Identification of NDUFAF1 in mediating K-Ras induced mitochondrial dysfunction by a proteomic screening approach.

// Peng Wang 1, 2, * , Ming Song 1, * , Zhao-lei Zeng 1 , Chao-feng Zhu 1 , Wen-hua Lu 1 , Jing Yang 1 , Ming-zhe Ma 1 , A-min Huang 1 , Yumin Hu 1 , Peng Huang 1, 3 1 Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China 2 Department of Emergency Medicine, Sun Yat-sen Memorial Hospital, Guangzhou, China 3 Department of Translational Molecular Pathology, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA * These authors have contributed equally to this work Correspondence to: Yumin Hu, e-mail: huym@sysucc.org.cn Peng Huang, e-mail: huangpeng@sysucc.org.cn Keywords: K-Ras, mitochondria, NDUFAF1, glycolysis Received: July 21, 2014      Accepted: December 17, 2014      Published: February 27, 2015 ABSTRACT Increase in aerobic glycolysis and mitochondrial dysfunction are important biochemical features observed in human cancers. Recent studies suggest oncogenic K-Ras can cause suppression of mitochondrial respiration and up-regulation of glycolytic activity through a yet unknown mechanism. Here we employed proteomic approach and used a K-Ras G12V inducible cell system to investigate the impact of oncogenic K-Ras on mitochondria and cell metabolism. Mitochondria isolated from cells before and after K-Ras induction were subjected to protein analysis using stable isotope labeling with amino acids (SILAC) and liquid chromatography coupled with mass spectrometry (LC-MS). 70 mitochondrial proteins with significant expression alteration after K-Ras induction were identified. A majority of these proteins were involved in energy metabolism. Five proteins with significant decrease belong to mitochondrial respiratory chain complex I. NADH dehydrogenase 1 alpha subcomplex assembly factor 1 (NDUFAF1) showed most significant decrease by 50%. Such decrease was validated in primary human pancreatic cancer tissues. Knockdown of NDUFAF1 by siRNA caused mitochondrial respiration deficiency, accumulation of NADH and subsequent increase of glycolytic activity. Our study revealed that oncogenic K-Ras is able to induce significant alterations in mitochondrial protein expression, and identified NDUFAF1 as an important molecule whose low expression contributes to mitochondrial dysfunction induced by K-Ras.