Aconitine-containing agent enhances antitumor activity of dichloroacetate against Ehrlich carcinoma

Significant variability of anticancer efficacy of dichloroacetate (DCA) stimulated an active search for the agents capable to enhance it antitumor action. Therefore, the aim of this work is the study of capability of aconitine-containing antiangiogenic agent BC1 to enhance anticancer activity of DCA...

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Published in:Experimental Oncology
Date:2015
Main Authors: Pyaskovskaya, O.N., Boychuk, I.V., Fedorchuk, A.G., Kolesnik, D.L., Dasyukevich, O.I., Solyanik, G.I.
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Language:English
Published: Інститут експериментальної патології, онкології і радіобіології ім. Р.Є. Кавецького НАН України 2015
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Cite this:Aconitine-containing agent enhances antitumor activity of dichloroacetate against Ehrlich carcinoma / O.N. Pyaskovskaya, I.V. Boychuk, A.G. Fedorchuk, D.L. Kolesnik, O.I. Dasyukevich, G.I. Solyanik // Experimental Oncology. — 2015. — Т. 37, № 3. — С. 192-196. — Бібліогр.: 27 назв. — англ.

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
id nasplib_isofts_kiev_ua-123456789-145487
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spelling Pyaskovskaya, O.N.
Boychuk, I.V.
Fedorchuk, A.G.
Kolesnik, D.L.
Dasyukevich, O.I.
Solyanik, G.I.
2019-01-22T12:57:25Z
2019-01-22T12:57:25Z
2015
Aconitine-containing agent enhances antitumor activity of dichloroacetate against Ehrlich carcinoma / O.N. Pyaskovskaya, I.V. Boychuk, A.G. Fedorchuk, D.L. Kolesnik, O.I. Dasyukevich, G.I. Solyanik // Experimental Oncology. — 2015. — Т. 37, № 3. — С. 192-196. — Бібліогр.: 27 назв. — англ.
1812-9269
https://nasplib.isofts.kiev.ua/handle/123456789/145487
Significant variability of anticancer efficacy of dichloroacetate (DCA) stimulated an active search for the agents capable to enhance it antitumor action. Therefore, the aim of this work is the study of capability of aconitine-containing antiangiogenic agent BC1 to enhance anticancer activity of DCA against Ehrlich carcinoma. Materials and Methods: DCA (total dose was 1.3 g/kg of b.w.) and BC1 (total dose was 0.9 mg/kg of b.w.) were administered per os starting from the 2nd and 3rd days, respectively (8 admini­strations for each agent). Antitumor efficacy of agents was estimated. Lactate level, LDH activity and the state of mitochondrial electron transport chain in tumor cells as well as phagocytic activity and reactive oxygen species (ROS) production of tumor-associated macrophages (TAM) were studied. Results: Combined administration of DCA and ВС1 resulted in 89.8% tumor growth inhibition (p < 0.001), what is by 22.5% (p < 0.05) higher that that of DCA alone. This combined treatment was accompanied with a decrease of lactate level in tumor tissue by 30% (p < 0.05) and significant elevation of LDH activity by 70% (p < 0.01). Increased level of NO-Fe-S clusters and 2-fold reduction of Fe-S cluster content were revealed in tumor tissue of mice after DCA and BC1 administration. It was shown that combined therapy did not effect TAM quantity and their phagocytic activity but stimulated ROS production by TAMs by 78% (p < 0.05) compared to this index in control animals. Conclusion: Antiangiogenic agent ВС1 in combination with DCA considerably enhances antitumor activity of DCA via significant decrease of Fe-S-containing protein level resulted from substantial elevation of nitrosylation of these proteins. Key Words: Ehrlich carcinoma, dichloroacetate, aconitine-containing agent, tumor-associated macrophages, mitochondrial electron transport chain.
en
Інститут експериментальної патології, онкології і радіобіології ім. Р.Є. Кавецького НАН України
Experimental Oncology
Original contributions
Aconitine-containing agent enhances antitumor activity of dichloroacetate against Ehrlich carcinoma
Article
published earlier
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
title Aconitine-containing agent enhances antitumor activity of dichloroacetate against Ehrlich carcinoma
spellingShingle Aconitine-containing agent enhances antitumor activity of dichloroacetate against Ehrlich carcinoma
Pyaskovskaya, O.N.
Boychuk, I.V.
Fedorchuk, A.G.
Kolesnik, D.L.
