Objectives: to provide a rationale for existing approaches for the evaluation of chemoresistance of ovarian cancer in vitro, to perform a comparative analysis of the methods and to assess the perspectives of their further application.

Materials and methods. For the review preparation, we analyzed articles on experimental testing of ovarian cancer resistance to chemotherapeutic agents, available at biomedical literature databases SciVerse Scopus (158), PubMed (323), Web of Science (285), RSCI (64). The review cited 37 recent publications, 12 of them being published over the past three years, and 16 articles being referred as pioneer publications on techniques previously and used today.

Results. Peculiarities of the main methods for assessing the resistance and sensitivity of a cancer to various chemotherapeutic drugs using primary cultures of tumor cells obtained from biopsy or surgical material are analyzed. Proliferative and metabolic activities as well as the level of cell death were considered as the main evaluated characteristics of tumor cells. The methodological features of the described methods are discussed, as well as the prospects for their further application.

Conclusion. Predictive detection of chemoresistance of ovarian cancer is based on testing the viability of tumor cells in the presence of a chemotherapeutic drug. The results of studies of the key mechanisms of chemoresistance development in tumor cells provide the rationale for improving in vitro testing.

Background. Over 600,000 people die from hepatocellular carcinoma (HCC) each year worldwide. The disease is often detected at advanced stages and in many cases is not curable. Early diagnostic and monitoring of HCC recurrences remains a substantial problem in clinical oncology. That determines the need for a search for highly sensitive and specific biomarkers for the non-invasive of HCC diagnostics.

The objective of the study. Identification of the hypermethylated locus in the promoter region of the septin 9 (Sept9) gene based on the annotated methylomes from the public databases. Experimental validation of methylation on a pilot panel of paired clinical samples of patients with HCC, as well as tissue samples from patients with benign liver tumors and lymphocytes from healthy donors.

Materials and methods. To analyze the methyl data, samples of HCC from TCGA, hepatocellular adenoma from GEO (Gene Expression Omnibus) depository, peripheral blood cells and tissues of healthy donors from Methbank were used. Experimental validation of methylation levels of the identified site was carried out on a pilot panel of clinical samples by bisulphite pyrosequencing using PyroMark Q24.

Results. Based on the analysis of methylome data, we selected cg20275528 site, which is characterized by high level of methylation in HCC tissues and minimal levels of methylation in non-tumor liver tissue, hepatocellular adenoma and peripheral blood of healthy donors. Experimental testing on a pilot panel of clinical specimens showed that the level of marker site methylation in HCC (42 % median) is significantly higher than in non-tumor liver tissues (3 % median) and benign neoplasms (1.5 % median) and exceeds the threshold value in HCC compared to paired samples of adjacent non-tumor liver tissue in 20 out of 30 studied cases (66.6 %). The general possibility for cg20275528 methylation detection in circulating DNA of plasma in HCC patients was shown.

Conclusion. The obtained results indicate that the approach to the detection and experimental verification of diagnostically significant markers developed and tested in this study can be used to identify new differentially methylated sites and to establish new approaches for non-invasive HCC diagnosis.

Lynch syndrome is the most common cancer-prone syndrome associated with a high risk of colorectal cancer (CRC), neoplasms of the upper gastrointestinal system, the urinary tract, the female reproductive system, brain tumours and others. The only known form of hereditary endometrial cancer is also diagnosed as part of Lynch syndrome. One or more pathogenic germline mutations in one of the mismatch repair (MMR) genes are the cause of Lynch syndrome. Mapping of MMR genes and the discovery of microsatellite instability (MSI) have given rise to the possibility of using these clue characteristics of the pathogenic process for the elaboration of a screening test for Lynch syndrome. Being highly accurate and superior to all previously developed clinical criteria and guidelines, MSI-testing along with the assessment of the expression patterns of MMR proteins by immunohistochemistry has taken the leading role in the early diagnosis of Lynch syndrome. This article focuses on a brief review about the main evolutionary stages of clinical, anamnestic, molecular and genetic criteria for Lynch syndrome together with the results of our own research on the accuracy of the Amsterdam criteria, the Bethesda guidelines and MSI-diagnostics in the determination of the indications for MMR-genotyping in colorectal cancer patients suspected for Lynch syndrome.

Background. Activating mutations in the BRAF gene leads to a constitutive activation of the MAPK signaling. The highly selective BRAFV600E inhibitor, vemurafenib, improves the overall survival of BRAF-mutant melanoma patients. However, despite the excellent results of response rate, the average duration of the response was short and acquired resistance develops in most BRAF mutated melanoma patients within a few months.

Objective: to derive melanoma cell lines from surgical species of patients with BRAF mutant melanomas resistant to vemurafenib and to elucidate the mechanisms involved in acquired drug resistance.

