MicroRNA-34a targets epithelial to mesenchymal transition-inducing transcription factors (EMT-TFs) and inhibits breast cancer cell migration and invasion

// Saber Imani 1, 2, * , Chunli Wei 1, 3, * , Jingliang Cheng 1, * , Md. Asaduzzaman Khan 1, 4, * , Shangyi Fu 5 , Luquan Yang 1 , Mousumi Tania 1, 6 , Xianqin Zhang 1 , Xiuli Xiao 7 , Xianning Zhang 8 , Junjiang Fu 1, 3 1 Key Laboratory of Epigenetics and Oncology, Research Center for Precision Medicine, Southwest Medical University, Luzhou, Sichuan, China 2 Chemical Injuries Research Center, Baqiyatallah Medical Sciences University (BMSU), Tehran, Iran 3 State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau (SAR), China 4 Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam 5 The Honors College, University of Houston, Houston, TX, USA 6 Division of Computer Aided Drug Design, Red-Green Computing Centre, Dhaka, Bangladesh 7 Pathology Department, Southwest Medical University, Luzhou, Sichuan, China 8 Department of Cell Biology and Medical Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China * These authors have contributed equally to this work Correspondence to: Junjiang Fu, email: fujunjiang@swmu.edu.cn , fujunjiang@hotmail.com Keywords: microRNA-34a, thymoquinone, epithelial-mesenchymal transition, metastasis, breast cancer Received: December 27, 2016      Accepted: January 25, 2017      Published: February 09, 2017 ABSTRACT MicroRNA-34a (miR-34a) plays an essential role against tumorigenesis and progression of cancer metastasis. Here, we analyzed the expression, targets and functional effects of miR-34a on epithelial to mesenchymal transition-inducing transcription factors (EMT-TFs), such as TWIST1, SLUG and ZEB1/2, and an EMT-inducing protein NOTCH1 in breast cancer (BC) cell migration and invasion and its correlation with tumorigenesis and clinical outcomes. Expression of miR-34a is downregulated in human metastatic breast cancers (MBC) compared to normal breast tissues and is negatively correlated with clinicopathological features of MBC patients. Ectopic expression of miR-34a in MBC cell-line BT-549 significantly inhibits cell migration and invasion, but exhibits no clear effect on BC cell growth. We found that miR-34a is able to inactivate EMT signaling pathway with mediatory of NOTCH1, TWIST1, and ZEB1 upon 3′-UTR activity in MBC cell lines, but has no inhibitory effects on SLUG and ZEB2. Furthermore, we investigated the synergistic effects of Thymoquinone (TQ) and miR-34a together on the expression of EMT-associated proteins. Results showed that co-delivery of miR-34a and TQ is able to inactivate EMT signaling pathway by directly targeting TWIST1 and ZEB1 in BT-549 cell line, indicating that they might be a promising therapeutic combination against breast cancer metastasis. Epigenetic inactivation of the EMT-TFs/miR-34a pathway can potentially alter the equilibrium of these regulations, facilitating EMT and metastasis in BC. Altogether, our findings suggest that miR-34a alone could serve as a potential therapeutic agent for MBC, and together with TQ, their therapeutic potential is synergistically enhanced.