Experimental studies of antitumor effects ofangiogenesis inhibitor TNP-470 with a chemotherapeutic agent on a malignant brain tumor.

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The aim of this study is to investigate antitumor effects of angiogenesis inhibitor TNP-470 alone and in combination with a chemotherapeutic agent on rat brain tumors.Rat brain endotherial cells and rat C6 glioma cells were grown as mono ayers. Triple-label accumulation studies (^<14>C-TdR,^3H-FDG, ^<99m>Tc-DTPA) were perforated. The cells and medium were weighed and assayed for radioactivity after various periods of incubation (10-60 min). Uptake values of tracers, which were corrected for extracellular fluid and damaged cells using ^<99m>Tc-DTPA, were quantified as a corrected cell-to-medium concentration ratio. Ki values of ^<14>C-TdR and ^3H-FDG were calculated. Proliferation (Ki for ^<14>C-TdR) and glucose metabolism (Ki fo ^3H-FDG) of rat brain endothelial cells increased in a dose - dependent manner of VEGF concentration of medium (0.5-25 ng/ml). The Ki values of ^<14>C-TdR and ^3H-FDG were decreased under various conceSration of TNP470 (10 ng/ml - 5 μ g/ml) in brain endotherial … More cells. In contrast, the antiproliferaion effects on C6 glioma cells were only observed at the highest concentration of TNP470.In an in vivo brain-tumor model, the therapeutic effects of TNP470 were also confirmed. TNP470 (30mg/kg) was given s.c. on days 6, 8, 10 following intracranial implantation of rat C6 glioma cells in Sprague-Dawley rats. On the 11th day after tumor implantation, autobiographic images were obtained using (^<14>C-methyl)-L-methionine (Met). The tracer uptake, represented as tumor/non-tumor (T/NT), was measured in rats treated with and without an intravenous injection of 30mg/kg of cytotoxic drug (ACNU) before or after TNP470 treatment, and control (neither TNP470 nor ACNU treatment). In TNP470-treated rats, tumor volume and Met-uptake were significantly reduced by 47% and 68% compared to the control, respectively. In combination regimens using angiogenesis inhibitor TNP470 and ACNU, both the tumor volume and Met uptake were lowest in the rats treated with the administration of TNP470 following ACNU treatment. The inhibitory effects of ACNU following TNP470 treatments were almost the same as those of TNP470 alone. Angiogenesis inhibitor TNP470 treatment following cytotoxic drugs is a promising protocol in tumor dormant therapy of brain tumors. Less