title: Phosphorylation of a constrained azacyclic FTY720 analog enhances anti-leukemic activity without inducing S1P receptor activation.
abstract: The frequency of poor outcomes in relapsed leukemia patients underscores the need for novel therapeutic approaches. The Food and Drug Administration-approved immunosuppressant FTY720 limits leukemia progression by activating protein phosphatase 2A and restricting nutrient access. Unfortunately, FTY720 cannot be re-purposed for use in cancer patients due to on-target toxicity associated with S1P receptor activation at the elevated, anti-neoplastic dose. Here we show that the constrained azacyclic FTY720 analog SH-RF-177 lacks S1P receptor activity but maintains anti-leukemic activity in vitro and in vivo. SH-RF-177 was not only more potent than FTY720, but killed via a distinct mechanism. Phosphorylation is dispensable for FTY720's anti-leukemic actions. However, chemical biology and genetic approaches demonstrated that the sphingosine kinase 2 (SPHK2)-mediated phosphorylation of SH-RF-177 led to engagement of a pro-apoptotic target and increased potency. The cytotoxicity of membrane-permeant FTY720 phosphonate esters suggests that the enhanced potency of SH-RF-177 stems from its more efficient phosphorylation. The tight inverse correlation between SH-RF-177 IC50and SPHK2 mRNA expression suggests a useful biomarker for SH-RF-177 sensitivity. In summary, these studies indicate that FTY720 analogs that are efficiently phosphorylated but fail to activate S1P receptors may be superior anti-leukemic agents compared to compounds that avoid cardiotoxicity by eliminating phosphorylation.
authors: Department of Developmental and Cell Biology, University of California, Irvine, CA, USA.
authors: A N
authors: AN
authors: McCracken
authors: Department of Developmental and Cell Biology, University of California, Irvine, CA, USA.
authors: R J
authors: RJ
authors: McMonigle
authors: Department of Chemistry, Université de Montréal, Montreal, Quebec, Canada.
authors: J
authors: J
authors: Tessier
authors: Department of Chemistry, Université de Montréal, Montreal, Quebec, Canada.
authors: R
authors: R
authors: Fransson
authors: Department of Chemistry, Université de Montréal, Montreal, Quebec, Canada.
authors: M S
authors: MS
authors: Perryman
authors: Department of Chemistry, Université de Montréal, Montreal, Quebec, Canada.
authors: B
authors: B
authors: Chen
authors: Department of Community and Environmental Medicine, School of Medicine, University of California, Irvine, CA, USA.
authors: A
authors: A
authors: Keebaugh
authors: Department of Developmental and Cell Biology, University of California, Irvine, CA, USA.
authors: E
authors: E
authors: Selwan
authors: Department of Developmental and Cell Biology, University of California, Irvine, CA, USA.
authors: S A
authors: SA
authors: Barr
authors: Department of Developmental and Cell Biology, University of California, Irvine, CA, USA.
authors: S M
authors: SM
authors: Kim
authors: Department of Developmental and Cell Biology, University of California, Irvine, CA, USA.
authors: S G
authors: SG
authors: Roy
authors: Department of Developmental and Cell Biology, University of California, Irvine, CA, USA.
authors: G
authors: G
authors: Liu
authors: Institute of Pharmacology, University of Bern, Bern, Switzerland.
authors: D
authors: D
authors: Fallegger
authors: Department of Chemistry, Université de Montréal, Montreal, Quebec, Canada.
authors: L
authors: L
authors: Sernissi
authors: The Wellcome Trust Sanger Genome Campus, Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK.
authors: C
authors: C
authors: Brandt
authors: Department of Chemistry, McGill University, Montréal, Québec, Canada.
authors: N
authors: N
authors: Moitessier
authors: Cancer Center and Department of Medicine, Stony Brook University, Stony Brook, NY, USA.|Northport Veterans Affairs Medical Center, Northport, NY, USA.
authors: A J
authors: AJ
authors: Snider
authors: The Wellcome Trust Sanger Genome Campus, Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK.
authors: S
authors: S
authors: Clare
authors: Department of Laboratory Medicine, University of California, San Francisco, CA, USA.
authors: M
authors: M
authors: Müschen
authors: Institute of Pharmacology, University of Bern, Bern, Switzerland.
authors: A
authors: A
authors: Huwiler
authors: Department of Community and Environmental Medicine, School of Medicine, University of California, Irvine, CA, USA.
authors: M T
authors: MT
authors: Kleinman
authors: Department of Chemistry, Université de Montréal, Montreal, Quebec, Canada.|Department of Pharmaceutical Sciences, University of California Irvine, Irvine, CA, USA.
authors: S
authors: S
authors: Hanessian
authors: Department of Developmental and Cell Biology, University of California, Irvine, CA, USA.
authors: A L
authors: AL
authors: Edinger
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005260:Female; D000068876:Fingolimod Hydrochloride / Q000494:pharmacology*; D006801:Humans; D007938:Leukemia / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051379:Mice; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics; D049349:Receptors, Lysosphingolipid / Q000819:agonists / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays; D000099157:Sphingosine Kinase
chemical_list: D000970:Antineoplastic Agents; D000068876:Fingolimod Hydrochloride; D017853:Phosphotransferases (Alcohol Group Acceptor); D049349:Receptors, Lysosphingolipid; C000594250:sphingosine kinase 2, human; D000099157:Sphingosine Kinase