Suppression of tumor cell growth and proliferation is the main goal of chemotherapy which is an integral part of the treatment for cancer patients. In addition to high antitumor activity, the cytotoxic effects of chemotherapeutic agents also extend to immune cells, resulting in pancytopenia and weakened immune response. Nevertheless, the effect of chemotherapy on the immune system is multifaceted, as it simultaneously exerts a suppressive influence while also stimulating the antitumor activity of lymphoid and myeloid populations. This review focuses on the analysis and generalization of modern data regarding the effects of chemotherapeutic drugs used in standard antitumor therapy regimens on the functioning of the immune system. The suppressive mechanisms of chemotherapy, including the development of cytopenia, are reviewed. Special attention is paid to the analysis of data on modulation of antitumor immune response depending on the class of chemotherapeutic agent. Mechanisms enhancing immune recognition and stimulating immune cells in response to increased expression of tumor antigens are described. The data regarding the effects of chemotherapy on the tumor microenvironment, including the reprogramming of immunosuppressive profiles and the activation of immune effectors, is presented. The summarized data underscore the dual nature of chemotherapy’s effects on the state of the immune system and its influence on the formation of antitumor immune responses.

Clonal hematopoiesis of indeterminate potential (CHIP) is associated with aging and is a risk factor of many diseases including malignant neoplasms (MNPs). It originates through somatic mutations in hematopoietic stem and/or progenitor cells, promotes development of hematological MNPs and underlies unfavorable prognosis in solid malignant tumors. Results of recent largescale genome-wide studies confirmed that CHIP plays a role in oncological diseases. Mutations associated with this pathology were found in stem and/or progenitor cells in patients with both hematological and solitary MNPs which indicates that CHIP potentially mediates development of malignant tumors. Cytotoxic chemoradiation therapy is closely associated with CHIP development and causes emergence of aggressive and treatment-resistant hematological MNPs. In patients with solitary MNPs, TET2 gene mutations with high variant allele frequencies were also found in the tumors. This phenomenon was named tumor-infiltrating clonal hemopoiesis. Further populational studies of patients with solitary MNPs will allow to evaluate the role of tumor-infiltrating clonal hemopoiesis in oncogenesis. The ability of age-associated somatic clonal expansions in one tissue, namely hematopoietic compartment, to affect oncogenesis in another tissue is a new concept requiring further investigation and potentially capable of providing deeper understanding of cancer biology.
The review explores the association between CHIP, aging, and oncological diseases with a particular emphasis on solitary MNPs. The ways for better understanding of the role of CHIP in oncogenesis and possibilities of using its clinical potential for cancer treatment are discussed.

Diagnosis and selection of effective therapy of soft tissue sarcomas (STS) are complicated by low incidence and significant histological variability of these tumors. Development of molecular and genetic testing methods is aimed at improving differential diagnosis of different types of STS and identification of genetic abnormalities which can potentially serve as targets for therapy. Development of effective treatment methods requires adequate preclinical models capable of recreating biological features of the tumors. The article presents molecular and genetic testing methods for STS diagnosis and therapy, advances in in vitro STS models, problems with their use in preclinical studies, as well as possibilities of using primary cell cultures for personalized treatment.

Introduction. Tumor cells are known not to undergo replicative aging – usually due to hyperactivation of telomerase, which restores telomere length during each cell division cycle. However, it is possible to induce aging in tumor cells through sublethal doses of cytostatics or irradiation – this is the so-called stress-induced or non-replicative senescence. Studying the mechanisms and regulatory pathways of this process is one of the important areas of modern oncology.
Aim. To investigate the mechanisms of doxorubicin-induced senescence in different breast cancer cell subtypes and to explore possible approaches to regulating non-replicative aging.
Materials and methods. The experiments were performed on in vitro cultured breast cancer cell lines MCF-7 and MDA-MB-231. Cellular senescence was assessed by β-galactosidase activity, morphological changes, and activation of the p53/p21 signaling pathway. Colorimetric assays, reporter analysis, and immunoblotting were used to evaluate the expression and activity of cellular proteins. DNA methyltransferase 3A (DNMT3A) knockdown was achieved using a standard lentiviral vector encoding antisense RNA against DNMT3A.
Results. A potentiating effect of tamoxifen on doxorubicin-induced senescence – including in estrogen-independent breast cancer cells – was demonstrated. Enhanced non-replicative senescence was observed in resistant cells characterized by constitutive suppression of DNMT3A expression. For the first time, it was shown that DNMT3A suppression – either via decitabine treatment or DNMT3A knockdown – leads to an increase and maintenance of non-replicative senescence in MCF-7 cells.
Conclusion. The findings indicate that non-replicative senescence in breast cancer cells can be enhanced and sustained in the presence of the antiestrogen tamoxifen, and underscore the key role of DNMT3A in regulating doxorubicin-induced senescence.

