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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.

Original publication

DOI

10.1172/JCI80402

Type

Journal article

Journal

J Clin Invest

Publication Date

06/2015

Volume

125

Pages

2385 - 2398

Keywords

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