Basic Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 14, 2016; 22(22): 5193-5200
Published online Jun 14, 2016. doi: 10.3748/wjg.v22.i22.5193
Chitooligosaccharides promote radiosensitivity in colon cancer line SW480
Fu-Shi Han, Shi-Jie Yang, Mou-Bin Lin, Ying-Qun Chen, Ping Yang, Jin-Ming Xu
Fu-Shi Han, Jin-Ming Xu, Department of Imaging, Tongji University Affiliated Yangpu Hospital, Shanghai 200090, China
Shi-Jie Yang, Tongji University School of Medicine, Shanghai 200092, China
Mou-Bin Lin, Department of General Surgery, Tongji University Affiliated Yangpu Hospital, Shanghai 200090, China
Ying-Qun Chen, Department of Traditional Chinese Medicine, Tongji University Affiliated Yangpu Hospital, Shanghai 200090, China
Ping Yang, Department of Gastroenterology, Tongji University Affiliated Yangpu Hospital, Shanghai 200090, China
Author contributions: Han FS, Yang SJ and Lin MB designed research; Han FS, Yang SJ, Lin MB, Chen YQ, Yang P and Xu JM performed research; Yang SJ, Lin MB and Chen YQ contributed new reagents/analytic tools; Han FS, Yang P and Xu JM analyzed data; and Han FS and Xu JM wrote the paper.
Supported by National Natural Science Foundation of China, No. 81272480.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Jin-Ming Xu, Chief Physician, Department of Imaging, Tongji University Affiliated Yangpu Hospital, No. 450 Tengyue Road, Shanghai 200090, China. xu10611@hotmail.com
Telephone: +86-21-65690520
Received: January 24, 2016
Peer-review started: January 25, 2016
First decision: February 18, 2016
Revised: March 2, 2016
Accepted: March 18, 2016
Article in press: March 18, 2016
Published online: June 14, 2016
Processing time: 129 Days and 18.6 Hours
Abstract

AIM: To investigate the anti-proliferation and radiosensitization effect of chitooligosaccharides (COS) on human colon cancer cell line SW480.

METHODS: SW480 cells were treated with 0, 1.0, 2.0, 3.0, 4.0 and 5.0 mg/mL of COS for 48 h. CCK-8 assay was employed to obtain the cell survival ratio of SW480 cells, and the anti-proliferation curve was observed with the inhibition ratio of COS on SW480 cells. The RAY + COS group was treated with 1.0 mg/mL of COS for 48 h, while both the RAY and RAY+COS groups were exposed to X-ray at 0, 1, 2, 4, 6 and 8 Gy, respectively. Clonogenic assay was used to analyze cell viability in the two groups at 10 d after treatment, and a cell survival curve was used to analyze the sensitization ratio of COS. The RAY group was exposed to X-ray at 6 Gy, while the RAY+COS group was treated with 1.0 mg/mL of COS for 48 h in advance and exposed to X-ray at 6 Gy. Flow cytometry was employed to detect cell cycle and apoptosis rate in the non-treatment group, as well as in the RAY and RAY + COS groups after 24 h of treatment.

RESULTS: COS inhibited the proliferation of SW480 cells, and the inhibition rate positively correlated with the concentration of COS (P < 0.01). Cell viability decreased as radiation dose increased in the RAY and RAY+COS groups (P < 0.01). Cell viabilities in the RAY+COS group were lower than in the RAY group at all doses of X-ray exposure (P < 0.01), and the sensitization ratio of COS on SW480 cells was 1.39. Compared with the non-treatment group, there was a significant increase in apoptosis rate in both the RAY and RAY + COS groups; while the apoptosis rate in the RAY+COS group was significantly higher than in the RAY group (P < 0.01). In comparing these three groups, the percentage of G2/M phase in both the RAY and RAY + COS groups significantly increased, and the percentage of the S phase and G0/G1 phase was downregulated. Furthermore, the percentage in the G2/M phase was higher, and the percentage in the S phase and G0/G1 phase was lower in the RAY + COS group vs RAY group (P < 0.01).

CONCLUSION: COS can inhibit the proliferation of SW480 cells and enhance the radiosensitization of SW480 cells, inducing apoptosis and G2/M phase arrest.

Keywords: Chitooligosaccharides; Cancer of colon; Radiotherapy; Radiosensitization; Apoptosis; Cell cycle

Core tip: In this study, the colorectal cancer cell line SW480 that is homologous with colon-rectum was used as the research tool. It was confirmed that chitooligosaccharides (COS) not only directly blocked SW480 cell proliferation, but also enhanced radiotherapy effects. Furthermore, COS induced a large amount of SW480 cell apoptosis, and induced a large number of cells to remain in the G2/M phase with radiation-sensitive killing effect. Thus, the sensitivity of SW480 cells to radiation was effectively enhanced 1.39 times. This is beneficial for the therapeutic effect.