title: Lenalidomide induces lipid raft assembly to enhance erythropoietin receptor signaling in myelodysplastic syndrome progenitors.
abstract: Anemia remains the principal management challenge for patients with lower risk Myelodysplastic Syndromes (MDS). Despite appropriate cytokine production and cellular receptor display, erythropoietin receptor (EpoR) signaling is impaired. We reported that EpoR signaling is dependent upon receptor localization within lipid raft microdomains, and that disruption of raft integrity abolishes signaling capacity. Here, we show that MDS erythroid progenitors display markedly diminished raft assembly and smaller raft aggregates compared to normal controls (p = 0.005, raft number; p = 0.023, raft size). Because lenalidomide triggers raft coalescence in T-lymphocytes promoting immune synapse formation, we assessed effects of lenalidomide on raft assembly in MDS erythroid precursors and UT7 cells. Lenalidomide treatment rapidly induced lipid raft formation accompanied by EpoR recruitment into raft fractions together with STAT5, JAK2, and Lyn kinase. The JAK2 phosphatase, CD45, a key negative regulator of EpoR signaling, was displaced from raft fractions. Lenalidomide treatment prior to Epo stimulation enhanced both JAK2 and STAT5 phosphorylation in UT7 and primary MDS erythroid progenitors, accompanied by increased STAT5 DNA binding in UT7 cells, and increased erythroid colony forming capacity in both UT7 and primary cells. Raft induction was associated with F-actin polymerization, which was blocked by Rho kinase inhibition. These data indicate that deficient raft integrity impairs EpoR signaling, and provides a novel strategy to enhance EpoR signal fidelity in non-del(5q) MDS.
authors.affiliation: Department of Malignant Hematology, H. Lee Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL 33612, United States of America.
authors.forename: Kathy L
authors.initials: KL
authors.lastname: McGraw
authors.affiliation: Department of Malignant Hematology, H. Lee Moffitt Cancer Center-Cancer Biology Ph.D. Program, University of South Florida, 12902 Magnolia Drive, Tampa, FL, 33612, United States of America.
authors.forename: Ashley A
authors.initials: AA
authors.lastname: Basiorka
authors.affiliation: Analytic Microscopy Core Facility, H. Lee Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL, 33612, United States of America.
authors.forename: Joseph O
authors.initials: JO
authors.lastname: Johnson
authors.affiliation: Department of Malignant Hematology, H. Lee Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL 33612, United States of America.
authors.forename: Justine
authors.initials: J
authors.lastname: Clark
authors.affiliation: Morsani Molecular Diagnostic Laboratory, H. Lee Moffitt Cancer Center, 10902 N. McKinley Drive, Tampa, FL, 33612, United States of America.
authors.forename: Gisela
authors.initials: G
authors.lastname: Caceres
authors.affiliation: Department of Malignant Hematology, H. Lee Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL 33612, United States of America.
authors.forename: Eric
authors.initials: E
authors.lastname: Padron
authors.affiliation: Department of Pathology, University of Arizona, 1501 N Campbell Ave, Tucson, AZ, 85724, United States of America.
authors.forename: Ruth
authors.initials: R
authors.lastname: Heaton
authors.affiliation: Department of Hematology, Japanese Red Cross Nagoya First Hospital, 3-35 Michishita-cho, Nakamura-ku, Aichi, 453-8511, Japan.
authors.forename: Yukiyasu
authors.initials: Y
authors.lastname: Ozawa
authors.affiliation: Department of Immunology, H. Lee Moffitt Cancer Center, 12902 Magnolia Drive Tampa, FL, 33612, United States of America.
authors.forename: Sheng
authors.initials: S
authors.lastname: Wei
authors.affiliation: Department of Malignant Hematology, H. Lee Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL 33612, United States of America.
authors.forename: Lubomir
authors.initials: L
authors.lastname: Sokol
authors.affiliation: Department of Malignant Hematology, H. Lee Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL 33612, United States of America.
authors.forename: Alan F
authors.initials: AF
authors.lastname: List
mesh_terms: D000199:Actins / Q000378:metabolism; D000368:Aged; D000369:Aged, 80 and over; D000577:Amides / Q000494:pharmacology; D045744:Cell Line, Tumor; D004353:Drug Evaluation, Preclinical; D015672:Erythroid Precursor Cells / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006801:Humans; D007155:Immunologic Factors / Q000494:pharmacology*; D000077269:Lenalidomide; D008297:Male; D021962:Membrane Microdomains / Q000378:metabolism*; D009190:Myelodysplastic Syndromes / Q000188:drug therapy / Q000473:pathology; D055503:Protein Multimerization / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology; D017467:Receptors, Erythropoietin / Q000378:metabolism*; D015398:Signal Transduction; D013792:Thalidomide / Q000031:analogs & derivatives* / Q000494:pharmacology; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000199:Actins; D000577:Amides; D007155:Immunologic Factors; D011725:Pyridines; D017467:Receptors, Erythropoietin; C108830:Y 27632; D013792:Thalidomide; D054460:rho-Associated Kinases; D000077269:Lenalidomide