RARβ2 gene methylation level in the circulating DNA from blood of patients with lung cancer

Alterations in the patterns of DNA methylation are among the earliest and most common events in tumorigenesis. Epigenetic changes were shown to be detectable in DNA, circulating in blood (cirDNA) of cancer patients, indicating the resources to create the minimally invasive diagnostic tests based on tumor-specific DNA markers. RAR beta 2 methylation level was significantly increased in plasma cirDNA and cell surface-bound cirDNA (csb-cirDNA) from patients with non-small cell lung cancer compared with healthy individuals (7620 and 1083 copies/ml in the csb fractions, 3589 and 1068 copies/ml in the blood plasma; P = 0.003 and 0.001). The cell-bound-to-cell-free RAR beta 2 methylation ratio was found to be elevated in patients with non-small cell lung cancer compared with control (2.12 and 1.01, respectively; P = 0.023). RAR beta 2 methylation level in csb-cirDNA and plasma cirDNA was higher in stage III patients compared with stage I-II patients (P = 0.02 and 0.03). In the subgroup of patients with squamous cell carcinoma, RAR beta 2 methylation level in the cbs-cirDNA was higher compared with patients with adenocarcinoma (P = 0.04). Epigenetic alterations of tumor suppressor gene RAR beta 2 in the total cirDNA (plasma cirDNA and csb-cirDNA) were found to be associated with lung cancer progression. The data obtained indicate that cirDNA-based testing provides a valuable source for subsequent verification of methylated DNA markers for lung cancer diagnostics and prognosis. European Journal of Cancer Prevention 20: 453-455 (C) 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins.