The Antidepressant Drug Amitriptyline Affects Human SH-SY5Y Neuroblastoma Cell Proliferation and Modulates Autophagy

Abstract

Amitriptyline is a tricyclic antidepressant commonly used for depressive disorders and pre-scribed off-label for several neurological conditions like neuropathic pain, migraine and anxiety. Amitriptyline potentiates the monoaminergic transmission by blocking the reuptake of norepi-nephrine and serotonin. However, antidepressants also act on additional targets that contribute to either therapeutic or adverse effects and may suggest new indications for their repurposing. Furthermore, since depression is often a co-morbidity in patients with chronic conditions (i.e. cancer, neurodegenerative diseases) the use of antidepressants interfering with pathways in-volved in cell homeostasis may affect the progression and outcome of these pathologies. Here we investigate the effects of amitriptyline on proliferation and autophagy in human SH-SY5Y neuroblastoma cells. Dose and time-dependent upregulation of the autophagy markers LC3II and autophagy receptor p62, with accumulation of LAMP1 positive compartments, were observed in SH-SY5Y cells exposed to amitriptyline. Alteration of autophagy was accompanied by reduced cell viability and decreased clonogenic capacity, without a significant induction of apoptosis. Decrease viability and clonogenic activity were still observed in autophagy deficient Atg5 -/- MEF and following pre-treatment of SH-SY5Y culture with the autophagy inhibitor chloroquine suggesting that the amitriptyline’s effects on cell proliferation were not caused by the modulation of autophagy. Our findings demonstrate that amitriptyline acts on pathways that are crucial for cell and tissue homeostasis and pose the basis for further studies on the potential application of these effects and the consequences during long-term antidepressant treatment.