TRAIL-activated stress kinases suppress apoptosis through transcriptional upregulation of MCL-1

J. K. Son, S. Varadarajan, S. B. Bratton

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30 Scopus citations

Abstract

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potentially useful anticancer agent with exquisite selectivity for cancer cells. Unfortunately, many cancers show or acquire resistance to TRAIL. In this study we report that TRAIL activates a TGF-Β-activated kinase 1 → mitogen-activated protein kinase (MAPK) kinase 3 (MKK3)MKK6 → p38 pathway in prostate cancer cells that transcriptionally upregulates expression of the antiapoptotic BCL-2 family member MCL-1. TRAIL alone triggered robust formation of the death-inducing signaling complex (DISC), activation of the initiator caspase-8, and truncation of the BH3-only protein BID (tBID). Nevertheless, simultaneous disruption of the p38 MAPK pathway was required to suppress MCL-1 expression, thereby allowing tBID to activate the proapoptotic BCL-2 family member BAK and stimulate mitochondrial outer membrane permeabilization (MOMP). Release of the inhibitor-of-apoptosis (IAP) antagonist, SmacDIABLO, from the intermembrane space was sufficient to promote TRAIL-induced apoptosis, whereas release of cytochrome c and activation of the apoptosome was dispensable. Even after MOMP, however, mitochondrial-generated reactive oxygen species (ROS) activated a secondary signaling pathway, involving c-Jun N-terminal kinases (JNKs), that similarly upregulated MCL-1 expression and partially rescued some cells from death. Thus, stress kinases activated at distinct steps, before and after mitochondrial injury, mediate TRAIL resistance through maintenance of MCL-1 expression.

Original languageEnglish (US)
Pages (from-to)1288-1301
Number of pages14
JournalCell death and differentiation
Volume17
Issue number8
DOIs
StatePublished - Aug 1 2010

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ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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