Introduction. The proteins of the urokinase system, including serine protease urokinase (uPA), its receptor (uPAR), and inhibitors PAI-1 and PAI-2, play a key role in tumor biology by influencing cellular proliferation and tumor growth, invasion, metastasis, and angiogenesis. Despite the established role of these proteins in the carcinogenesis of many tumor types, the mechanisms underlying their action, including their effects on cell migration, epithelial-mesenchymal transition, and stemness, remain insufficiently studied.
Aim. To evaluate the influence of the urokinase receptor gene PLAUR on the expression of adhesion and stemness genes, as well as on the migration of human glioma and neuroblastoma cells.
Materials and methods. The study utilized two human glioma cell lines, U87 and U251, and the human neuroblastoma cell line SH-SY5Y. To achieve the overexpression of the PLAUR gene, a non-viral plasmid was created, followed by the transfection of the cells. Relative gene expression was assessed using real-time polymerase chain reaction. For evaluating cell migration, a Wound Healing Assay was performed, with image analysis conducted using ImageJ software and MRI Wound Healing Tool. Statistical analysis of the results was carried out using GraphPad Prism v.10.
Results. High expression of the urokinase receptor gene PLAUR is associated with a significant increase in cell migration and complex phenotypic changes. Specifically, in U251 glioma cells, there is an induction of the expression of the genes CD56, CDH1, CDH2, ZEB2, and SOX2. In U87 glioma cells, the expression of the genes PLAU, CD56, CDH1, ZEB1, ZEB2, SNAI1, SNAI2, SOX2, and NANOG is induced, while the expression of the gene CDH2 is suppressed. In SH-SY5Y neuroblastoma cells, there is an induction of the expression of the genes CD56, CDH1, ZEB1, ZEB2, SNAI2, and SOX2, along with a suppression of the expression of the urokinase gene PLAU compared to cells transfected with the control plasmid pGFP.
Conclusion. The results highlight the complexity of the regulation of carcinogenesis processes involving the PLAUR gene and deepen our understanding of tumour biology. High expression of the PLAUR gene may enhance the activity and invasion of tumor cells by regulating the epithelial-mesenchymal transition and altering the expression of key transcription factors.

Introduction. Glioblastoma is the most common malignant brain tumor in adults with a poor prognosis. Treatment of patients includes surgical resection, radiation and the alkylating agent temozolomide (TMZ). The therapeutic efficacy of TMZ is due to its ability to damage DNA and induce apoptosis, but it is neutralized by the expression of the DNA repair enzyme O6-methylguanine-DNA-methyltransferase (MGMT). Methylation of the MGMT gene promoter suppresses the synthesis of the corresponding enzyme and increases the cytotoxic efficiency of TMZ.
Aim. To determine the MGMT promoter methylation in glioblastoma patients and to evaluate the prognostic significance of this phenomenon.
Materials and methods. Bisulfite-treated DNA samples isolated from formalin-fixed paraffin-embedded tumor tissues obtained from glioblastoma patients were analyzed. MGMT methylation was assessed by qualitative methylation-specific polymerase chain reaction. The prognostic significance of this phenomenon in conjunction with a number of other clinical parameters was assessed by means of univariate and multivariate analysis.
Results. MGMT promoter methylation was found to be one of the most significant favorable prognostic factors of glioblastoma: the likelihood of disease reappearance or a fatal outcome at a specific point in time is approximately two-fold lower in such patients than in those with intact MGMT.
Conclusion. The methylation-specific polymerase chain reaction, which is routinely used in clinical practice, adequately assesses MGMT methylation status as a prognostic factor, but it does not allow for the evaluation of its predictive potential.

