Dual Inhibitory Pathways of Metallofullerenol Gd@C82(OH)22 on Matrix Metalloproteinase-2: Molecular insight into drug-like nanomedicine

Cancer metastasis is an important criterion to evaluate tumor malignancy. Matrix metalloproteinases (MMPs) play a crucial role in cancer proliferation and migration by virtue of their proteolytic functions in angiogenesis and extracelluar matrix (ECM) degradation, making them potential targets of anti-metastaic therapeutics. Recently we showed with both in vivo and in vitro experiments that metallofullerenol Gd@C-82(OH)(22) can effectively inhibit MMP-2 and MMP-9 with high antitumoral efficacy. Furthermore, our in silico study revealed that Gd@C-82(OH)(22) could indirectly inhibit the proteolysis of MMP-9 via allosteric modulation exclusively at the ligand specificity S1' loop. Here, we expand our study toward another gelatinase, MMP-2, using molecular dynamics simulations. Despite the high structural similarity with 64.3% sequence identity, their responses to Gd@C-82(OH)(22) were quite different. Toward MMP-2, Gd@C-82(OH)(22) could block either the Zn2+-catalylitic site directly or the S1' loop indirectly. Surface electrostatics uniquely determines the initial adsorption of Gd@C-82(OH)(22) on MMP-2, and then its further location of the most favorable binding site(s). These findings not only illustrated how the inhibitory mechanism of Gd@C-82(OH)(22) is distinguished between the two gelatinase MMPs with atomic details, but also shed light on the de novo design of anti-metastatic nanotherapeutics with enhanced target specificity.