[Mechanistic investigation of a natural compound against tumors via modulation of nuclear receptor RXRα-mediated...

Cancer treatment urgently requires individualized and precise strategies, and the development of highly selective drugs targeting specific molecular targets has become the core direction of current research. This study focused on the antitumor activity of the flavonoid compound cudratricusxanthone E(CAS 740810-46-2, C7), finding that it can significantly inhibit the proliferation of human cervical cancer HeLa cells in a time-dependent manner. Through the intervention of different cell death inhibitors, this study preliminarily revealed the potential pathway by which C7 induced cell death. The experiments found that the autophagy inhibitor chloroquine effectively blocked C7-mediated cell death, whereas the apoptosis inhibitor z-Val-Ala-Asp(OMe)-fluoromethylketone(Z-VAD-FMK) and the necroptosis inhibitor necrostatin-1(Nec-1) showed no significant effect. This suggested that C7 primarily induced cell death by activating the autophagy pathway, rather than through apoptosis or necroptosis, providing a key clue for understanding the compound's mechanism of action. To further elucidate its molecular mechanism, the study combined network pharmacology predictions with dual-luciferase reporter gene assays, identifying for the first time that the retinoid X receptor α(RXRα) was the target of C7. RXRα is a key regulatory factor in the nuclear receptor family, playing multiple roles in cell proliferation, differentiation, and metabolic regulation. In recent years, it has also been found to have regulatory significance in certain tumor processes. Subsequent experiments confirmed that C7 specifically bound to RXRα, triggering the phosphorylation of downstream adenosine monophosphate-activated protein kinase(AMPK). The activation of AMPK, as a central hub in cellular energy homeostasis and autophagy initiation, significantly promoted autophagic flux. Therefore, C7 drove autophagic cell death in HeLa cells by activating the RXRα/AMPK signaling axis, thereby exerting its antitumor effects. In summary, this study systematically elucidates the novel mechanism by which C7 induces tumor cell death, revealing the complete signaling pathway from the compound targeting RXRα to AMPK activation and ultimately leading to autophagic cell death.