Dasyukevich, O.I.
Solyanik, G.I.
Original contributions
title_short Aconitine-containing agent enhances antitumor activity of dichloroacetate against Ehrlich carcinoma
title_full Aconitine-containing agent enhances antitumor activity of dichloroacetate against Ehrlich carcinoma
title_fullStr Aconitine-containing agent enhances antitumor activity of dichloroacetate against Ehrlich carcinoma
title_full_unstemmed Aconitine-containing agent enhances antitumor activity of dichloroacetate against Ehrlich carcinoma
title_sort aconitine-containing agent enhances antitumor activity of dichloroacetate against ehrlich carcinoma
author Pyaskovskaya, O.N.
Boychuk, I.V.
Fedorchuk, A.G.
Kolesnik, D.L.
Dasyukevich, O.I.
Solyanik, G.I.
author_facet Pyaskovskaya, O.N.
Boychuk, I.V.
Fedorchuk, A.G.
Kolesnik, D.L.
Dasyukevich, O.I.
Solyanik, G.I.
topic Original contributions
topic_facet Original contributions
publishDate 2015
language English
container_title Experimental Oncology
publisher Інститут експериментальної патології, онкології і радіобіології ім. Р.Є. Кавецького НАН України
format Article
description Significant variability of anticancer efficacy of dichloroacetate (DCA) stimulated an active search for the agents capable to enhance it antitumor action. Therefore, the aim of this work is the study of capability of aconitine-containing antiangiogenic agent BC1 to enhance anticancer activity of DCA against Ehrlich carcinoma. Materials and Methods: DCA (total dose was 1.3 g/kg of b.w.) and BC1 (total dose was 0.9 mg/kg of b.w.) were administered per os starting from the 2nd and 3rd days, respectively (8 admini­strations for each agent). Antitumor efficacy of agents was estimated. Lactate level, LDH activity and the state of mitochondrial electron transport chain in tumor cells as well as phagocytic activity and reactive oxygen species (ROS) production of tumor-associated macrophages (TAM) were studied. Results: Combined administration of DCA and ВС1 resulted in 89.8% tumor growth inhibition (p < 0.001), what is by 22.5% (p < 0.05) higher that that of DCA alone. This combined treatment was accompanied with a decrease of lactate level in tumor tissue by 30% (p < 0.05) and significant elevation of LDH activity by 70% (p < 0.01). Increased level of NO-Fe-S clusters and 2-fold reduction of Fe-S cluster content were revealed in tumor tissue of mice after DCA and BC1 administration. It was shown that combined therapy did not effect TAM quantity and their phagocytic activity but stimulated ROS production by TAMs by 78% (p < 0.05) compared to this index in control animals. Conclusion: Antiangiogenic agent ВС1 in combination with DCA considerably enhances antitumor activity of DCA via significant decrease of Fe-S-containing protein level resulted from substantial elevation of nitrosylation of these proteins. Key Words: Ehrlich carcinoma, dichloroacetate, aconitine-containing agent, tumor-associated macrophages, mitochondrial electron transport chain.
issn 1812-9269
url https://nasplib.isofts.kiev.ua/handle/123456789/145487
citation_txt Aconitine-containing agent enhances antitumor activity of dichloroacetate against Ehrlich carcinoma / O.N. Pyaskovskaya, I.V. Boychuk, A.G. Fedorchuk, D.L. Kolesnik, O.I. Dasyukevich, G.I. Solyanik // Experimental Oncology. — 2015. — Т. 37, № 3. — С. 192-196. — Бібліогр.: 27 назв. — англ.
