FTY720 (Fingolimod™), a synthetic analogue of sphingosine 1-phosphate (S1P), activates four of the five EDG-family S1P receptors and is in a phase-III clinical study for the treatment of multiple sclerosis. (S)-FTY720-phosphate (FTY720-P) causes S1P 1 receptor internalization and targeting to the proteasomal degradative pathway, and thus acts as a functional antagonist of S1P 1 by depleting the functional S1P 1 receptor from the plasma membrane. Here we describe the pharmacological characterization of two unsaturated phosphonate enantiomers of FTY720, (R)-and (S)-FTY720-vinylphosphonate. (R)-FTY720-vinylphosphonate was a full agonist of S1P 1 (EC 50 20 ± 3 nM). In contrast, the (S) enantiomer failed to activate any of the five S1P GPCRs and was a full antagonist of S1P 1,3,4 (K i 384 nM, 39 nM, and 1190 nM, respectively) and a partial antagonist of S1P 2 , and S1P 5 . Both enantiomers dose-dependently inhibited lysophospholipase D (recombinant autotaxin) with K i values in the low micromolar range, although with different enzyme kinetic mechanisms. When injected into mice, both enantiomers caused transient peripheral lymphopenia. (R)-and (S)-FTY720-vinylphosphonates activated ERK1/2, AKT, and exerted an antiapoptotic effect in camptothecin-treated IEC-6 intestinal epithelial cells, which primarily express S1P 2 transcripts and traces of S1P 5 . (S)-FTY720-vinylphosphonate is the first pan-antagonist of S1P receptors and offers utility in probing S1P responses in vitro and in vivo. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The biological effects of the (R)-and (S)-FTY720-vinylphosphonate analogues underscore the complexity of FTY720 cellular targets. NIH Public Access

Lysophosphatidic acid (LPA) is a highly potent endogenous lipid mediator that protects and rescues cells from programmed cell death. Earlier work identified the LPA 2 G proteincoupled receptor subtype as an important molecular target of LPA mediating antiapoptotic signaling. Here we describe the results of a virtual screen using single-reference similarity searching that yielded compounds 2-((9-oxo-9H-fluoren-2-yl) carbamoyl)benzoic acid (NSC12404), 2-((3-(1,3-dioxo-1H-benzo- [de]isoquinolin-2(3H)-yl)propyl)thio)benzoic acid (GRI977143), 4,5-dichloro-2-((9-oxo-9H-fluoren-2-yl)carbamoyl)benzoic acid (H2L55-47924), and 2-((9,10-dioxo-9,10-dihydroanthracen-2-yl)carbamoyl) benzoic acid (H2L5828102), novel nonlipid and drug-like compounds that are specific for the LPA 2 receptor subtype. We characterized the antiapoptotic action of one of these compounds, GRI977143, which was effective in reducing activation of caspases 3, 7, 8, and 9 and inhibited poly(ADP-ribose)polymerase 1 cleavage and DNA fragmentation in different extrinsic and intrinsic models of apoptosis in vitro.Furthermore, GRI977143 promoted carcinoma cell invasion of human umbilical vein endothelial cell monolayers and fibroblast proliferation. The antiapoptotic cellular signaling responses were present selectively in mouse embryonic fibroblast cells derived from LPA 1&2 double-knockout mice reconstituted with the LPA 2 receptor and were absent in vector-transduced control cells. GRI977143 was an effective stimulator of extracellular signal-regulated kinase 1/2 activation and promoted the assembly of a macromolecular signaling complex consisting of LPA 2 , Na ϩ -H ϩ exchange regulatory factor 2, and thyroid receptor interacting protein 6, which has been shown previously to be a required step in LPA-induced antiapoptotic signaling. The present findings indicate that nonlipid LPA 2 -specific agonists represent an excellent starting point for development of lead compounds with potential therapeutic utility for preventing the programmed cell death involved in many types of degenerative and inflammatory diseases.

Due to its antiapoptotic action, derivatives of the lipid mediator lysophosphatidic acid (LPA) provide potential therapeutic utility in diseases associated with programmed cell death. Apoptosis is one of the major pathophysiological processes elicited by radiation injury to the organism. Consequently, therapeutic explorations applying compounds that mimic the antiapoptotic action of LPA have begun. Here we present a brief account of our decade-long drug discovery effort aimed at developing LPA mimics with a special focus on specific agonists of the LPA2 receptor subtype, which was found to be highly effective in protecting cells from apoptosis. We describe new evidence that 2-((3-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)propyl)thio)benzoic acid (GRI977143), a prototypic nonlipid agonist specific to the LPA2 receptor subtype, rescues apoptotically condemned cells in vitro and in vivo from injury caused by high-dose γ-irradiation. GRI977143 shows the features of a radiomitigator because it is effective in rescuing the lives of mice from deadly levels of radiation when administered 24 h after radiation exposure. Our findings suggest that by specifically activating LPA2 receptors GRI977143 activates the ERK1/2 prosurvival pathway, effectively reduces Bax translocation to the mitochondrion, attenuates the activation of initiator and effector caspases, reduces DNA fragmentation, and inhibits PARP-1 cleavage associated with γ-irradiation-induced apoptosis. GRI977143 also inhibits bystander apoptosis elicited by soluble proapoptotic mediators produced by irradiated cells. Thus, GRI977143 can serve as a prototype scaffold for lead optimization paving the way to more potent analogs amenable for therapeutic exploration.

