Identification of diarylsulfonamides as agonists of the free fatty acid receptor 4 (FFA4/GPR120).

The exploration of a diarylsulfonamide series of free fatty acid receptor 4 (FFA4/GPR120) agonists is described. This work led to the identification of selective FFA4 agonist 8 (GSK137647A) and selective FFA4 antagonist 39. The in vitro profile of compounds 8 and 39 is presented herein.

Discovery of 3,5-disubstituted-1H-pyrrolo[2,3-b]pyridines as potent inhibitors of the insulin-like growth factor-1 receptor (IGF-1R) tyrosine kinase.

Exploration of the SAR around a series of 3,5-disubstituted-1H-pyrrolo[2,3-b]pyridines led to the discovery of novel pyrrolopyridine inhibitors of the IGF-1R tyrosine kinase. Several compounds demonstrated nanomolar potency in enzyme and cellular mechanistic assays.

Discovery and optimization of imidazo[1,2-a]pyridine inhibitors of insulin-like growth factor-1 receptor (IGF-1R).

The optimization of imidazo[1,2-a]pyridine inhibitors as potent and selective inhibitors of IGF-1R is presented. Further optimization of oral exposure in mice is also discussed. Detailed selectivity, in vitro activity, and in vivo PK profiles of an optimized compound is also highlighted.

Discovery of 4,6-bis-anilino-1H-pyrrolo[2,3-d]pyrimidines: potent inhibitors of the IGF-1R receptor tyrosine kinase.

The evaluation of a series of 4,6-bis-anilino-1H-pyrrolo[2,3-d]pyrimidines as inhibitors of the IGF-1R (IGF-IR) receptor tyrosine kinase is reported. Examples demonstrate nanomolar potencies in in vitro enzyme and mechanistic cellular assays as well as promising in vivo pharmacokinetics in rat.

Optimization of 4,6-bis-anilino-1H-pyrrolo[2,3-d]pyrimidine IGF-1R tyrosine kinase inhibitors towards JNK selectivity.

The SAR of C5' functional groups with terminal basic amines at the C6 aniline of 4,6-bis-anilino-1H-pyrrolo[2,3-d]pyrimidines is reported. Examples demonstrate potent inhibition of IGF-1R with 1000-fold selectivity over JNK1 and 3 in enzymatic assays.

Substrate specificity and novel selective inhibitors of TNF-alpha converting enzyme (TACE) from two-dimensional substrate mapping.

We report a systematic analysis of the P1' and P2' substrate specificity of TNF-alpha converting enzyme (TACE) using a peptide library and a novel analytical method, and we use the substrate specificity information to design novel reverse hydroxamate inhibitors. Initial truncation studies, using the amino acid sequence around the cleavage site in precursor-TNF-alpha, showed that good turnover was obtained with the peptide DNP-LAQAVRSS-NH2. Based on this result, 1000 different peptide substrates of the form Biotin-LAQA-P1'-P2'-SSK(DNP)-NH2 were prepared, with 50 different natural and unnatural amino acids at P1' in combination with 20 different amino acids at P2'. The peptides were pooled, treated with purified microsomal TACE, and the reaction mixtures were passed over a streptavidin affinity column to remove unreacted substrate and the N-terminal biotinylated product. C-terminal cleavage products not binding to streptavidin were subjected to liquid chromatography/mass spectrometry analysis where individual products were identified and semiquantitated. 25 of the substrates were resynthesized as discrete peptides and assayed with recombinant TACE. The experiments show that recombinant TACE prefers lipophilic amino acids at the P1' position, such as phenylglycine, homophenylalanine, leucine and valine. At the P2' position, TACE can accommodate basic amino acids, such as arginine and lysine, as well as certain non-basic amino acids such as citrulline, methionine sulfoxide and threonine. These substrate preferences were used in the design of novel reverse hydroxamate TACE inhibitors with phenethyl and 5-methyl-thiophene-methyl side-chains at P1', and threonine and nitro-arginine at P2'.

Metalloproteinase inhibitors for the disintegrin-like metalloproteinases ADAM10 and ADAM17 that differentially block constitutive and phorbol ester-inducible shedding of cell surface molecules.

The transmembrane metzinkin-proteases of the ADAM (a disintegrin and a metalloproteinase)-family ADAM10 and ADAM 17 are both implicated in the ectodomain shedding of various cell surface molecules including the IL6-receptor and the transmembrane chemokines CX3CL1 and CXCL16. These molecules are constitutively released from cultured cells, a process that can be rapidly enhanced by cell stimulation with phorbol esters such as PMA. Recent research supports the view that the constitutive cleavage predominantly involves ADAM10 while the inducible one is mediated to a large extent by ADAM17. We here describe the discovery of hydroxamate compounds with different potency against ADAM10 and ADAM17 and different ability to block constitutive and inducible cleavage of IL6R, CX3CL1 and CXCL16 by the two proteases. By screening a number of hydroxamate inhibitors for the inhibition of recombinant metalloproteinases, a compound was found inhibiting ADAM10 with more than 100-fold higher potency than ADAM17, which may be explained by an improved fit of the compound to the S1' specificity pocket of ADAM10 as compared to that of ADAM17. In cell-based cleavage experiments this compound (GI254023X) potently blocked the constitutive release of IL6R, CX3CL1 and CXCL16, which was in line with the reported involvement of ADAM10 but not ADAM17 in this process. By contrast, the compound did not affect the PMA-induced shedding, which was only blocked by GW280264X, a potent inhibitor of ADAM17. As expected, GI254023X did not further decrease the residual release of CX3CL1 and CXCL16 in ADAM10-deficient cells verifying that the compound's effect on the constitutive shedding of these molecules was exclusively due to the inhibition of ADAM10. Thus, GI254023X may by of use as a preferential inhibitor of constitutive shedding events without effecting the inducible shedding in response to agonists acting similar to PMA.

Inhibition of the tumor necrosis factor-alpha-converting enzyme by its pro domain.

Tumor necrosis factor-alpha-converting enzyme (TACE) is a disintegrin metalloproteinase that processes tumor necrosis factor and a host of other ectodomains. TACE is biosynthesized as a zymogen, and activation requires the removal of an inhibitory pro domain. Little is known about how the pro domain exerts inhibition for this class of enzymes. To study the inhibitory properties of the pro domain of TACE, we have expressed it in isolation from the rest of the protease. Here we show that the TACE pro domain (TACE Pro) is a stably folded protein that is able to inhibit this enzyme. TACE Pro inhibited the catalytic domain of TACE with an IC(50) of 70 nm. In contrast, this inhibitory potency decreased over 30-fold against a TACE form containing the catalytic plus disintegrin/cysteine-rich domains (IC(50) greater that 2 microm). The disintegrin/cysteine-rich region in isolation also decreases the interaction of TACE Pro with the catalytic domain. Surprisingly, we found that the cysteine switch motif located in TACE Pro was not essential for inhibition of the enzymatic activity of TACE; the pro domain variant C184A showed the same inhibitory potency against both TACE forms as wild type TACE Pro. X-ray absorption spectroscopy experiments indicate that binding of TACE Pro to the catalytic domain does include ligation of the catalytic zinc ion via the sulfur atom of its conserved Cys(184) residue. Moreover, the binding of TACE Pro to the catalytic zinc ion partially oxidizes the catalytic zinc ion of the enzyme. Despite this, the nature of the interaction between the pro and catalytic domains of TACE is not consistent with a simple competitive model of inhibition based on cysteine switch ligation of the zinc ion within the active site of TACE.