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fulltext 192 Experimental Oncology 37, 192–196, 2015 (September) ACONITINE-CONTAINING AGENT ENHANCES ANTITUMOR ACTIVITY OF DICHLOROACETATE AGAINST EHRLICH CARCINOMA O.N. Pyaskovskaya, I.V. Boychuk, A.G. Fedorchuk, D.L. Kolesnik, O.I. Dasyukevich, G.I. Solyanik* R.E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, NAS of Ukraine, Kyiv 03022, Ukraine Significant variability of anticancer efficacy of dichloroacetate (DCA) stimulated an active search for the agents capable to enhance it antitumor action. Therefore, the aim of this work is the study of capability of aconitine-containing antiangiogenic agent BC1 to en- hance anticancer activity of DCA against Ehrlich carcinoma. Materials and Methods: DCA (total dose was 1.3 g/kg of b.w.) and BC1 (total dose was 0.9 mg/kg of b.w.) were administered per os starting from the 2nd and 3rd days, respectively (8 admini strations for each agent). Antitumor efficacy of agents was estimated. Lactate level, LDH activity and the state of mitochondrial electron transport chain in tumor cells as well as phagocytic activity and reactive oxygen species (ROS) production of tumor-associated macrophages (TAM) were studied. Results: Combined administration of DCA and ВС1 resulted in 89.8% tumor growth inhibition (p < 0.001), what is by 22.5% (p < 0.05) higher that that of DCA alone. This combined treatment was accompanied with a decrease of lactate level in tumor tissue by 30% (p < 0.05) and significant elevation of LDH activity by 70% (p < 0.01). Increased level of NO-Fe-S clusters and 2-fold reduction of Fe-S cluster content were revealed in tumor tissue of mice after DCA and BC1 ad- ministration. It was shown that combined therapy did not effect TAM quantity and their phagocytic activity but stimulated ROS production by TAMs by 78% (p < 0.05) compared to this index in control animals. Conclusion: Antiangiogenic agent ВС1 in com- bination with DCA considerably enhances antitumor activity of DCA via significant decrease of Fe-S-containing protein level re- sulted from substantial elevation of nitrosylation of these proteins. Key Words: Ehrlich carcinoma, dichloroacetate, aconitine-containing agent, tumor-associated macrophages, mitochondrial electron transport chain. The achievements of recent years in regard to genetic mechanisms of cell metabolic regulation, mitochondrial functioning and synthesis of macromo- lecules have turn an attention to energy metabolism of tumor cells and Warburg effect [1]. Numerous metabolic pathways which are supposed to be impor- tant for tumor growth and progression are considered as perspective targets for the development of effective anticancer drugs [2, 3]. Among such drugs dichloro- acetate (DCA) could be mentioned [4, 5]. It is known that DCA inhibits pyruvate dehydrogenase kinase what results in elevation of pyruvate dehydrogenase acti- vity what in turn promotes the shift of cell metabolism from glycolysis toward oxidative phosphorylation, i.e. the state of tumor cells when their proliferative acti- vity is decreased and apoptosis risk is enhanced [6, 7]. Apart from glycolysis inhibition, DCA may cause significant decrease of lactacidosis level in tumor cell microenvironment which is known to promote tumor cell viability [8]. For 30 years DCA has been used for correction of lacticemia, caused by high intensity of glycolysis or defective cell respiration. In 2008 Canadian scien- tists have shown that DCA is highly effective against many tumor types and possesses low toxicity toward normal tissues [9]. Such features of DCA have moti- vated an initiation of active scientific studies of this drug in oncology. At present time, the data on anticancer efficacy of DCA are in large part contradictory. From one side, there are conclusive evidences obtained in ex- periments in vitro and in vivo on feasibility of DCA use as anticancer drug [10]. There has been documented an ability of DCA to suppress proliferation of many tumor cell lines with no impact on their death rates [6, 11]. Also, it has been shown that DCA induces apop- tosis only at high doses and is active against cells with defective electron-transport chain [12, 13]. From other side, as it has been shown in preclinical studies DCA is ineffective against many experimental tumor models including lung cancer, neuroblastoma, lymphoma, sar- coma [14]. An analysis of the results of clinical studies performed in recent years has also revealed significant variability of anticancer efficacy of DCA: from its high efficacy to complete inefficacy [15, 16]. In the last years there is an active search for the agents capable to enhance anticancer action of DCA. Among such agents a special place