Recent development of molecular and genetic technologies has demonstrated at the molecular level the co-evolutionary principles of interaction between microbiota, virome and the host organism, as well as the role of microorganisms and viruses both in maintaining physiological homeostasis and in the development of various diseases, including malignant neoplasms. The presented review is devoted to the analysis and generalization of modern data on microorganisms and viruses inhabiting the human body, their role in the processes of initiation, promotion and progression of carcinogenesis. The review provides information on known oncogenic viruses and microorganisms according to the modern classification of carcinogenic agents of the International Agency for Research on Cancer. Mechanistic data on the procarcinogenic effect of microbiota and virome are considered in accordance with the modern concept of key characteristics of a carcinogenic agent. Particular attention is paid to the analysis of data on the influence of microbiota and virome on the immunity of the host organism, including both the first results of immunotherapy with Coley toxin of soft tissue sarcomas and osteosarcomas, and data on the influence of individual types of microorganisms on the formation of the immunocompetent cell profile of the host organism. In addition, the influence of intratumor and intracellular microbiota, respectively, on the microenvironment of tumor cells and cellular signaling, including in solid tumors that have no contact with the external environment are also discussed. The data presented are important in terms of the holobiota concept, showing the interdependent existence of the human body, microorganisms and viruses, to improve the prevention and therapy of malignant neoplasms.

Malignant gliomas are one of the most common brain tumors in adults arising from glial cells with an extremely poor prognosis. Generally, therapy of malignant gliomas consists of radical surgical removal followed by radio- and/or chemotherapy. However, prognosis of the disease remains unfavorable.
The review presents main clinical, morphological and molecular characteristics of gliomas, their prognostic significance and role in the choice of targeted therapy based on using tyrosine kinase inhibitors and/or monoclonal antibodies. The current aspects of immunotherapy of gliomas (i.e., activation of immune cells, or blockage of immunosuppressive signaling) are discussed in detail. One of the well-known approaches of cancer immunotherapy is based on immune checkpoint inhibitors. These drugs might be effective in treatment of malignant gliomas overexpressing the molecules that suppress immune cells functions. Another promising approach of gliomas immunotherapy is based on genetically modified CAR-T cells (CAR – chimeric antigen receptor) which might identify and eliminate cancer cells. Cytokine therapy is also perspective treatment approach, as well as gene therapy which is associated with editing viral genes for production of oncolytic viruses used as anticancer vaccines. Vaccines are being developed to generate the specific antibodies recognized cancer cells and thereby stimulate the immune system to identify and destroy tumor cells.
Despite the promising potential of various gliomas immunotherapy methods, most of them are at different stages of preclinical and clinical trials. Some of them demonstrate promising results and good perspective for the further use to treat glioma patients.

The methionine cycle is responsible for the metabolism of substances associated with methionine, one of the essential amino acids for protein synthesis. The methionine cycle dysregulation leads to non-proteinogenic amino acid homocysteine accumulation that can have a negative impact on a health. Numerous studies describe homocysteine effect on cardiovascular pathology development but its role in carcinogenesis remains poorly understood. Therefore, the purpose of this review is to analyze scientific data regarding the role of methionine catabolism dysregulation in a cell neoplastic transformation and tumor growth. Understanding cellular alterations of methionine metabolism is important for novel anti-cancer drugs development as well as establishing approaches for combinatorial treatment strategies aiming to overcome metabolic plasticity of cancer cells and their drug resistance.

Introduction. Heat shock proteins (HSP), also known as molecular chaperones, are a large family of proteins that play crucial roles in histogenesis, homeostasis, and the folding and functional regulation of numerous client proteins. Among them, HSP90 is a key player, particularly in supporting the growth of tumor cells. HSP90 impacts multiple carcinogenic signaling pathways, including BCR-ABL, Raf-1, AKT, human epidermal growth factor receptor 2 (ERBB2/HER2), hypoxia-inducible factor 1-α (HIF-1α), janus kinase 2 (JAK2), STAT3, p53, and estrogen receptor α (ERα). As a result, the search for new, selective inhibitors of this chaperone is a high priority in medicinal chemistry and oncology.
Aim. To evaluate the antiproliferative activity of a novel HSP90 inhibitor, THB5T-1, on ERα-positive breast cancer cell lines and assess its anti-estrogenic potential and selectivity.
Materials and methods. The study was conducted on hormone-dependent breast cancer cell lines MCF7 and T47D, along with the normal fibroblast line hFB-hTERT. The antiproliferative activity of THB5T-1 was measured using the MTT assay, while immunoblotting was employed to analyze the effects of HSP90 inhibition on cell signaling pathways. Anti-estrogenic activity was assessed in MCF7 cells via a reporter assay, and molecular modeling was used to construct a model of THB5T-1 interaction with the ligand-binding domain of ERα.
Results. The half-maximal inhibitory concentration (IC50) of THB5T-1 was determined to be 4.3 μM for MCF7 cells and 5.6 μM for T47D cells. At a concentration of 25 μM, cell survival decreased to 20%. The selectivity index for THB5T-1 varied from 3.7 to 5.0 in different breast cancer cell lines. The compound’s effects on hormonal pathways in MCF7 cells, as observed via reporter assay and immunoblotting, were dose-dependent. These findings were further supported by molecular docking studies, showing THB5T-1 interaction with the ligand-binding domain of ERα. Additionally, the antiproliferative activity of THB5T-1 in MCF7 cells was associated with reduced expression of cell cycle regulators cyclin D1 and cyclin-dependent kinase 4 (CDK4). Significant efficacy of compound THB5T-1 in combination with a selective AKT inhibitor was revealed.
Conclusion. Compound THB5T-1 demonstrated significant antiproliferative effects on ERα-positive breast cancer cells and exhibited high selectivity. Its anti-estrogenic effects highlight its potential as a selective inhibitor of the HSP90/ ERα/GREB1 pathway, effectively blocking ERα-mediated cell proliferation.

