The cytoplasmic actins (β and γ) play crucial roles during key cellular processes like adhesion, migration, polarization and cytokinesis. The understanding of their specific underlying mechanisms would be of major relevance not only for fundamental research but also for clinical applications, since modulations of actin isoforms are directly or indirectly correlated with severe pathologies. The major goal of the research was to elucidate the function of the actin isoforms during motile activities, adhesions and cell division and to investigate whether their expression and/or structural organization is related to pathological function. Selective depletion of β- and γ-cytoplasmic actins allowed attributing functional diversities of β- and γ-сytoplasmic actins. β-Сytoplasmic actin plays a preferential role in contractile activities, whereas γ-cytoplasmic actin mainly participates in the formation of a submembranous network necessary for cell shape flexibility and motile activity. The roles of isoforms in regulating the integrity of adherens and tight junctions respectively were demonstrated. Unique roles of β- and γ-cytoplasmic actins in normal cells were shown. Similar results were obtained in cancer cells compared with normal epithelial cells in culture and in human pathological tissue sections of mammary gland, colon, lung and cervix. Malignant cell transformation requires changes in the ability of cells to migrate. The disruption of actin cytoskeleton and intercellular adhesions is an important component of the acquisition of invasive properties in epithelial malignancies.

In the review the role of the thymidine kinase (TK) to ensure the replication of DNA de novo and spare (salvage the) way in health and activate alternate ways in carcinogenesis is described. The structure of cytoplasmic TK (TК-1), also called fetal, and the level of regulation of its activity in the cells and their change during the cell cycle is described. Considering the data about the absence of TK-1 in resting (G0) cells, TK-1 is positioned as a marker of proliferating cells, which activity is recorded from late G1 phase, peaking in S-phase, it is stored in the G2 and mitosis, quickly decreasing to undetectable levels in the early G1 phase. Data on the expression TK-1 (as compared with Ki-67 and PCNA (proliferating cell nuclear antigen)) in tumor tissues (colorectal, breast, cervical, lung, renal, prostate and ovarian cancer), as well as some benign and precancerous pathological processes in relation to the clinical and diagnostic features of these processes are systemized. These data suggest that the proliferative index studies on TK-1 (antibody to the domain HRA-210) should be used together with Ki-67 and PCNA, for a more complete assessment of the proliferative status of malignant tumors and pre-cancerous and benign conditions, with the aim of prognosis of the tumor process and treatment planning.

There are a lot of studies that dedicated to genetic differences between the primary tumor and metastases. This becomes relevant not only for molecular biologists for understanding carcinogenesis, but also becoming increasingly important for medical oncologists, due to the possible impact on the choice of therapy for metastatic disease. In this regard, colon cancer is an interesting model for studying the heterogeneity of the primary tumor and possible clonal evolution, because we have predictive genetic markers for target therapy. In this article, we analyzed studies on the concordance of the mutation status of the genes, intratumoral heterogeneity and processes of clonal evolution in colorectal cancer.

Currently, treatment and diagnostics of neuroendocrine tumors are associated with a number of problems, including absence of a registry for these diseases. The article considers the main approaches and problems of immunohistochemical diagnostics of neuroendocrine tumors.

Introduction. Searching for specific and sensitive molecular tumor markers is one of the important tasks of modern oncology. These markers can be used for early tumor diagnosis and prognosis as well as for prediction of therapeutic response, estimation of tumor volume or to assess disease recurrence through monitoring. Gene expression data base mining followed by experimental validation of results obtained is one of the promising approaches for searching of that kind.

Objective: to identify several membrane proteins which can be used for serum diagnosis of intestinal type of gastric adenocarcinoma.

Materials and methods. We used bioinformatic-driven search using Gene Ontology and The Cancer Genome Atlas (TCGA) data to identify mRNA up-regulated in gastric cancer (GC). Then, the expression levels of the mRNAs in 55 pare clinical specimens were investigated using reverse transcription polymerase chain reaction.

