RNLS hypomethylation as a potential epigenetic marker of lung cancer metastasis: an epigenome-wide association study.

[BACKGROUND] Lung cancer is highly lethal because most patients have already developed metastases at diagnosis, yet the epigenetic mechanisms driving metastasis are unclear.

[METHODS] We performed an epigenome-wide association study on 42 lung cancer patients to identify differentially methylated positions (DMPs) in pulmonary tumour (PT), paratumor (PP), and normal (PN) tissues, and in peripheral blood. The impact of DMPs on gene expression and associated signalling pathways was examined. Functional validation included gene silencing in A549 and H1299 cells, analysis of the affected signalling pathway, and assessment of metastasis using mice injected with genetically edited cells.

[RESULTS] We identified 22 significant DMPs between PP and PN tissues, with several mapped to the RNLS promoter region, showing progressive hypomethylation from PN, PP, to PT. This hypomethylation was also present in the peripheral blood of patients who later developed metastasis. RNLS methylation was inversely correlated with its expression across multiple tissue types. The DMPs were enriched in Notch signalling. Silencing RNLS inhibited cancer cell proliferation and migration, and downregulated Notch signalling. RNLS deficiency reduced metastatic burden in mice.

[CONCLUSIONS] RNLS hypomethylation is an epigenetic alteration associated with lung cancer metastasis, with potential as an early biomarker and as a therapeutic target.