Chromatin remodeling is the one of the main epigenetic ways of gene expression regulation both in normal cells and in oncological diseases. Genes encoding protein subunits of SWI/ SNF remodeling complexes often mutate and/or change their expression in human tumors, affecting the expression programs of many genes during carcinogenesis, which is associated with the occurrence and progression of cancer. Today, there are no therapeutic drugs that could directly change the structure of chromatin because of complexity of this process with involvement of a large number of genes, proteins, non-coding transcripts and other intermediary molecules. However, the chromatin remodeling complexes can be affected by consistent influence on the subunits and the genes encoding them, as well as the non-coding RNAs that regulate the operation of these complexes and direct them to the target gene regions. Today, several successful strategies have been proposed to influence epigenetic regulators associated with chromatin in order to cause synthetic lethality of cancer cells and block tumor growth. To influence the processes of chromatin remodeling, various strategies and mechanisms are being investigated, from inhibitors of bromodomains of individual subunits to direct effects on the function of SWI/ SNF by destroying its main adenosine triphosphatase subunit. In our review, we analyze the ways and mechanisms of influencing the SWI/ SNF chromatin remodeling complex in order to obtain a stable antitumor effect, from experiments on tumor cells and animal models to the combined use of clinical drugs for the treatment of cancer patients.

Possible breast cancer (BC) association with oncogenic human papilloma viruses (HPV) remains subject for discussion. DNA of these viruses was found in numerous BC samples in predominant majority of researches into the problem, that being the main argument in favour of their involvement into genesis of the given tumor. The principal objection to the opinion is that the HPV genomes number per a single cancer cell in HPV-positive BC is several orders of magnitude inferior to the similar indicator for cervical cancer. Urgency of the issue of possible BC association with oncogenic HPVs increases under the development of effective preventive vaccines against HPV infection. To clarify this matter the data might help either confirming or disproving the oncogenic HPV genome activity in DNA HPV-positive BC.

Introduction. Glucocorticoids are actively used in the treatment of various diseases, however their long-term use leads to numerous negative side-effects, the molecular mechanisms of which remain poorly understood.

Aim. Study of the short-term (1–10 days) effects of various doses of dexamethasone (Dex) (0,1–10 mg/kg) on the expression of the glucocorticoid receptor (GR, Nr3c1), core proteins of main proteoglycans and heparan sulfate metabolism-involved genes, as well as the content of carbohydrate macromolecules of glycosaminoglycans in the brain tissue of experimental animals.

Materials and methods. In the study, C57Bl/6 mice were used. The expression of GR, proteoglycan core proteins and heparan sulfate metabolism-involved genes was determined by real-time polymerase chain reaction with reverse transcription. The content and localization of GR protein molecule were studied by Western blot and immunohistochemical analysis, and the glycosaminoglycan content was determined by dot-blot analysis and Alcian Blue staining.

Results. It was shown that a single Dex administration leads to fast (1–3 days) short-term activation of GR expression (+1.5 times, p <0.05), proteoglycan’s genes (syndecan-3, Sdc3; perlecan, Hspg2; phosphacan, Ptprz1; neurocan, Ncan; +2–3-fold; p <0.05) and heparan sulfate-metabolism-involved genes (Ndst1, Glce, Hs2st1, Hs6st1, Sulf1 / 2; +1.5–2-fold; p <0.05) in the mouse brain, with a return to control values by 7–10 days after Dex administration. At the same time, the effect of Dex on carbohydrate macromolecules of glycosaminoglycans was more delayed and stable, increasing the content of low-sulfated glycosaminoglycans in the brain tissue in a dose-dependent manner starting from day 1 after Dex administration. Highly-sulfated glycosaminoglycans showed more delayed response to Dex administration, and an increase in their content was observed only at higher doses (2.5 and 10 mg/kg) and only on 7–10 days after its administration, apparently, mainly due to an increase in heparan sulfate content.

Conclusion. In general, the effect of a single injection of Dex on the transcriptional activity of GR, proteoglycan core proteins and heparan sulfate metabolism-involved genes were short-termed, and the genes expression quickly returned to the normal levels. However, even a single use of Dex significantly increased the content of total as well as highly sulfated glycosaminoglycans in the mouse brain tissue, which can lead to the changes in the composition and structure of the brain tissue, as well as its functional characteristics.

Introduction. Perioperative FLOT chemotherapy has improved prognosis in patients with locally advanced resectable gastric cancer (GC). However, in 80 % of cases, the tumor is resistant to the therapy, resulting in unnecessary toxicity and delayed surgical treatment.

Aim. Evaluation of clinico-morphological patterns of microsatellite instability, HER2 gene amplification, changes in gene copy number and their relationship with the response to perioperative FLOT chemotherapy in patients with locally advanced resectable GC.

