Lung cancerLong interspersed nuclear element-1 methylation status in the circulating DNA from blood of patients with malignant and chronic inflammatory lung diseasesPonomaryova, Anastasia A.a; Rykova, Elena Yub,,c; Azhikina, Tatyana L.d; Bondar, Anna A.b; Cheremisina, Olga V.a; Rodionov, Evgeniy O.a; Boyarko, Valentina V.e; Laktionov, Pavel P.b; Cherdyntseva, Nadezhda V.a,,fAuthor Information aCancer Research Institute, Tomsk National Research Medical Center, Tomsk bInstitute of Chemical Biology and Fundamental Medicine, Siberian Division of the Russian Academy of Sciences cNovosibirsk Technical State University, Novosibirsk dShemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow eSiberian State Medical University fTomsk State University, Tomsk, Russia Received 12 February 2020 Accepted 23 March 2020 Correspondence to Anastasia A. Ponomaryova, PhD, Cancer Research Institute, Tomsk National Research Medical Center, 5, Kooperativny Street, Tomsk, 634009, Russia, Tel: +3822 28 26 76 x3340; fax: +3822 28 26 76; e-mail: [email protected] European Journal of Cancer Prevention: March 2021 - Volume 30 - Issue 2 - p 127-131 doi: 10.1097/CEJ.0000000000000601 Buy Metrics Abstract Along with other malignant diseases, lung cancer arises from the precancerous lung tissue state. Aberrant DNA methylation (hypermethylation of certain genes and hypomethylation of retrotransposons) is known as one of the driving forces of malignant cell transformation. Epigenetic changes were shown to be detectable in DNA, circulating in the blood (cirDNA) of cancer patients, indicating the possibility to use them as cancer markers. The current study is the first to compare the Long interspersed nuclear element-1 (LINE-1) methylation level in the blood from lung cancer patients before treatment versus different control groups as healthy subjects, patients with bronchitis and patients with chronic obstructive pulmonary disease (COPD). The concentration of LINE-1 methylated fragments, region 1 (LINE-1 methylated, LINE-1-met) was estimated by quantitative methyl-specific PCR. The total concentration of the circulating LINE-1 copies was measured by qPCR specific for LINE-1 region 2, which was selected due to its CpG methylation–independent sequence (LINE-1-Ind). Both LINE-1 methylation level and LINE-1 methylation index (LINE-1-met/LINE-1-Ind ratio) was decreased in lung cancer patients compared with the joint control group (healthy subjects + patients with bronchitis + COPD patients) (Mann–Whitney U-test, P = 0.016). We also found that the tendency of LINE-1 methylation index decreases in the cirDNA from lung cancer patients versus COPD patients (Mann–Whitney U-test, P = 0.07). Our data indicate that the quantitative analysis of the LINE-1 methylation level in the cirDNA is valuable for discrimination of lung cancer patients from patients with chronic inflammatory lung diseases. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.