The article reviews studies highlighting the role of extracellular molecules in non-invasive diagnosis of glioblastoma recurrence. Glioblastoma is the most common malignant tumor of the brain characterized by fatal outcome prognosis. Current treatment of tumor recurrence allows to increase patient survival, improve functional outcome and decrease caregivers» load. The standard method of recurrence diagnosis is neuroimaging which at early stages cannot distinguish between tumor recurrence and post-radiation changes. Currently in oncology, liquid biopsy and marker detection in circulating extracellular vesicles are considered promising approaches allowing to obtain early and differential tumor diagnosis, determine dynamic molecular and genetic status of the tumor, diagnose tumor recurrence at early stages. In this context, the most promising approach to glioblastoma diagnosis is associated with studying of expression of glial fibrillary acidic protein (GFAP), epidermal growth factor receptor (EGFR), its mutant variant EGFRvIII, podoplanin (PDPN) and isocitrate dehydrogenase 1 (IDH1) in extracellular vesicles; for primary glioblastoma diagnosis and early recurrence: studying of microRNA-210, -301a, -222, -123-3p, -21; for control of immunotherapy effectiveness in patients with recurrent forms of glioblastoma after standard treatment: evaluation of СD9+ / GFAP+ / survivin+ exosomes in plasma.

Neuroendocrine neoplasms (NENs) are a heterogeneous group of rare epithelial tumors that arise from cells with a neuroendocrine phenotype. NENs are found in the gastrointestinal tract and pancreas – 60 % of all localities. The incidence of gastric NENs is about 9 % of all neuroendocrine tumors of the gastrointestinal tract and 0.3 % of all stomach tumors. Stomach neuroendocrine tumors (NETs) are classified into three clinico-pathological types, based on etiology, pathogenesis and morphology. There are also separate neuroendocrine cancers: small- and large-cell. The prognosis and approach to treatment of various types of gastric NENs differs significantly. Modern methods of instrumental diagnostics, immunohistochemical methods of morphological research, along with light microscopy, do not always allow us to accurately assess the malignant potential of a tumor and individualize the treatment process. One of the promising directions in the study of NETs is to determine the molecular mechanism underlying their development, in particular the role of microRNAs. This direction can open a new vector of understanding the pathogenesis, determining the prognosis of the disease, as well as finding new application points for the drug treatment of NETs. MicroRNAs are a class of short non-coding RNA molecules (18–25 nucleotides). MicroRNAs can be involved in the regulation of all major cellular processes, including proliferation and differentiation, metabolism, signaling pathways, and apoptosis. A study of microRNA expression in tissues revealed tumor-specific microRNAs. In contrast to a number of other malignant tumors, microRNA expression in patients diagnosed with NENs is poorly understood. MicroRNA-222 and microRNA-202 are among the few microRNAs that have been demonstrated in the NETs of the stomach.

Epstein–Barr virus (EBV) associated gastric carcinoma is a special form of gastric adenocarcinoma that arises against the background of clonal growth of EBV-infected epithelial cells of the gastric mucosa. This subtype of tumors has unique genetic and epigenetic features that determine its characteristic phenotype. Determination of the molecular features of EBV-associated gastric cancer made it possible to identify potential targets for drug therapy of this subtype of tumors. The review presents modern data on the epidemiology and pathogenesis of EBVassociated gastric cancer, describes its unique pathomorphological and molecular features. Particular attention is paid to the prognostic role of EBV infection and drug therapy potentially applicable to the treatment of EBV-positive gastric cancer.

Background. High-grade gliomas are characterized by a wide range of genetic abnormalities. The heterogeneous genomic landscape of pediatric high-grade gliomas allows identifying distinct subgroups of the disease in children and young adults. Most importantly, these subgroups differ by clinical course and prognosis, as well as treatment response to standard therapy.

Objective: to assess the profile of molecular genetic markers of high-grade gliomas in children.

Materials and methods. In the current study, we examine the frequency of H3F3A, Hist1H3B, BRAF, IDH1 / 2 mutations, the copy number alterations of CDKN2A / 2B genes and the expression of ETV6‑NTRK3 fusion gene in a cohort of 53 pediatric high-grade gliomas.

Results. Driver mutations and CDKN2A / 2B deletions were observed in 24 (45 %) and 15 (28 %) of 53 tumors, respectively. Overall, the studied high-grade gliomas harbored 41 genetic aberrations including 24 (58.5 %) somatic missense mutations, 1 (2.4 %) genetic variant of unknown clinical significance, 1 (2.4 %) oncogenic fusion gene and 15 (36.6 %) deletions of the tumor suppressor genes.

Conclusion. These findings point to the importance of molecular profiling of tumors for the optimal clinical care and development of new approaches to treatment aimed at molecular targets for personalized anticancer therapies.

The VHL gene alterations are the early and characteristic feature of clear cell renal cell carcinoma (ccRCC). We have examined VHL mutations in sporadic 98 ccRCC cases to evaluate their localization in relation to functionally important motifs of the VHL protein. The DNA samples were obtained from snap-frozen carcinoma biopsies and used for Sanger sequencing, while 62 ccRCC DNA cases were studied by next generation sequencing (NGS) analysis in parallel. In 73 (74.4 %) оf 98 ccRCC cases the somatic non-silent VHL mutations were identified. Loss of function VHL mutations (nonsilent, frameshifts or in splicing sites) were detected in 40 (40.8 %) ccRCC, while missense mutations – in 35 (35.7 %) ccRCC. In total 76 mutations important for VHL functioning were detected in 72 (73 %) ccRCC samples, of them 15 mutations (deletion / insertion in-frame or frameshifts) were identified for the first time. Four ccRCC cases contained two mutations each. Most of missense mutations disturb the sites of VHL interactions with HIF, РКС or kinesin. The pathogenicity of p.P154P silent mutation and intronic mutations near mRNA VHL splicing sites was discussed. The obtained results are important for understanding the role of VHL mutations in ccRCC progression and prognosis.

The most effective treatment of the hormone-dependent breast cancer is based on the antiestrogens SERM and aromatase inhibitor treatment, however its efficiency is limited by the acquired resistance to the drugs.

Previously we have revealed the effect of the transferring of the hormonal resistance from the resistant to the sensitive cells under in vitro cell co-cultivation, and demonstrated exosomes involvement in this process. Here we have shown that the exosomes of the resistant cells caused the marked inhibition of the estrogen signaling in the recipient cells, and identified microRNAs – ERα suppressors that overexpressed in the resistant exosomes.

Taken together, the results obtained demonstrate the important role of the estrogen signaling suppression in the exosome-induced transferring of the hormonal resistance, and revealed the involvement of the exosomal microRNA in the ERα down-regulation.