The small heat shock protein αB-crystallin is a novel inhibitor of TRAIL-induced apoptosis that suppresses the activation of caspase-3

Academic Article

Abstract

  • Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor α family of cytokines that preferentially induces apoptosis in transformed cells, making it a promising cancer therapy. However, many neoplasms are resistant to TRAIL-induced apoptosis by mechanisms that are poorly understood. We demonstrate that the expression of the small heat shock protein αB-crystallin (but not other heat shock proteins or apoptosis-regulating proteins) correlates with TRAIL resistance in a panel of human cancer cell lines. Stable expression of wild-type αB-crystallin, but not a pseudophosphorylation mutant impaired in its assembly and chaperone function, protects cancer cells from TRAIL-induced caspase-3 activation and apoptosis in vitro. Furthermore, selective inhibition of αB-crystallin expression by RNA interference sensitizes cancer cells to TRAIL. In addition, wild-type αB-crystallin promotes xenograft tumor growth and inhibits TRAIL-induced apoptosis in vivo in nude mice, whereas a pseudophosphorylation αB-crystallin mutant impaired in its anti-apoptotic function inhibits xenograft tumor growth. Collectively, these findings indicate that αB-crystallin is a novel regulator of TRAIL-induced apoptosis and tumor growth. Moreover, these results demonstrate that targeted inhibition of αB-crystallin promotes TRAIL-induced apoptosis, thereby suggesting a novel strategy to overcome TRAIL resistance in cancer. © 2005 by The American Society for Biochemistry and Molecular Biology, Inc.
  • Published In

    Digital Object Identifier (doi)

    Author List

  • Kamradt MC; Lu M; Werner ME; Kwan T; Chen F; Strohecker A; Oshita S; Wilkinson JC; Yu C; Oliver PG
  • Start Page

  • 11059
  • End Page

  • 11066
  • Volume

  • 280
  • Issue

  • 12