Inhibition of ARC decreases the survival of HEI-OC-1 cells after neomycin damagein vitro

// Ming Guan 1, 2, 3 , Qiaojun Fang 4, 5 , Zuhong He 4, 5 , Yong Li 1, 2 , Fuping Qian 4, 5 , Xiaoyun Qian 3, 6 , Ling Lu 3, 6 , Xiaoli Zhang 6 , Dingding Liu 6 , Jieyu Qi 4, 5 , Shasha Zhang 4, 5 , Mingliang Tang 4, 5 , Xia Gao 3, 6 , Renjie Chai 4, 5 1 Department of Otolaryngology, The Affiliated Hangzhou Hospital of Nanjing Medical University, Hangzhou 310006, China 2 Department of Otolaryngology, Hangzhou First People’s Hospital, Hangzhou 310006, China 3 Department of Otolaryngology, Nanjing Drum Tower Hospital, Clinical College of Nanjing Medical University, Nanjing 210008, China 4 MOE Key Laboratory of Developmental Genes and Human Disease, State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, China 5 Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China 6 Department of Otolaryngology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008, China Correspondence to: Renjie Chai, email: renjiec@seu.edu.cn Xia Gao, email: xiagaogao@hotmail.com Keywords: cochlea, hair cell, apoptosis, reactive oxygen species, mitochondrial function Received: April 06, 2016 Accepted: August 10, 2016 Published: August 20, 2016 ABSTRACT Hearing loss is a common sensory disorder mainly caused by the loss of hair cells (HCs). Noise, aging, and ototoxic drugs can all induce apoptosis in HCs. Apoptosis repressor with caspase recruitment domain(ARC) is a key factor in apoptosis that inhibits both intrinsic and extrinsic apoptosis pathways; however, there have been no reports on the role of ARC in HC loss in the inner ear. In this study, we used House Ear Institute Organ of Corti 1 (HEI-OC-1) cells, which is a cochlear hair-cell-like cell line, to investigate the role of ARC in aminoglycoside-induced HC loss. ARC was expressed in the cochlear HCs as well as in the HEI-OC-1 cells, but not in the supporting cells, and the expression level of ARC in HCs was decreased after neomycin injury in both cochlear HCs and HEI-OC-1 cells, suggesting that reduced levels of ARC might correlate with neomycin-induced HC loss. We inhibited ARC expression using siRNA and found that this significantly increased the sensitivity of HEI-OC-1 cells to neomycin toxicity. Finally, we found that ARC inhibition increased the expression of pro-apoptotic factors, decreased the mitochondrial membrane potential, and increased the level of reactive oxygen species (ROS) after neomycin injury, suggesting that ARC inhibits cell death and apoptosis in HEI-OC-1 cells by controlling mitochondrial function and ROS accumulation. Thus the endogenous anti-apoptotic factor ARC might be a new therapeutic target for the prevention of aminoglycoside-induced HC loss.