Potent and selective inhibition of matrix metalloproteinases by lanthanide trichloride

Matrix metalloproteinases (MMPs) are a family of Zn-containing and Ca-dependent proteases with vital roles in extracellular matrix remodeling. Deregulation of MMPs occurs in many pathological conditions such as cardiovascular diseases, inflammation, and cancer. The therapeutic potential of MMP inhibitors has been demonstrated in diseases such as arthritis and cancer. Here we demonstrated that the 3-valent lanthanide compounds LaCl₃, TbCl₃, GdCl₃, YbCl₃, and EuCl₃ inhibit MMPs such as MMP-2, MMP-13, and MMP-14 (MT1-MMP). The inhibition is more potent and selective toward MT1-MMP compared to the other MMPs. EuCl₃ was further selected to study the enzyme kinetics of the MT1-MMP inhibition. The results showed that the inhibition is a mixed type with anti-competition and non-competitive types, which indicated that inhibition was achieved by the compound bound to the non-active center of MT1-MMP and changing the enzyme conformation. The interaction between EuCl₃ and MT1-MMP was further studied by UV-visible (UV-vis) light absorption. EuCl₃ caused a slight blue shift of the maximum absorption wavelength of MT1-MMP, indicating the interaction reduced protein hydrophobicity. Moreover, EuCl₃ exerted substantial inhibitory effects on the migration of HT-1080 cells. Thus, EuCl₃ may play a role in modulating tumor cell behavior by inhibiting MMPs activities especially the MT1-MMP activity. These findings provide initial insight into the biological activity and potential therapeutic value of EuCl₃.