title: Downregulation of Enhancer of Zeste Homolog 2 (EZH2) is essential for the Induction of Autophagy and Apoptosis in Colorectal Cancer Cells.
abstract: Increasing evidence indicates that elevated expression of enhancer of zeste homolog 2 gene (EZH2) in many human malignant tumors acts a significant role in the oncogenic process. However, the underlying molecular mechanism is still unclarified. It is evident that apoptosis and autophagy of tumor cells is crucial for the tumorigenesis and progression of cancer, however, the exact role of EZH2 plays in apoptosis and autophagy has not been fully elucidated in colorectal cancer (CRC). Our previous study found that the expression level of EZH2 was higher in CRC tumor tissues than in the paired normal tissues using immunohistochemical analysis. We also recently found that the autophagy-related gene-related protein Ambra1 plays an important role in the autophagy pathway in CRC cells. In this study, mRNA and protein expression of EZH2 in four CRC cell lines were tested at first and RKO and HCT116 cells showed the highest levels among them. Here we transfected with EZH2-shRNA, or added DZNep (an EZH2 inhibitor) to RKO and HCT116 cells in order to detect the effect of EZH2 on autophagy via determining the change of the protein expression of LC3 and Ambra1. The outcome indicated an obvious decrease of autophagy level in cells transfected with EZH2-shRNA or DZNep. We also found the apoptotic rate of cells was elevated significantly after downregulation of EZH2. In addition, compared to control group, CRC cells transfected with EZH2-shRNA or added DZNep revealed a significantly increased G1 cell cycle rate and an obvious decrease in the G2 cell cycle rate. Further analysis showed that knockdown of EZH2 induced cell-cycle arrest in CRC cells. Meanwhile, downregulation of EZH2 in CRC cells induces autophagy and apoptosis. Taken together, our results suggest that EZH2 plays a critical role in autophagy and apoptosis in the progression of CRC, which potentially facilitates the development of an ideal strategy for combating colorectal cancer.
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou 215006, China. yaoyizhou2014@163.com.
authors.forename: Yizhou
authors.initials: Y
authors.lastname: Yao
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou 215006, China. lidechun1955@163.com.
authors.forename: Hao
authors.initials: H
authors.lastname: Hu
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou 215006, China. yaoyizhou2014@163.com.
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Gastrointestinal Surgery, Changshu No.2 Hospital, Suzhou 215500, China. chowgq@sina.com.
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Zhou
authors.affiliation: Department of Radiation Medicine, Medical College of Soochow University, Suzhou 215006, China. zengfu.shang@suda.edu.cn.
authors.forename: Zengfu
authors.initials: Z
authors.lastname: Shang
authors.affiliation: Department of General Surgery, The Second Affiliated Hospital of Soochow University, Suzhou 215006, China. wjyxd@163.com.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of General Surgery, The Affiliated Hospital of Jiangsu University, Zhenjiang 212001, China. doctorsunkang@126.com.
authors.forename: Kang
authors.initials: K
authors.lastname: Sun
authors.affiliation: Department of Pathology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China. hesongbing1979@suda.edu.cn.
authors.forename: Shenghua
authors.initials: S
authors.lastname: Zhan
authors.affiliation: Department of Oncology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China. strongeryy1985@163.com.
authors.forename: Zhengyuan
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Medical Engineering and Maintenance Center, Chinese PLA General Hospital, Beijing 100853, China. li_peiyao@163.com.
authors.forename: Peiyao
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou 215006, China. 1030705022@suda.edu.cn.
authors.forename: Guofeng
authors.initials: G
authors.lastname: Pan
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou 215006, China. 1130705026@suda.edu.cn.
authors.forename: Liang
authors.initials: L
authors.lastname: Sun
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou 215006, China. zxg45@hotmail.com.
authors.forename: Xinguo
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou 215006, China. captain_hsb@163.com.
authors.forename: Songbing
authors.initials: S
authors.lastname: He
keywords: EZH2;  DZNep;  apoptosis;  autophagy;  colorectal cancer;  shRNA