Increased activation of poly(ADP-ribose) polymerase (PARP) enzyme has been implicated in the pathogenesis of acute and chronic myocardial dysfunction. We have demonstrated the protective effect of PARP inhibitors against postinfarction myocardial remodeling and heart failure. The primary aim of our recent work was to compare the effect and efficacy of a potent PARP-inhibitor (L-2286) to enalapril, a widely used angiotensin-converting enzyme (ACE) inhibitor. in experimental heart failure model. Both L-2286 and enalapril were tested in a rat model of chronic heart failure after isoproterenol-induced myocardial infarction. After a 12-week treatment period, echocardiography was performed, cardiac hypertrophy and interstitial collagen deposition were assessed, and the phosphorylation state of Akt-1/GSK-3beta pathway as well as the PKC and MAPK kinases were determined. Both PARP and ACE inhibition reduced the progression of postinfarction heart failure by attenuating cardiac hypertrophy and interstitial fibrosis. More importantly, PARP inhibition increased the activity of the prosurvival signal transduction factors (Akt-1/GSK-3beta pathway, PKCepsilon). Due to these effects, L-2286 improved the systolic left ventricular function. Enalapril treatment exerted a similar, but weaker protective effect against postinfarction myocardial remodeling and heart failure. In conclusion, we demonstrated in an experimental heart failure model that L-2286 decreased the postinfarction myocardial remodeling more effectively than enalapril treatment.

We studied cardioprotective as well as Akt and extracellular signal-activated kinase (ERK) activating effect of a Ca(2+) antagonist and a beta-adrenergic receptor blocker during ischemia-reperfusion, and compared these properties of the substances with that of a poly(ADP-ribose) polymerase (PARP) inhibitor used as a positive control throughout the experiments. Langendorff-perfused isolated rat hearts were subjected to 25 min global ischemia followed by 45 min reperfusion, and recovery of energy metabolism as well as functional cardiac parameters were monitored. Although to varying extents, all substances improved recovery of creatine phosphate, ATP, intracellular pH, and reutilization of inorganic phosphate. These favorable changes were accompanied by improved recovery of heart function parameters and reduced infarct size. In addition and again to varying extents, all studied substances decreased oxidative damage (lipid peroxidation and protein oxidation), and activated Akt, glycogen synthase kinase (GSK)-3beta, and ERK1/2. Correlation between cardioprotective and kinase activating effectivity of the compounds proved to be statistically significant. Physiological significance of these kinase activations was established by demonstrating that inhibition of Akt by LY294002 and ERK1/2 by PD98059 compromised the cardioprotective effect of all the substances studied. In conclusion, we demonstrated for the first time that activation of phosphatidylinositol-3-kinase (PI-3K)-Akt and ERK2 pathways significantly contributed to cardioprotective effects of a Ca(2+) antagonist and a beta-adrenergic receptor blocker. Furthermore, we found a strong correlation between cardioprotective and kinase-activating potencies of the substances studied (Verapamil, Metoprolol and two PARP inhibitors), which indicated the potentiality of these kinases as drug-targets in the therapy of ischemic heart disease.

Vitrectomy with ILM peeling is a promising approach to eyes with CSME. It appears to offer visual improvement at a much higher rate than laser therapy and with a longer-lasting effect than that of intravitreal triamcinolone. A larger study is necessary to confirm these preliminary findings.

FTY720 phosphate, an analogue of sphingosine‐1‐phosphate (S1P) is in a phase‐III clinical study for the treatment of multiple sclerosis. FTY720P causes S1P1 receptor internalization rendering the lymphocytes unresponsive to S1P. Here we describe the first enantioselective synthesis of chiral isosteric phosphonate analogues of FTY720 and the pharmacological characterization of two enantiomers, FTY720 S‐ene phosphonate and FTY720 R‐ene phosphonate. Pharmacological analysis of the enantiomers revealed that R‐ene was a full agonist of S1P1 (EC50 38±5 nM). In contrast, S‐ene was a full antagonist of S1P1,3,4 (Ki 208 nM, 15 nM, and 1190 nM, respectively) and a partial antagonist of S1P2 and S1P4. Both enantiomers dose‐dependently inhibited lysophospholipase D (IC50 182 nM for S‐ene and 169 nM for R‐ene). When injected into mice, S‐ene caused transient peripheral lymphopenia, which is consistent with its antagonist activity at S1P1. FTY720 S‐ene phosphonate also activated ERK1/2 in a pertussis toxin‐sensitive mechanism, suggesting that it also activated a yet unidentified GPCR. FTY720 S‐ene phosphonate exerted an antiapoptotic effect in IEC‐6 intestinal epithelial cells challenged with camptothecin. S‐ene is the first pan‐antagonist of S1P receptors and offers utility in probing S1P responses in vitro and in vivo. Supported by NIH Grants HL083187, AI80405 and CA92160.

Novel compounds significantly interfering with the mitochondrial energy production may have therapeutic value in triple-negative breast cancer (TNBC). This criterion is clearly fulfilled by desethylamiodarone (DEA), which is a major metabolite of amiodarone, a widely used antiarrhythmic drug, since the DEA previously demonstrated anti-neoplastic, anti-metastasizing, and direct mitochondrial effects in B16F10 melanoma cells. Additionally, the more than fifty years of clinical experience with amiodarone should answer most of the safety concerns about DEA. Accordingly, in the present study, we investigated DEA’s potential in TNBC by using a TN and a hormone receptor positive (HR+) BC cell line. DEA reduced the viability, colony formation, and invasive growth of the 4T1 cell line and led to a higher extent of the MCF-7 cell line. It lowered mitochondrial transmembrane potential and induced mitochondrial fragmentation. On the other hand, DEA failed to significantly affect various parameters of the cellular energy metabolism as determined by a Seahorse live cell respirometer. Cyclooxygenase 2 (COX-2), which was upregulated by DEA in the TNBC cell line only, accounted for most of 4T1’s DEA resistance, which was counteracted by the selective COX-2 inhibitor celecoxib. All these data indicate that DEA may have potentiality in the therapy of TNBC.