title: Peptidyl-prolyl cis/trans isomerase Pin1 is critical for the regulation of PKB/Akt stability and activation phosphorylation.
abstract: The serine/threonine protein kinase B (PKB, also known as Akt) plays a pivotal role in diverse cellular functions. Elevated expression of activated Akt has been detected in a wide variety of human cancers; however, the mechanism of Akt protein stability regulation remains unclear. In this study, we showed a strong correlation between the expression levels of an oncogenic peptidyl-prolyl cis/trans isomerase Pin1 and levels of Akt phosphorylation at S473 in multiple cancer types (P<0.0001). Akt-pS473 status combined with Pin1 expression levels predicted a poorer prognosis than did either one alone in patients with breast cancer (P=0.0052). We further showed that Pin1 regulated Akt stability and phosphorylation on S473 through the phosphorylated Thr-Pro motifs of Akt. These motifs are conserved evolutionary and are required for the maintenance of Akt stability and its interaction with Pin1. In addition, repressing Pin1 expression through either homologue Pin1 knockout or small interfering RNA-mediated knockingdown compromised its ability to protect Akt from degradation. Our results show how Akt protein stability is regulated by the peptidyl-prolyl cis/trans isomerase Pin1 and highlight the importance of this oncogenic network in human disease pathogenesis.
authors.affiliation: Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Liao
authors.forename: Y
authors.initials: Y
authors.lastname: Wei
authors.forename: X
authors.initials: X
authors.lastname: Zhou
authors.forename: J-Y
authors.initials: JY
authors.lastname: Yang
authors.forename: C
authors.initials: C
authors.lastname: Dai
authors.forename: Y-J
authors.initials: YJ
authors.lastname: Chen
authors.forename: N K
authors.initials: NK
authors.lastname: Agarwal
authors.forename: D
authors.initials: D
authors.lastname: Sarbassov
authors.forename: D
authors.initials: D
authors.lastname: Shi
authors.forename: D
authors.initials: D
authors.lastname: Yu
authors.forename: M-C
authors.initials: MC
authors.lastname: Hung
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D002460:Cell Line; D004789:Enzyme Activation; D004795:Enzyme Stability; D015972:Gene Expression Regulation, Neoplastic; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D016297:Mutagenesis, Site-Directed; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism / Q000628:therapy; D019696:Peptidylprolyl Isomerase / Q000378:metabolism*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D005982:Glutathione Transferase; D051057:Proto-Oncogene Proteins c-akt; C000606846:PIN1 protein, human; D019696:Peptidylprolyl Isomerase; C000606850:Pin1 protein, mouse