title: High-throughput screen identifies novel inhibitors of cancer biomarker α-methylacyl coenzyme A racemase (AMACR/P504S).
abstract: α-methylacyl coenzyme A racemase (AMACR) is a metabolic enzyme whose overexpression has been shown to be a diagnostic indicator of prostatic adenocarcinoma and other solid tumors. Here, we confirm that attenuation of AMACR expression diminishes the growth of prostate cancer cell lines by using stably expressed short-hairpin RNA constructs. This observation strongly suggests that the AMACR enzyme may be a target for therapeutic inhibition in prostate cancer. To this end, we report here a novel assay capable of screening libraries of diverse small molecules for inhibitors of AMACR activity. This assay facilitated the screening of approximately 5,000 unique compounds and the discovery of 7 distinct chemical entities capable of inhibiting AMACR at low micromolar concentrations. The most potent inhibitor discovered is the seleno-organic compound ebselen oxide [inhibitory concentration (IC(50)): 0.80 μmol/L]. The parent compound, ebselen (IC(50): 2.79 μmol/L), is a covalent inactivator of AMACR (K(I)((inact)): 24 μmol/L). Two of the AMACR inhibitors are selectively toxic to prostate cancer cell lines (LAPC4/LNCaP/PC3) that express AMACR compared to a normal prostate fibroblast cell line (WPMY1) that does not express the protein. This report shows the first high-throughput screen for the discovery of novel AMACR inhibitors, characterizes the first nonsubstrate-based inhibitors, and validates that AMACR is a viable chemotherapeutic target in vitro.
authors: Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors: Brice A P
authors: BA
authors: Wilson
authors: Haofan
authors: H
authors: Wang
authors: Benjamin A
authors: BA
authors: Nacev
authors: Ronnie C
authors: RC
authors: Mease
authors: Jun O
authors: JO
authors: Liu
authors: Martin G
authors: MG
authors: Pomper
authors: William B
authors: WB
authors: Isaacs
mesh_terms: D001393:Azoles / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000037:antagonists & inhibitors* / Q000378:metabolism; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D055785:Gene Knockdown Techniques; D057166:High-Throughput Screening Assays; D006801:Humans; D054833:Isoindoles; D007700:Kinetics; D016566:Organoselenium Compounds / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D019998:Racemases and Epimerases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015203:Reproducibility of Results; D054852:Small Molecule Libraries / Q000378:metabolism
chemical_list: D001393:Azoles; D014408:Biomarkers, Tumor; D004791:Enzyme Inhibitors; D054833:Isoindoles; D016566:Organoselenium Compounds; D034741:RNA, Small Interfering; D054852:Small Molecule Libraries; C042986:ebselen; D019998:Racemases and Epimerases; C108352:alpha-methylacyl-CoA racemase