The PITX2/CKMT1B axis promotes lung adenocarcinoma stemness via lipid accumulation

Dysregulated expression of mitochondrial Creatine Kinase 1B (CKMT1B), a member of the Creatine Kinase family, has been linked to tumor progression. However, its specific function in lung adenocarcinoma (LUAD) remains unclear. Bioinformatics analyses were performed to evaluate CKMT1B and its upstream transcription factor PITX2 in LUAD. CKMT1B and PITX2 expression levels were determined by quantitative PCR. The functional impact on cell stemness was subsequently evaluated using CCK-8, sphere formation assay, flow cytometry, and western blot. CKMT1B-mediated lipid accumulation was examined via BODIPY staining and measurements of triglyceride and glycerol concentration. The PITX2-CKMT1B interaction was validated through dual-luciferase reporter and chromatin immunoprecipitation (ChIP) assays, with the regulatory mechanism further substantiated by functional rescue experiments. CKMT1B was upregulated in LUAD and linked with poor prognosis. Its knockdown suppressed cell proliferation, sphere-forming capacity, and stemness-related protein expression (CD133, Bmi-1, SOX-2). Furthermore, CKMT1B overexpression facilitated lipid accumulation and stemness, effects that were reversible by the Lipase Inhibitor Orlistat. Mechanistically, PITX2 was identified as an upstream transcription factor of CKMT1B. PITX2 expression was positively correlated with CKMT1B, and high PITX2 expression predicted poor outcomes. In functional rescue experiments, PITX2 knockdown significantly reduced lipid accumulation and stemness, while these effects were partially restored by CKMT1B overexpression. PITX2 promotes lipid accumulation and enhances stemness in LUAD cells by transcriptionally activating CKMT1B, suggesting the PITX2/CKMT1B axis as a potential therapeutic target for LUAD treatment.

CKMT1B; PITX2; lipid accumulation; lung adenocarcinoma; tumor stemness.