The tricyclic antidepressant amitriptyline is cytotoxic to HTB114 human leiomyosarcoma and induces p75(NTR)-dependent apoptosis.

Nerve growth factor (NGF) receptors, TrKA and p75(NTR), are being investigated in cancer therapy. Our previous data show that, in HTB114 uterine leiomyosarcoma cells, p75(NTR)-dependent apoptosis is inducible by cytotoxic drugs and can suppress nerve growth factor-dependent growth. Although amitriptyline can kill cancer cells and bind TrKA/B, its effects on p75-dependent apoptosis are unknown. The aim of this paper was to evaluate the antineoplastic potential of amitriptyline, and the role of p75(NTR)-dependent apoptosis in the chemoresistant uterine HTB114 leiomyosarcoma. Using proliferation assays and fluorescence-activated cell sorting analysis, we found that amitriptyline caused a marked reduction in HTB114 cell viability, associated with the parallel upregulation of p75(NTR) expression. This converted the TrKA⁺-proliferating cells into TrKA⁺/p75(NTR⁺), leading to downregulation of TrKA-prosurvival signaling (AKT) and activation of p75(NTR)-dependent apoptosis (through caspase-3). Overall, we provide novel evidence that HTB114 uterine leiomyosarcoma cells are highly sensitive to amitriptyline, supporting the role of p75(NTR)-dependent apoptosis as a novel cytotoxic mechanism of this drug and of p75(NTR) as an inducible stress receptor and a novel target in clinical oncology.