ING5 knockdown enhances migration and invasion of lung cancer cells by inducing EMT via EGFR/PI3K/Akt and IL-6/STAT3 signaling pathways

// Xin-Li Liu 1, * , Xu-Tao Zhang 1, * , Jin Meng 2, 3, * , Hong-Fei Zhang 1 , Yong Zhao 4 , Chen Li 1 , Yang Sun 1 , Qi-Bing Mei 1 , Feng Zhang 1 and Tao Zhang 2 1 Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, China 2 Department of Thoracic Surgery, Tangdu Hospital, Fourth Military Medical University, Xi’an, China 3 Department of Pharmcy, Hospital of PLA, Beijing, China 4 Laboratory Animal Center, Fourth Military Medical University, Xi’an, China * These authors contributed equally to this work Correspondence to: Tao Zhang, email: zhangft@fmmu.edu.cn Feng Zhang, email: zhangf037@163.com Keywords: ING5, lung cancer, epithelial mesenchymal transition (EMT), EGFR/PI3K/Akt, IL-6/STAT3 Received: November 24, 2016 Accepted: April 11, 2017 Published: April 21, 2017 ABSTRACT ING5 belongs to the Inhibitor of Growth (ING) candidate tumor suppressor family, whose functions have been involved in the regulation of chromatin remodeling, cell cycle progression, proliferation and apoptosis. Our previous study has shown that ING5 overexpression inhibits lung cancer aggressiveness via suppressing epithelial to mesenchymal transition (EMT). However, the mechanisms remain largely unknown. In the current study, by Phospho-Kinase array and western blot, we have defined significantly upregulated EGFR/PI3K/Akt and IL-6/STAT3 oncogenic signaling pathways in ING5 knockdown A549 cells, which could be downregulated by ING5 overexpression. PI3K inhibitor ZSTK474 or STAT3 inhibitor Niclosamide not only abolished ING5 knockdown-promoted proliferation, colony formation, migration and invasion of lung cancer A549 cells, but also impaired ING5 knockdown-stimulated metastasis of cancer cells in mouse xenograft models with tail vein injection of A549 cells. Furthermore, treatment with ZSTK474 or Niclosamide decreased protein level of EGFR, p-Akt, IL-6 and p-STAT3, and reversed ING5 knockdown-promoted EMT, as indicated by downregulated expression of EMT marker E-cadherin, an epithelial marker, increased expression of N-cadherin, a mesenchymal marker, and EMT-related transcription factors including Snail, Slug, Smad3 and Twist. Taken together, these results demonstrate that loss of ING5 enhances aggressiveness of lung cancer cells by promoting EMT via activation of EGFR/PI3K/Akt and IL-6/STAT3 signaling pathways.