Hypoxia-induced p53 modulates both apoptosis and radiosensitivity via AKT

J Clin Invest. 2015 Jun;125(6):2385-98. doi: 10.1172/JCI80402. Epub 2015 May 11.

Abstract

Restoration of hypoxia-induced apoptosis in tumors harboring p53 mutations has been proposed as a potential therapeutic strategy; however, the transcriptional targets that mediate hypoxia-induced p53-dependent apoptosis remain elusive. Here, we demonstrated that hypoxia-induced p53-dependent apoptosis is reliant on the DNA-binding and transactivation domains of p53 but not on the acetylation sites K120 and K164, which, in contrast, are essential for DNA damage-induced, p53-dependent apoptosis. Evaluation of hypoxia-induced transcripts in multiple cell lines identified a group of genes that are hypoxia-inducible proapoptotic targets of p53, including inositol polyphosphate-5-phosphatase (INPP5D), pleckstrin domain-containing A3 (PHLDA3), sulfatase 2 (SULF2), B cell translocation gene 2 (BTG2), cytoplasmic FMR1-interacting protein 2 (CYFIP2), and KN motif and ankyrin repeat domains 3 (KANK3). These targets were also regulated by p53 in human cancers, including breast, brain, colorectal, kidney, bladder, and melanoma cancers. Downregulation of these hypoxia-inducible targets associated with poor prognosis, suggesting that hypoxia-induced apoptosis contributes to p53-mediated tumor suppression and treatment response. Induction of p53 targets, PHLDA3, and a specific INPP5D transcript mediated apoptosis in response to hypoxia through AKT inhibition. Moreover, pharmacological inhibition of AKT led to apoptosis in the hypoxic regions of p53-deficient tumors and consequently increased radiosensitivity. Together, these results identify mediators of hypoxia-induced p53-dependent apoptosis and suggest AKT inhibition may improve radiotherapy response in p53-deficient tumors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism
  • Apoptosis*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cell Hypoxia / genetics
  • Cell Line, Tumor
  • Humans
  • Immediate-Early Proteins / genetics
  • Immediate-Early Proteins / metabolism
  • Inositol Polyphosphate 5-Phosphatases
  • Neoplasms / genetics
  • Neoplasms / metabolism*
  • Neoplasms / pathology
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
  • Phosphoric Monoester Hydrolases / genetics
  • Phosphoric Monoester Hydrolases / metabolism
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Radiation Tolerance*
  • Sulfatases
  • Sulfotransferases / genetics
  • Sulfotransferases / metabolism
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • CYFIP2 protein, human
  • Carrier Proteins
  • Immediate-Early Proteins
  • KANK3 protein, human
  • Nuclear Proteins
  • TP53 protein, human
  • TSSC3 protein
  • Tumor Suppressor Protein p53
  • Tumor Suppressor Proteins
  • BTG2 protein, human
  • Proto-Oncogene Proteins c-akt
  • Sulfotransferases
  • Phosphoric Monoester Hydrolases
  • Inositol Polyphosphate 5-Phosphatases
  • INPP5D protein, human
  • Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
  • SULF2 protein, human
  • Sulfatases