Gamabufotalin impedes NSCLC progression by inhibiting the mitochondrial factor CHCHD2 and modulating XAF1 expression

Non-small cell lung cancer (NSCLC) continues to be the primary contributor to deaths associated with cancer. Current treatments are often limited by drug resistance and toxicity, highlighting the need for novel therapeutic approaches. Building on previous findings demonstrating that Gamabufotalin (CS-6) is effective against hepatocellular carcinoma, this study explores its mechanism of action in NSCLC. The findings indicate that CS-6 suppresses the proliferation and migratory capacity of NSCLC cells in a concentration-dependent manner, while significantly inducing apoptosis. The 48-hour half-maximal inhibitory concentration (IC₅₀) ranged from 30 to 80 nM. In xenograft models, CS-6 effectively suppressed tumor growth (P < 0.05) without causing significant systemic toxicity at effective doses (25 mg/kg and 50 mg/kg). Mechanistically, coiled-coil-helix-coiled-coil-helix domain-containing protein 2 (CHCHD2) was identified as the direct molecular target of CS-6 through Limited Proteolysis-Mass Spectrometry (LiP-MS), validated by cell thermal shift assay (CETSA), MicroScale Thermophoresis (MST), and Surface Plasmon Resonance (SPR). CHCHD2, also known as mitochondrial nuclear retrograde regulator 1 (MNRR1), is a bi-organelle regulator located primarily in the mitochondrial intermembrane space, where it controls respiratory chain stability and cristae structure, thereby regulating cell survival and apoptosis[1-3]. CHCHD2 is essential for NSCLC cell survival, as both its knockdown and overexpression reduced the efficacy of CS-6. Furthermore, transcriptomic analysis revealed that targeting CHCHD2 with CS-6 activates interferon signaling and significantly upregulates the tumor suppressor X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1). In conclusion, these findings establish the mitochondrial CHCHD2-XAF1 axis as a key mediator of CS-6 activity, thereby highlighting CS-6 as a promising candidate for targeted therapy in NSCLC.