Novel Silver(I) and Gold(I) N-Heterocyclic Carbene Complexes Induce ROS-Dependent Autophagic Cell Death in Human Hepatoma Cell Line HepG2.

Hepatocellular carcinoma is one of the most aggressive malignancies worldwide, with limited treatment options and high resistance to conventional therapies. Developing novel therapeutic strategies that target alternative cell death mechanisms is crucial for overcoming treatment resistance. This study evaluated the cytotoxicity of eight sulfonated silver(I) and gold(I) N-heterocyclic carbene (NHC) complexes-four newly synthesized-against human liver cancer cells and investigated the mechanisms of the compounds that exhibited higher selectivity for cancer cells compared to non-malignant liver cells. Morphological analysis revealed distinct features of autophagy rather than apoptosis, as confirmed by the absence of chromatin condensation, caspase-3 activation, and PARP-1 cleavage. Instead, both complexes strongly upregulated Beclin-1 and LC3-II expression-key autophagy markers-while inhibiting the AKT/mTOR signaling pathway. The observed cytotoxic effects were associated with a significant increase in reactive oxygen species (ROS) production. Pre-treatment with the antioxidant N-acetyl-L-cysteine completely abolished both cytotoxicity and autophagy induction. These findings demonstrate that silver(I) and gold(I) NHC complexes induce ROS-dependent autophagic cell death in this kind of cancer cells. The ability of these compounds to trigger non-apoptotic cell death mechanisms highlights their potential as promising candidates for overcoming apoptosis resistance in HCC therapy, warranting further in vivo investigations.