Evaluation of informativeness of DNA methylation degree of DKK4 gene as a diagnostic criterion in breast adenocarcinoma

Abnormalities of DNA methylation play a significant role in initiation and progression of tumors. The aim of the study was the evaluation of the quantitative determination of hypermethylation of DKK4 gene first exon as a biomarker of the breast epithelial cells malignant transformation in patients with adenocarcinoma (2-3 stage). The analysis of DNA methylation was performed by quantitative pyrosequencing using the set PSQ96MA (Qiagen, USA). It was established that DKK4 methylated DNA content in breast adenocarcinoma tissue samples significantly exceeds the same indexes in the unchanged breast tissue taken from the same patients. The average methylated DNA level in conditions of breast cancer equals to 36,8±12,63 percents whereas the same normal breast indexes equal to 19,37±7,1 percents, р≤0,01. The increased content of methylated DNA in DKK4 gene first exon was revealed in 20 samples of breast adenocarcinoma tissues out of 23 (86.96%, P ≤ 0,01); in the rest 3 samples the investigated content of methylated DNA was comparable with the same index in the normal breast tissues.