A derivative of cytisine N-isoflavone from Sophora alopecuroides L., suppresses non-small cell lung cancer by targeting mTOR.

Non-small cell lung cancer (NSCLC) remains a leading cause of cancer-related deaths worldwide, highlighting the urgent requirement for innovative therapeutic strategies. Cytisine N-methylene-(4',5,7-trihydroxy)-isoflavone (named CNI3), a natural derivative of cytisine N-isoflavone isolated from Sophora alopecuroides L., exhibits promising anticancer potential. The present study aimed to investigate the anticancer efficacy of CNI3 against NSCLC and elucidate its underlying mechanisms both in vitro and in vivo. In vitro, CNI3 elevated intracellular reactive oxygen species (ROS) levels, inhibited the viability of A549 and H1299 cells, and induced apoptosis by upregulating BCL-2-associated X protein (Bax) and cleaved cysteine-dependent aspartate-specific protease-3 (Cleaved caspase-3), while downregulating B-cell lymphoma 2 (Bcl-2). Furthermore, CNI3 promoted autophagy, as evidenced by increased microtubule-associated protein 1 light chain 3B (LC3B) expression and decreased sequestosome 1 (p62) levels. In vivo, CNI3 significantly suppressed the growth of H1299 xenograft tumors without obvious systemic toxicity, while activating key apoptotic and autophagic biomarkers within tumor tissues. Mechanistically, CNI3 directly targeted the mechanistic target of rapamycin (mTOR) and downregulated phosphorylated ribosomal S6 kinase (p-S6K) and phosphorylated 4E binding protein 1 (p-4E-BP1), leading to the induction of apoptosis and autophagy. These findings identify CNI3 as a potent mTOR-targeting natural compound that suppresses NSCLC progression through the coordinated induction of apoptosis and autophagy, highlighting its potential as a safe and effective therapeutic candidate for the treatment of NSCLC.