Case Control Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Feb 7, 2020; 26(5): 499-513
Published online Feb 7, 2020. doi: 10.3748/wjg.v26.i5.499
Upregulation of miR-34c after silencing E2F transcription factor 1 inhibits paclitaxel combined with cisplatin resistance in gastric cancer cells
Hong Zheng, Jin-Jing Wang, Xiao-Rong Yang, Yong-Lin Yu
Hong Zheng, Jin-Jing Wang, Xiao-Rong Yang, Yong-Lin Yu, Department of Pathology, the Affiliated Hospital of Zunyi Medical University, Zunyi 563003, Guizhou Province, China
Author contributions: Zheng H designed the research; Wang JJ performed the research; Yang XR and Yu YL analyzed the data and wrote the paper.
Institutional review board statement: The study was approved by the Ethics Committee of the Affiliated Hospital of Zunyi Medical University (Guizhou, China).
Informed consent statement: All patients gave informed consent.
Conflict-of-interest statement: No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
Data sharing statement: No additional data are available.
STROBE statement: The authors have read the STROBE statement-checklist of items, and the manuscript was prepared and revised according to the STROBE Statement-checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (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:
Corresponding author: Hong Zheng, PhD, Chief Physician, Department of Pathology, the Affiliated Hospital of Zunyi Medical University, No. 149, Dalian Road, Zunyi 563003, Guizhou Province, China.
Received: November 5, 2019
Peer-review started: November 5, 2019
First decision: December 7, 2019
Revised: December 13, 2019
Accepted: January 2, 2020
Article in press: January 3, 2020
Published online: February 7, 2020
Research background

Gastric cancer (GC) is one of the most common types of cancer. The detailed roles of miR-34c and E2F transcription factor 1 (E2F1) have been proven in various cancer types. However, the relationship between them and GC has not been understood.

Research motivation

The promoter region of miR-34c was predicted to have a binding site in E2F1 by PROMO database. E2F1 was increased but miR-34c was decreased in GC. The relationship between them in GC has not been understood. Thus, it is required to study the function of E2F1/miR-34c in GC.

Research objective

To investigate the effect of miR-34c and its upstream transcription factor E2F1 on paclitaxel combined with cisplatin resistance in GC cells.

Research methods

Paired GC tissues and adjacent normal tissues were randomly sampled from 74 GC patients. MiR-34c and E2F1 were detected by qPCR and Western blot. In addition, the drug resistance of GC cells to paclitaxel and cisplatin was induced by the concentration gradient increasing method, and changes in miR-34c and E2F1 during this process were detected. Furthermore, E2F1 and miR-34c overexpression or low expression vectors were constructed and transfected into drug resistant GC cells. Moreover, MTT was employed to detect the sensitivity of cells to paclitaxel combined with cisplatin, qPCR was adopted to detect the expression of miR-34c, Western blot was applied to detect the expression of E2F1, drug resistance-related protein and apoptosis-related protein, and flow cytometry was used to detect cell apoptosis and cell cycle status.

Research results

E2F1 was overexpressed while miR-34c was underexpressed in GC. After inducing GC cells to be resistant to paclitaxel and cisplatin, E2F1 expression increased while miR-34c expression decreased. Both silencing E2F1 and over-expressing miR-34c could increase the sensitivity of drug-resistant GC cells to paclitaxel combined with cisplatin, promote cell apoptosis and inhibit cell proliferation. Among which, silencing E2F1 could reduce the expression of drug resistance-related proteins and apoptosis-related proteins, while over-expression of miR-34c could upregulate the expression of apoptosis-related proteins without affecting the expression of MDR-1, MRP and other drug resistance-related proteins. Rescue experiments demonstrated that inhibiting miR-34c could significantly weaken the sensitization of drug resistant cells and Si E2F1 to paclitaxel combined with cisplatin.

Research conclusion

E2F1 inhibits miR-34c to promote the proliferation of GC cells and enhance the resistance to paclitaxel combined with cisplatin, while silencing E2F1 is conducive to improving the efficacy of paclitaxel combined with cisplatin in GC cells.

Research perspective

Slicing E2F1 or increasing miR-34c improves the sensitivity of GC cells to paclitaxel combined with cisplatin, and enhances the therapeutic effect of drugs. To advance research on the effect of E2F1/miR-34c on GC cell resistance, further discussion will be conducted in future studies: (1) Whether E2F1 directly targeting regulates MRP and MDR-1; (2) Which downstream target genes are implicated in the regulation of E2F1/miR-34c on the proliferation and apoptosis of GC cells; and (3) The relationship between miR-34c and the drug resistance of GC cells, which all require further study.