Introduction. Breast cancer (BC) represents a group of malignant neoplasms with various molecular profiles, which are characterized by aberrations in the mechanisms of epigenetic transcription regulation. One of these disruptions associated with a worse prognosis is the overexpression of the BET protein family, responsible for the interaction of transcription factors with histone-rich acetylated regions. Previously, for the multitargeted epigenetically active agent curaxin CBL0137 (CBL), we have shown the ability to inhibit the expression of BRD2, BRD3, BRD4 proteins in HeLa TI cells and BRD3, BRD4 proteins in BC cells.
Aim. To analyze the molecular mechanisms of CBL0137 action on BC cells in vitro, including: 1) assessment of cytotoxicity, 2) analysis of the effect on the cell cycle, 3) assessment of the ability to trigger apoptosis, 4) cause DNA damage, and 5) analyze the effect on the expression of genes involved in proliferation, apoptosis and repair processes.
Materials and methods. The cytotoxicity of CBL on BC cells (MCF7, MDA-MB-231, SKBR3) was assessed using the MTT assay. The effect of the agent on the cell cycle and activation of apoptosis was analyzed by flow cytometry. Analysis of DNA damage under the action of CBL was performed using the comet assay. Changes in the expression of genes associated with proliferation, repair and apoptosis were evaluated using real-time polymerase chain reaction.
Results. The half maximal inhibitory concentration (IC₅₀) on BC cells under the action of CBL0137 were 1 μM at 72-hour exposure, 14–25 μM at 24-hour. Curaxin CBL (0.5 and 1 μM) caused G2/M cell cycle arrest, and also triggered apoptosis in all cell lines. Under the action of 1 μM CBL, an increase in the degree of DNA damage in MCF7 and SKBR3 cells was recorded, and under the action of both concentrations in MDA-MB-231 cells. The gene expression profile involved in proliferation also corresponded to the arrest in the G2/M phase of the cell cycle. Also, under the action of CBL, the activation of p53-dependent repair genes occurred. An increase in the expression of pro-apoptotic and a decrease in anti-apoptotic genes was shown.
Conclusion. Curaxin CBL0137 showed differential effects on molecular processes in BC cells. We have identified a cytostatic effect of the compound, confirmed at various molecular levels. The data obtained indicate the ability of CBL0137 to inhibit tumor processes in BC cells, which makes it a potentially interesting agent for combination therapy.

Introduction. The active use of highly toxic chemotherapy in the treatment of soft tissue sarcomas determines the need to search for criteria and markers of chemoresistance of patients to the therapy.
Aim. To study the connection between tumor cell resistance to chemotherapy and expression levels of apoptosis-regulating proteins (PUMA, PMAIP-1, PIDD-1, AIFM-2, Bax, GADD45a) in primary cultures of soft tissue sarcomas.
Materials and methods. Primary cultures of soft tissue sarcomas were obtained using enzymatic digestion, cell death was evaluated using resazurine assay. Gene expression was measured using real-time polymerase chain reaction, protein levels using immunoblotting assay.
Results. 73 primary cultures of soft tissue sarcomas were obtained, for which chemosensitivity to doxorubicin, ifosfamide, docetaxel, gemcitabine, pazopanib and their combinations was determined using a resazurin cytotoxicity test. Associations of AIFM-2 gene expression with resistance to pazopanib, doxorubicin and its combination with ifosfamide were found in liposarcoma, synovial and undifferentiated pleomorphic sarcomas. In addition, associations between the expression of the Bax, PUMA, PMAIP-1, GADD45a and PIDD-1 genes and resistance to the studied drugs in various nosological subgroups of sarcomas were identified. When studying the amount of protein, it was revealed that undifferentiated pleomorphic and synovial sarcomas with a low content of GADD45a are more resistant to the studied drugs. Liposarcomas with high Bax expression are more resistant to docetaxel and gemcitabine, while synovial sarcomas with high Bax expression are more sensitive to doxorubicin and ifosfamide.
Conclusion. The data obtained indicate a relationship between the activity of the studied genes-regulators of apoptosis and resistance to drugs used in the treatment of soft tissue sarcomas.

