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Background. To solve the problems of personalized medicine in oncology, preclinical studies based on the use of three-dimensional cellular models of tumors in vitro, including spheroids / tumoroids, are of great importance. They are an interesting tool for genetic, epigenetic, biomedical and pharmacological studies aiming to determine the most effective individual therapeutic approaches, since they allow modeling the dynamic evolution of a tumor disease from early stages to metastatic spread through interaction with the microenvironment.The purpose of the study was to compare characteristic features of formation and spatial organization of spheroids, obtained from solid malignant tumors cells with various histogenesis: melanomas, soft tissue sarcomas and osteosarcomas, epithelial tumors.Material and Methods. Solid tumor cell lines of patients who were treated from 2015 to 2021 were the basis for the creation of 3D-cell models. Fragments of tumor tissue were obtained intraoperatively: 15 samples of melanoma, 20 samples of soft tissue sarcomas and osteosarcomas, and 9 samples of epithelial tumors. All tumor cells were cultured for at least 10 passages. Methods of phase contrast, confocal microscopy, and histological techniques were used to study spheroids. Using ELISA methods and multiplex analysis, the supernatants of monolayer cell cultures and spheroids were studied for the presence of a wide range of biologically active substances that provide the processes of immunosuppression, invasion and metastasis.Results. The use of low adhesion surfaces was proven to be preferable to obtain spheroids of a given seed concentration and size of interest. The average cultivation time of spheroids was 4.7 days, and the optimal seeding concentration was 10,000 cells per well, while the spheroid diameter varied from 300 to 1000 μm depending on the type of malignant cells: the largest spheroids formed melanoma cultures. In general, the efficiency of spheroid formation was 88.6 % (39 out of 44). The introduction of fibroblasts into the 3D construct led to increasing in the invasive potential of tumor cells, which was associated with the production of IL8 (rho=0.636, p=0.035), HGF (rho=0.850, p=0.004), SCF (rho=0.857, p=0.014), FST (rho=0.685, p=0.029), Prolactin (rho=0.810, p=0.015), PECAM1 (rho=0.788, p=0.004).Conclusion. The technology of low-adhesive surfaces makes it possible to successfully create three-dimensional models of a tumor node from malignant tumors cells of various histogenesis. The colonization of a three-dimensional structure with fibroblasts enhances the biologically aggressive properties of tumor cells and demonstrates complex reciprocal interactions between the cellular elements of the tumor stroma and malignant cells, which brings the model closer to a real clinical situation.

Purpose of the study: to review in vivo studies on the relationship and role of various molecular genetic components of the circadian rhythm system in the initiation and development of malignant neoplasms. in contrast to clinical and epidemiological studies, animal models, including transgenic animal models, can model various changes and disturbances in the activity of clock genes and track the results of these changes.Material and Methods. the review includes data from studies carried out over the past 10 years in animal models, studying the mechanisms and effects of disturbances in the system of circadian rhythms related to the formation and development of tumors. the data sources for the review were the Medline, embase and scopus databases.Results. analysis of the literature has shown that interference with the work of the «biological clock» by changing the light cycle, disrupting the expression of clock genes and other manipulations is a factor predisposing to the development of tumors. in tumors of various types, the expression of clock genes is often mismatched, and it is unclear at what stage of their formation this occurs. in addition, the development of tumors disrupts the circadian homeostasis of the body. there are three key areas of research aimed at studying the role of circadian rhythms in tumor development: disturbance of circadian rhythms as a carcinogenic factor, disturbances in the clock gene system in a tumor, disturbances in the clock gene system of the whole organism, provoked by tumor development.Conclusion. the results of studies on animal models demonstrate that the relationship between the disturbance of circadian rhythms and the tumor process is complex since the causal relationship has not yet been studied. in this regard, the prospect of targeted pharmacological correction of circadian rhythms in clinical practice in cancer patients does not seem to be the nearest one.

Background. Photodynamic Therapy is one of the treatment methods used in modern oncology. Evaluation of the efficacy in vivo of photosensitizers on tumor models is generally accepted, but the photodynamic therapy technique in mice is not without drawbacks.The purpose of the study was evaluation of the efficacy of photodynamic therapy in mice with Ehrlich tumor model after subcutaneous and intracutaneous injection of tumor cells.Material and Methods. The study was conducted on BAL B/C mice of both sexes. Fotoditazin® and Radachlorin® were used as photosensitizers. For photoactivation, the Alod laser apparatus with a wavelength of 662 nm was used.Results. A comparison of photodynamic therapy with subcutaneous and intracutaneous localization of Ehrlich tumor was performed. It was shown that depending on the location and depth of inoculation of Ehrlich tumor, the pharmacokinetics (both the fluorescence intensity over time and the contrast ratio of the tumor/surrounding tissue) and pharmacodynamics (tumor growth inhibition, survival) of photosensitizers are significantly different. Higher contrast of the tumor/surrounding tissue is observed with intracutaneous localization of the tumor.Conclusion. A model with intracutaneous localization of Ehrlich tumor can be recommended for a primary assessment of efficacy; it allows the use of fewer animals in the experiment. When planning experiments to study photosensitizers and evaluating their results, the advantages and disadvantages of different methods for modeling tumors in mice should be taken into account.

Because of the high risk of brain metastases from HER2-positive breast cancer, the study of the anticancer activity of drugs used to treat brain tumors, in particular lomustine, is of great importance. In the FVB/N Her-2 transgenic mice bearing HER2-positive breast cancer (BC HER2+), a single oral administration of lomustine at a dose of 50 mg/kg resulted in a significant tumor growth inhibition (up to 96 %, p

To study the mechanisms underlying the effects of intraperitoneal chemoperfusion and to develop the optimal chemoperfusion regimen, an animal model of peritoneal carcinomatosis closely resembles a human model of peritoneal carcinomatosis is required. In our study, the model of peritoneal carcinomatosis in rats with ascitic ovarian cancer was used. material and methods. There were three groups of rats with ascitic ovarian cancer: 1 – the control group (n=15) having no treatment; 2 – rats receiving normothermic intraperitoneal chemoperfusion with cisplatin, 40 mg/kg (n=12); 3 – rats receiving hyperthermic intraperitoneal chemoperfusion with cisplatin, 20 mg/kg (n=14). All animals were euthanized with subsequent autopsy. results. Ascitic ovarian cancer developed in 100 % of the animals injected with the tumor cells. The median overall survival of rats in the control group was 9.5 days. At autopsy, all rats had ascites, and rats surviving 15‒17 days after the tumor cell injection had white tumor nodes measuring 1–3 mm in the greater omentum, intestinal mesentery, parietal and visceral peritoneum. The nodes were histologically verified as metastases of low-differentiated ovarian tumor. In 2 and 5 rats from groups 2 and 3 respectively, metastases in paratracheal lymph nodes and tumor hydrothorax were detected with no evidence of peritoneal carcinomatosis. The median survival of rats in groups 2 and 3 was significantly higher than that in the control group, being 37.5 and 25.5 months, respectively (р=0,256). conclusion. This in vivo study proved that localization of ascitic ovarian tumor, development of the tumor in all animals injected with tumor cells, fast ascites progression and peritoneal carcinomatosis make this ascitic ovarian cancer an adequate preclinical model of peritoneal carcinomatosis to study intraperitoneal chemoperfusion. Further studies are needed to understand the reasons and mechanisms of the tumor hydrothorax development in rats after intraperitoneal chemoperfusion.