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.

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.

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Summary. Aim: To investigate the content of essential elements (EE): copper, zinc, magnesium, iron and calcium and the evaluation of the activity of metal-containing enzymes — ceruloplasmin (CP), myeloperoxidase (MPO) and the content of transferrin (TF) in blood plasma (BP) and tumor tissue (TT) of animals with Walker-256 carcinosarcoma treated with lactoferrin (LF). Materials and Methods: The study of the EE content and the activity of the abovementioned enzymes was carried out on rats with Walker-256 carcinosarcoma treated with LF at the doses of 1 and 10 mg/kg of body weight. The quantitative content of EE in BP and TT of animals was determined using the inductively coupled plasma atomic emission spectroscopy (ICP-AES). Determination of CP activity, content of TF and hemochromes was performed using the method of electron paramagnetic resonance (EPR), and MPO — by unified biochemical method. Results: The introduction of LF at the doses of 1 and 10 mg/kg resulted in a decrease in the ratio of Cu/Zn in BP and even more expressed decrease of Ca/Mg ratio in TT. Administration of LF, especially at a dose of 10 mg/kg, affected the increase in CP and MPO activity in BP. It has been shown that administration of LF at a dose of 10 mg/kg led to an increase in oxidative products of destruction of the hemoglobin-hemochrom system in the TT, against the background of lowering the TF content. Conclusions: The administration of LF, especially at a dose of 10 mg/kg, led to metabolic alterations associated with inhibition of the tumor process. The detected modulating effect of LF on the content of the EE and the activity of the CP and MPO may be a basis for correction of the elemental balance in carcinogenesis.