A novel small-form NEDD4 regulates cell invasiveness and apoptosis to promote tumor metastasis

// Chia-Jung Liao 1 , Hsiang-Cheng Chi 1 , Chung-Ying Tsai 1 , Chi-De Chen 2 , Sheng-Ming Wu 1 , Yi-Hsin Tseng 1 , Yang-Hsiang Lin 1 , I-Hsiao Chung 1 , Ching-Ying Chen 1 , Syuan-Ling Lin 1 , Shiu-Feng Huang 3 , Ya-Hui Huang 4 , Kwang-Huei Lin 1 1 Department of Biochemistry, Chang-Gung University, Taoyuan, Taiwan 333, Republic of China 2 Chang Gung Molecular Medicine Research Center, Chang-Gung University, Taoyuan, Taiwan 333, Republic of China 3 Institute of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli, Taiwan 350, Republic of China 4 Medical Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan 333, Republic of China Correspondence to: Kwang-Huei Lin, e-mail: khlin@mail.cgu.edu.tw Keywords: Hepatoma, prognosis, sNEDD4, metastasis, apoptosis Received: October 21, 2014      Accepted: February 09, 2015      Published: March 20, 2015 ABSTRACT Despite numerous investigations on metastasis, the determinants of metastatic processes remain unclear. We aimed to identify the metastasis-associated genes in hepatocellular carcinoma (HCC). Potent metastatic SK-hep-1 (SK) cells, designated ‘SKM’, were generated using Transwell assay followed by selection in a mouse model. Genes expressed differentially in SKM and SK cells were identified via microarray analyses. A small form of Neural precursor cell-expressed developmentally downregulated 4 (sNEDD4) was identified to be overexpressed in SKM cells, which was confirmed as a novel transcript using liquid chromatography-mass spectrometry. In clinical specimens, sNEDD4 was significantly overexpressed in tumors and serves as a poor prognostic factor for male patients with HCC ( P = 0.035). Upon subcutaneous introduction of sNEDD4-overexpressing SK cells into flanks of nude mice, tumors grew faster than those of the control group. Furthermore, sNEDD4-mediated promotion of tumor metastasis was demonstrated in the orthotopic mouse model. Overexpression of sNEDD4 increased the invasive ability of SK cells through upregulation of matrix metalloproteinase 9 and inhibited serum deprivation-induced apoptosis via upregulation of myeloid cell leukemia 1. In conclusion, sNEDD4 is a novel metastasis-associated gene, which prevents apoptosis under nutrient restriction conditions. The present findings clearly support the prognostic potential of sNEDD4 for HCC.