title: Protective effect of metformin against cisplatin-induced ototoxicity in an auditory cell line.
abstract: Metformin, an antidiabetic drug with potent anticancer activity, is known to prevent oxidative stress-induced cell death in several cell types through a mechanism dependent on the mitochondria. In the present study, we investigated the influence of metformin on cisplatin ototoxicity in an auditory cell line. Cell viability was determined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (Sigma, St. Louis, MO, USA) cell proliferation assay. Oxidative stress and apoptosis were assessed by flow cytometry analysis, Hoechst 33258 staining, reactive oxygen species (ROS) measurement, and western blotting. Intracellular calcium concentration changes were detected using calcium imaging. Pretreatment with 1 mM metformin prior to the application of 20 μM cisplatin significantly decreased the frequency of late apoptosis in HEI-OC1 cells and also significantly attenuated the cisplatin-induced increase in ROS. In addition, metformin inhibited the activation of caspase-3 and levels of poly-ADP-ribose polymerase (PARP). Pretreatment with metformin prevented the cisplatin-induced elevation in intracellular calcium concentrations. We propose that metformin protects against cisplatin-induced ototoxicity by inhibiting the increase in intracellular calcium levels, preventing apoptosis, and limiting ROS production.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Anam-Dong 5-Ga 126-1, Sungbuk-Gu, 136-705, Seoul, Korea.
authors.forename: Jiwon
authors.initials: J
authors.lastname: Chang
authors.forename: Hak Hyun
authors.initials: HH
authors.lastname: Jung
authors.forename: Ji Yoon
authors.initials: JY
authors.lastname: Yang
authors.forename: Sehee
authors.initials: S
authors.lastname: Lee
authors.forename: June
authors.initials: J
authors.lastname: Choi
authors.forename: Gi Jung
authors.initials: GJ
authors.lastname: Im
authors.forename: Sung Won
authors.initials: SW
authors.lastname: Chae
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity*; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000633:toxicity*; D019610:Cytoprotection / Q000187:drug effects; D006198:Hair Cells, Auditory / Q000166:cytology / Q000187:drug effects*; D008687:Metformin / Q000494:pharmacology*; D051379:Mice; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D017382:Reactive Oxygen Species; D008687:Metformin; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3; D002945:Cisplatin; D002118:Calcium