Identification of potent and compartment-selective small molecule furin inhibitors using cell-based assays

Abstract

The proprotein convertase furin is implicated in a variety of pathogenic processes such as bacterial toxin activation, viral propagation, and cancer. Several groups have identified non-peptide compounds with high inhibitory potency against furin in vitro, although their efficacy in various cellbased assays is largely unknown. In this study we show that certain guanidinylated 2,5-dideoxystreptamine derivatives exhibit interesting ex vivo properties. Compound 1b (1,1'-(4-((2,4-diguanidino-5-(4-guanidinophenoxy)cyclohexyl)oxy)-1,3-phenylene)diguanidine) is a potent and cell-permeable inhibitor of cellular furin, since it was able to retard tumor cell migration, block release of a Golgi reporter, and protect cells against Bacillus anthracis (anthrax) and Pseudomonas aeruginosa intoxication, with no evident cell toxicity. Other compounds based on the 2,5-dideoxystreptamine scaffold, such as compound 1g (1,1'-(4,6-bis(4-guanidinophenoxy)cyclohexane-1,3-diyl)diguanidine) also efficiently protected cells against anthrax, but displayed only moderate protection against Pseudomonas exotoxin A and did not inhibit cell migration, suggesting poor cell permeability. Certain bisguanidinophenyl ether derivatives such as 2f (1,3-bis(2,4-diguanidinophenoxy) benzene) exhibited micromolar potency against furin in vitro, low cell toxicity, and highly efficient protection against anthrax toxin; this compound only slightly inhibited intracellular furin. Thus, compounds 1g and 2f both represent potent furin inhibitors at the cell surface with low intracellular inhibitory action, and these particular compounds might therefore be of preferred therapeutic interest in the treatment of certain bacterial and viral infections.

Synthesis and investigation of the derivatives of amidinohydrazonelated aromatic compounds as furin inhibitors

“…Analysis of these data indicated that the replacement of the linkers containing the propoxy group (compounds 3b, k i = 1.70 μM and 3c, k i = 2.69 μM), on the "bridges" with the phenyl ring (compounds 6a, k i = 1.07 μM and 6b, k i = 0.74 ± 0.08 μM), led to an increase in the inhibitory effect of the compounds. This conclusion coincides with the results of studies previously pub- [20,26] lished by our group [17] and by other investigators of guanidilated aromatic compounds [27]. Among the derivatives (3a-c) with the amidinohydrazone group unsubstituted on the Megroup, the most active inhibitor was compound 3b (k i = 1.70 μM), which contains a positively charged group in the meta-position relative to the linker.…”

Targeting proprotein convertases in furin‐rich lung cancer cells results in decreased in vitro and in vivo growth

“…General inhibitors of PCs such as PDX and CMK have been used with success in in vitro and in vivo experimental settings . Several putative furin‐specific inhibitors that have promising properties have been recently proposed . Therapies using an autologous tumor‐based product containing a plasmid encoding granulocyte‐macrophage colony‐stimulating factor and a bifunctional short hairpin RNAi that targets furin called FANG or Vigil have been or are being evaluated in clinical trials with patients suffering from advanced cancer of the ovary, liver and sarcomas .…”

Proprotein convertase inhibition: Paralyzing the cell’s master switches

“…After the development of these derivatives to dideoxystreptamine, other groups developed the bisguanidinephenyl ethers derivatives of 2–5 dideoxystreptamine containing two guanidine residues [57]. These two positively charged guanidine group are attached to a phenyl group, respectively, and the guanidine phenyl moieties are linked by a three carbon bridge.…”