Circular RNA profile indicates circular RNA VRK1 is negatively related with breast cancer stem cells

// Ningning Yan 1, 2, * , Haiyan Xu 2, * , Jinnan Zhang 3 , Liang Xu 4 , Yanyun Zhang 5 , Le Zhang 1, 2 , Yingchun Xu 6 and Fengchun Zhang 1, 2 1 Department of Oncology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China 2 Department of Oncology, Suzhou Kowloon Hospital, Shanghai Jiaotong University School of Medicine, Suzhou 215021, China 3 Department of Neurosurgery, China-Japan Union Hospital, Jilin University, Changchun, 130031, China 4 Prevention and Cure Center of Breast Disease, Third Hospital of Nanchang, Nanchang, 330009, China 5 Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences & SJTUSM, Shanghai 200031, China 6 Department of Oncology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200127, China * These authors have Contributed equally to this work Correspondence to: Fengchun Zhang, email: fczhang2004@163.com Yingchun Xu, email: xiaoxu2384@163.com Keywords: breast cancer stem cells; circular RNA; RNA-sequencing; circVRK1 Received: April 27, 2017      Accepted: August 26, 2017      Published: September 23, 2017 ABSTRACT Circular RNAs (circRNAs), a novel type of noncoding RNAs (ncRNAs), have been shown to be implicated in biological processes including cancer as gene expression regulators. However, the roles of circRNAs in cancer stem cells (CSCs) have been unexplored. In the present study, we screened the circRNA profile in breast cancer stem cells (BCSCs) using RNA-Sequencing. Here, 27 circRNAs were found to be aberrantly expressed. Of these, 19 circRNAs were downregulated and 8 were upregulated and some of these circRNAs were validated by Q-PCR. Furthermore, we constructed the circRNA/miRNA network by bioinformatics approaches and hypothesized that circRNAs might be involved in stemness of BCSCs via serving as miRNA sponges. Importantly, we found that circular RNA VRK1 (circVRK1) could suppress BCSC’s expansion and self-renewal capacity. Collectively, the present work provides the first reported evidence of the circRNA profile and circRNA/miRNA interplay in BCSCs. In addition, these findings lay foundation to explore the functions of circRNAs in CSCs and indicate that circVRK1 might be a promising target for BCSCs.