Destabilization of CARP mRNAs by aloe-emodin contributes to caspase-8-mediated p53-independent apoptosis of human carcinoma cells

J Cell Biochem. 2011 Apr;112(4):1176-91. doi: 10.1002/jcb.23031.

Abstract

Using short hairpin RNA against p53, transient ectopic expression of wild-type p53 or mutant p53 (R248W or R175H), and a p53- and p21-dependent luciferase reporter assay, we demonstrated that growth arrest and apoptosis of FaDu (human pharyngeal squamous cell carcinoma), Hep3B (hepatoma), and MG-63 (osteosarcoma) cells induced by aloe-emodin (AE) are p53-independent. Co-immunoprecipitation and small interfering RNA (siRNA) studies demonstrated that AE caused S-phase cell cycle arrest by inducing the formation of cyclin A-Cdk2-p21 complexes through extracellular signal-regulated kinase (ERK) activation. Ectopic expression of Bcl-X(L) and siRNA-mediated Bax attenuation significantly inhibited apoptosis induced by AE. Cyclosporin A or the caspase-8 inhibitor Z-IETD-FMK blocked AE-induced loss of mitochondrial membrane potential and prevented increases in reactive oxygen species and Ca(++). Z-IETD-FMK inhibited AE-induced apoptosis, Bax expression, Bid cleavage, translocation of tBid to mitochondria, ERK phosphorylation, caspase-9 activation, and the release of cytochrome c, apoptosis-inducing factor (AIF), and endonuclease G from mitochondria. The stability of the mRNAs encoding caspase-8 and -10-associated RING proteins (CARPs) 1 and 2 was affected by AE, whereas CARP1 or 2 overexpression inhibited caspase-8 activation and apoptosis induced by AE. Collectively, our data indicate AE induces caspase-8-mediated activation of mitochondrial death pathways by decreasing the stability of CARP mRNAs in a p53-independent manner.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Apoptosis Regulatory Proteins
  • Blotting, Western
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Caspase 8 / genetics
  • Caspase 8 / metabolism*
  • Cell Cycle / drug effects
  • Cell Cycle Proteins
  • Cell Line
  • Cell Line, Tumor
  • Cyclin A / genetics
  • Cyclin A / metabolism
  • Cyclin-Dependent Kinase 2 / genetics
  • Cyclin-Dependent Kinase 2 / metabolism
  • Cyclin-Dependent Kinase Inhibitor p21 / genetics
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism
  • Emodin / pharmacology*
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • HEK293 Cells
  • Humans
  • Neoplasms / genetics
  • Neoplasms / metabolism
  • Neoplasms / pathology
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Phosphorylation / drug effects
  • Protein Binding / drug effects
  • Protein Kinase Inhibitors / pharmacology
  • RNA Interference
  • RNA Stability / drug effects
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*

Substances

  • Apoptosis Regulatory Proteins
  • CA11 protein, human
  • CCAR1 protein, human
  • CDKN1A protein, human
  • Carrier Proteins
  • Cell Cycle Proteins
  • Cyclin A
  • Cyclin-Dependent Kinase Inhibitor p21
  • Nerve Tissue Proteins
  • Protein Kinase Inhibitors
  • RNA, Messenger
  • Tumor Suppressor Protein p53
  • Cyclin-Dependent Kinase 2
  • Extracellular Signal-Regulated MAP Kinases
  • Caspase 8
  • Emodin