Abstract 1101: Visualization of epithelial-mesenchymal transition in inflammatory microenvironment-colorectal cancer network in vitro and in vivo

Abstract

Abstract Background: Epithelial-mesenchymal transition (EMT) is a biologic process by which epithelial cancer cells acquire mesenchymal phenotype with malignant properties for invasion and metastasis, leading to poor prognosis. Inflammatory microenvironment has been shown to be responsible for the development and progression of colorectal cancer (CRC). However, the precise role of inflammatory microenvironment in the EMT-related tumor progression remains unclear because EMT network is regulated by complex crosstalk between tumor and normal cells. In this study, we developed a fluorescence-guided live-cell imaging system for the spatiotemporal visualization of EMT state, and assessed the in vitro and in vivo visualization of EMT state in human CRC cells under the inflammatory microenvironment. Methods: We used two human CRC cell lines, HCT116 and RKO. The promoter of mesenchymal marker vimentin was used for inducing the EMT-dependent red fluorescence protein (RFP) expression in human CRC cells. The RFP expression was quantitatively analyzed to evaluate its association with EMT-related markers and malignant phenotype. Inflammatory cytokines, IL-1β (1 ng/ml) and TNF-α (20 ng/ml), or co-culture with inflammatory mouse macrophage cell line RAW264.7 stimulated by lipopolysaccharide (LPS) (200 ng/mL) were used as an inflammatory microenvironment. Biodistribution of EMT cells was analyzed using in vivo experiments with primary and metastatic CRC xenograft tumors. Results: Inflammatory cytokines reversely induced the RFP expression in association with EMT-related malignant phenotype, such as morphologic change, EMT marker modulation, and invasion ability, in HCT116 and RKO cells. Co-culture with LPS-stimulated inflammatory macrophages also induced the RFP expression by secreting inflammatory cytokines. In vivo experiments revealed that EMT cells were detected within tumor tissues at colon, liver and peritoneum. Conclusions: Our results suggest that inflammatory microenvironment has a great potential to induce EMT program in CRC cells. This fluorescence-guided EMT imaging system is a useful tool for monitoring the EMT state in the inflammation microenvironment-CRC network in vitro and in vivo. Citation Format: Hiroshi Tazawa, Takeshi Ieda, Shuya Yano, Satoru Kikuchi, Shinji Kuroda, Toshiaki Ohara, Kazuhiro Noma, Hiroyuki Kishimoto, Masahiko Nishizaki, Shunsuke Kagawa, Takashi Saitou, Takeshi Imamura, Toshiyoshi Fujiwara. Visualization of epithelial-mesenchymal transition in inflammatory microenvironment-colorectal cancer network in vitro and in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1101.