"Discovery of Novel Pharmacological Probes Targeting the ATX-LPA Signaling Axis Using Virtual Screening"

Thursday, 13 February 2014 - 4:15pm - 5:30pm
Dr. James Fells, Postdoctoral Fellow, University of Tennessee Health Science Center
LD 020

ATX (Autotaxin), a lysophospholipase D that generates LPA(lysophosphatidic acid), is among the 40 most upregulated genes in metastatic cancers.  ATX increases resistance to chemo- and radiation-therapy; and over expression of LPA receptors leads to malignant transformation, metastasis, and resistance to cell death. Difficult to treat cancers such as ovarian, glioblastoma, and triple-negative breast cancer (TNBC) commonly fit this profile, presenting a significant potential and application of ATX inhibitors. While several campaigns have attempted to develop ATX inhibitors, most target the enzyme active site causing the drug to ultimately fail due to poor solubility or bioavailability.  Examination of the recently solved ATX crystal structured provided key insight to alternative sites regarding the rational design of ATX inhibitors. In the presented study, we first developed a high-throughput assay for ATX. A total of 10,000 compounds were screened and 126 molecules were identified as ATX inhibitors.  Based on in silico modeling two classes of hits emerged: active site inhibitors and hydrophobic pocket inhibitors. One of the lead compounds, 918013 (IC50 31 nM), is highly effective in inhibition of experimental metastasis, while showing no toxicity to animals at highly efficacious doses.  Computational- guided modifications have resulted in the development of "2nd generation" sulfonamide aromatic analogs with up to 10-fold enhanced potencies.  Subsequent inclusion of predictive modeling improved the screening hit rate from 2% to 20% success rate.  Moreover, these molecular, functional and biochemical studies provide evidence that blocking the ATX hydrophobic pocket is sufficient in disrupting ATX activity. Thus, this novel class of ATX inhibitors will be useful for manipulating ATX signaling and developing new therapies against ATX pathway related diseases.