Introduction. Esophageal squamous cell carcinoma is a dangerous oncological disease for which there are no relevant molecular-biological and biochemical markers for diagnosis, monitoring, and prognosis. Non-coding RNAs, whose aberrant expression is characteristic of many neoplasms may be promising candidate markers.
Aim. To investigate the clinical significance of the expression of long non-coding RNAs (lncRNAs) SNGH18, LCAL1, IGFL2-AS1, LINC02301 and LINC01508 in esophageal squamous cell carcinoma depending on the phenotype of the tumor stroma.
Materials and methods. The study included 17 patients with esophageal squamous cell carcinoma, who were examined and treated at the N.N. Blokhin National Medical Research Center of Oncology. Gene expression levels were assessed using real-time polymerase chain reaction. Immunohistochemical analysis was conducted to evaluate the expression of CD68, CD163 and inducible nitric oxide synthase. Statistical analysis of the obtained results was performed using GraphPad Prizm v. 10. Differences in lncRNA expression between tumor samples and conditionally normal tissues were assessed using the Wilcoxon test for paired samples. Correlation analysis was carried out by calculating Spearman’s correlation coefficient. Survival analysis was conducted using Kaplan–Meier survival curves. A p-value of less than 0.05 was considered statistically significant.
Results. Aberrant expression of the lncRNAs LCAL1, LINC01508 and LINC02301 was observed in tumor tissue compared to conditionally normal tissue. Specifically, the expression of LCAL1 and LINC01508 was increased in tumor tissue (p = 0,001 and p = 0,007), while the expression of lncRNA LINC02301 was decreased (p = 0,004). The expression of lncRNAs SNGH18 and IGFL2-AS1 showed no significant changes. ROC-analysis indicated that examining these lncRNA expressions is not suitable for diagnosing esophageal squamous cell carcinoma. Clinical significance analysis revealed no correlation between the studied lncRNA expressions and the clinicopathological characteristics of the disease correlation analysis of the lncRNAs SNGH18, LCAL1, IGFL2-AS1, LINC02301 and LINC01508 with the phenotype of tumor stroma macrophages demonstrated that LINC01508 was significantly and positively correlated with both the total number of macrophages (r = 0.579; p = 0.017) and the number of macrophages with cytotoxic and immunosuppressive phenotypes (r = 0.567; p = 0.004 and r = 0.496; p = 0.045, accordingly). In contrast, LCAL1 expression was inversely correlated with the number of cytotoxic macrophages (r = –0.490; p = 0.037). Prognostic analysis revealed that only lncRNA IGFL2-AS1 expression was associated with favorable prognosis in esophageal squamous cell carcinoma (hazard ratio 0.374; p = 0.039).
Conclusion. Long non-coding RNAs are important regulatory elements in both normal and tumor cells, offering certain advantages for the diagnosis of oncological diseases due to their high specificity and stability in both tissues and circulating body fluids. Growing evidence from scientific research highlights the potential clinical application of lncRNA expression analysis as markers for early diagnosis and as potential therapeutic targets. In this study, we conducted a retrospective investigation and determined the clinical significance of lncRNAs SNGH18, LCAL1, IGFL2-AS1, LINC02301, LINC01508 in esophageal squamous cell carcinoma, thereby expanding our understanding of the molecular changes observed in the development of this disease.

