Abstract 5900: Transforming growth factor-beta (TGF-β) inhibitor modulates cancer stroma in a pancreatic cancer orthotopic mouse model

Abstract

Abstract Background: The tumor microenvironment (TME) contributes to the recalcitrance of this disease. Cancer-associated fibroblasts (CAFs) are thought to be important for the pancreatic cancer TME. Transforming growth factor-beta (TGF-β) has an important role for CAF induction. The present report describes the efficacy of a TGF-β-inhibitor to modulate pancreatic cancer stroma in an orthotopic mouse model. Materials and methods: BxPC-3 human pancreatic adenocarcinoma cells expressing green fluorescent protein (GFP) were implanted subcutaneously in athymic nude mice expressing red fluorescent protein (RFP). Established dual-color tumors, with GFP cancer cells and RFP stroma, were cut into small fragments and then implanted orthotopically onto the tail of the pancreas of RFP-expressing nude mice. Fourteen mice were randomized into control group (n = 7, vehicle, i.p., weekly, for 3 weeks) and treated group (n = 7, SB431542 (TGF-β inhibitor) 0.3 mg, i.p., weekly, for 3 weeks) when tumor diameters reached to 7 mm. Pancreatic cancer stroma was evaluated weekly for 3 weeks by real time intravital imaging with the FV-1000 confocal microscope. Stroma ratio, the percentage of the RFP fluorescence area from the stromal cells relative to the total fluorescence area, was calculated with ImageJ. Tumors were resected on the 21st day from the initial treatment for histological evaluation. Microvessel density using anti-CD31 antibody and expression of TGF-β were examined by immunohistochemical staining. Results: The GFP cancer cells and RFP stromal cells were distinctly imaged. The stroma ratio significantly decreased in the TGF-β-inhibitor treated mice compared to control untreated mice from day 7 to 21. TGF-β expression and microvessel density were reduced in the treated mice. Conclusions: The present study demonstrated selective anti-stromal and anti-angiogenetic activity of TGF-β inhibitor in a dual-color pancreatic orthotopic mouse model. These results indicate potential benefit of TGF-β inhibitor to facilitate drug delivery and improve chemotherapy of pancreatic cancer. Citation Format: Takashi Murakami, Yukihiko Hiroshima, Kentaro Miyake, Tasuku Kiyuna, Ho Kyoung Hwang, Kei Kawaguchi, Jonathan C. DeLong, Thinzer M. Lwin, Kentaro Igarashi, Ryusei Matsuyama, Ryutaro Mori, Takafumi Kumamoto, Takashi Chishima, Kuniya Tanaka, Michael Bouvet, Itaru Endo, Robert M. Hoffman. Transforming growth factor-beta (TGF-β) inhibitor modulates cancer stroma in a pancreatic cancer orthotopic mouse model [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 5900. doi:10.1158/1538-7445.AM2017-5900