2-Chloro-2′-deoxyadenosine-induced apoptosis in T leukemia cells is mediated via a caspase-3-dependent mitochondrial feedback amplification loop

David M. Conrad, Matthew R.J. Robichaud, Jamie S. Mader, Robert T.M. Boudreau, Angela M. Richardson, Carman A. Giacomantonio, David W. Hoskin

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19 Citations (Scopus)

Résumé

2-Chloro-2′-deoxyadenosine (CdA; cladribine) is a chemotherapeutic agent used in the treatment of certain leukemias. However, the signalling events that govern CdA-mediated cytotoxicity in leukemia cells remain unclear. We show here that CdA treatment caused Jurkat human T leukemia cells to die via apoptosis in a dose- and time-dependent fashion. Bcl-2 overexpression protected Jurkat T leukemia cells from CdA-induced apoptosis and loss of mitochondrial transmembrane potential (ΔΨm). Furthermore, mitochondria that were isolated from Jurkat T leukemia cells and then exposed to CdA showed a loss of ΔΨm, indicating that CdA directly compromised outer mitochondrial membrane integrity. CdA treatment of Jurkat T leukemia cells resulted in the activation of caspase-3, -8, and -9, while inhibition of these caspases prevented the CdA-induced loss of ΔΨm, as well as DNA fragmentation. In addition, caspase-3 inhibition prevented caspase-8 activation while caspase-8 inhibition prevented caspase-9 activation. Death receptor signalling was not involved in CdA-induced apoptosis since cytotoxicity was not affected by FADD-deficiency or antibody neutralization of either Fas ligand or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Taken together, these data suggested that CdA-induced apoptosis in Jurkat T leukemia cells was mediated via a caspase-3-dependent mitochondrial feedback amplification loop. CdA treatment also increased p38 mitogen-activated protein (MAPK) and extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation in Jurkat T leukemia cells. Although ERK1/2 inhibition did not affect CdA-mediated cytotoxicity, inhibition of p38 MAPK had an enhancing effect, which suggested a cytoprotective function for p38 MAPK. Agents that inhibit p38 MAPK might therefore increase the effectiveness of CdA-based chemotherapy.

Langue d'origineEnglish
Pages (de-à)1325-1333
Nombre de pages9
JournalInternational Journal of Oncology
Volume32
Numéro de publication6
DOI
Statut de publicationPublished - juin 2008

ASJC Scopus Subject Areas

  • Oncology
  • Cancer Research

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