TAp73alpha protects small cell lung carcinoma cells from caspase-2 induced mitochondrial mediated apoptotic cell death

Oncotarget. 2011 Dec;2(12):1145-54. doi: 10.18632/oncotarget.391.

Abstract

Caspase-2 is ubiquitously expressed and the most evolutionarily conserved mammalian caspase. It can be activated by a range of death stimuli prior to Bax activation and the occurrence of apoptotic mitochondrial dysfunctions. Caspase-2 has also been reported to exert tumour suppressor function in vivo. The full length TAp73alpha isoform is found up-regulated in various tumour types, and is reported in a cell-type specific manner to repress drug-induced apoptosis. Here, we report that TAp73alpha represses caspase-2 enzymatic activity and by this means reduce caspase-2 induced Bax activation, loss of mitochondrial transmembrane potential and resulting apoptosis. The inhibitory effect on caspase-2 requires the presence of the DNA binding domain and SAM domain region of TAp73alpha. In conclusion, the ability of TAp73alpha to act as an inhibitor of caspase-2-induced cell death together with its up-regulation in certain tumour types strengthen the potential oncogenic activities for this protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / genetics*
  • Caspase 2 / genetics
  • Caspase 2 / metabolism*
  • Cell Line, Tumor
  • Cysteine Endopeptidases / genetics
  • Cysteine Endopeptidases / metabolism*
  • DNA-Binding Proteins / metabolism*
  • Enzyme Activation
  • Humans
  • Lung Neoplasms / genetics
  • Lung Neoplasms / metabolism*
  • Lung Neoplasms / pathology
  • Membrane Potential, Mitochondrial
  • Mitochondria / metabolism*
  • Mitochondria / physiology
  • Nuclear Proteins / metabolism*
  • Small Cell Lung Carcinoma / genetics
  • Small Cell Lung Carcinoma / metabolism*
  • Small Cell Lung Carcinoma / pathology
  • Tumor Protein p73
  • Tumor Suppressor Proteins / metabolism*
  • bcl-2-Associated X Protein / genetics
  • bcl-2-Associated X Protein / metabolism

Substances

  • DNA-Binding Proteins
  • Nuclear Proteins
  • Tumor Protein p73
  • Tumor Suppressor Proteins
  • bcl-2-Associated X Protein
  • CASP2 protein, human
  • Caspase 2
  • Cysteine Endopeptidases