is oc- cupied by inhibitors of tumor angiogenesis providing the deficiency of the main energetic substrates (glu- cose and oxygen) via suppression of tumor vessel development [17]. Therefore, the aim of this work is the study of ca- pability of antiangiogenic agent to enhance anticancer activity of DCA against Ehrlich carcinoma. Aconitine-containing agent ВС1 has been used as an inhibitor of tumor angiogenesis. As it has been shown earlier, ВС1 exerts its antiangiogenic action via inhibition of endothelial cell proliferation which under- lies its significant antitumor activity against tumors with angiogenesis-dependent growth [18, 19]. Submitted: May 18, 2015. *Correspondence: E-mail: gsolyanik@gmail.com Abbreviations used: DCA — dichloroacetate; LDH — lactate dehydro- genase; MtETC — mitochondrial electron-transport chain; ROS — re- active oxigen species; TAM — tumor-associated macrophages. Exp Oncol 2015 37, 3, 192–196 Experimental Oncology 37, 192–196, 2015 (September) 193 MATERIALS AND METHODS Experimental animals and tumor strain. The study was carried out using 2.0–2.5 months white outbred mice weighting 18.5–21 g, bred at animal facility of R.E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology of the NAS of Ukraine (Kyiv, Ukraine). Animal study protocols and opera- tion procedures were carried out in accordance with the main requirements to keeping and working with laboratory animals and to the rules of local Bioethics Committee. E h r l i c h c a rc i n o m a c e l l s ( 1 . 2 • 10 6 c e l l s in 0.2 ml of physiological solution per animal) were transplanted subcutaneously in dorsal forelimb region. Design of the study. After tumor cell transplanta- tion the animals were distributed into 4 groups: control one and three experimental (Table 1). 0.4 ml of aque- ous DCA (Sigma, USA) solution were administered per os to animals from 1st and 3rd groups in a day starting from 2nd day after tumor cell transplantation (8 administrations in total). The total DCA dose was 1.3 g/kg of animal body weight. The mice from 3rd group were also treated with aconitine-containing agent ВС1 (Aksomed, Ukraine) each second day starting from 3rd day after tumor cell transplantation (8 administrations in total). Total ВС1 dose (by aconi- tine content) was 0.9 mg/kg of animal body weight. The animals from 2nd group were administered with ВС1 only, using the same dosage and regimen of administration as these for 3rd group. Animals from control group received water for injections by the cor- responding scheme. Table 1. The design of experiment Groups of mice Number of mice/group Type of treatment Control 12 H2O Experimental-1 10 DCA Experimental-2 7 ВС1 Experimental-3 10 DCA + ВС1 After tumor appearance its diameter has been measured triply per week using caliper. Tumor volumes were calculated by formula: V = 3.14 • d3/8, where d — tumor diameter. Antitumor activity was evaluated at 17th day after tumor cell transplantation with the use of tumor inhibi- tion index (D), calculated by the formula: D = (Vk – V) • 100% / Vk, where Vk and V — average tumor volumes in control and experimental groups, respectively. At the 2nd day after termination of the treatment (17 day of tumor growth) the animals were sacrificed under light ether narcosis. Tumor tissue was isolated. Then the effect of DCA on lactate level, lactate dehy- drogenase (LDH) activity, functional state of mitochon- drial electron-transport chain (MtETC), counts and functional activity of tumor-associated macrophages (TAM) have been analyzed. Each index has been evalu- ated in tumor tissue from 4–6 mice per each group. Lactate level in tumor tissue was determined by spectrophotometry using LDH (Sigma, USA). The method is based on the reaction of lactate oxidation into pyruvate by LDH resulting in generation of NADH from NAD [20]. Total LDH activity in frozen tumor tissue was mea- sured by spectrophotometric method which is based on determination of enzyme kinetics when pyruvate is converted to lactate [20]. For analysis of functional activity of MtETC in tumor cells, tumor tissue was cut into the samples of cylindrical shape (d = 4.0 mm, l = 25–35 mm), frozen and stored at −70 °C. EPR analysis of the samples was performed at 77 К using spectrometer Е-109 Varian (USA) at potential sweep speed of 500 Е/min, modu- lation amplitude of 1.25•10 Е, power of super-high- frequency radiation of 10.0 mW, constant session of apparatus of 1.0 s. The levels of reduced non heme iron-sulfur (Fe-S) centers (g = 1.94) of MtETC proteins, nitrosyl (NO) complexes of heme iron (gсер = 2.01) and Fe-S nitrosyl complexes (gсер = 2.03) were determined by the data of EPR spectra. Phagocytic activity (engulfing capacity) of TAM