Materials and methods. The retrospective study included 185 patients. All tumor samples were assessed for HER2 and microsatellite instability status. Among all cases there were 45 patients with locally advanced T2–4N1–2 M0 GC, who underwent a total or subtotal gastrectomy with D2 lymphadenectomy and perioperative chemotherapy with FLOT. Microsatellite instability detection was performed using fragment analysis, HER2 gene amplification testing – fluorescent in situ hybridization. Also 19 patients were tested for copy number changes of the FGFR1, FGFR2, KRAS, MET, EGFR, CCND1, MYC genes using Multiplex ligation-dependent probe amplification. The endpoints were progression-free survival and objective response rate.

Results. Microsatellite instability was detected in 4.8 % (9/185) of GC cases. Microsatellite instability was associated with advanced age (p = 0.005), low grade of differentiation (p = 0.011), presence of tumor-infiltrating lymphocytes (p = 0.0004), and high preoperative CA 72–4 levels (p = 0.025). Prevalence of HER2 amplification was 7.5 % (14/185). It was associated with low grade of differentiation (p = 0.048) and metastasis in regional lymph nodes (p = 0.037). PFS in patients with HER2-positive (HER2 – human epidermal growth factor receptor 2) GC treated with perioperative FLOT chemotherapy (4/45) was significantly lower than in patients with HER2-negative GC: the median was 156 and 317 days, respectively (hazard ratio 0.49; 95 % confidence interval 0.16–1.47; p = 0.0006). There was no correlation between the presence of the alteration and ORR (p = 1.0). Progression-free survival in GC patients with KRAS amplification (3/19) was significantly lower comparing with patients without it: the median was 98 and 327 days, respectively (hazard ratio 0.29; 95 % confidence interval 0.07–1.19; p <0.0001). There was no association between an increase in KRAS copy number and objective response rate (p = 1.0). For microsatellite instability and other studied markers no statistically significant correlation with progression-free survival and objective response rate was found (p >0.05).

Conclusion. The presence of HER2 and KRAS amplification have been shown as promising predictive markers of the treatment failure in patients treated with perioperative FLOT chemotherapy for locally advanced resectable GC.

Introduction. Colorectal cancer is a frequently diagnosed disease being in the third place among oncological diseases both in incidence and mortality. Currently, researchers focus on development of more accessible and reliable biomarkers of colorectal cancer to overcome the problems in diagnosis and progression prognosis of this pathology.

Aim. To investigate characteristics of microRNA expression in circulating tumor cells (CTC) of patients with colorectal cancer. Materials and methods. The study included blood samples from 299 patients with colon cancer, stages II (T3–4N0M0), III (T1–4N1–2M0) and IV (T1–4N0–2M1). Circulating tumor cells were identified using EpCAM marker detection system. Relative expression of hsa-let-7i-5p, hsa-miR-126-5p, hsa-miR-143-3p, hsa-miR-21-5p, hsa-miR-25-3p, hsa-miR-26a-5p, hsa-miR-92a-3p micro RNA in CTC was measured using polymerase chain reaction.

Results. Positive CTC status was observed in 188 (62.9 %) of 299 patients, negative in 111 (37.1 %). In the patient group with pT1–2 tumors, the majority of patients did not have CTC (53.3 %). In other patients with pT1–2 disease, the number of CTC was 1.2 and 4.4 times lower than in patients with pT3 and pT4 disease, respectively. In pT4, 1–3 CTC were found 2.7 and 1.7 times more frequently, 3 CTC 1.4 times more frequently than in pT1–2 and pT3, respectively (p ≤0.05). Presence of metastatic lesions increases the probability of CTC detection by the factor of 2.1: in metastases, >3 CTC were observed 60.1 times more frequently than in M0 (p ≤0.05). Expression of hsa-miR-143-3p and hsa-miR-26a-5p microRNA in CTC of patients with stage III colorectal cancer was respectively 2.5 and 5 times lower than in patients with stage II disease (p <0.05) and expression of hsa-miR-21-5p and hsa-miR-92a-3p microRNA was respectively 3.2 and 3 times higher (p <0.05). In CTC of patients with stage IV colorectal cancer, the relative level of expression of hsa-miR-143-3p and hsa-miR-26a-5p was respectively 4.6 and 5.3 times lower (p <0.05) compared to the level of expression in stage II disease, and hsa-miR-126-5p, hsa-miR-21-5p, hsa-miR-25-3p and hsa-miR-92a-3p expression levels were respectively 2.6, 4.6, 2.6 and 5.0 times higher (p<0.05) (statistically significant results).

Conclusion. The level of microRNA expression in CTC can be used for differential diagnosis of regional and distant metastases.

