No abstract

Immunogenic cell death (ICD) is a vital component of therapeutically induced anti‐tumor immunity. An iridium(III) complex (Ir1), containing an N,N‐bis(2‐chloroethyl)‐azane derivate, as an endoplasmic reticulum‐localized ICD inducer for non‐small cell lung cancer (NSCLC) is reported. The characteristic discharge of damage‐associated molecular patterns (DAMPs), that is, cell surface exposure of calreticulin (CRT), extracellular exclusion of high mobility group box 1 (HMGB1), and ATP, were generated by Ir1 in A549 lung cancer cells, accompanied by an increase in endoplasmic reticulum stress and reactive oxygen species (ROS). The vaccination of immunocompetent mice with Ir1‐treated dying cells elicited an antitumor CD8+ T cell response and Foxp3+ T cell depletion, which eventually resulted in long‐acting anti‐tumor immunity by the activation of ICD in lung cancer cells. Ir1 is the first Ir‐based complex that is capable of developing an immunomodulatory response by immunogenic cell death.

A series of mitochondria-targeting cyclometalated iridium(iii) complexes activated the oncosis-specific protein porimin and calpain 1, and exhibited good inhibitory activities on a wide range of cancer types including drug-resistant cancers.

Cisplatin was the first metal-based therapeutic agent approved for the treatment of human cancers, but its clinical activity is greatly limited by tumor drug resistance. This work utilized the parent complex [Ru(phen)2(PIP)]2+ (1) to develop three Ru(II) complexes (2–4) with different positional modifications. These compounds exhibited similar or superior cytotoxicities compared to cisplatin in HeLa, A549 and multidrug-resistant (A549R) tumor cell lines. Complex 4, the most potent member of the series, was highly active against A549R cancer cells (IC50 = 0.8 μM). This complex exhibited 178-fold better activity than cisplatin (IC50 = 142.5 μM) in A549R cells. 3D multicellular A549R tumor spheroids were also used to confirm the high proliferative and cytotoxic activity of complex 4. Complex 4 had the greatest cellular uptake and had a tendency to accumulate in the mitochondria of A549R cells. Further mechanistic studies showed that complex 4 induced A549R cell apoptosis via inhibition of thioredoxin reductase (TrxR), elevated intracellular ROS levels, mitochondrial dysfunction and cell cycle arrest, making it an outstanding candidate for overcoming cisplatin resistance.

Combining luminescent transition metal complex with super‐resolution microscopy is an excellent strategy for the long‐term visualization of the dynamics of subcellular structures in living cells. However, it remains unclear whether iridium(III) complexes are applicable for a particular type of super‐resolution technique, structured illumination microscopy (SIM), to image subcellular structures. Herein, an iridium(III) dye, to track mitochondrial dynamics in living cells under SIM is described. The dye demonstrates excellent specificity and photostability and satisfactory cell permeability. While using SIM to image mitochondria, an ≈80 nm resolution is achieved that allows the clear observation of the structure of mitochondrial cristae. The dye is used to monitor and quantify mitochondrial dynamics relative to lysosomes, including fusion involved in mitophagy, and newly discovered mitochondria–lysosome contact (MLC) under different conditions. The MLC remains intact and fusion vanishes when five receptors, p62, NDP52, OPTN, NBR1, and TAX1BP1, are knocked out, suggesting that these two processes are independent.