Dual functions of iridium(III) 2-phenylpyridine complexes: Metastasis inhibition and lysosomal damage

Six N-phenylcarbazole/triphenylamine-appended half-sandwich iridium(III) 2-phenylpyridine complexes ([(η⁵-Cp*)Ir(C^N)Cl]) were prepared and characterized. Compared with cisplatin, these complexes exhibited potential antitumor activity against A549 and HeLa tumor cells, with IC₅₀ values (half-maximum inhibitory concentration) that changed from 2.8 ± 0.8 μM to 39.5 ± 2.7 μM, and could block the migration of tumor cells. These complexes also effectively bound to protein (binding constant: ~10⁴ M^-1) and were transported through serum proteins, catalyzed the oxidation of coenzyme nicotinamide-adenine dinucleotide. Additionally, laser confocal microscopy and flow cytometry confirmed that these complexes possessed a non-energy-dependent cellular uptake mechanism, effectively accumulated in lysosomes (Pearson colocalization coefficient: ~0.74), damaged the integrity of acidic lysosomes, led to a change in the mitochondrial membrane potential, disrupted the cell cycle (G₀/G₁ phase), and eventually induced apoptosis. Above all, these complexes are potential antitumor agents with dual functions: metastasis inhibition and lysosomal damage.