Negative regulation of DAB2IP by Akt and SCFFbw7 pathways

Oncotarget. 2014 May 30;5(10):3307-15. doi: 10.18632/oncotarget.1939.

Abstract

Deletion of ovarian carcinoma 2/disabled homolog 2 (DOC-2/DAB2) interacting protein (DAB2IP), is a tumor suppressor that serves as a scaffold protein involved in coordinately regulating cell proliferation, survival and apoptotic pathways. DAB2IP is epigenetically down-regulated in a variety of tumors through the action of the histone methyltransferase EZH2. Although DAB2IP is transcriptionally down-regulated in a variety of tumors, it remains unclear if other mechanisms contribute to functional inactivation of DAB2IP. Here we demonstrate that DAB2IP can be functionally down-regulated by two independent mechanisms. First, we identified that Akt1 can phosphorylate DAB2IP on S847, which regulates the interaction between DAB2IP and its effector molecules H-Ras and TRAF2. Second, we demonstrated that DAB2IP can be degraded in part through ubiquitin-proteasome pathway by SCF(Fbw7). DAB2IP harbors two Fbw7 phosho-degron motifs, which can be regulated by the kinase, CK1δ. Our data hence indicate that in addition to epigenetic down-regulation, two additional pathways can functional inactivate DAB2IP. Given that DAB2IP has previously been identified to possess direct causal role in tumorigenesis and metastasis, our data indicate that a variety of pathways may pass through DAB2IP to govern cancer development, and therefore highlight DAB2IP agonists as potential therapeutic approaches for future anti-cancer drug development.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Blotting, Western
  • Carcinogenesis / metabolism*
  • Cell Line, Tumor
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Immunoprecipitation
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism*
  • SKP Cullin F-Box Protein Ligases / metabolism*
  • Signal Transduction / physiology*
  • Transfection
  • ras GTPase-Activating Proteins / metabolism*

Substances

  • DAB2IP protein, human
  • ras GTPase-Activating Proteins
  • SKP Cullin F-Box Protein Ligases
  • Proto-Oncogene Proteins c-akt