The induction of apoptosis in BEL-7402 cells by an iridium(III) complex through lysosome–mitochondria pathway

Liposome as drug delivery system enhance anticancer activity of iridium (III) complex

Herein an Ir(III) complex [Ir(Hppy)₂(HMNPIP)](PF₆) (Ir1, Hppy = 2-phenylpyridine, HMNPIP = 2-(1H-imidazo[4,5-f][1, 10]phenanthroline-3-yl)-6-methoxy-4-nitrophenol) was prepared and characterized. Due to the low anticancer activity of Ir1 when administered free drug, we prepared a liposome Ir1Lipo encapsulated form of Ir1 to improve the antitumor effect, furthermore, we explored the antitumor mechanism of both forms in vitro experiments on HepG2 cells. We investigated the inhibitory efficiency of Ir1 and Ir1Lipo on cell viability and proliferation using MTT (MTT = 3-(4,5-dimethylthiazole)-2,5-diphenltetraazolium bromide) and colony-forming assay. Intracellular accumulation of reactive oxygen species (ROS) was examined using a fluorescence microscope (High Content Screening System, ImageXpress Micro XLS System, Molecular Devices LLC, Sunnyvale, CA), programmed cell death cells stained with acridine orange/ethidium bromide (AO/EB) using flow cytometry detection and western blot have been performed. An in vivo study where HepG2 cells were transplanted into nude nice as xenografts. Tumour volume and body weight were monitored during the 10 days of administration. After encapsulation in liposomes Ir1Lipo displayed high potency against a variety of tumour cells in vitro, especially against HepG2 (IC₅₀ = 4.6 ± 0.5 μM). Mechanism studies indicated that Ir1Lipo initiated apoptosis by generating intracellular ROS that regulate lysosomal-mitochondrial dysfunction, followed by microtubule disruption that subsequently leads to a G0/G1 phase of cell cycle arrest. Additionally, Ir1Lipo significantly curbed tumour growth in nude mice. The tumour inhibitory rate was 51.2% (5.6 mg/kg). Therefore, liposome as a drug delivery system greatly enhances anticancer activity of Ir1 by a factor of relatively minor side effects.

Iridium(III) Complexes Targeting Apoptotic Cell Death in Cancer Cells

Targeting apoptosis is a principal strategy in the design of anticancer drugs. In recent years, non-platinum-based scaffolds have been exploited as viable candidates for the exploitation of anticancer agents with potentially lower toxicity than the widely used cisplatin analogues. This review highlights the latest advances in developing iridium(III) complexes as anticancer agents that act particularly via targeting apoptotic cell death in cancer cells.

Evaluation of anticancer activity in vitro and in vivo of iridium(iii) polypyridyl complexes

Three new iridium(iii) polypyridyl complexes were synthesized. The cytotoxic activity in vitro and in vivo, apoptosis, cell cycle arrest, mitochondrial membrane potential, ROS and the expression of Bcl-2 family proteins were investigated.