Abstract 1613: A novel live imaging system for inflammation-induced epithelial-mesenchymal transition in colorectal cancers
Authors: Ieda Takeshi , Tazawa Hiroshi , Kikuchi Satoru , Kuroda Shinji , Ohara Toshiaki , Noma Kazuhiro , Kishimoto Hiroyuki , Nagasaka Takeshi , Nishizaki Masahiko , Kagawa Shunsuke , Fujiwara Toshiyoshi 
Published: July 2016

Background: Epithelial-mesenchymal transition (EMT) is a biological process, by which epithelial cancer cells acquire the mesenchymal phenotype with malignant properties for invasion and metastasis, leading to poor prognosis. However, as EMT is a reversible process and depends on tumor microenvironment, the precise role of EMT in cancer progression remains unclear. Inflammatory microenvironment has been shown to be responsible for the development and progression of colorectal cancers. To evaluate the implication of EMT in the inflammation-mediated colorectal cancer progression, a live imaging system for EMT is needed on the in vitro and in vivo experiments. In this study, we generated the EMT-detectable colorectal cancer cells by introducing mesenchymal cell marker promoter-driven fluorescence protein expression vector, and investigated whether inflammation-induced EMT is detectable in vitro.

Methods: To generate the EMT-detectable colorectal cancer cells HCT116-VIM635, human colorectal cancer cell line HCT116 was stably transfected with vimentin promoter-driven red fluorescence protein TurboFP635 expression vector. EMT was induced in HCT116-VIM635 cells by treatment with inflammatory cytokines, IL-1β (1 ng/ml) and TNF-α (20 ng/ml), or by co-culture with mouse macrophage cell line RAW264.7 in the presence of lipopolysaccharide (LPS) (200 ng/ml). The time-lapse live imaging was observed by confocal laser scanning microscope. Migration and invasion properties were examined by transwell chamber assays. The fluorescence intensity was measured by microplate reader and flow cytometric analysis. The expression of EMT-related markers was assessed by Western blot analysis.

Results: Administration of IL-1β or TNF-α induced the TurboFP635 expression in consistent with morphological change like mesenchymal phenotype in HCT116-VIM635 cells. Removal of these inflammatory cytokines attenuated the TurboFP635 expression and morphological change in HCT116-VIM635 cells, suggesting the detection of reverse EMT process in these cells. Inflammatory cytokines also induced the migration and invasion properties and the expression of EMT-related markers in HCT116-VIM635 cells. Moreover, co-culture with RAW264.7 cells stimulated with LPS also induced the TurboFP635 expression and morphological change as well as inflammatory cytokines in HCT116-VIM635 cells.

Conclusions: Our results suggest that this unique live imaging system for EMT has a great potential to detect reversible EMT process during inflammation-induced cancer progression. This system would be useful strategy to assess the role of EMT during inflammation-mediated cancer progression in vivo.

Citation Format: Takeshi Ieda, Hiroshi Tazawa, Satoru Kikuchi, Shinji Kuroda, Toshiaki Ohara, Kazuhiro Noma, Hiroyuki Kishimoto, Takeshi Nagasaka, Masahiko Nishizaki, Shunsuke Kagawa, Toshiyoshi Fujiwara. A novel live imaging system for inflammation-induced epithelial-mesenchymal transition in colorectal cancers. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1613.