Brief Article
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World J Gastroenterol. Nov 21, 2013; 19(43): 7758-7765
Published online Nov 21, 2013. doi: 10.3748/wjg.v19.i43.7758
MicroRNA-143 suppresses gastric cancer cell growth and induces apoptosis by targeting COX-2
Xiao-Li Wu, Bin Cheng, Pei-Yuan Li, Huan-Jun Huang, Qiu Zhao, Zi-Li Dan, De-An Tian, Peng Zhang
Xiao-Li Wu, Bin Cheng, Pei-Yuan Li, Huan-Jun Huang, Qiu Zhao, Zi-Li Dan, De-An Tian, Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei Province, China
Peng Zhang, Department of Gastrointestinal Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei Province, China
Author contributions: Wu XL performed the majority of experiments and wrote the manuscript; Cheng B, Li PY, Huang HJ, Zhao Q and Dan ZL provided vital reagents and analytical tools; Tian DA provided financial support for this work; and Zhang P designed the study and edited the manuscript.
Correspondence to: Peng Zhang, MD, PhD, Department of Gastrointestinal Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, Hubei Province, China. zhangpeng@tjh.tjmu.edu.cn
Telephone: +86-27-83665256 Fax: +86-27-83665256
Received: May 30, 2013
Revised: September 20, 2013
Accepted: September 29, 2013
Published online: November 21, 2013
Processing time: 201 Days and 12.5 Hours
Abstract

AIM: To investigate the function of microRNA-143 (miR-143) in gastric cancer and explore the target genes of miR-143.

METHODS: A quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis was performed to evaluate miR-143 expression in gastric cancer cell lines. After transfecting gastric cancer cells with miR-143-5p and miR-143-3p precursors, Alamar blue and apoptosis assays were used to measure the respective proliferation and apoptosis rates. Cyclooxygenase-2 (COX-2) expression was determined by real-time RT-PCR and Western blot assays after miR-143 transfection. Reporter plasmids were constructed, and a luciferase reporter assay was used to identify the miR-143 binding site on COX-2.

RESULTS: Both miR-143-5p and miR-143-3p were significantly downregulated in multiple gastric cancer cell lines. Forced miR-143-5p and miR-143-3p expression in gastric cancer cells produced a profound cytotoxic effect. MiR-145-5p transfection into gastric cancer cells resulted in a greater growth inhibitory effect (61.23% ± 3.16% vs 46.58% ± 4.28%, P < 0.05 in the MKN-1 cell line) and a higher apoptosis rate (28.74% ± 1.93% vs 22.13% ± 3.31%, P < 0.05 in the MKN-1 cell line) than miR-143-3p transfection. Further analysis indicated that COX-2 expression was potently suppressed by miR-143-5p but not by miR-143-3p. The activity of a luciferase reporter construct that contained the 3’-untranslated region (UTR) of COX-2 was downregulated by miR-143-5p (43.6% ± 4.86%, P < 0.01) but not by miR-143-3p. A mutation in the miR-145-5p binding site completely ablated the regulatory effect on luciferase activity, which suggests that there is a direct miR-145-5p binding site in the 3’-UTR of COX-2.

CONCLUSION: Both miR-143-5p and miR-143-3p function as anti-oncomirs in gastric cancer. However, miR-143-5p alone directly targets COX-2, and it exhibits a stronger tumor suppressive effect than miR-143-3p.

Keywords: Gastric cancer, MicroRNA-143, Anti-oncomir, Cyclooxygenase-2, Apoptosis

Core tip: MicroRNA-143 (miR-143) has been reported to be a tumor suppressor. However, the functions of miR-143-5p and miR-143-3p have never been compared. In this study, we found that both miR-143-5p and miR-143-3p function as tumor suppressors in gastric cancer; however, miR-143-5p alone directly targets cyclooxygenase-2, and it exhibits a stronger tumor suppressive effect than miR-143-3p.