Abstract 2862: Tumor-targeting salmonella typhimurium a1-r inhibited angiogenesis of osteosarcoma cells visualized by color-coded imaging in the in vivo absorbable gelatin sponge assay

Abstract

Abstract INTRODUCTION We already have reported a color-coded imaging model that showed the sponge agngiogenesis assay using absorbable gelatin sponge implanted in nestin-driven green fluorescent protein (ND-GFP) nude mice and that osteosarcoma cells promote angiogenesis in this sponge assay. We report here that Salmonella typhimurium A1-R (A1-R) inhibits angiogenesis of osteosarcoma cells in the sponge angiogenesis assay in ND-GFP mice. METHODS Sponge was initially transplanted subcutaneously in the flank of transgenic ND-GFP nude mice. Seven days after transplantation of sponge, skin flaps were made and 143B-RFP human osteosarcoma cells expressing red fluorescent protein (RFP) were injected into the transplanted sponge. After establishment of tumors in the sponge, the control-group mice were treated with PBS via tail-vein injection and A1-R treated group with A1-R likewise. Skin flaps were made at days 14, 21, and 28 after transplantation of the sponge to allow imaging of vascularization in the sponge using a variable-magnification small animal imaging system and confocal fluorescence microscopy. RESULTS: Vessel length in the sponge was measured after treatment with FV10-ASW Fluoview software. Nascent blood vessels grew in the sponge in a time-dependent manner. A random 3 fields were quantified in each group). The mean length of ND-GFP expressing blood vessels in the sponge in mice with A1-R treated group were 9.40, 12.40, and 10.12 mm/mm2, at days 14, 21, and 28, respectively. The mean length of ND-GFP expressing blood vessels in the sponge in mice of the control group were 8.86, 14.50, and 15.81 mm/mm2 on day 14, 21, and 28, respectively. ND-GFP expressing blood vessels of the mice in the osteosarcoma cells treated with A1-R had shorter vessels than the control group (on days 28, P < 0.05), suggested the extent of nascent blood vessel growth was significantly inhibited by A1-R treatment. Besides, we evaluated the RFP colored area of the sponge in both groups, which almost represent the viable tumor size. The mean RFP colored area of A1-R treated group in the sponge were 4.49, 7.53 and 8.15 mm2, at days 14, 21, and 28, respectively and that of control group were 3.78, 6.40, and 7.49 mm2 at days 14, 21, and 28, respectively. The size of possibly viable RFP colored tumor area between A1-R treated group and control group at days 28 did not show significant area difference, indicated A1-R treated osteosarcoma cells showed shorter nascent vessel length than control group, not due to the tumor size difference but due to the difference of angiogenesis inhibitory effect. As a result of both outcomes above, the extent of nascent blood vessel growth was significantly inhibited by A1-R treatment on days 28. CONCLUSION: In the present study, we reported the effect of angiogenesis inhibition of A1-R in vivo sponge assay, and suggest A1-R has potential for anti-angiogenic target therapy for osteosarcoma. Citation Format: Tasuku Kiyuna. Tumor-targeting salmonella typhimurium a1-r inhibited angiogenesis of osteosarcoma cells visualized by color-coded imaging in the in vivo absorbable gelatin sponge assay [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2862. doi:10.1158/1538-7445.AM2017-2862