TUSC3 induces autophagy in human non-small cell lung cancer cells through Wnt/β-catenin signaling
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Yun Peng1, Jun Cao2, Xiao-Yi Yao3, Jian-Xin Wang4, Mei-Zuo Zhong3, Ping-Ping Gan3 and Jian-Huang Li3
1International Medical Center, Xiangya Hospital, Central South University, Changsha 410008, P.R. China
2Department of Medical Oncology, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha 410008, P.R. China
3Department of Oncology, Xiangya Hospital, Central South University, Changsha 410008, P.R. China
4School of Information Science and Engineering, Central South University, Changsha 410008, P.R. China
Jian-Huang Li, email: firstname.lastname@example.org
Keywords: non-small cell lung cancer, A549 cells, tumor suppressor candidate 3, Wnt/β-catenin signaling pathway, autophagy
Received: October 31, 2016 Accepted: March 19, 2017 Published: May 08, 2017
We investigated the effects of tumor suppressor candidate 3 (TUSC3) on autophagy in human non-small cell lung cancer (NSCLC) cells. A total of 118 NSCLC patients (88 males and 30 females) who underwent surgery at our institute were enrolled in the study. Immunohistochemical analysis revealed that TUSC3 protein expression was lower in NSCLC specimens than adjacent normal tissue. Correspondingly, there was greater methylation of TUSC3 in NSCLC than adjacent normal tissue. After transient transfection of A549 NSCLC cells with constructs designed to up-regulate or down-regulate TUSC3 expression, we analyzed the effects of inhibiting the Wnt pathway (XAV939) and autophagy (chloroquine, CQ) on the behavior of NSCLC cells. We also performed TOP/FOP-Flash reporter assays, MTT assays, Annexin V-FITC/propidium iodide staining, and acridine orange staining to evaluate Wnt/β-catenin signaling, cell proliferation, apoptosis, and autophagy, respectively. Expression of Wnt/β-catenin pathway components and autophagy-related proteins was analyzed using qRT-PCR and Western blotting. We found that TUSC3 inhibited cell proliferation and promoted both apoptosis and autophagy in A549 cells. In addition, TUSC3 increased expression of autophagy-related proteins. It also increased expression of Wnt/β-catenin signaling pathway components and promoted nuclear transfer of β-catenin, resulting in activation of Wnt/β-catenin signaling. TUSC3 thus induces autophagy in human NSCLC cells through activation of the Wnt/β-catenin signaling pathway.
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