title: Src inhibitors, PP2 and dasatinib, increase retinoic acid-induced association of Lyn and c-Raf (S259) and enhance MAPK-dependent differentiation of myeloid leukemia cells.
abstract: All-trans-retinoic-acid (ATRA)-induced differentiation of human myeloid leukemia cells is characterized by persistent mitogen-activated protein kinase (MAPK) signaling. Fragmentary data suggests Src family kinase (SFK) inhibitors enhance differentiation, and thus have potential therapeutic value. The present study shows that SFK inhibitors PP2 and dasatinib enhance aspects of MAPK signaling and regulate a panel of differentiation markers, including CD11b and p47(phox). HL-60 and NB4 myeloid leukemia cells show accelerated ATRA-induced G1/0 arrest/differentiation with inhibitor co-treatment. We also identified components of a Lyn- and c-Raf-containing MAPK signaling complex augmented by the inhibitors. PP2 and dasatinib increased the ATRA-induced expression of Lyn and c-Raf (total and c-RafpS259) and their interaction. The Lyn-associated serine/threonine kinase, casein kinase II (CK2), also complexed with c-Raf and c-RafpS259, and the kinase suppressor of Ras 1 (KSR1) scaffold protein bound c-Raf, Lyn and extracellular signal-regulated kinase (ERK). c-Raf/ERK association was increased by the inhibitors, which is significant as ERK may cause c-Raf C-terminal domain (CTD) phosphorylation in a putative feedback mechanism. Consistent with this, inhibitor treatment caused more CTD phosphorylation. Lyn knockdown decreased c-Raf CTD and S259 phosphorylation. This is the first evidence suggesting SFK inhibitors enhance ATRA-induced differentiation through a possible feedback loop involving KSR1-scaffolded c-Raf and ERK complexed with Lyn and CK2.
authors.affiliation: Department of Biomedical Sciences, Cornell University, Ithaca, NY 14853, USA.
authors.forename: J
authors.initials: J
authors.lastname: Congleton
authors.forename: R
authors.initials: R
authors.lastname: MacDonald
authors.forename: A
authors.initials: A
authors.lastname: Yen
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects*; D000069439:Dasatinib; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D047468:Immunoprecipitation; D007951:Leukemia, Myeloid / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D011743:Pyrimidines / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013844:Thiazoles / Q000494:pharmacology*; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D019061:src-Family Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: C412373:AG 1879; D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D034741:RNA, Small Interfering; D013844:Thiazoles; D014212:Tretinoin; D011494:Protein Kinases; C097199:KSR-1 protein kinase; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D019908:Proto-Oncogene Proteins c-raf; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; D000069439:Dasatinib