Mitochondria-targeted ruthenium complexes can be generated in vitro and in living cells to target triple-negative breast cancer cells by autophagy inhibition

Triple-negative breast cancer (TNBC) is the most aggressive type of breast cancer, which owned severe resistance to platinum-based anticancer agents. Herein, we report a new metal-arene complex, Ru-TPE-PPh3, which can be synthesized in vitro and in living cells with copper catalyzed the cycloaddition reaction of Ru-azide and alkynyl (CuAAC). The complex Ru-TPE-PPh3 exhibited superior inhibition of the proliferation of TNBC MDA-MB-231 cells with an IC50 value of 4.0 μM. Ru-TPE-PPh3 could induce the over production of reactive oxygen species (ROS) to initiate the oxidative stress, and further damage the mitochondria both functionally and morphologically, as loss of mitochondrial membrane potential (MMP) and cutting the supply of adenosine triphosphate (ATP), the disappearance of cristae structure. Moreover, the damaged mitochondria evoked the occurrence of mitophagy with the autophagic flux blockage and cell death. The complex Ru-TPE-PPh3 also demonstrated excellent anti-proliferative activity in 3D MDA-MB-231 multicellular tumor spheroids (MCTSs), indicating the potential to inhibit solid tumors in living cells. This study not only provided a potent agent for the TNBC treatment, but also demonstrated the universality of the bioorthogonally catalyzed lethality (BCL) strategy through CuAAC reation. In this study, a ruthenium-arene complex, Ru-TPE-PPh3, was designed for triple-negative breast cancer therapy. Ru-TPE-PPh3 can be selectively synthesized in situ within the mitochondria of cancer cells. Ru-TPE-PPh3 synthesized in vitro exhibits high cytotoxicity against triple-negative breast cancer cells, causing damage to the mitochondria, upregulating the expression of p62 and PINK1, and inducing cell death by blocking autophagy. [Display omitted] •Ru-TPE-PPh3 could be synthesized in vitro and in living cells.•Ru-TPE-PPh3 exhibited high cytotoxicity against the triple-negative breast cancer cell.•Ru-TPE-PPh3 damaged the mitochondria both functionally and morphologically.•Ru-TPE-PPh3 upregulated the expression of p62 and PINK1, inducing cell death by blocking autophagy.•Ru-TPE-PPh3 indicated excellent anti-proliferation activity in 3D multicellular tumor spheroids (MCTSs).