Results. Comparative analysis of the mRNA levels in normal and tumor tissues using a new bioinformatics algorithm allowed to identify 3 high-copy transcripts (SULF1, PMEPA1 and SPARC), intracellular content of which markedly increased in GC. Expression analysis of these genes in clinical specimens showed significantly higher mRNA levels of PMEPA1 and SPARC in tumor as compared to normal gastric tissue. Interestingly more than twofold increase in expression level of these genes was observed in 75 % of intestinal-type GC. The same results were found only in 25 and 38 % of diffuse-type GC respectively.

Conclusions. As a result of original bioinforamtic analysis using TCGA data base two genes (PMEPA1 and SPARC) were shown to be significantly upregulated in intestinal-type gastric adenocarcinoma. The findings show the importance of further investigation to clarify the clinical value of their expression level in stomach tumors as well as their role in carcinogenesis.

Polymerase chain reaction (PCR) followed by DNA melting analysis with TaqMan probes effectively reveals mutations in the human genome “hot” spots. The necessity to carry out PCR in the asymmetric variant causes, however, a number of restrictions of this method: 1) an inability of quantitative estimates of gene copy numbers; 2) the need for 2 independent PCR tests for detection of mutations in both complementary strands of an amplicon (this approach improves reliability and sensitivity of the analysis); 3) the complication of PCR design and decrease in efficiency of amplification. Overcoming these restrictions was possible by means of symmetric PCR with primers containing the specific and universal sequences: the single-stranded “hairpins” (sense and antisense) are not capable to anneal with each other, but they can hybridize independently with 2 TaqMan probes present in the reaction mixture. The proposed approach allows quantitative and qualitative characterization of a DNA sample (the copy number estimates as well as mutation scanning of both complementary amplicon strands).

Gliomas are the most common brain tumors. It is difficult to detect them at early stages of disease and there is a few available therapies providing significant improvement in survival. Mutations of isocitrate dehydrogenase 1 and 2 genes (IDH1 and IDH2) play significant role in gliomogenesis, diagnostics and selection of patient therapy. We tested the distribution of IDH1 and IDH2 mutations in gliomas of different histological types and grades of malignancy by DNA melting analysis using our protocol with a sensitivity of 5 %. The results of this assay were confirmed by conventional Sanger sequencing. IDH1/2 mutations were detected in 74 % of lower grade gliomas (II and III, World Health Organization) and in 14 % of glioblastomas (IV, World Health Organization). Mutation rate in gliomas with oligodendroglioma component were significantly higher then in other glioma types (р = 0.014). The IDH1 mutations was the most common (79 % of general mutation number). IDH1/2 mutations can induce aberrant gene methylation. Detection of methylation rate of the gene encoding for O6-methylguanine-DNA-methyltransferase (MGMT), predictive biomarker for treatment of gliomas with the alkylating agents, has demonstrated a partial association with IDH1/2 mutations. In 73 % of IDH1/2-mutant tumors MGMT promoter methylation were observed. At the same time IDH1/2 mutations were not revealed in 67 % tumors with MGMT promoter methylation. These results indicate existence of another mechanism of MGMT methylation in gliomas. Our data strong support for necessity of both markers testing when patient therapy is selected.

The riboside derivative acadesine (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside) is currently being tested in clinical trials as a promising anti-tumor drug. Intracellular target of acadesine is adenosine monophosphate-activated protein kinase (АМРК), an important regulatory molecule of energy metabolism. It is expected that acadesine would be active in tumors under hypoxia conditions. In normoxia (cells incubated in 21 % oxygen), acadesine inhibited proliferation and induced cell death of breast adenocarcinoma, including the triple negative breast cancer line. When oxygen partial pressure was decreased to 1 % (experimental hypoxia), acadesine inhibited activation of reporter construct responsive to HIF-1α (hypoxia inducible factor 1 alpha) transcription factor. This effect was observed for acadesine in concentrations close to cytotoxic. Acadesine retained cytotoxicity under hypoxia and decreased the survival of the MDA-MB-231 cell line when used in combination with cisplatin. These results considerably widen acadesine’s field of application and allow to assume its efficacy in chemotherapy combination regimens for breast cancer, including the tumors with low oxygenation.