Basic Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Oct 14, 2016; 22(38): 8528-8539
Published online Oct 14, 2016. doi: 10.3748/wjg.v22.i38.8528
Special AT-rich sequence-binding protein 2 acts as a negative regulator of stemness in colorectal cancer cells
Ying Li, Yu-Hong Liu, Yu-Ying Hu, Lin Chen, Jian-Ming Li
Ying Li, Yu-Ying Hu, Lin Chen, Jian-Ming Li, Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, Guangdong Province, China
Yu-Hong Liu, Department of Pathology, Baoan Hospital, Southern Medical University, Shenzhen 518101, Guangdong Province, China
Jian-Ming Li, Department of Pathology, Soochow University Medical School, Suzhou 215123, Jiangsu Province, China
Author contributions: Li Y and Liu YH contributed equally to this work; Li Y, Liu YH and Li JM contributed to study concept and design; Li Y, Hu YY and Chen L contributed to data acquisition; Li Y, Hu YY and Li JM contributed to statistical analysis; Li Y and Li JM contributed to data analysis and interpretation; Li Y and Li JM contributed to drafting of the manuscript for important intellectual content; Liu YH contributed to technical or material support; Li JM contributed to obtaining funding; and Li JM contributed to study supervision.
Supported by National Natural Science Foundation of China, No. 81525020, No. 81502033, No. 81272300 and No. 31570753.
Institutional review board statement: This study was approved by the Institutional Review Board of Nanfang Hospital, Southern Medical University, China.
Conflict-of-interest statement: The authors declare that there are no conflicts of interest.
Data sharing statement: Technical appendix, statistical code, and dataset available from the corresponding author at lixinyue@fimmu.com. Participants gave informed consent for data sharing.
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: Jian-Ming Li, MD, PhD, DSc, Professor, Chief, Department of Pathology, Nanfang Hospital, Southern Medical University, No. 1838 Guangzhou Road North, Guangzhou 510515, Guangdong Province, China. lixinyue@fimmu.com
Telephone: +86-512-65882673
Received: May 19, 2016
Peer-review started: May 20, 2016
First decision: July 12, 2016
Revised: July 29, 2016
Accepted: August 19, 2016
Article in press: August 19, 2016
Published online: October 14, 2016
Processing time: 145 Days and 22.1 Hours
Abstract
AIM

To find the mechanisms by which special AT-rich sequence-binding protein 2 (SATB2) influences colorectal cancer (CRC) metastasis.

METHODS

Cell growth assay, colony-forming assay, cell adhesion assay and cell migration assay were used to evaluate the biological characteristics of CRC cells with gain or loss of SATB2. Sphere formation assay was used to detect the self-renewal ability of CRC cells. The mRNA expression of stem cell markers in CRC cells with upregulated or downregulated SATB2 expression was detected by quantitative real-time polymerase chain reaction. Chromatin immunoprecipitation (ChIP) was used to verify the binding loci of SATB2 on genomic sequences of stem cell markers. The Cancer Genome Atlas (TCGA) database and our clinical samples were analyzed to find the correlation between SATB2 and some key stem cell markers.

RESULTS

Downregulation of SATB2 led to an aggressive phenotype in SW480 and DLD-1 cells, which was characterized by increased migration and invasion abilities. Overexpression of SATB2 suppressed the migration and invasion abilities in SW480 and SW620 cells. Using sequential sphere formation assay to detect the self-renewal abilities of CRC cells, we found more secondary sphere formation but not primary sphere formation in SW480 and DLD-1 cells after SATB2 expression was knocked down. Moreover, most markers for stem cells such as CD133, CD44, AXIN2, MEIS2 and NANOG were increased in cells with SATB2 knockdown and decreased in cells with SATB2 overexpression. ChIP assay showed that SATB2 bound to regulatory elements of CD133, CD44, MEIS2 and AXIN2 genes. Using TCGA database and our clinical samples, we found that SATB2 was correlated with some key stem cell markers including CD44 and CD24 in clinical tissues of CRC patients.

CONCLUSION

SATB2 can directly bind to the regulatory elements in the genetic loci of several stem cell markers and consequently inhibit the progression of CRC by negatively regulating stemness of CRC cells.

Keywords: Special AT-rich sequence-binding protein 2, Colorectal cancer, Stemness, Metastasis

Core tip: We found that special AT-rich sequence-binding protein 2 (SATB2) had a suppressive effect on the tumor growth, adhesion and migration in vitro. Moreover, SATB2 could negatively regulate the stemness of colorectal cancer (CRC) cells by directly binding to the regulatory elements in the genetic loci of several stem cell markers. Our study provides a new mechanism for the involvement of SATB2 in CRC progression and helps us to better understand the metastasis traits of cancer stem cells.