Up-regulation of c-Jun-NH2-kinase pathway contributes to the induction of mitochondria-mediated apoptosis by α-tocopheryl succinate in human prostate cancer cells

Ke Zu, Lesleyann Hawthorn, Clement Ip

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

Previously, α-tocopheryl succinate (α-TOS) has been reported to induce caspase-mediated apoptosis in PC-3 human prostate cancer cells. Caspase-9 was among several initiator caspases activated by α-TOS, suggesting a potential contribution of the intrinsic apoptotic pathway in mediating the response to α-TOS. Gene expression microarray was carried out as a screen to identify novel signaling molecules modulated by α-TOS, with a special focus on those known to play a role in mitochondria-mediated apoptosis. We discovered that Ask1, GADD45β, and Sek1, three key components of the stress-activated mitogen-activated protein kinase pathway, are novel targets of α-TOS. Western blot analysis showed increased levels of phospho-Sek1 and phospho-c-Jun-NH2-kinase (JNK) in addition to total Ask1, GADD45β, and Sek1. α-TOS also altered JNK-specific phosphorylation of Bcl-2 and Bim in a manner consistent with enhanced mitochondrial translocation of Bax and Bim. Because the expression level of most Bcl-2 family members remained unchanged, the posttranslational modification of Bcl-2 and Bim by JNK is likely to be a driving force in α-TOS activation of the intrinsic apoptotic pathway. Based on our findings, we propose working model to capture the salient features of the poptotic signaling circuitry of α-TOS.

Original languageEnglish (US)
Pages (from-to)43-50
Number of pages8
JournalMolecular cancer therapeutics
Volume4
Issue number1
StatePublished - Jan 2005
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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