Abstract 1377: Vascular shutdown effects of tetra-arsenic oxide in solid murine tumors

Abstract

Abstract Tetra-arsenic oxide [As4O6, 2,4,6,8,9,10-Hexaoxa-1,3,5,7-tetraarsatricyclo(3.3.1.13,7) decane]- one kind of arsenic compound, has shown more potent antitumor effect on cervix cancer cells. As4O6 also showed an inhibitory effect on tube formation of endothelial cells in vitro. The aim of this study was investigate the vascular shutdown effects of As4O6 on TC-1 cell implanted mice. TC-1 cell, which is HPV 16 E6/E7 transfected cell, was used both in vitro and in vivo study. In vitro experiments: to assess cell viability MTT assay was employed, and morphology was determined by microscopy. In vivo experiments, 6 weeks old C57BL/6, female mice were used. 5′106 TC-1 cells were inoculated subcutaneously to abdomen and when tumor size reach to 350∼400 mm3 (12 to 14 days after inoculation when reaching a surface diameter of 8 to 10 mm), tumor bearing mice were randomly divided into two groups of PBS injected (n=14) and As4O6 (10 mg/kg b.w., i.p.) injected groups (n=14). Tumor volume was measured by caliper every two or three days for 3 weeks and recorded as volume diameter [longest surface length (a), width (b) and height (c), (a x b x c)]. Hoechst 33342 uptake method has been performed. One minute before harvest tumor tissue sections, Hoechst 33342 was injected and make frozen section. Tumor tissue were observed under 365nm microscope and photographed at x40. Each tumor image was constituted by 15∼35 pieces of view. Through MTT assay, it was shown cell growth inhibitory effects of As4O6 on TC-1 cell lines. Cell proliferation reduced to 52.74%, when treat 4.00 uM As4O6, IC50 value was 4.05 uM after 24 hours treatment. There were also many changes on morphology after 24hours of As4O6 treatment, include: cell number was reduced, cell membrane became weak, and cytoplasm got scarce. In TC-1 cells challenged C57BL/6 mice, As4O6 delayed tumor growth. 3 weeks after As4O6 treatment, the tumor volume suppressed nearly 89.8% compared with control group (p<0.05). Hoechst 33342 can stain tumor area which has vasculature. We detected that Hoechst 33342 stained areas was significantly disappeared in the central of the tumor tissue from one hour after As4O6 injection. While non-treated tumor tissue was 100% stained, one hour treated As4O6 tumor tissue was stained only 12.5 %. Conclusion: This study shows that As4O6 can make strong vascular shutdown effects on TC-1 cells implanted mice. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1377.