Tetrahydrobenzofuro[3,2-b]quinoline: A dual-acting autophagy-dependent DHODH inhibitor that provokes ferroptosis in lung cancer cells.

Autophagy-dependent ferroptosis-characterized by its unique metabolic regulatory mechanisms and tumor-selective cytotoxicity-has emerged as a promising therapeutic strategy for lung cancer. In this study, we conducted mechanistic investigations on a series of tetrahydroquinoline-fused heterocycles designed via a pseudo-natural products (PNPs) strategy, as previously reported by our group. Among the tetrahydrobenzofuro[3,2-b]quinolines, the key compound 3af demonstrated potent anti-proliferative activity against lung cancer cells (A549), with minimal cytotoxic effects on normal cells. Further mechanistic investigations revealed that 3af induced ferroptosis through mitochondrial dysfunction, lipid peroxidation, and excessive accumulation of reactive oxygen species. Moreover, western blotting and rescue experiments confirmed that 3af promoted the degradation of dihydroorotate dehydrogenase via an autophagy-dependent pathway, thereby elucidating a molecular crosstalk mechanism between autophagy and ferroptosis. In a murine xenograft tumor model, compound 3af exhibited significant antitumor efficacy at a dose of 20 mg/kg. It achieved a tumor inhibition rate of 58.33 %, with no notable toxicity observed in the treated animals. These findings support the potential of PNP-based compounds as novel therapeutic agents targeting the autophagy-ferroptosis signaling axis in lung cancer.