Aim: To investigate the mechanisms of cytotoxic activity and pro-/antioxidant effect of lactoferrin on hormone receptor-positive and receptor-negative breast cancer cells in vitro. Materials and Methods: The study was performed on receptor-positive (MCF-7, T47D) and receptor-negative (MDA-MB-231, MDA-MB-468) human breast cancer cell lines. Immunocytochemical staining, flow cytometry, low-temperature electron paramagnetic resonance, and the Comet assay were used. Results: Upon treatment with lactoferrin, the increased levels of reactive oxygen species (ROS) (p < 0.05), NO generation rate by inducible NO-synthase (p < 0.05) and the level of “free” iron (p < 0.05) were observed. Moreover, the effects of lactoferrin were more pronounced in receptor-negative MDA-MB-231 and MDA-MB-468 cells. These changes resulted in increased expression of proapoptotic Bax protein (p < 0.05), reduced expression of the antiapoptotic Bcl-2 protein (p < 0.05) and level of not-oxidized mitochondrial cardiolipin (1.4–1.7-fold, p < 0.05). This, in turn, caused an increase in the percentage of apoptotic cells (by 14–24%, p < 0.05). Cytotoxic effects of lactoferrin were accompanied by an increase in the percentage of DNA in the comet tail and blocking cell cycle at G2/M phase, especially in receptor-negative cell lines. Conclusion: The study showed that exogenous lactoferrin causes a violation of an antioxidant balance by increasing the level of ROS, “free” iron and NO generation rate, resalting in the blocking of cell cycle at G2/M-phase and apoptosis of malignant cells.

Aim: To study indices of energy metabolism, content of K+ and Mg++ both in peripheral blood and in Walker-256 carcinosarcoma during development of resistance to doxorubicin. Methods: Resistance of Walker-256 carcinosarcoma to doxorubicin has been developed through 12 subsequent transplantations of tumor after the chemotherapy. Parental strain was inhibited by drug by 65%, while transitional resistant substrains — by 30% and 2%, respectively. Determination of biochemical indices in blood serum and homogenates of tumor tissue, level of potassium, magnesium, lactate, glucose, activities of lactate dehydrogenase and glucose6-phosphate dehydrogenase was performed with the help of biochemical and immune-enzyme analyzer GBG ChemWell 2990 (USA) using standard kits. Polarography was used to determine indices of mitochondrial oxidative phosphorylation. Study of mitochondrial membrane potential was carried out on flow cytometer Beckman Coulter Epics XL using dye JC-1. Results: It has been determined that development of drug resistance causes the decrease of K+, Mg++, glucose content in blood serum and increase of these indices in tumor tissue. At the same time, gradual tumor’s loss of sensitivity is characterized by decrease of glycolysis activity in it and activation of mitochondrial oxidative phosphorylation and pentose phosphate pathway of glucose degradation, which causes more intensive formation of NADPH. Conclusion: Development of drug resistance of tumor causes certain metabolic changes in organism and tumor. Further study of such changes will make possible to determine tumor and extratumor markers of resistance.

Aim: To study the cytostatic and some biological effects of aminoferrocene using mice with L1210 lymphoid leukemia. Materials and Methods: Experiments were performed on BDF1 male mice (DBA/2, female × C57Bl/6, male) with transplantable L1210 lymphoid leukemia. Determination of antitumor activity of Benzyl-Fc Boron (Bn), it was injected intraperitoneally 6 times daily, starting on day 2 after L1210 leukemia cell transplantation. Doses of Bn such as 26; 260 and 2600 μg/kg were used. The determination of intracellular content of cardiolipin, thiols, reactive oxygen species (ROS) and also analysis of Annexin V positivity and mitochondrial transmembrane potential (JC-1 staining) were performed with use of flow cytometry. The levels of “free iron” complexes, transferrin active forms and the rate of NO generation were measured by EPR-specroscopy. Results: Six daily injections of Bn at a dose of 26 μg/kg resulted in an increased survival of mice with L1210 leukemia by 28% (p < 0.05). Bn led to an increase of apoptotic cells number and ROS amount in leukemia cells. Besides, Bn caused a decrease of cardiolipin and nonprotein thiol compounds content. The membrane electrochemical potential of cell mitochondria was decreased also after Bn administration. Studies using EPR-spectroscopy revealed a significant increase in a level of “free iron”, content of transferrin active species and generation rate of NO by inducible NO-synthase in L1210 cells after aminoferrocene administration. Conclusion: Our data indicate that Benzyl-Fc Boron can be promising candidate for realizing a new strategy of anticancer therapy with the use of ROS-inducing agents.

Summary. This review presents up-to-date information on the effects of microbiota on the individual chemotherapy sensitivity in cancer treatment. Recent studies have shown that a fine balance between the intestinal microbiota and the immune system is crucial for maintaining an efficacy of cancer chemotherapy. A number of antitumor drugs have complex mechanisms of action involving not only direct effects but also the activity of the intestinal microbiota and the immune system. A unique combination of these factors contributes to the individual chemotherapy sensitivity.

The study was aimed at determining the changes of metal-containing proteins in blood serum and tumor tissue of animals with parental and doxorubicin-resistant strains of Walker-256 carcinosarcoma before and after the cytostatic administration. It has been shown that upon doxorubicin action the levels of total iron and transferrin in the tissues from the both groups of animals decreased while that of ferritine simultaneously increased with more pronounced pattern in the group of animals with resistant tumor strain. It has been shown that upon the action of doxorubicin in tumor tissue of animals with different sensitivity to the cytostatic there could be observed oppositely directed changes in the redox state of these cells that in turn determined the content of “ free iron” complexes, RO S generation and concentration of active forms of matrix metaloproteinase- 2 and matrix metaloproteinase-9, namely, the increase of these indexes in animals with parental strain and their decrease in animals with the resistant one. So, our study has demonstrated the remodulating effect of doxorubicin on the state of metal-containing proteins and redox characteristics of tumor dependent on its sensitivity to cytostatic, at the levels of the tumor and an organism. These data may serve as a criterion for the development of programs for the correction of malfunction of iron metabolism aimed at elevating tumor sensitivity to cytostatic agents.