Smart mitochondrial-targeted cancer therapy: Subcellular distribution, selective TrxR2 inhibition accompany with declined antioxidant capacity

Targeting mitochondrial redox homeostasis is an appealing methodology for cancer therapeutics because of the upregulated antioxidant capacity in drug resistance cases. By coupling triphenylamine (TPA) with an excellent fluorescent group BODIPY, a novel mitochondrial-targeted fluorescent probe, BODIPY-TPA (BTPA), was synthesized and characterized. Confocal microscopic colocalization imaging indicated that BTPA exhibited a subcellular mitochondrial distribution. Cytotoxicity experiments suggested that BTPA exhibited selective anticancer activity via the induction of mitochondrial dysfunction in BGC-823 cancer cells. BTPA induced alterations in mitochondrial redox homeostasis because of the electron-donating property of TPA and mitochondrial selectivity. In further studies, TrxR2 in the mitochondria was alternatively inhibited, which contributed to MtROS accumulation further attenuated PI3K/Akt signaling pathway. The resultant decline in mitochondrial antioxidant capacity aggravated mitochondrial oxidative stress, which is responsible for cytochrome C release and caspase-9 activation. NAC completely reversed BTPA-induced ROS-dependent mitochondrial-mediated intrinsic apoptosis. Therefore, BTPA was designed as a superior fluorescent cancer-imaging probe and a mitochondrial redox-targeting anticancer agent.