Adibekian_2011_Probe.Report__5

Protein palmitoylation is an essential post-translational modification necessary for trafficking and localization of regulatory proteins that play key roles in cell growth and signaling. Multiple oncogenes, including HRAS and SRC, require palmitoylation for malignant transformation. We and others have previously identified lysophospholipase 1 (LYPLA1) as a candidate protein palmitoyl thioesterase responsible for HRAS depalmitoylation in mammalian cells. Seeking chemical tools to investigate biochemical pathway involvement and potential roles in cancer pathogenesis, we conducted a fluorescence polarization-based competitive activity-based protein profiling (FluoPol ABPP) high throughput screening (HTS) campaign to identify inhibitors of LYPLA1 and the structurally related LYPLA2. HTS identified a micromolar triazole urea inhibitor, which we successfully optimized via several rounds of structure activity relationship (SAR)-by-synthesis to produce ML211 (SID 99445338), a low nanomolar dual inhibitor of LYPLA1 and LYPLA2. The reported probe operates by a covalent mechanism of action and is active both in vitro and in situ. Out of more than 20 serine hydrolases (SHs) profiled by gel-based competitive ABPP, ML211 is observed to have one anti-target, alpha/beta hydrolase domain-containing protein 11 (ABHD11). However, during our SAR campaign, we fortuitously discovered a selective ABHD11 inhibitor from among the synthetic triazole urea library compounds. This compound, ML226, is presented as an anti-probe for control studies.