Cationic Amphiphilic Tris-Cyclometalated Iridium(III) Complexes Induce Cancer Cell Death via Interaction with Ca2+-Calmodulin Complex

In our previous paper, we reported on the preparation of some cationic amphiphilic Ir complexes (2c, 2d) containing KKGG peptides that induce and detect cell death of Jurkat cells. Mechanistic studies suggest that 2c interacts with anionic molecules and/or membrane receptors on the cell surface to trigger an intracellular Ca2+ response, resulting in the induction of cell death, accompanied by membrane disruption. We have continued the studies of cell death of Jurkat cells induced by 2c and found that xestospongin C, a selective inhibitor of an inositol 1,4,5-trisphosphate receptor located on the endoplasmic reticulum (ER), reduces the cytotoxicity of 2c, suggesting that 2c triggers the release of Ca2+ from the ER, leading to an increase in the concentration of cytosolic Ca2+, thus inducing cell death. Moreover, we synthesized a series of new amphiphilic cationic Ir complexes 5a–c containing photoreactive 3-trifluoromethyl-3-phenyldiazirine (TFPD) groups, in an attempt to identify the target molecules of 2...