Chemotherapy-mediated p53-dependent DNA damage response in clear cell renal cell carcinoma: role of the mTORC1/2 and hypoxia-inducible factor pathways

Cell Death Dis. 2013 Oct 17;4(10):e865. doi: 10.1038/cddis.2013.395.

Abstract

The DNA-damaging agent camptothecin (CPT) and its analogs demonstrate clinical utility for the treatment of advanced solid tumors, and CPT-based nanopharmaceuticals are currently in clinical trials for advanced kidney cancer; however, little is known regarding the effects of CPT on hypoxia-inducible factor-2α (HIF-2α) accumulation and activity in clear cell renal cell carcinoma (ccRCC). Here we assessed the effects of CPT on the HIF/p53 pathway. CPT demonstrated striking inhibition of both HIF-1α and HIF-2α accumulation in von Hippel-Lindau (VHL)-defective ccRCC cells, but surprisingly failed to inhibit protein levels of HIF-2α-dependent target genes (VEGF, PAI-1, ET-1, cyclin D1). Instead, CPT induced DNA damage-dependent apoptosis that was augmented in the presence of pVHL. Further analysis revealed CPT regulated endothelin-1 (ET-1) in a p53-dependent manner: CPT increased ET-1 mRNA abundance in VHL-defective ccRCC cell lines that was significantly augmented in their VHL-expressing counterparts that displayed increased phosphorylation and accumulation of p53; p53 siRNA suppressed CPT-induced increase in ET-1 mRNA, as did an inhibitor of ataxia telangiectasia mutated (ATM) signaling, suggesting a role for ATM-dependent phosphorylation of p53 in the induction of ET-1. Finally, we demonstrate that p53 phosphorylation and accumulation is partially dependent on mTOR activity in ccRCC. Consistent with this result, pharmacological inhibition of mTORC1/2 kinase inhibited CPT-mediated ET-1 upregulation, and p53-dependent responses in ccRCC. Collectively, these data provide mechanistic insight into the action of CPT in ccRCC, identify ET-1 as a p53-regulated gene and demonstrate a requirement of mTOR for p53-mediated responses in this tumor type.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apigenin / pharmacology
  • Apoptosis / drug effects
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Camptothecin / pharmacology
  • Carcinoma, Renal Cell / drug therapy*
  • Carcinoma, Renal Cell / genetics
  • Carcinoma, Renal Cell / pathology*
  • Cell Hypoxia / drug effects
  • Cell Hypoxia / genetics
  • Cell Line, Tumor
  • DNA Damage* / genetics
  • Endothelin-1 / genetics
  • Endothelin-1 / metabolism
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
  • Kidney Neoplasms / drug therapy*
  • Kidney Neoplasms / genetics
  • Kidney Neoplasms / pathology
  • Mechanistic Target of Rapamycin Complex 1
  • Mechanistic Target of Rapamycin Complex 2
  • Multiprotein Complexes / metabolism*
  • Protein Biosynthesis / drug effects
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Signal Transduction / drug effects
  • Signal Transduction / genetics
  • TOR Serine-Threonine Kinases / metabolism*
  • Tumor Suppressor Protein p53 / metabolism*

Substances

  • Basic Helix-Loop-Helix Transcription Factors
  • Endothelin-1
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Multiprotein Complexes
  • RNA, Messenger
  • Tumor Suppressor Protein p53
  • endothelial PAS domain-containing protein 1
  • Apigenin
  • Mechanistic Target of Rapamycin Complex 1
  • Mechanistic Target of Rapamycin Complex 2
  • TOR Serine-Threonine Kinases
  • Camptothecin