was determined by flow cytometer FACSCalibur (Bec- ton Dickinson, USA). TAMs were identified with the use of anti-СD14 antibodies according to the instructions of the manufacturer (Becton Dickinson, USA). Analysis of phagocytic activity of СD14+ cells was performed with the use of FITC-labeled staphylococcus [21]. Reactive oxigen species (ROS) production by TAM was carried out using 2.7-dichlorodihydrofluorescein diacetate (Sigma, USA) [21] by flow cytometry. Statistical analysis of the data was performed with the use of descriptive statistics, parametric Student’s t-test and nonparametric Mann — Whitney U test, with the use of Microsoft Excel, Microcal Origin and Statistica. The data in the tables and figures are presented as mean ± standard error. RESULTS AND DISCUSSION The performed studies have shown sufficiently high antitumor activity of DCA against Ehrlich carcinoma. The percent of tumor growth inhibition after the therapy (17th day of tumor growth) achieved 73.3% (Table 2), what is in complete accordance with the results pre- sented in the study [22]. Table 2. Antitumor efficacy of DCA, BC1 and their combination against Ehrlich carcinoma Groups of mice Tumor volume, mm3 Inhibition index, % Control 7828.0 ± 893.0 − Experimental-1 2092.0 ± 380.3* 73.3 Experimental-2 5306.8 ± 1595.3 − Experimental-3 805.1 ± 137.8* 89.8 Note: *p < 0.05. In the group of animals treated with ВС1, there was observed a tendency to inhibition of Ehrlich carcinoma growth which did not reach statistical significance due to variability of tumor volumes. This result is in agree- ment with our previous data on anticancer activity of BC1 against solid form of Ehrlich carcinoma. In this study growth kinetic analysis has shown that adminis- tration of BC1 (at the total dose of 0.9 mg/kg of b.w.) 194 Experimental Oncology 37, 192–196, 2015 (September) did not affect tumor volume till 15th day and only after that tumor inhibition indices constantly increased growing up to 77.3% in a week after therapy comple- tion [23]. Despite the fact that administration of antiangio- genic aconitine-containing drug ВС1 to mice did not cause significant inhibition of tumor growth, intro- duction of this agent into DCA-based therapy signifi- cantly enhanced anticancer action of DCA. Combined administration of DCA and ВС1 resulted in 89.8% tumor growth inhibition (p < 0.001), what is by 22.5% (p < 0.05) higher that that of DCA alone (see Table 2). Antitumor activity of DCA administered alone or in combination with BC1 was accompanied with sta- tistically significant decrease of lactate level in tumor tis- sue by 22% (p < 0.05) and 30% (p < 0.05), respectively (Fig. 1, a), which may be caused by activation of DCA- dependent oxidative decarboxylation of pyruvate and its conversion to acetyl-coenzyme А (the main substrate for Krebs cycle). Adaptive reaction of the cell on lactate level decrease is elevation of LDH activity; LDH activity increase by 120% (p < 0.001) and 70% (p < 0.01) was observed in mice treated with DCA and DCA + ВС1, respectively (Fig. 1, b). Such activation of the enzyme could not compensate completely the decrease of lac- tate level at the background of DCA administration what could be possibly caused by higher rate of the pyruvate conversion to acetyl-coenzyme А than to lactate. In the work [24] it has been shown that the DCA-dependent decrease of lactate level and increase of LDH activity in human colorectal cancer cells and prostate carci- noma cells has been accompanied with significant decrease of pyruvate-to-lactate exchange rate. 0 20 40 60 80 100 120 Control DCA DCA + BC1 Tu m or la ct at e le ve l ( % ) 0 50 100 150 200 250 Control DCA DCA + BC1 LD H ac tiv ity (% ) * * * * Fig. 1. Lactate level (a) and LDH activity (b) in tumor tissue of LLC/R9 bearing mice: control, DCA-treated and DCA + BC1- treated groups. *p < 0.05 compared to control Our study has shown that administration of DCA alone or DCA in combination with ВС1 resulted in signifi- cant increase of ROS production in tumor cells as well as normal cells involved in tumor process (TAM). High ROS production in tumor cells was manifested in en- hancement of nitrosylation both heme proteins (with generation of NO-heme complexes) and non-heme proteins (with generation of dinitrosyl-iron complexes; DNIC). The latest play a key role in MtETC functioning. As one may see on Fig. 2, administration of DCA alone or in combination with ВС1 caused statistically significant elevation of DNIC level (Fig. 2, a) by 140% (p < 0.05) and 180% (p < 0.01), as well as NO-heme complexes (Fig. 2, b) by 85% (p < 0.05) and 43% (p < 0.05), respectively. 