Synthetic small molecule furin inhibitors derived from 2,5-dideoxystreptamine

Abstract

Furin plays a crucial role in embryogenesis and homeostasis and in diseases such as Alzheimer's disease, cancer, and viral and bacterial infections. Thus, inhibition of furin may provide a feasible and promising approach for therapeutic intervention of furin-mediated disease mechanisms. Here, we report on a class of small molecule furin inhibitors based on 2,5-dideoxystreptamine. Derivatization of 2,5-dideoxystreptamine by the addition of guanidinylated aryl groups yielded a set of furin inhibitors with nanomolar range potency against furin when assayed in a biochemical cleavage assay. Moreover, a subset of these furin inhibitors protected RAW 264.7 macrophage cells from toxicity caused by furin-dependent processing of anthrax protective antigen. These inhibitors were found to behave as competitive inhibitors of furin and to be relatively specific for furin. Molecular modeling revealed that these inhibitors may target the active site of furin as they showed site occupancy similar to the alkylating inhibitor decanoyl-Arg-Val-LysArg-CH 2Cl. The compounds presented here are bona fide synthetic small molecule furin inhibitors that exhibit potency in the nanomolar range, suggesting that they may serve as valuable tools for studying furin action and potential therapeutics agents for furindependent diseases.serine endoprotease ͉ prohormone ͉ proprotein convertase F urin is a membrane-anchored, calcium-dependent serine endoprotease and is expressed in all tissues and cell lines examined (1-3). It is the first and, so far, the best-characterized member of the mammalian subtilisin-like family of prohormone/proprotein convertases (PCs), which convert precursors of many secreted proteins and peptide hormones into their biologically active forms (1-3). Furin is predominantly localized in the trans-Golgi network and cycles between this compartment, the cell surface, and the endosomes (2, 4). Hence, furin is able to access and efficiently process a diverse spectrum of substrates including growth factors, receptors, serum proteins, matrix metalloproteinases, viral envelope glycoproteins, and bacterial toxins, typically at sites with the consensus sequence Arg-Xaa-Lys/Arg-Arg 2 (2).Although furin plays an essential role in embryogenesis and homeostasis, this endoprotease has also been implicated in the neurodegeneration associated with Alzheimer's disease, and tumor metastasis and the activation and virulence of many bacterial and viral pathogens (2). It has been demonstrated that furin inhibitors modulate tumor growth (5) and attenuate the toxicity of anthrax (6) and Pseudomonas aeruginosa (7) toxins and cytomegalovirus (8) in cell culture and animal models. Therefore, furin inhibitors hold great promise as potential therapeutic agents for treating furinmediated diseases and viral and bacterial infections, particularly for short-term therapy.To date, most furin inhibitors reported in the literature have been proteins (9-19) or peptides (20-24), which show excellent potency against furin, and largely mimic the substrate in bindi...

Synthetic Small-Molecule Prohormone Convertase 2 Inhibitors

“…Much more potent furin inhibitors have been generated recently by derivatization of 2,5-dideoxytryptamine with the addition of guanidinylated aryl groups (Jiao et al, 2006) and by using cell-based assays for screening (Coppola et al, 2007). For example, guanidinylated aryl compounds exhibit nanomolar K i values and possess excellent specificity (Jiao et al, 2006). These data support the idea that convertases can be specifically and potently inhibited by small molecules.…”

“…Andrographolide paniculata diterpines of the labdane family were the first example of such nonpeptide convertase inhibitors (Basak et al, 1999); however, inhibition was quite weak and nonspecific. Much more potent furin inhibitors have been generated recently by derivatization of 2,5-dideoxytryptamine with the addition of guanidinylated aryl groups (Jiao et al, 2006) and by using cell-based assays for screening (Coppola et al, 2007). For example, guanidinylated aryl compounds exhibit nanomolar K i values and possess excellent specificity (Jiao et al, 2006).…”

“…Many smallmolecule inhibitors have been reported to date against the proprotein convertase furin (Basak et al, 1999;Podsiadlo et al, 2004;Jiao et al, 2006); these may be useful in blocking many furin-dependent pathological processes (Fugere and Day, 2005). However, no small-molecule inhibitors of proprotein convertases other than furin have yet been identified.…”

Targeting Host Cell Furin Proprotein Convertases as a Therapeutic Strategy against Bacterial Toxins and Viral Pathogens

“…The intact toxins and viral proteins are incapable of accomplishing these processes. Evidence suggests that the inhibition of cellular furin prevents aggressive disease (2,5). These results lead to the logical suggestion that furin is a promising drug target in infectious diseases; an experimental confirmation, however, has been limited because research efforts have been focused primarily on anthrax (5-7).…”

Structure of the unliganded form of the proprotein convertase furin suggests activation by a substrate-induced mechanism

“…The PCs are also involved in a large number of pathologies, including bacterial and viral infections, as well as cancer and metastasis. Therefore, these enzymes are intensely investigated as drug targets (3), using for example, peptide-derived compounds (4)(5)(6)(7)(8)(9), nonpeptidic small molecule compounds (10,11), and protein-based inhibitors (12)(13)(14)(15).…”