Novel 2-arylthiopropanoyl-CoA inhibitors of α-methylacyl-CoA racemase 1A (AMACR; P504S) as potential anti-prostate cancer agents

Abstract

Branched-chain fatty acid metabolism Castrate-resistant prostate cancer (CRPC) Drug lipophilicity Enzyme inhibitors Ibuprofen Mixed competitive inhibition Rational drug design Structure-activity relationships ABSTRACT α-Methylacyl-CoA racemase (AMACR; P504S) catalyses an essential step in the degradation of branched-chain fatty acids and the activation of ibuprofen and related drugs. AMACR has gained much attention as a drug target and biomarker, since it is found at elevated levels in prostate cancer and several other cancers. Herein, we report the synthesis of 2-(phenylthio)propanoyl-CoA derivatives which provided potent AMACR inhibitory activity (IC50 = 22-100 nM), as measured by the AMACR colorimetric activity assay. Inhibitor potency positively correlates with calculated logP, although 2-(3-benzyloxyphenylthio)propanoyl-CoA and 2-(4-(2-methylpropoxy) phenylthio)propanoyl-CoA were more potent than predicted by this parameter. Subsequently, carboxylic acid precursors were evaluated against androgen-dependent LnCaP prostate cancer cells and androgen-independent Du145 and PC3 prostate cancer cells using the MTS assay. All tested precursor acids showed inhibitory activity against LnCaP, Du145 and PC3 cells at 500 µM, but lacked activity at 100 µM. This is the first extensive structureactivity relationship study on the influence of side-chain interactions on the potency of novel rationally designed AMACR inhibitors.

Peroxisome Metabolism in Cancer

“…AMACR activity inhibitors identified by small molecule screening were reported to impair the proliferation and survival of prostate cancer cells [ 93 , 94 ]. Additional AMACR inhibitors designed on the basis of a structure–activity relationship analysis also efficiently suppressed prostate cancer progression [ 95 ]. Although it remains to be determined whether pharmacological perturbation of peroxisome metabolism is clinically effective in human cancer, these studies underscore the potential of peroxisome lipid metabolism as a useful target for anticancer treatment.…”

Racemases and epimerases operating through a 1,1-proton transfer mechanism: reactivity, mechanism and inhibition

“…161 A notable example of this approach is the elimination reaction of an unnatural acyl-CoA substrate 37 by AMACR to give 2,4dinitrophenoxide 38 and acyl-CoA 39 (Scheme 9); 127 this assay was used in a high-throughput screening campaign of 20 387 compounds which identified novel pyrazoloquinolines and pyrazolopyrimidines as inhibitors 163 and also in the first extensive inhibitor structure-activity relationship studies on any racemase/epimerase (vide infra). 164,165…”

“…29). 165 Preventing the removal of the a-proton These types of inhibitors fall into two types: those in which the C a -H has been replaced by an alternative group and those with neighbouring groups which decrease the acidity of the C a -H. A number of different groups have been used to replace the C a -H (in addition to the substrate/product analogues with a second side-chain noted above), including fluorine atoms, e.g. 49,191 and methylene groups, e.g.…”

“…6 Representative inhibitors with increased C a -H acidity. 136,165,190 Fig. 7 Representative inhibitors in which the C a -H is replaced.…”

Through the Looking Glass: Chiral Recognition of Substrates and Products at the Active Sites of Racemases and Epimerases

“…[151,152] Elevated levels of AMACRh ave been associated with variousc ancers [153][154][155] and the enzymei saputative biomarker for prostate cancer, [156][157][158] as well as ap otential target for the development of therapeutic agents directed against the disease. [159][160][161][162][163][164][165] Extensive structural, kinetic, and site-directed mutagenesis studies have been conducted on the AMACR homologue from Mycobacterium tuberculosis (MCR) which has 43 %a mino acid sequence homology to human AMACR. [91,166] The enantiospecific Brønsted base catalysts of MCR have been identified as His126a nd Asp156, which abstract the a-proton from substrates with the 2S-a nd 2R-stereochemisties, respectively (Scheme 8).…”