title: Targeting BCR tyrosine177 site with novel SH2-DED causes selective leukemia cell death in vitro and in vivo.
abstract: Emergence of resistance to imatinib mesylate complicates the treatment of chronic myeloid leukemia (CML). Second-generation tyrosine kinase inhibitors are capable to overcome resistance mediated by most mutations except T315I. As this mutation is causative for 20% of clinically observed resistances, the need for novel treatment strategies becomes obvious and urgent. The autophosphorylated BCR/ABL Tyr177 recruits Grb2 via its SH2 domain, which is required for efficient induction of the myeloproliferative disease by BCR/ABL. The death effector domain (DED) is the critical factor for activation of caspase-8 induced apoptosis signal. We thus speculated that transduction of an exogenous SH2-DED (SD) fragment into the CML cells may inhibit the binding of BCR/ABL Tyr177 and Grb2, activate caspase-8 induced apoptosis and serve as a novel CML treatment strategy. The infection of the recombinant adenovirus Ad5/F35-SD was verified to show both cell proliferation-inhibitory and apoptosis-inducing effect. Further exploration into the underlying mechanisms revealed that Ad5/F35-SD exerted its function by binding to the phospho-BCR/ABL Tyr177 site, reducing Ras, MAPK and AKT kinase activities, and activating caspase-8 induced apoptosis signal by DED protein binding to DED domain of precursor caspase-8. Moreover, high anti-proliferative activity of Ad5/F35-SD was observed in nude mice and its leukemia-protective effect was evident in chronic myeloid leukemia model mice injected with BCR/ABL(+) BaF3 cells. In conclusion, Ad5/F35-SD exhibits anti-proliferative and pro-apoptotic activity on BCR/ABL positive leukemia cells in vitro and in vivo through disruption of Grb2 SH2-phospho-BCR/ABL Tyr177 complex formation and induction of caspase-8 activation.
authors.affiliation: Department of Clinical Hematology, Key Laboratory of Laboratory Medical Diagnostics Designated by the Ministry of Education; Chongqing Medical University, 1 Yixueyuan Road, Yuzhong District, Chongqing 400016, PR China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Peng
authors.forename: Ying
authors.initials: Y
authors.lastname: Yuan
authors.forename: Ya-Juan
authors.initials: YJ
authors.lastname: Li
authors.forename: Hai-Xia
authors.initials: HX
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Shi
authors.forename: Wei-Xi
authors.initials: WX
authors.lastname: Cao
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Luo
authors.forename: Jing-Rong
authors.initials: JR
authors.lastname: Deng
authors.forename: Wen-Li
authors.initials: WL
authors.lastname: Feng
mesh_terms: D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D002453:Cell Cycle; D045744:Cell Line, Tumor; D005260:Female; D016044:Fusion Proteins, bcr-abl / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D012097:Repressor Proteins / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*; D018909:src Homology Domains
chemical_list: C402637:AATF protein, human; D051017:Apoptosis Regulatory Proteins; D012097:Repressor Proteins; D014443:Tyrosine; D016044:Fusion Proteins, bcr-abl