Basic Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 28, 2016; 22(24): 5532-5539
Published online Jun 28, 2016. doi: 10.3748/wjg.v22.i24.5532
MicroRNA-21 promotes phosphatase gene and protein kinase B/phosphatidylinositol 3-kinase expression in colorectal cancer
Wei-Zhong Sheng, Yu-Sheng Chen, Chuan-Tao Tu, Juan He, Bo Zhang, Wei-Dong Gao
Wei-Zhong Sheng, Yu-Sheng Chen, Bo Zhang, Wei-Dong Gao, Department of General Surgery, Fudan University affiliated Zhongshan Hospital, Shanghai 200032, China
Chuan-Tao Tu, Juan He, Department of Digestion, Fudan University affiliated Zhongshan Hospital, Shanghai 200032, China
Author contributions: Sheng WZ and Chen YS contributed equally to this study, Sheng WZ, Chen YS and Gao WD designed research; Sheng WZ, Chen YS, Gao WD, Tu CT, He J and Zhang B performed research; Gao WD, Tu CT, He J and Zhang B contributed new reagents or analytic tools; Sheng WZ and Chen YS analyzed data; Sheng WZ and Gao WD wrote the paper.
Institutional review board statement: The study was reviewed and approved by the Fudan University affiliated Zhongshan Hospital Institutional review board.
Conflict-of-interest statement: We declare that there are no conflicts of interest to disclose.
Data sharing statement: No additional data are available.
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: Wei-Dong Gao, MD, Associate Professor, Department of General Surgery, Fudan University affiliated Zhongshan Hospital, NO. 180 Fenglin Road, Shanghai 200032, China. gao.weidong@zs-hospital.sh.cn
Telephone: +86-21-64041990 Fax: +86-21-64041990
Received: February 19, 2016
Peer-review started: February 20, 2016
First decision: March 21, 2016
Revised: April 11, 2016
Accepted: May 4, 2016
Article in press: May 4, 2016
Published online: June 28, 2016
Abstract

AIM: To explore the regulatory mechanism of the target gene of microRNA-21 (miR-21), phosphatase gene (PTEN), and its downstream proteins, protein kinase B (AKT) and phosphatidylinositol 3-kinase (PI3K), in colorectal cancer (CRC) cells.

METHODS: Quantitative real-time PCR (qRT-PCR) and Western blot were used to detect the expression levels of miR-21 and PTEN in HCT116, HT29, Colo32 and SW480 CRC cell lines. Also, the expression levels of PTEN mRNA and its downstream proteins AKT and PI3K in HCT116 cells after downregulating miR-21 were investigated.

RESULTS: Comparing the miR-21 expression in CRC cells, the expression levels of miR-21 were highest in HCT116 cells, and the expression levels of miR-21 were lowest in SW480 cells. In comparing miR-21 and PTEN expression in CRC cells, we found that the protein expression levels of miR-21 and PTEN were inversely correlated (P < 0.05); when miR-21 expression was reduced, mRNA expression levels of PTEN did not significantly change (P > 0.05), but the expression levels of its protein significantly increased (P < 0.05). In comparing the levels of PTEN protein and downstream AKT and PI3K in HCT116 cells after downregulation of miR-21 expression, the levels of AKT and PI3K protein expression significantly decreased (P < 0.05).

CONCLUSION: PTEN is one of the direct target genes of miR-21. Thus, phosphatase gene and its downstream AKT and PI3K expression levels can be regulated by regulating the expression levels of miR-21, which in turn regulates the development of CRC.

Keywords: MicroRNA-21, Protein kinase B, Colorectal cancer, Phosphatidylinositol 3-kinase, Phosphatase and tensin homolog

Core tip: RT-PCR and Western blot were applied to detect the expression level of microRNA-21 (miR-21) and Phosphatase gene (PTEN), including its downstream proteins protein kinase B (AKT) and phosphatidylinositol 3-kinase (PI3K) in colorectal cancer (CRC) cell lines, and to explore the regulatory mechanism of the expression of miR-21 in inhibiting CRC, respectively. Their associations were investigated to clarify whether one of the direct target genes of miR-21 is PTEN. The expression levels of miR-21, PTEN and its downstream proteins AKT and PI3K are regulated and controlled to manage the occurrence and progression of CRC.