Materials and methods. Mel Ki and Mel F1702 melanoma cells were obtained from metastases of disseminated melanoma patients with BRAFV600E mutation. 2D tumor cell culture, MTT test, immunicytochemistry, flow cytometry, real-time polimerase chain reaction and osteogenic and adipocytic differentiation were used in the study.

Results. We have derived two melanoma cell lines Mel Ki and Mel F1702 from tumor samples of patients with BRAFV600E mutation resistant to vemurafenib. These cells were homogenous and had fibroblastic morphology. The IC50 values for Mel Ki and Mel F1702 were 4.7 and 6.3 μM, respectively. The expression of cancer-testis antigens was not detected in both types of cells suggesting the stemness of Mel Ki and Mel F1702 melanoma cells. The immunophenotypic profile of the vemurafenib resistsant melanoma cells showed the expression of typical mesenchymal stem cells markers such as CD90, CD105 and CD44. In addition, we found that the melanoma cell lines derived from tumor resistant to vemurafenib differentiated into osteoblastand adipocyte-like cells.

Conclusion. In this study we are offering an experimental evidence of the phenotypic transition of the vemurafenib-resistant melanoma cells into mesenchymal stem-like cells.

Background. Curaxin CBL0137 is a novel non-genotoxic compound with anti-cancer activity based on CBL0137 ability of non-covalent interaction with DNA causing histone chaperone FACT relocation. Anti-cancer activity of this drug was demonstrated previously on the wide panel of solid cancer models in vitro and in vivo.

Objectives. Estimation of anticancer effects of CBL0137 on the acute myeloblastic leukemia cells (THP-1) and acute lymphoblastic leukemia (CCRF-CEM).

Materials and methods. CBL0137 cytotoxicity was analyzed using the MTT test, the effects on the cell cycle and the induction of apoptosis was assessed by flow cytometry, the activity of signaling pathways in cells treated with CBL0137 was determined by real-time polymerase chain reaction.

Results. Cell treatment with CBL0137 led to cell cycle arrest and apoptosis induction. In the study of CBL0137 effect on target gene clusters of 10 signal transduction pathways involved in the pathogenesis of acute leukemia we have showed that CBL0137 inhibited the expression of down-stream genes of WNT and Hedgehog signaling in both cell lines. In THP-1 cells we also observed the inhibition of the expression of PPARγ target and hypoxia-activated genes. In CCRF-CEM cells CBL0137 also induced the expression of Notch signaling target genes.

Conclusion. The antitumor activity of CBL0137 was demonstrated on acute leukemia cell cultures, the drug possesses cytotoxicity, causes cell cycle arrest and activation of apoptosis. Significant changes in the expression of efferent gene clusters of several signaling pathways were observed in the cells treated with CBL0137.

Background. The incidence of brain gliomas firmly occupies a leading position among all central nervous system tumors – 40–50 % of the cases detected, more than half of them are glioblastoma. Existing cell lines and cultivation methods do not reflect all the features of the three-dimensional (3D) organization of native glioblastoma. The use of temozolomide leads to the development of drug resistance and acute relapse, followed by a poor clinical outcome. The development of resistance is largely associated with the presence of tumor stem cells in the population and intratumoral heterogeneity. Obtaining 3D cultures from the primary material will allow us to save the stem cell pool and tumor-specific features.

The study objective. Get a 3D model based on primary cell cultures, which allows you to save a heterogeneous population and the original phenotype of tumor cells.

Materials and methods. We used U-87MG human glioma cells and GBM002 primary cell culture obtained from surgical material with a confirmed diagnosis of glioblastoma. Neurospheres were obtained from cell lines, the growth of which was monitored using the InCell Analyzer 6000 automatic cell analysis system. Flow cytometry was used to determine the CD133+ cell content. The expression of the receptor tyrosine kinases VEGFR1, VEGFR2 (endothelial growth factor type 1 and 2 receptors), FGFR2 (fibroblast growth factor receptor type 2) and the hypoxia marker HIF-1α (hypoxia inducible factor, 1α) in the neurospheres was evaluated using confocal microscopy.

Results. GBM002 glioblastoma cells isolated from the surgical material formed neurospheres, while the number of CD133+ cells increased from 1–2 to 16–19 % compared with two-dimensional cultures. During long-term cultivation of cells with non-cytotoxic doses of temozolomide, it was found that such cells form smaller neurospheres compared to control cells. It was shown that the expression of receptor tyrosine kinases during cultivation of GBM002 glioblastoma cells in neurospheres differs from that in two-dimensional cultures. We found that in neurospheres, the expression of FGFR2 and VEGFR1, is significantly increased.

Conclusion. 3D cultivation of primary cultures allows one to obtain a more heterogeneous population of tumor cells that reflects the spatial heterogeneity of cells, increase the pool of stem cells and recreate hypoxia conditions inside the brain micro-tumors.