tumor types compared to corresponding non-tumor tissues. Survival analysis indicated that low NCKAP1 expression was associated with poor OS, DFS, and advanced cancer stage (P < 0.05) specifically in KIRC. Genetic alterations in NCKAP1 were linked to clinical outcome in cancer patients, and a positive correlation was observed between NCKAP1 expression and cancer-associated fibroblast infiltration (P < 0.05). Gene Ontology analysis revealed that NCKAP1 regulates the actin cytoskeleton and interacts with proteins such as CYFIP1, ABI2, WASF2, and BRK1. IHC staining showed significantly lower NCKAP1 levels in KIRC tissues compared to normal tissues. Overexpression of NCKAP1 in KIRC cell lines reduced cell proliferation, invasion, and migration (P < 0.05). NCKAP1 was also positively correlated with macrophage, neutrophil, and CD4+ T cell infiltration (P < 0.001).

Conclusion: NCKAP1 may serve as a prognostic and immunological marker and may be a therapeutic target for KIRC.