Research Article Establishment of a Novel Model for Anticancer Drug Resistance in Three-Dimensional Primary Culture of Tumor Microenvironment Tatsuya Usui, 1 Masashi Sakurai, 2 Shuhei Enjoji, 3 Hideyoshi Kawasaki, 3 Koji Umata, 3 Takashi Ohama, 3 Nobuyuki Fujiwara, 3 Ryotaro Yabe, 3 Shunya Tsuji, 3 Hideyuki Yamawaki, 4 Shoichi Hazama, 5,6 Hiroko Takenouchi, 6 Masao Nakajima, 6 Ryouichi Tsunedomi, 6 Nobuaki Suzuki, 6 Hiroaki Nagano, 6 and Koichi Sato 3 1 Laboratory of Veterinary Toxicology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan 2 Laboratory of Veterinary Pathology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan 3 Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan 4 Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada, Aomori 034-8628, Japan 5 Department of Translational Research and Developmental Terapeutics against Cancer, School of Medicine, Yamaguchi University, 1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan 6 Department of Gastroenterological, Breast and Endocrine Surgery, Graduate School of Medicine, Yamaguchi University, 1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan Correspondence should be addressed to Tatsuya Usui; usui@yamaguchi-u.ac.jp Received 16 October 2016; Revised 28 November 2016; Accepted 6 December 2016 Academic Editor: Dominik Wolf Copyright © 2016 Tatsuya Usui et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Tumor microenvironment has been implicated in tumor development and progression. As a three-dimensional tumor microenvi- ronment model, air liquid interface (ALI) organoid culture from oncogene transgenic mouse gastrointestinal tissues was recently produced. However, ALI organoid culture system from tissues of colorectal cancer patients has not been established. Here, we developed an ALI organoid model from normal and tumor colorectal tissues of human patients. Both organoids were successfully generated and showed cystic structures containing an epithelial layer and surrounding mesenchymal stromal cells. Structures of tumor organoids closely resembled primary tumor epithelium. Expression of an epithelial cell marker, E-cadherin, a goblet cell marker, MUC2, and a fbroblast marker, vimentin, but not a myofbroblast marker, -smooth muscle actin (SMA), was observed in normal organoids. Expression of E-cadherin, MUC2, vimentin, and -SMA was observed in tumor organoids. Expression of a cancer stem cell marker, LGR5 in tumor organoids, was higher than that in primary tumor tissues. Tumor organoids were more resistant to toxicity of 5-fuorouracil and Irinotecan than colorectal cancer cell lines, SW480, SW620, and HCT116. Tese fndings indicate that ALI organoid culture from colorectal cancer patients may become a novel model that is useful for examining resistance to chemotherapy in tumor microenvironment. 1. Introduction Colorectal cancer is one of the most common cancers and is one of the leading causes of morbidity and mortality all over the world [1]. Te main causes of death in colorectal cancer are tumor progression and metastasis [2]. Primary tumor tissues contain a few cancer stem cells (CSCs), which have the capacity to metastasize and cause resistance to chemotherapy [3]. Terefore, the therapeutic target for progressed colorectal cancer focusing on CSCs has been explored in various types Hindawi Publishing Corporation Stem Cells International Volume 2016, Article ID 7053872, 10 pages http://dx.doi.org/10.1155/2016/7053872