0 50 100 150 200 250 300 350 Control DCA DCA + BC1 DN IC le ve l ( % ) 0 50 100 150 200 250 300 350 Control DCA DCA + BC1 Le ve l o f N O -h em e (% )* * * * Fig. 2. Levels of DNIC (a) and NO-heme (b) in tumor tissue of LLC/R9 bearing mice: control, DCA-treated and DCA + BC1- treated groups. *p < 0.05 compared to control It is known that generation of NO-Fe-S clusters (DNIC) could lead to inactivation of Fe-S cluster proteins in MtETC, disturb coupling of oxidative phosphorylation with respiration and cause tumor cell death [25]. As it is shown on Fig. 3, significant in- crease of DNIC level in tumor tissue of mice after DCA administration did not lead to decrease of Fe-S cluster content, but at the same time Fe-S cluster content was 2-fold lower (p < 0.01) in tumor tissue of mice treated with DCA and ВС1 than that indices in control group of animals. These results have indicated that stimula- tion of ROS production induced by DCA administration did not cause MtETC dysfunction and had insignificant impact in anticancer activity of this agent. In contrary, stimulation of ROS production observed after com- bined administration of DCA and ВС1 and decreased levels of Fe-S clusters made a contribution in the antitumor activity of combined therapy. 0 20 40 60 80 100 120 140 Control DCA DCA + BC1 Le ve l o f F e- S cl us te rs (% ) * Fig. 3. Levels of Fe-S clusters in tumor tissue of LLC/R9 be aring mice: control, DCA-treated and DCA + BC1-treated groups. *p < 0.01 compared to control It is known that nitric oxide species appear in tumor tissue via its increased synthesis by mitochondrial NO- synthase (a constitutive isoform localized on internal mitochondrial membrane) and also by inducible NO- synthase of TAM. TAMs develop from circulating monocytes recruited in the region of tumor growth because recognition and elimination of transformed cells is among physiologic functions of immune system [26]. Recruited mono- Experimental Oncology 37, 192–196, 2015 (September) 195 cytes in tumor lesion are capable to undergo functional diversification in two populations: macrophages with М2-phenotype which reveal proangiogenic action promoting tumor growth and progression; macro- phages with М1-phenotype which participate in acti- vation of antitumor immunity and reveal an expressed cytotoxic action against tumor cells [27]. Antitumor action of TAMs could be exerted by two mechanisms: phagocytic activity and ROS production. Analysis of functional activity of TAM has shown significant increase of ROS production level by 241.0% (p < 0.01) in tumor tissue of mice after DCA admini- stration at monoregimen compared to control ani- mals (Fig. 4, c). The high level of ROS is determined by an expressed tendency to increased TAM counts in tumor tissue (Fig. 4, a) as well as activation of ROS production by TAM. DCA administration also led to activation of TAM phagocytic activity (Fig. 4, b): in DCA-treated animals phagocytic activity of TAM was by 70.5% (p < 0.05) higher than that in control mice. Such activation of cytotoxic activity of TAM evidences on significant impact of TAM on antitumor activity of DCA. 0 50 100 150 200 250 300 Nu m be r o f T AM (% ) 0 50 100 150 200 250 En gu lfi ng c ap ac ity o f T AM (% ) 0 100 200 300 400 500 Le ve l o f R O S (% ) Co nt ro l DC A DC A + BC 1 Co nt ro l DC A DC A + BC 1 Co nt ro l DC A DC A + BC 1 * * * Fig. 4. Number of TAM (a), their phagocytic activity (b) and ROS production (c): control, DCA-treated and DCA + BC1-treated groups. *p < 0.05 compared to control It is necessary to note that an effect of DCA com- bined with ВС1 toward counts and functional activity of TAM differed from that of DCA alone. As it is shown on Fig. 4, the combined therapy has no effect on TAM quantity and their phagocytic activity. After the com- bined therapy ROS production by TAM increased by 78% (p < 0.05) compared to this index in control animals but was significantly lower compared to cor- responding index in mice treated with DCA alone. So, this fact points on insignificant impact of cytotoxic activity of TAM in sufficiently high antitumor activity of DCA in combination with ВС1. In conclusion, the presented results have demon- strated that DCA exerts significant antitumor activity against Ehrlich carcinoma mainly via induced activa- tion of cytotoxic activity of TAM. Antiangiogenic agent ВС1 in combination with DCA significantly enhances antitumor activity of DCA via significant decrease of Fe- S-containing protein level resulted from significant elevation of nitrosylation of these proteins. REFERENCES 1. Warburg O. On the origin of cancer cells. Science 1956; 123: 309–14. 2. Jha MK, Suk K. Pyruvate dehydrogenase kinase as a po- tential therapeutic target for malignant gliomas. 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