ANALISI DELLA MORTE CELLULARE INDOTTA DAL CISPLATINO E STUDIO DI EVENTUALI SOSTANZE PROTETTIVE SU MODELLI IN VITRO

Cisplatin (cis-DDP) is a chemotherapy agent that is used as a treatment for several types of cancer. Unfortunately it could injure several areas of the cochlea, including outer hair cells in the Organ of Corti, the spiral ganglion and the stria vascularis. Cis-DDP has been shown to induce auditory sensory cell apoptosis in vitro and in vivo. The mechanisms appear to involve the production of reactive oxygen species (ROS) and depletion of antioxidant enzymes which can trigger cell death. Approaches to chemoprevention include the administration of antioxidants to protect against ROS. The Ginkgo biloba extract (EGb 761 o Ginkgoselect®) is known to have antioxidant proprieties with a free radicals scavenging effect, and protecting cells against apoptosis. It has been used for otoprotection study only in vivo model, with positive effects. One of the goal of this study was that to verify the protective effects of ginkgoselect on a mouse inner ear cell line (OC-k3). Our data showed that Ginkgo biloba extract protects against cisplatin-induced ototoxicity. The calcium ion (Ca2+) regulates hair and neuronal cells function in the inner ear. It’s involved in the mechanical signal transduction, and release of neurotransmitters. Changes in its intracellular concentration determines the cell’s fate. It’s a second messenger that regulates the activation of proteins involved in apoptosis. Calcium channel antagonist drugs was studied as another mechanism to protect cells from cisplatin ototoxicity. Flunarizine is a calcium blocker drug, currently used to treat diseases of the inner ear, such as vertigo. There are very few data on flunarizine protective effect against cisplatin damages. The PC12 cell (rat pheochromocytoma cell line) within several days of NGF exposure, differentiate in sym-pathetic neurons, it’s therefore always used as a neuronal model. In this thesis we have been evaluated the cisplatin toxicity on these cells, undifferentiated and differentiated, and the ability of flunarizina to protect cells, in order to conduct a basic survey focused on the mechanism of both drugs. In sum, flunarizina is a good protector against the cisplatin toxicity, it’s able to preventing apoptosis by acting on expression of proteins involved in programmed cell death (14-3-3β, protein kinase C and GAPDH). Present results are of great interest to conduct further investigations on spiral ganglion primary neurons cultures. Key words: inner ear, OC-k3, PC12, cisplatin, Ginkgo biloba, flunarizine, apoptosis.