title: Functional analysis of non-hotspot AKT1 mutants found in human breast cancers identifies novel driver mutations: implications for personalized medicine.
abstract: The phosphatidylinositol 3-kinase (PI3-kinase)-Akt-mTOR pathway is mutated at high frequency in human breast cancer, and this pathway is the focus of active drug discovery and clinical investigation. Trials of personalized cancer therapy seek to leverage knowledge of cancer gene mutations by using mutations to guide the choice of targeted therapies. At the same time, cancer genome sequencing studies are identifying low frequency variants of unknown significance in known cancer genes, as well as genes of unknown function. We have performed functional analysis of six non-hotspot AKT1 pleckstrin homology domain mutants identified in recent large-scale breast cancer sequencing studies. Three of these mutants cause constitutive activation of Akt1 in the absence of growth factors, leading to phosphorylation of downstream target proteins. Like the hotspot E17K mutation, these mutants confer constitutive membrane localization of Akt1. Finally, the same three mutants showed oncogenic activity in a cellular transformation assay. The other three mutants were inactive in all assays. These findings validate novel driver mutations in AKT1, and extend the number and type of mutations that activate the PI3-kinase pathway in human breast cancers.
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Kyung H
authors.initials: KH
authors.lastname: Yi
authors.forename: Jossette
authors.initials: J
authors.lastname: Axtmayer
authors.forename: John P
authors.initials: JP
authors.lastname: Gustin
authors.forename: Anandita
authors.initials: A
authors.lastname: Rajpurohit
authors.forename: Josh
authors.initials: J
authors.lastname: Lauring
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D061986:MCF-7 Cells; D018613:Microscopy, Confocal; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics*; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D049452:Green Fluorescent Proteins; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; C546842:MTOR protein, human; C494918:AKT1 protein, human