Identifying Lysophosphatidic Acid Acyltransferase Beta (Lpaat-Beta) As The Target Of A Nanomolar Angiogenesis Inhibitor From A Phenotypic Screen Using The Polypharmacology Browser Ppb2

By screening a focused library of kinase inhibitor analogues in a phenotypic co-culture assay for angiogenesis inhibition, we identified an aminotriazine that acts as a cytostatic nanomolar inhibitor. However, this aminotriazine was found to be completely inactive in a whole-kinome profiling assay. To decipher its mechanism of action, we used the online target prediction tool PPB2 (), which suggested lysophosphatidic acid acyltransferase beta (LPAAT-beta) as a possible target for this aminotriazine as well as several analogues identified by structure-activity relationship profiling. LPAAT-beta inhibition (IC50 approximate to 15 nm) was confirmed in a biochemical assay and by its effects on cell proliferation in comparison with a known LPAAT-beta inhibitor. These experiments illustrate the value of target-prediction tools to guide target identification for phenotypic screening hits and significantly expand the rather limited pharmacology of LPAAT-beta inhibitors.