Amonafide Targeting NTSR1-PI3K/AKT/mTOR Signaling Attenuates Vascular Remodeling in Pulmonary Arterial Hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a progressive disease driven by pulmonary vascular remodeling, largely due to the abnormal proliferation and phenotypic switching of pulmonary artery smooth muscle cells.
METHODS: Levels of topoisomerase II α were evaluated in the lungs from patients with idiopathic PAH, 2 rodent PAH models (SU5416 combined with hypoxia and monocrotaline-induced), and in pulmonary artery smooth muscle cells stimulated with platelet-derived growth factor BB (PDGF-BB). The therapeutic potential of amonafide, a topoisomerase II inhibitor, was also evaluated in these models. Integrated transcriptomic and metabolomic analyses were used to identify amonafide-regulated pathways. The role of neurotensin receptor 1 (NTSR1) was further investigated through overexpression and knockdown experiments in pulmonary artery smooth muscle cells.
RESULTS: Topoisomerase II α was significantly upregulated in the lungs of patients with idiopathic PAH, SU5416 combined with hypoxia-, and monocrotaline-induced rodent PAH models, and PDGF-BB-stimulated pulmonary artery smooth muscle cells. This upregulation was associated with increased DNA damage and apoptosis resistance. Amonafide treatment markedly improved hemodynamics, attenuated right ventricular hypertrophy, and suppressed pulmonary vascular remodeling in both animal models. In vitro, amonafide inhibited PDGF-BB-induced pulmonary artery smooth muscle cell proliferation, migration, apoptosis resistance, and DNA damage. Mechanistically, amonafide downregulated NTSR1 expression and inhibited the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin  signaling pathway. Crucially, NTSR1 overexpression abolished the beneficial effects of amonafide, whereas NTSR1 knockdown enhanced them.
CONCLUSIONS: Our findings unveil the pivotal role of amonafide in PAH pathogenesis and suggest that targeting topoisomerase II α and NTSR1 may be a promising therapeutic approach for treating PAH.