Matrix metalloproteinases (MMPs) are a family of zinc- and calcium-dependent endopeptidases which are secreted or anchored in the cell membrane and are capable of degrading the multiple components of the extracellular matrix (ECM). MMPs are frequently overexpressed or highly activated in numerous human diseases. Owing to the important role of MMPs in human diseases, many MMP inhibitors (MMPIs) have been developed as novel therapeutics, and some of them have entered clinical trials. However, so far, only one MMPI (doxycycline) has been approved by the FDA. Therefore, the evaluation of the activity of a specific subset of MMPs in human diseases using clinically relevant imaging techniques would be a powerful tool for the early diagnosis and assessment of the efficacy of therapy. In recent years, numerous MMPIs labeled imaging agents have emerged. This article begins by providing an overview of the MMP subfamily and its structure and function. The latest advances in the design of subtype selective MMPIs and their biological evaluation are then summarized. Subsequently, the potential use of MMPI-labeled diagnostic agents in clinical imaging techniques are discussed, including positron emission tomography (PET), single-photon emission computed tomography (SPECT) and optical imaging (OI). Finally, this article concludes with future perspectives and clinical utility.

Water solubility is a key aspect that needs to be addressed to obtain drug-like compounds. In an effort to improve the water solubility of our recently reported nanomolar matrix metalloproteinase type 2 (MMP-2) inhibitors based on triazole-substituted hydroxamates, we synthesized a new series of α-sulfone, α-tetrahydropyran and α-piperidine, α-sulfone clicked hydroxamates and determined their inhibitory activities against both MMP-2 and MMP-9. The best results were found for 13e, a water-soluble compound that displays a low nanomolar activity against MMP-2 and is 26-fold less active against MMP-9. This finding allowed us to pursue in vitro permeability through the Caco-2 monolayer and opened the possibility of carrying out further preclinical investigations. Docking and MD simulations have been performed in order to rationalize the biological results. The inhibitory activity of this compound against a panel of ten MMPs was determined showing an interesting MMP-2/MMP-1, -8, and -14 selectivity profile. The cytotoxicity and anti-invasive activity of the compounds on highly metastatic human fibrosarcoma tumor cells (HT1080) were determined, showing, at 10 μM concentration, a decrease in cell invasiveness up to 80%.

A new series of MMP2 inhibitors is described, following a fragment-based drug design approach. One fragment containing an azide group and a well known hydroxamate Zinc Binding Group in a α-sulfone, α-tetrahydropyrane scaffold, has been synthesized. Water-LOGSY, STD and competition-STD experiments indicate that this fragment binds to the active site of the enzyme. A click chemistry reaction was used to connect the azide to lipophilic alkynes selected to interact selectively with the S1' subunit of MMP2, as shown by docking and molecular dynamic experiments of the designed compounds. The most potent compounds 18 and 19 displayed an IC(50) of 1.4 and 0.3 nM against MMP2 respectively, and showed negligible activity towards MMP1 and MMP7, two metalloproteinases which have a shallow S1' subsite. Compound 18 also showed a promising selectivity profile against some antitarget metalloproteinases, such as MMP8, and considerably less activity against MMP14 (IC(50) = 65 nM), and MMP9 (IC(50) = 98 nM), other MMPs characterized by having a deep S1' pocket and, therefore, more similar to MMP2.

Looking for water-soluble inhibitors of matrix metalloproteinase-2 (MMP-2 or gelatinase A), we have previously reported compound 1, a potent MMP-2 inhibitor with a promising selectivity over the structurally homologous MMP-9 (gelatinase B). Here we report the results of Molecular Dynamics (MD) simulations for both gelatinases (MMP-2 and MMP-9), and for the corresponding MMP/1 complexes, in an attempt to shed light on the observed selectivity between the two enzymes. These studies indicated a higher plasticity of MMP-2 at the S1' pocket and suggested an induced-fit effect at the "back door" of this pocket. On the basis of these observations, we designed 11 a-d to aid further discrimination between MMP-2 and MMP-9. Those compounds displayed notably lower inhibitory activities against MMP-9; in particular, 11 b proved to be over 100 times more active against MMP-2 than against MMP-9. MD simulations of the MMP/11 b complexes and thermodynamic integration calculations provided structural insight and relative binding energies consistent with the experimentally observed activity data. These findings demonstrate that structural differences in the S1' pocket bottom permit an improvement in selectivity in the inhibition of MMP-2 over that of MMP-9; this is of great relevance for future structure-based drug design because MMP-2 is a validated target for cancer therapy, whereas MMP-9 plays both detrimental and protective roles in cancer. This study also supports the need to consider the dynamics of the S1' pocket in order to achieve selectivity in the inhibition of MMPs.

Hypothermia has been proved to have a beneficial effect on several pathologies. CIRBP is one of the so termed cold-shock proteins involved in this process. In this work, we have detected small molecules capable of modulating the activity of CIRBP in the absence of a cold stimulus, by High Throughput Virtual Screening (HTVS) of the Diversity Set IV of the NCI and 15 compounds of our in-house data base. Fifteen compounds were selected from the HTVS to carry out a second screening through a cell-based Western blot assay. This assay, together with molecular modeling studies allowed us to select compound zr17-2 for an in vivo experiment, which showed an interesting increase of CIRBP expression in several organs of experimental animals. Therefore, we have demonstrated that the effect of hypothermia can be mimicked by small molecules, which can be developed as first-in-class new drugs for the treatment of several diseases.