title: Upregulation of IGF1R by mutant RAS in leukemia and potentiation of RAS signaling inhibitors by small-molecule inhibition of IGF1R.
abstract: OBJECTIVE
  Activating mutations in the RAS oncogene occur frequently in human leukemias. Direct targeting of RAS has proven to be challenging, although targeting of downstream RAS mediators, such as MEK, is currently being tested clinically. Given the complexity of RAS signaling, it is likely that combinations of targeted agents will be more effective than single agents.
  
  
  METHODS
  A chemical screen using RAS-dependent leukemia cells was developed to identify compounds with unanticipated activity in the presence of an MEK inhibitor and led to identification of inhibitors of IGF1R. Results were validated using cell-based proliferation, apoptosis, cell-cycle, and gene knockdown assays; immunoprecipitation and immunoblotting; and a noninvasive in vivo bioluminescence model of acute myeloid leukemia (AML).
  
  
  RESULTS
  Mechanistically, IGF1R protein expression/activity was substantially increased in mutant RAS-expressing cells, and suppression of RAS led to decreases in IGF1R. Synergy between MEK and IGF1R inhibitors correlated with induction of apoptosis, inhibition of cell-cycle progression, and decreased phospho-S6 and phospho-4E-BP1. In vivo, NSG mice tail veins injected with OCI-AML3-luc+ cells showed significantly lower tumor burden following 1 week of daily oral administration of 50 mg/kg NVP-AEW541 (IGF1R inhibitor) combined with 25 mg/kg AZD6244 (MEK inhibitor), as compared with mice treated with either agent alone. Drug combination effects observed in cell-based assays were generalized to additional mutant RAS-positive neoplasms.
  
  
  CONCLUSIONS
  The finding that downstream inhibitors of RAS signaling and IGF1R inhibitors have synergistic activity warrants further clinical investigation of IGF1R and RAS signaling inhibition as a potential treatment strategy for RAS-driven malignancies.
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts. ellen_weisberg@dfci.harvard.edu james_griffin@dfci.harvard.edu.
authors.forename: Ellen
authors.initials: E
authors.lastname: Weisberg
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nonami
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
authors.forename: Erik
authors.initials: E
authors.lastname: Nelson
authors.affiliation: High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, PR China.
authors.forename: Yongfei
authors.initials: Y
authors.lastname: Chen
authors.affiliation: High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, PR China.
authors.forename: Feiyang
authors.initials: F
authors.lastname: Liu
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts.
authors.forename: HaeYeon
authors.initials: H
authors.lastname: Cho
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts.
authors.forename: Jianming
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
authors.forename: Martin
authors.initials: M
authors.lastname: Sattler
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
authors.forename: Constantine
authors.initials: C
authors.lastname: Mitsiades
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
authors.forename: Kwok-Kin
authors.initials: KK
authors.lastname: Wong
authors.affiliation: High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, PR China.
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts.
authors.forename: Nathanael S
authors.initials: NS
authors.lastname: Gray
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts. ellen_weisberg@dfci.harvard.edu james_griffin@dfci.harvard.edu.
authors.forename: James D
authors.initials: JD
authors.lastname: Griffin
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001562:Benzimidazoles / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D005260:Female; D011905:Genes, ras / Q000235:genetics*; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy / Q000235:genetics*; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics; D011743:Pyrimidines / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D017526:Receptor, IGF Type 1 / Q000037:antagonists & inhibitors* / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics; D054852:Small Molecule Libraries / Q000494:pharmacology*; D015854:Up-Regulation / Q000235:genetics*
chemical_list: C517975:AZD 6244; D001562:Benzimidazoles; C501177:NVP-AEW541; D011743:Pyrimidines; D011758:Pyrroles; D054852:Small Molecule Libraries; D017526:Receptor, IGF Type 1; D020929:Mitogen-Activated Protein Kinase Kinases