Introduction. Over the past decade, tongue cancer has maintained a leading position in the overall structure of the incidence of head and neck malignant tumors. Squamous cell carcinoma of the tongue is an aggressive form and has a clinically unpredictable prognosis. Currently, there are several histological subtypes of this disease. And the search for new prognostic factors that could reflect the actual state of tumor progression and give an objective prognosis of disease development is an important research area in molecular oncology. Such factors may be certain transcriptomic characteristics of tumors, which determine the features of pathogenesis in each specific case.

Aim. To research genes transcriptional activity features in various histological subtypes of tongue squamous cell carcinoma using bioinformatic and molecular approaches.

Materials and methods. The stage of screening bioinformatics analysis was performed using an interactive web server for analyzing data on messenger RNA expression of 9736 tumors and 8587 normal samples from the The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) projects using a standard processing pipeline (GEPIA). The main (validation) stage of the study was performed on 300 patients with locally advanced malignant tumors of the tongue. The quantitative real-time polymerase chain reaction method was used to determine the values of the relative expression of genes identified at the stage of bioinformatic analysis.

Results. Bioinformatic analysis identified 1488 genes that increase expression and 589 genes that decrease expression in tongue squamous cell carcinoma. Of these 2077 genes, 23 genetic loci were selected that most strongly alter expression in tumor tissue relative to normal tissue of the tongue. Of these, when validated by polymerase chain reaction, only 14 changed their transcriptional profile in tumor tissue relative to normal: MMP1, MMP11, CA9, PTHLH, MMP9, LAMC2, MMP3, ANXA1, MT-ND6, CRNN, MAL, TGM3, IL1RN and CLU. The analysis of polymerase chain reaction data revealed significant heterogeneity in a number of biological samples studied. Cluster analysis made it possible to divide the total sample of 300 patients into 3 groups differing in gene expression: cluster 1 (n = 90), cluster 2 (n = 101) and cluster 3 (n = 109), corresponding to the basaloid, acantholytic and usual histological subtypes. Thus, the study made it possible to identify a number of molecular markers of tongue squamous cell carcinoma (MMP1, MMP11, CA9, PTHLH, MMP9, LAMC2, MMP3, ANXA1, MT-ND6, CRNN, MAL, TGM3, IL1RN and CLU), as well as to reveal the transcriptional features of various histological subtypes of this disease.

Introduction. Adoptive immunotherapy based on chimeric antigen receptors (CAR) is considered as a promising direction in the treatment of solid malignant tumors. To produce genetically modified human T-lymphocytes, lenti/retroviral transduction is currently most often used. However, safety concerns associated with the viral vector production and possible unwanted genome modification limit the clinical utility of CAR-T cells. Therefore, non-viral transfection methods, in particular electroporation, using of DNA or RNA vectors, are being actively studied as a method for producing CAR-T lymphocytes.

Aim. To evaluate in vivo antitumor activity of the new high-tech drug carplasmin, intended for CAR-T therapy of tumors expressing carcinoembryonic antigen (CEA). Materials and methods. Carplasmin was obtained by electroporation of activated human lymphocytes with plasmid DNA carrying the third generation CAR gene specific to CEA. The study was performed on a human colorectal cancer xenograft model obtained by intraperitoneal injection of CEA-positive HCT116 cell line to athymic Balb/c nude mice. Carplasmin treatment was carried out once a week, starting from the third day after HCT116 cell inoculation. Mice in the two control groups were treated with either electroporated lymphocytes without plasmid addition (pulse-lymphocytes) or RPMI-1640 culture medium (group without treatment).

Results. In vivo, carplasmin demonstrated a pronounced antitumor effect. Seven weekly injections of the drug to inoculated mice led to a prominent effect of antitumor therapy: 80 % of the animals in the experimental group survived (with 40 % of the mice had a complete remission without signs of a detectable tumor), compared to 100 % death in the control group (without treatment).

Conclusion. The results of preclinical efficacy studies demonstrate that carplasmin is a promising drug for the treatment of CEA-positive intraperitoneal tumors.

Gastric cancer is one of the most common malignancies worldwide. Approximately 10 % of patients with gastric cancer are characterized by accumulation of gastric cancer cases in their family. The hereditary forms of gastric cancer account for 1–3 % of all gastric cancer cases. Hereditary diffuse GC syndrome is caused by germline mutations in CDH1 gene and determines a high risk of developing diffuse GC and lobular breast cancer. In this article, we present a clinical case of a 41-year-old patient with diffuse gastric cancer, who was found to be a carrier of novel germline mutation in the CDH1 gene. Next-generation sequencing (NGS) has facilitated an identification of CDH1 c.1596G>A genetic variant, thus enabling an accurate clinical diagnosis hereditary diffuse gastric cancer.