Introduction. The results of genomic profiling of muscle-invasive bladder cancer (BC) based on messenger RNA (mRNA) extraction showed significant molecular variety of the tumors underlying the wide spectrum of clinical manifestations and responses to traditional treatment methods. However, despite the valuableness of molecular mRNA profiling for understanding biological behavior of the tumor, its implementation in routine clinical practice is complicated due to technological complexity and high cost of genomic sequencing. Therefore, determination of BC molecular subtype based on immunohistochemical examination can be considered an alternative to mRNA profiling. However, the method should be validated using clinical material.
Aim. To evaluate prognostic significance of immunohistochemical method in determination of urothelial cancer molecular subtype using a surrogate panel consisting of 13 markers and semiquantitative calculation of the histochemical index.
Materials and methods. The retrospective cohort study included 49 patients with BC who underwent radical cystectomy (RC) after previous transurethral resection (TURBT) between 2013 and 2016 at the center. The inclusion criteria were patient age between 18 and 75 years, histologically verified BC, and availability of formalin-fixed paraffin embedded blocks after TURBT and RC at the Clinical Laboratory of Morphology. The exclusion criteria were rare histological types of BC, grade IV–V surgical complications per the Clavien–Dindo classification during hospitalization, TURBT performed at other medical facilities. Molecular subtypes were determined using the immunohistochemical method on the Ventana BenchMark XT (Roche, USA) immunostainer per the traditional technique for deparaffinized sections with subtype-specific panel consisting of 13 antibodies recommended by the Lund taxonomy (LundTax). Depending on the hyperexpression level of basal and/or luminal antibodies, 4 urothelial cancer subtypes were identified: luminal А (UroA), luminal В (UroB), basal and genomically unstable (GU). The first endpoint of the study was 5-year recurrence-free survival on TURBT and RC material, secondary endpoint was 5-year overall survival on the same material.
Results. Using immunohistochemical analysis with a surrogate marker panel of preserved histological material after TURBT, urothelial cancer subtype was determined in 38 (77.6 %) patients, after RC – in 39 (79.5 %) patients. Percentages of UroA, UroB and GU subtypes after TURBT and RC were almost identical; the rarest type was Basal with 4 (8.2 %) and 5 (10.2 %) cases, respectively. Evaluation of the primary endpoint showed that 5-year recurrence-free survival after TURBT (log-rank test; p = 0.85) and RC (log-rank test; p = 0.95) did not differ in various urothelial cancer subtypes. Evaluation of the secondary endpoint did not show significant statistical difference in 5-year OS₁ (log-rank test; p = 0.94) and OS₂ (log-rank test; p = 0.92). Multivariate regression analysis showed that the most significant predictors of BC recurrence after radical treatment were clinical stage IIIA (p = 0.017) and pathomorphological stage II (p = 0.021), while OS rates were significantly affected by pathomorphological stages IIIA (p = 0.003) and IVA (p = 0.019).
Conclusion. Determination of urothelial cancer molecular subtype using a surrogate panel of 13 markers and semiquantitative calculation of the histochemical index did not show effectiveness and prognostic significance: the identified 4 subtypes of urothelial cancer did not significantly affect long-term oncological outcomes.

Introduction. The sodium-dependent phosphate transporter NaPi2b is a promising target for targeted antitumor therapy. There is the largest extracellular domain (ECD) containing a cryptic MX35 epitope, against which therapeutic antibodies have been developed and are undergoing preclinical and clinical trials. The accessibility of the MX35 epitope to antibodies is higher in tumor cells and depends on the conformation of the ECD, determined by disulfide bonds between cysteine residues C303, C322, C328 and C350. The number of these disulfide bonds and cysteine residues that participate in the NaPi2b ECD conformation maintaining, regulation of its transport activity and stability is unknown. Isolation and purification of transmembrane proteins, including NaPi2b, for structural and functional studies is difficult, therefore it is necessary to develop an in vitro model to study the formation of disulfide bonds in the ECD region of the NaPi2b transporter and their role in ensuring the availability of the cryptic MX35 epitope and transporter activity in living cells.
Aim. To create a panel of clonal sublines of human ovarian carcinoma OVCAR-8 containing recombinant variants of the wild-type NaPi2b transporter, as well as with single and double substitutions of cysteine residues in the ECD region with alanine residues.
Materials and methods. OVCAR-8 ovarian carcinoma cells that do not express the NaPi2b transporter gene were transduced with lentiviral particles carrying nucleotide sequences encoding the wild-type NaPi2b transporter or its mutant variants with single and double substitutions of cysteine residues C303, C322, C328 and C350 with alanine residues to simulate reduction of potential disulfide bonds between them. After selecting transduced cells, clonal sublines were obtained, in the lysates of which the content of recombinant variants of the NaPi2b transporter was assessed using Western blot analysis and dot blot analysis.
Results. A panel of 9 clonal sublines of OVCAR-8 ovarian carcinoma containing the wild-type recombinant NaPi2b transporter and its mutant variants was obtained. The effect of the introduced amino acid substitutions on the content and electrophoretic mobility of the NaPi2b transporter was noted.
Conclusion. The resulting panel of clonal sublines can be used as an in vitro model to study the conformation of the ECD transporter NaPi2b, determined by disulfide bonds, which will reveal the mechanism of formation of the cryptic MX35 epitope and shed light on the role of ECD in the regulation of NaPi2b transport activity. Understanding the mechanism of formation of the cryptic MX35 epitope will make it possible to find new cryptic epitopes in the extracellular domains of transmembrane proteins, which can be used as targets for antitumor therapy.