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The endogenous lipid mediator lysophosphatidic acid (LPA) regulates fundamental cellular responses, ranging from survival through proliferation to motility and migration. Acting through one of its cell membrane receptors, the LPA2 receptor, LPA protects against chemotherapy- and Gamma-irradiation-induced apoptosis. Virtual screening led to the identification of GRI977143 (GRI), a novel nonlipid LPA2 receptor agonist. GRI reduced activation of caspases 3, 7, 8, and 9, and inhibited Bax translocation, poly (ADP-ribose) polymerase 1 cleavage, and DNA fragmentation in the serum withdrawal, Adriamycin, TNF- , and Gamma-irradiation apoptosis models. GRI acted as a radiomitigator and rescued the lives of mice when administered 24 h after lethal radiation exposure. GRI also inhibited bystander apoptosis elicited by proapoptotic mediators produced by irradiated cells. Prosurvival and radiomitigative effect of GRI may in part be attributed to the LPA2 receptor-mediated activation of the extracellular signal regulated kinases 1 and 2. GRI represents an excellent candidate for further development of radiomitigative drugs, and agents that prevent apoptosis in degenerative and inflammatory diseases.

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Gyongyi Nagyne Kiss M.D., Ph.D. is assistant professor at the Department of Biochemistry and Medical Chemistry, University of Pécs, Medical School, Pécs, Hungary. Gabor Tigyi M.D., Ph.D is Harriet Van Vleet Professor and department chair at the Department of Physiology, University of Tennessee Health Science Center, Memphis, United States.

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