[Somatic genome variations in vascular tissues and peripheral blood leukocytes in patients with atherosclerosis].

The first data on the existence of multiple genomic rearrangements, such as copy number variation (CNV) and copy neutral loss of heterozygosity, in vascular tissues and peripheral blood leukocytes from patients with atherosclerosis, are presented. Compared to internal mammary arteries and peripheral blood leukocytes, right coronary arteries in the atherosclerotic plaque area presented with a higher CNV length and number of genes located in their vicinity. In each of the patients, 6-16% of CNVs were common to the three types of tissues examined. Therefore, most of the copy number variations in the tissues affected by atherosclerosis (from 68 to 91% in each of the patients) were of somatic origin. The gains in 3p21.31 (CACNA2D2), 7q32.1 (FLNC), 19p13.3 (C19orf29, PIP5K1C), and 21q22.3 (COL6A1) were detected in vascular tissues but not in peripheral blood leukocytes. Moreover, the gain in 7p15.2 (SKAP2), detected in the patients with atherosclerosis, did not overlap with any CNV regions currently reported in The Database of Genomic Variants. The loss of heterozygosity in 12 out of 13 chromosomal regions was copy neutral and covered tumor suppressor genes (SFRP1, CEBPD, RB1CC1, DIRAS3, TUSC3, and ZDHHC2).

[Dynamics of methylation changes within functional groups of genes during breast cancer progression].

For the first time in a comparative perspective the epigenetic status of the benign proliferative processes, breast cancer, and metastases to regional lymph nodes was studied using DNA methylation microarray "GoldenGate Cancer Panel I" ("Illumina", USA). The functional groups of differentially methylated genes were identified in each set of samples. The genes that regulate cell proliferation and mobility were methylated in samples with benign proliferative processes. An aberrant methylation of the genes responsible for cell differentiation and proliferation, as well as protein phosphorylation and cell mobility was observed in the samples with malignant phenotype. Differential methylation of the genes that regulate cell adhesion, the formation of anatomical structures, angiogenesis, immune response, signal transduction, and protein phosphorylation was found in the samples with metastases to regional lymph nodes in comparison with the morphologically unaltered breast epithelium. The tissues from the benign proliferative processes and metastases to regional lymph nodes were generally characterized by a relatively lower level of epigenetic variability in comparison with the tissues of the primary tumor.

[Epigenetic effects of trisomy 16 in the human placenta].

The methylation profiles of the placental tissues of human embryos with normal karyotype and trisomy 16 were compared using Infinium HumanMethylation27 BeadChip array (Illumina, United States). Numerous differences between the extraembryonic tissues with diploid and aneuploid karyotypes were observed. The extraembryonic mesoderm of embryos with trisomy 16 appeared to be less methylated compared to the diploid tissue, whereas the cytotrophoblast of aneuploid embryos was hypermethylated. The presence of the supernumerary chromosome was shown to influence the epigenetic profile of the genome changing the level of methylation of CpG sites of all chromosomes. However, the biggest number of differentially methylated loci was found on the chromosome 16. Besides, more often the epimutations were tissue-specific. The hypomethylated genes in both tissues belong to the groups of genes responsible for different metabolic processes, whereas the hypermethylated genes control the processes of development, cell adhesion, immune response, and response to stimulus.

[Multilocus epimutations of imprintome in the pathology of embryo development].

Genomic imprinting is one of the most significant epigenetic phenomena, which is involved in the support of eutherians and human embryo development. Molecular mechanisms of imprinting disturbance in the pathology of pre- and postnatal ontogeny are related to a considerable degree to aberrant DNA methylation of imprinted genes. At present time data about multiple abnormalities of DNA methylation arising simultaneously in several imprinted loci are accumulated. This fact brings up the problem of interpretation of imprintome structural and functional organization, as well as interaction of imprinted genes. At present study DNA methylation analysis of 51 imprinted genes in placental tissues of human spontaneous abortions was performed. The presence of several epimutations affected from four to 12 imprinted genes was observed in each embryo. Majority of epimutations (78%) had a postzygotic origin. It was shown for the first time that the total incidence of abnormal DNA methylation of maternal and paternal alleles of imprinted genes, which lead to suppression of embryo development, is significantly higher than the incidence of epimutations, which can lead to stimulation of ontogenesis processes. This fact supports at the epigenetic level the "sex conflict" hypothesis, which explains the appearance of monoallelic imprinted genes expression in the evolution of mammals.

[DNA methylation profile in human placental tissues].

For the first time using genome-wide Infinium HumanMethylation27 BeadChip Array (Illumina, USA) DNA methylation pattern was determined in the human cytotrophoblast and extraembryonic mesoderm. These tissues are the derivatives of trophectoderm and inner cell mass of blastocyst and have substantial differences in dynamics of epigenetic genome reprogramming during early stages of differentiation. The genome of the extraembryonic mesoderm cells has been shown to be more methylated compared to the cytotrophoblast similarly to other mammalian species. Differences in methylation pattern of single CpG-dinucleotides and dinucleotides localized within promoter CpG-islands have been found. It has been shown that the majority of single CpG-dinucleotides in both tissues were methylated whereas promoter CpG-island sites were not. Comparative analysis revealed 202 differentially methylated genes in extraembryonic mesoderm and 40 genes in cytotrophoblast. These genes are responsible for diverse biological processes. However, in the extraembryonic mesoderm the main functional groups included genes responsible for DNA binding and transcriptional factors' activity whereas in the cytotrophoblast--for transport and protein and cytokine secretion.

[Epigenetic aspects of early lymphogenic metastasis in breast cancer].

Metastasizing is one of the key stages in tumor development. Understanding this process is necessary for effective diagnosis, therapy and prediction of clinical outcome. Some recent data suggest the possibility of metastatic phenotype cells appearance at the early stages of tumor evolution in contravention with generally accepted hypothesis of linear metastatic process development. In this study we have performed a comparative analysis of the array-based DNA methylation profile in biopsy samples of patients with benign breast disorders, breast cancer and lymphogenous metastases. In some cases the biopsy samples dated back to different stages of the same tumor. For the analysis the GoldenGate Methylation Cancer Panel I was used. The DNA methylation level in 1,505 CpG-sites was similar in samples from patients with benign breast disorders and lymphogenous metastases. Our data support the hypothesis of the early appearance of cell clones responsible for the tumor limphogenous dissemination. Epigenetic component apparently plays an important role in this process.