• MMPs
• MMP-12
• Dimeri
• COPD

The extracellular matrix (ECM) plays many important physiological functions such as providing support, segregating tissues from one another, and regulating intercellular communication. ECM is not static: it is remodeled constantly, which implies constant breakdown by proteases, notably the family of matrix metalloproteases (MMPs). MMPs are extracellular enzymes that need a bivalent metallic ion, Zinc, for their activity. The mechanism by which they perform their function of degradation is proteolysis that allows these enzymes to perform numerous physiological functions but that, unlike other modifications, produces an irreversible change. It is not surprising that these proteins are tightly controlled through a system of endogenous inhibitors (TIMPs)at many levels: transcription, activation and inhibition. A disorder or loss of this control can lead, as evidenced by numerous studies, to an uncontrolled activity of MMPs and the onset of various disease. In particular, Human Macrophage Metalloelastase (HME, MMP-12) is one of these MMPs found initially in the alveolar macrophages of cigarette smokers. As the matter of fact the destruction of elastic lung tissue, caused by an imbalance in the control of this protein, producesemphysema and chronic inflammation of the airways that leads to Chronic obstructive pulmonary disease (COPD)1.
Some MMPs can undergo a homodimerization process that has been found naturally occurring in some signalling pathways, especially those related to cell migration processes2. An artificial protein dimerization has been observed by X-ray crystallographic studies performed on MMP inhibitors developed by Prof.Rossello’s group in complex with some MMPs (particularly MMP-9 and MMP-12)3. The best results were obtained using a dimeric dicarboxylate inhibitor (LC20), which was able to arrest human glioblastoma cancer cell invasiveness(unpublished results).
During my thesis work I was involved in the synthesis of three new dimers containing two carboxylate or two hydroxamate groups as zinc-binding group (ZBG). Starting from the structure of LC20, a biphenyl-sulfonamidobased symmetric dimer containing two carboxyl groups as ZBG, I synthesized two new asymmetric dimers. These are dimeric dicarboxylate inhibitors obtained by linking two different heads (MMP binding moieties) with a proper spacer. The third synthesized compound, however, is a symmetric dimer with the same biphenyl-sulfonamidic structure as the others and a different spacer, having two hydroxamates as ZBG.
In order to verify if the new compounds were active and selective for MMP-12 over the other MMPs, in vitro assays were conducted on human recombinant MMPs by fluorometricHTS methods, using a fluorogenic peptide as substrate. They demonstrated a nanomolar activity against MMP-12.
Further X-ray crystallographic and cell studies will be performed on the new dimers in order to prove their mechanism of action.