J Cancer 2020; 11(10):2759-2768. doi:10.7150/jca.37718 This issue

Research Paper

Circular RNA CCDC66 promotes gastric cancer progression by regulating c-Myc and TGF-β signaling pathways

Guifang Xu1,2#, Yanke Chen2#, Min Fu1,2, Xueyan Zang2, Mingming Cang1,2, Yanlong Niu1,2, Weiya Zhang2, Yu Zhang2, Zheying Mao2, Meng Shao2, Hui Qian2, Wenrong Xu2, Hui Cai3✉, Pengcheng Jiang1✉, Xu Zhang2,3✉

1. Institute of Digestive Diseases, The Affiliated People's Hospital of Jiangsu University, Zhenjiang, Jiangsu 212002, China
2. Jiangsu Key Laboratory of Medical Science and Laboratory Medicine, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, China
3. Key Laboratory of Molecular Diagnostics and Precision Medicine for Surgical Oncology in Gansu Province, Gansu Provincial Hospital, Gansu 730000, China
# These authors contributed equally to this work.

This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/). See http://ivyspring.com/terms for full terms and conditions.
Xu G, Chen Y, Fu M, Zang X, Cang M, Niu Y, Zhang W, Zhang Y, Mao Z, Shao M, Qian H, Xu W, Cai H, Jiang P, Zhang X. Circular RNA CCDC66 promotes gastric cancer progression by regulating c-Myc and TGF-β signaling pathways. J Cancer 2020; 11(10):2759-2768. doi:10.7150/jca.37718. Available from https://www.jcancer.org/v11p2759.htm

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Background: CircRNAs play important roles in cancer development and progression and have the potential to serve as cancer biomarkers. The aim of this study was to investigate the role of circular RNA CCDC66 (circCCDC66) in gastric cancer and to reveal the underlying mechanisms.

Methods: The expression of circCCDC66 in GC tissues and cell lines was examined by qRT-PCR. The correlation between circCCDC66 expression level and clinicopathological characteristics was analyzed. The biological roles of circCCDC66 in GC cell apoptosis, proliferation, migration and invasion were determined by flow cytometry, cell counting, cell colony formation, wound healing, transwell migration and matrigel invasion assays. The role of circCCDC66 in GC growth was further confirmed by mouse xenograft tumor model. Western blot and qRT-PCR were used to explore the effects of circCCDC66 on epithelial-mesenchymal transition (EMT)-related gene and protein expression.

Results: CircCCDC66 expression was elevated in both GC tissues and cell lines compared to adjacent normal tissues and normal gastric epithelial cell line. The upregulation of circCCDC66 in GC tissues was related to tumor stage and lymphatic metastasis. CircCCDC66 knockdown significantly inhibited GC cell proliferation, migration and invasion and induced cell apoptosis in GC cells. On the contrary, circCCDC66 overexpression had the opposite effects. In addition, circCCDC66 knockdown suppressed the tumorigenesis of GC cells in nude mice. Furthermore, circCCDC66 knockdown inhibited the activation of c-Myc and TGF-β signaling pathways and reversed EMT in GC cells. c-Myc and TGF-β interference blocked circCCDC66-mediated promotion of gastric cancer cell proliferation, migration and invasion.

Conclusion: CircCCDC66 promotes GC growth and metastasis by activating c-Myc and TGF-β signaling pathways, suggesting that it may serve as a potential biomarker for GC.

Keywords: circular RNA, gastric cancer, circCCDC66, EMT, progression