CLK1 is a potential tumor suppressor for NSCLC by regulating cell proliferation and immune infiltration.

[BACKGROUND] Lung cancer is the malignancy with the highest global incidence and mortality. Non-small cell lung cancer (NSCLC) accounts for approximately 85% of cases and is characterized by complex drug resistance and poor prognosis. While CLK1 has been implicated in Alzheimer's disease, pancreatic cancer proliferation, and chemotherapy resistance in lymphoma, its role in NSCLC, particularly in the context of tumor immune infiltration, remains unexplored.

[METHODS] CLK1 expression and prognostic significance were analyzed across cancers and in LUAD using bioinformatics platforms (GEPIA, UALCAN). Functional enrichment analyses (GSEA, KEGG, GO) elucidated associated pathways and immune correlations. Drug sensitivity screening (GDSC, CTRP, CellMiner) identified potential compounds targeting CLK1-high tumors. Experimental validation was performed using clinical samples from NSCLC patients (n = 12) and assays with A549 and H1299 cell lines to assess CLK1 expression and its effect on proliferation.

[RESULTS] Contrary to its oncogenic role in other cancers, CLK1 acts as a tumor suppressor in NSCLC. High CLK1 expression correlated with prolonged survival, suppressed cell cycle and metabolism pathways, and enhanced anti-tumor immunity-particularly CD4 T cell infiltration. Clinically, high CLK1 was associated with increased tumor mutational burden and greater sensitivity to chemotherapy. Consistent with this, CLK1 was downregulated in NSCLC patient tissues of NSCLC, and its overexpression directly inhibits cancer cell proliferation .

[CONCLUSION] Our findings demonstrate that CLK1 functions as a tumor suppressor gene in NSCLC, inhibiting proliferation and promoting immune infiltration. It also correlates positively with sensitivity to multiple chemotherapeutic agents. Thus, CLK1 may serve as a novel prognostic biomarker and a potential target for combination therapy in NSCLC.