Ir(III) Compounds Containing a Terdentate Ligand Are Potent Inhibitors of Proliferation and Effective Antimetastatic Agents in Aggressive Triple-Negative Breast Cancer Cells

Herein, we report a series of new octahedral iridium(III)
complexes Ir1–Ir9 of the type [Ir(N^N^N)(C^N)Cl]PF6 (N^N^N = 4′-(p-tolyl)-2,2′:6′,2″-terpyridine;
C^N = deprotonated 2-arylbenzimidazole backbone) to introduce new
metal-based compounds for effective inhibition of metastatic processes
in triple-negative breast cancer (TNBC). The results show that the
structural modifications within the C^N scaffold strongly impact the
antimetastatic properties of these complexes in TNBC cells. Furthermore,
testing the antimetastatic effects of the investigated Ir complexes
revealed that the highest antimetastatic activity in TNBC cells is
exhibited by complex Ir1. This result was in contrast
to the effects of the clinically used drug doxorubicin used in conventional
chemotherapy of TNBC, which conversely promoted metastatic properties
of TNBC cells. Thus, the latter result suggests that doxorubicin chemotherapy
may increase the risk of metastasis of breast cancer cells, so the
search for new drugs to treat breast cancer that would show better
antitumor effects than doxorubicin is justified.