A Precision Epigenetic Approach to Non-Invasive Lung Cancer Screening Using Gene- Specific cfDNA Methylation

Purpose Lung cancer remains the leading cause of cancer-related death worldwide, underscoring the need for reliable biomarkers for early detection. This study evaluated the promoter methylation and expression of MAX, MTURN, HLA-B, and CAV1 in tumor and tumor-free tissues and validated their methylation status in plasma cfDNA from patients with NSCLC and SCLC. It further assessed the potential of this multi-gene methylation panel as a non-invasive surrogate biomarker for early lung cancer detection and improved therapeutic outcomes. Methods In this study, we profiled promoter methylation in LC tissues and evaluated matched plasma-derived circulating cell-free DNA (cfDNA) as a “tissue-mirror” biomarker. mRNA expression of MAX, MTURN, HLA-B and CAV1 was quantified in tumor tissue (TT) from non-small cell (NSCLC) and small cell (SCLC) lung cancers versus tumor-free tissue (TF), and promoter methylation in tissue gDNA was assessed by methylation-specific PCR (MSP). The same loci were interrogated in plasma cfDNA from NSCLC and SCLC cases relative to healthy controls. Results In TT, methylation frequencies for MAX, MTURN and HLA-B were significantly elevated 68.45%, 56.94%, and 75.97%—compared with TF (20.42%, 15.28%, and 29.57%; p < 0.05 to p < 0.001). Correspondingly, TT showed down-regulation of gene expression (p < 0.01) with strong inverse associations to hypermethylation; CAV1 was the exception, demonstrating up-regulation with hypomethylation in NSCLC TT. Plasma cfDNA recapitulated tissue patterns, exhibiting significant hypermethylation in LC versus controls (p ≤ 0.05 to p ≤ 0.001) and yielding positive predictive values of 59.33–77.47% and negative predictive values of 52.47–67.33%. Conclusion Collectively, these findings indicate that promoter methylation of this four-gene panel in plasma can aid LC diagnosis and functions as a minimally invasive, tissue-reflective biomarker.