Strategy to gain selectivity within the gelatinase subfamily. Design and synthesis of novel matrix metalloprotease-2 (mmp-2) inhibitors

Resumen

Scientific background: Matrix metalloproteinases (MMPs) are zinc endopeptidases that mediate the degradation and the remodelling of the extracellular matrix (ECM). MMPs are involved in several pathological conditions such as disorders of the central nervous system (CNS) or the cardiovascular system, immuno-inflammatory diseases and cancer. Pre-clinical studies clearly demonstrated the involvement of MMPs in cancer and a great hope was put on MMP inhibitors (MMPIs) as new complementary treatment. However, clinical trials were disappointing, and MMPIs showed poor efficiency. One of the main arguments raised for such failure is the lack of selectivity of this first generation of MMPIs (broad spectrum inhibitors were then used). For this reason, the improvement of the MMPIs selectivity is a key step toward the development of effective drugs. The mammalian MMP family is divided into six subfamilies, among which the gelatinases one, formed by MMP-2 and MMP-9. While MMP-2 is a validated target for cancer treatment, MMP-9 is considered as an anti-target. Taking this in consideration, this work aimed at developing small molecules that selectively inhibit MMP-2 over MMP-9. For this, our group previously developed a series of hydroxamate-based MMP-2 inhibitors (the hydroxamate group is a potent chelator of the proteases catalytic zinc ion) obtained via click-chemistry, what allows a rapid screening of the S1' pocket of MMPs (this pocket is of primary importance for selectivity among MMPs). _________________________________________________________________________________________ Work carried out: This work faced three main challenges: following the same click approach, (1) to design and synthesise hydroxamate inhibitors with improved water-solubility to allow further biological investigations (2) and MMP-2/MMP-9 selectivity, (3) and to develop new group(s) able to coordinate the MMP catalytic zinc ion (group known as zinc binding group, ZBG), alternative to the hydroxamate group. (1) First, a series of MMP-2 inhibitors, based on our first hydroxamate derivatives, was synthesised. We synthesised an azide core containing the hydroxamate ZBG. This fragment was clicked to alkyne residues, chosen to specifically interact with the S1' pocket of MMPs. Following this methodology we discovered a potent MMP-2 inhibitor with a good solubility in water, in vitro anti-invasive activity, cacao-2 cell monolayer permeability and a promising selectivity profile. (2) We then performed extensive computational studies (MQ, QM/MM) on the mode of binding of this inhibitor with both gelatinases, to rationalize its MMP-2/MMP-9 selectivity. This led us to propose that the higher plasticity of the S1' pocket of MMP-2 could be effectively used to design inhibitors with improved selectivity within the gelatinase subfamily. Following this hypothesis, we designed and synthesised a new series of hydroxamate-based inhibitors that kept good solubility in water. Supporting our hypothesis, all these compounds displayed a lower inhibition activity against MMP-9. In particular, one of the inhibitors showed a high MMP-2/MMP-9 selectivity (half maximal inhibitory concentrations -IC50- ratio over 100), rarely observed for such potent hydroxamate inhibitors. (3) In the last step, we aimed at transferring this discovery to compounds bearing a non-hydroxamate ZBG. Although the hydroxamate group is an excellent metal chelator, it presents toxicity, metabolic liability and low selectivity among metalloproteinases. Based on previous works on oxadiazole derivatives, we discovered a thiadiazolesulfonamide derivative that inhibit MMP-2 at micromolar concentrations. We proposed that such moiety could act as a new ZBG. Furthermore, based on the known thiirane ZBG, we developed new clicked thiirane compounds as promising gelatinases inhibitors with submicromolar IC50. In overall this work presents advancements in the selective inhibition of MMP-2, as a strategy to treat cancer.