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

UNLABELLED: 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 2(nd) and 3(rd) 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 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.

Effect of dichloroacetate on Lewis lung carcinoma growth and metastasis.

UNLABELLED: A hallmark of malignancy is excessive tumor glycolysis, even in the presence of oxygen, which causes lactacidosis in the tumor microenvironment and favors tumor cell proliferation and survival. For this reason antimetabolic agents which target tumor cell metabolism are being researched extensively as promising anticancer drugs. AIM: To study the effect of lactacidosis on survival of Lewis lung carcinoma (LLC) cells at the conditions of nutritional substrate deficiency in vitro and evaluate antitumor and antimetastatic activity against LLC/R9 in vivo. MATERIALS AND METHODS: LLC variant LLC/R9 was used as experimental tumor model. Tumor cell viability was determined using trypan blue staining. Apoptosis level was counted with the use of Hoechst 33258 dye. Lactate content in the tumor tissue was evaluated by enzyme method with the use of lactate dehydrogenase. Reactive oxygen species was determined using 2.7-dichlorofluorescein diacetate. Effects of dichloroacetate (DCA) on the growth and metastasis of LLC/R9 were analyzed by routine procedures. Evaluation of DCA effect toward electron-transport chain (ETC) components was performed using EPR. RESULTS: It has been shown that at the conditions of lactacidosis and glucose deficiency, LLC/R9 cell viability in vitro was higher by 30% (p < 0.05) and apoptosis level was triply lower (p < 0.05) than these indices at the conditions of glucose deficiency only. In mice with transplanted LLC/R9 tumors treated for 3 weeks per os with DCA at the total dose of 1.5 g/kg of body weight starting from the next day after tumor transplantation, the primary tumor volume was just by 30% lower than that in control group. At the same time, the number and volume of lung metastases in animals treated with DCA were by 59% (p < 0.05) and 94% (p < 0.05) lower, respectively, than these indices in the control group. DCA treatment resulted in nearly 30% increase (p < 0.05) of lactate content in tumor tissue compared to that in the control, but did not affect significantly the levels of heme iron complexes with NO (at g med = 2.007) in mitochondrial ETC proteins and Fe-S cluster proteins (at g = 1.94) in tumor cells. CONCLUSIONS: It has been shown that lactacidosis significantly promoted LLC/R9 cell survival at the conditions of glucose deficiency in vitro. If LLC/R9 developed in vivo, DCA as the compound with antilactacidosis activity did not suppress significantly the primary tumor growth but exerted significant antimetastatic activity.