Micro-calpain regulates caspase-dependent and apoptosis inducing factor-mediated caspase-independent apoptotic pathways in cisplatin-induced apoptosis

Int J Cancer. 2009 Dec 15;125(12):2757-66. doi: 10.1002/ijc.24626.

Abstract

Cisplatin, an effective anticancer agent, can induce tumor cell apoptosis via caspase-dependent and-independent pathways. However, the precise mechanism that regulates the pathways remains unclear. In this study, we showed that micro-calpain mediated both caspase-dependent and-independent pathways during cisplatin-induced apoptosis in human lung adenocarcinoma cells. After cisplatin treatment, calpain activation, as measured by a fluorescent substrate, was an early event, taking place well before apoptosis inducing factor (AIF) release and caspase-9/-3 activation. Confocal imaging of cells transfected with AIF-GFP demonstrated that AIF release occurred about 9 hr after cisplatin treatment. The increase of micro-calpain activity proved to be a crucial event in the apoptotic machinery, as demonstrated by the significant protection of cell death in samples suppressed the endogenous micro-calpain expression level, as well as cotreated with the calpain inhibitors, calpeptin and PD150606. Inhibition of mu-calpain not only significantly reduced caspase-9/-3 activities but also completely blocked AIF redistribution. Our study also showed that endogenous mitochondrial micro-calpain could directly induce the truncation and release of AIF, while caspases and cathepsins were not necessary for this process. In conclusion, the study demonstrated that activation of micro-calpain played an essential role in regulating both caspase-dependent and AIF-mediated caspase-independent apoptotic pathways in cisplatin-induced apoptosis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / drug therapy
  • Adenocarcinoma / metabolism*
  • Adenocarcinoma / pathology
  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects*
  • Apoptosis Inducing Factor / metabolism*
  • Blotting, Western
  • Calpain / antagonists & inhibitors
  • Calpain / genetics
  • Calpain / metabolism*
  • Caspases / metabolism*
  • Cisplatin / pharmacology*
  • Flow Cytometry
  • Humans
  • Lung Neoplasms / drug therapy
  • Lung Neoplasms / metabolism*
  • Lung Neoplasms / pathology
  • Membrane Potential, Mitochondrial / drug effects
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • RNA, Small Interfering / pharmacology
  • Subcellular Fractions
  • Tumor Cells, Cultured

Substances

  • Antineoplastic Agents
  • Apoptosis Inducing Factor
  • RNA, Small Interfering
  • Calpain
  • Caspases
  • mu-calpain
  • Cisplatin