A series of seven novel iridium complexes were synthetized and characterized as potential photosensitizers for photodynamic therapy (PDT) applications. Among them, four complexes were evaluated in vitro for their anti-proliferative activity with and without irradiation on a panel of five cancer cell lines, namely PC-3 (prostate cancer), T24 (bladder cancer), MCF7 (breast cancer), A549 (lung cancer) and HeLa (cervix cancer), and two non-cancerous cell models (NIH-3T3 fibroblasts and MC3T3 osteoblasts). After irradiation at 458 nm, all tested complexes showed a strong selectivity against cancer cells, with a selectivity index (SI) ranging from 8 to 34 compared with non-cancerous cells. The cytotoxic effect of all these complexes was found to be independent of the anti-apoptotic protein Bcl-xL. The compound exhibiting the best selectivity, complex 4a, was selected for further investigations. Complex 4a was mainly localized in the mitochondria. We found that the loss of cell viability and the decrease in ATP and GSH content induced by complex 4a were independent of both Bcl-xL and caspase activation, leading to a non-apoptotic cell death. By counteracting the intrinsic or acquired resistance to apoptosis associated with cancer, complex 4a could be an interesting therapeutic alternative to be studied in preclinical models.
我们合成了一系列七种新型铱配合物,并将其表征为潜在的光敏剂,用于光动力疗法(PDT)。其中,四种复合物在体外对五种癌细胞系(PC-3(前列腺癌)、T24(膀胱癌)、MCF7(乳腺癌)、A549(肺癌)和 HeLa(宫颈癌))以及两种非癌细胞模型(NIH-3T3 成纤维细胞和 MC3T3 成骨细胞)进行了照射或不照射的抗增殖活性评估。经 458 纳米波长照射后,所有测试的复合物对癌细胞都有很强的选择性,与非癌细胞相比,选择性指数(SI)从 8 到 34 不等。研究发现,所有这些复合物的细胞毒性作用都与抗凋亡蛋白 Bcl-xL 无关。研究人员选择了选择性最好的复合物 4a 进行进一步研究。复合物 4a 主要定位于线粒体。我们发现,复合物 4a 诱导的细胞活力丧失、ATP 和 GSH 含量降低与 Bcl-xL 和 caspase 激活无关,从而导致细胞非凋亡性死亡。通过抵消与癌症相关的细胞凋亡的内在或获得性抗性,复合物 4a 可以成为一种有趣的治疗选择,在临床前模型中进行研究。