title: Disruption of Src function potentiates Chk1-inhibitor-induced apoptosis in human multiple myeloma cells in vitro and in vivo.
abstract: Ras/MEK/ERK pathway activation represents an important compensatory response of human multiple myeloma (MM) cells to checkpoint kinase 1 (Chk1) inhibitors. To investigate the functional roles of Src in this event and potential therapeutic significance, interactions between Src and Chk1 inhibitors (eg, UCN-01 or Chk1i) were examined in vitro and in vivo. The dual Src/Abl inhibitors BMS354825 and SKI-606 blocked Chk1-inhibitor-induced extracellular signal-regulated kinase 1/2 (ERK1/2) activation, markedly increasing apoptosis in association with BimEL up-regulation, p34(cdc2) activation, and DNA damage in MM cell lines and primary CD138(+) MM samples. Loss-of-function Src mutants (K297R, K296R/Y528F) or shRNA knock-down of Src prevented the ERK1/2 activation induced by Chk1 inhibitors and increased apoptosis. Conversely, constitutively active Ras or mitogen-activated protein kinase/ERK kinase 1 (MEK1) significantly diminished the ability of Src inhibitors to potentiate Chk1-inhibitor lethality. Moreover, Src/Chk1-inhibitor cotreatment attenuated MM-cell production of vascular endothelial growth factor and other angiogenic factors (eg, ANG [angiogenin], TIMP1/2 [tissue inhibitor of metalloproteinases 1/2], and RANTES [regulated on activation normal T-cell expressed and secreted]), and inhibited in vitro angiogenesis. Finally, coadministration of BMS354825 and UCN-01 suppressed human MM tumor growth in a murine xenograft model, increased apoptosis, and diminished angiogenesis. These findings suggest that Src kinase is required for Chk1-inhibitor-mediated Ras → ERK1/2 signaling activation, and that disruption of this event sharply potentiates the anti-MM activity of Chk1 inhi-bitors in vitro and in vivo.
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, Virginia Commonwealth University, and the Massey Cancer Center, Richmond, VA 23298, USA.
authors.forename: Yun
authors.initials: Y
authors.lastname: Dai
authors.forename: Shuang
authors.initials: S
authors.lastname: Chen
authors.forename: Rena
authors.initials: R
authors.lastname: Shah
authors.forename: Xin-Yan
authors.initials: XY
authors.lastname: Pei
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Almenara
authors.forename: Lora B
authors.initials: LB
authors.lastname: Kramer
authors.forename: Paul
authors.initials: P
authors.lastname: Dent
authors.forename: Steven
authors.initials: S
authors.lastname: Grant
mesh_terms: D000814:Aniline Compounds / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D016203:CDC2 Protein Kinase / Q000378:metabolism; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1; D004249:DNA Damage; D000069439:Dasatinib; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D066298:In Vitro Techniques; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D008819:Mice, Nude; D009101:Multiple Myeloma / Q000188:drug therapy / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology*; D009154:Mutation; D009389:Neovascularization, Pathologic / Q000188:drug therapy; D009570:Nitriles / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011494:Protein Kinases / Q000502:physiology*; D011743:Pyrimidines / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D053484:RecQ Helicases / Q000037:antagonists & inhibitors; D013844:Thiazoles / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000502:physiology; D019061:src-Family Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology
chemical_list: D000814:Aniline Compounds; D009570:Nitriles; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D011804:Quinolines; D013844:Thiazoles; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C471992:bosutinib; D011494:Protein Kinases; D019061:src-Family Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C000605869:Chek1 protein, mouse; D016203:CDC2 Protein Kinase; C097151:Bloom syndrome protein; D053484:RecQ Helicases; D000069439:Dasatinib