Introduction. Gastric cancer remains a serious public health problem. Cancer-testicular antigen genes (CT-genes) in gastric cancer may be promising targets for immunotherapy due to their limited expression in normal tissues. Competing endogenous RNA networks (ceRNAs) play an important role in regulating CT-gene expression in gastric cancer. These networks are complex and require comprehensive bioinformatics and experimental study.
Aim. To conduct a bioinformatic analysis followed by validation of СT-gene expression and its regulation in malignant gastric tumors.
Materials and methods. Data for the bioinformatics stage were downloaded from GEO. Identification of differentially expressed genes was carried out using GEO2R, microRNA targeting genes – using the Random forest machine learning method. An analysis of the interaction of microRNA and long non-coding RNA (lncRNAs) was also performed. The clinical material for the experimental stage was tissues (tumor and conditionally normal) of 100 patients with a histologically confirmed diagnosis of gastric cancer. The relative expression values of 6 CT-genes (MAGEA10, MAGEA2, MAGEA12, MAGEA3, MAGEA6, MAGEH1), as well as their targeting microRNAs and lncRNAs, were determined using real-time polymerase chain reaction.
Results. Using GEO2R, 18,617 differentially expressed loci were detected, including protein-coding genes, microRNA and lncRNAs. Of these, a change in the expression of 6 CT-genes was revealed – MAGEA10, MAGEA2, MAGEA12, MAGEA3, MAGEA6, MAGEH1, interacting with 40 microRNAs, in turn interacting with 17 lncRNAs. In the patients tumor tissue, an increase in expression of the MAGEA10, MAGEA3 and MAGEA6 genes (p <0.0001), a decrease in expression of miR-1207-5p, -6858-5p, -3127-3p, -3940-3p, -6807-3p, -3085-3p, -3934-5p, -4488, -4530, -6777-3p, -99a-3p (p <0.0001) and an increase in expression of miR-7113-3p, miR-874-3p, as well as an increase in expression of LINC01089, AC145285.6, GAS5, AC005034.3, AL691447.2 (p <0.001) and decreased expression of SNHG14, AC002101.1, SLC9A3-AS1 and AL118506.1 (p <0.001) was found. Based on the obtained data, a model of the regulatory network for CT-genes in gastric cancer was constructed.
Conclusion. The study showed disturbances in the CT-genes competitively interacting RNA network in gastric adenocarcinoma. The obtained data are important for understanding the fundamental mechanisms of CT-gene regulation, as well as for improving approaches to immunotherapy (new targets and regulatory molecules) and diagnostics (new molecular markers) of this disease. 

One of the most challenging issues in the treatment of ovarian cancer is the high level of tumor cell chemoresistance, which leads to early tumor recurrence and low overall survival. In the case of tumor cell chemoresistance, the therapy is ineffective, resulting in unnecessary drug consumption and harm to the patient due to toxic side effects and time losses during its implementation. One approach to solving this problem is experimental predictive testing of tumor cell chemoresistance in vitro.
Aim. To develop a protocol of experimental testing of chemoresistance of ovarian cancer cells to chemotherapy drugs. We analyzed changes in the number of viable cells of A-1847, Ovcar-3 and Ovcar-4 cell lines cultured in hypo-adhesive conditions and optimized a method of cell viability determination based on resazurin metabolism. It was shown that viability of ovarian cancer cells of the studied cell lines is approximately the same in the presence of 1^st and 2^nd line antitumor drugs measured in accordance with the developed culture protocol in hypo-adhesive conditions and using ATP-tumor chemosensitivity assay (ATP-TCA) (DCS Innovative Diagnostik-Systeme, Germany) approved for use in clinical practice. The developed method is based on readily available and inexpensive reagents and expendables which makes it economically attractive.

Introduction. Cancer remains a major cause of mortality worldwide, with adverse environmental factors such as pesticides contributing significantly to its development. Despite the widespread use of various pesticides, the molecular mechanisms underlying their actions and carcinogenic potential have been studied for only a limited number of models, especially in normal human cells.
Aim. To study the molecular effects of pesticides carbaryl, chlorpyrifos, mancozeb, thiram, and pendimethalin in nonmalignant HaCaT and MCF10A cells.
Materials and methods. Non-toxic concentrations of pesticides were determined using the MTT assay. Genotoxicity was analyzed by the comet assay. Proliferative potential was assessed by clonogenic assay. Changes in the expression of genes associated with carcinogenesis were evaluated by real-time polymerase chain reaction.
Results. Carbaryl caused DNA damage in MCF10A cells, promoted proliferation in both cell lines during clonogenic assay, as well as caused activation of biotransformation genes (AHR, GSTA4) in MCF10A cells, repression (CYP1B1, GSTA4) genes in HaCaT cells and lowered expression of inflammation genes (IL1a, IL1b, PTGES, IFNGR1). Chlorpyrifos did not have genotoxic effect and did not affect clonogenicity but caused induction of biotransformation (CYP1A1, CYP1B1), inflammation (IL1b, PTGES) genes, and genes BCL2 and DNMTs. Mancozeb and thiram did not show genotoxicity in HaCaT and MCF10A cells but activated individual repair genes (ATR/ATM). Thiram stimulated HaCaT cell proliferation in clonogenic assay, and mancozeb activated expression of proliferation regulation genes (CCND2, CCNE1, Ki-67) but did not affect colony growth; both fungicides decreased expression of inflammation genes (COX2, IL1a, IL1b). Pendimethalin caused DNA damage and activation of repair genes (ATR, GADD45a, PCNA) in both cell lines, as well as decreased expression of GLUT3 in HaCaT cells and induced expression of CYP1A1 in HaCaT cells and CYP1B1 in MCF10A cells.
Conclusion. In this study, we performed a comprehensive assessment of the effects of pesticides on normal human cells. Our results indicate that pendimethalin, chlorpyrifos, and carbaryl exert the most procarcinogenic effect.