Hyperthermia enhances mapatumumab-induced apoptotic death through ubiquitin-mediated degradation of cellular FLIP(long) in human colon cancer cells

X. Song, S. Y. Kim, Z. Zhou, E. Lagasse, Y. T. Kwon, Y. J. Lee*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Colorectal cancer is the third leading cause of cancer-related mortality in the world; the main cause of death of colorectal cancer is hepatic metastases, which can be treated with hyperthermia using isolated hepatic perfusion (IHP). In this study, we report that mild hyperthermia potently reduced cellular FLIP(long), (c-FLIPL), a major regulator of the death receptor (DR) pathway of apoptosis, thereby enhancing humanized anti-DR4 antibody mapatumumab (Mapa)-mediated mitochondria-independent apoptosis. We observed that overexpression of c-FLIPL in CX-1 cells abrogated the synergistic effect of Mapa and hyperthermia, whereas silencing of c-FLIP in CX-1 cells enhanced Mapa-induced apoptosis. Hyperthermia altered c-FLIPL protein stability without concomitant reductions in FLIP mRNA. Ubiquitination of c-FLIPL was increased by hyperthermia, and proteasome inhibitor MG132 prevented heat-induced downregulation of c-FLIPL. These results suggest the involvement of the ubiquitinproteasome system in this process. We also found lysine residue 195 (K195) to be essential for c-FLIPL ubiquitination and proteolysis, as mutant c-FLIPL lysine 195 arginine (arginine replacing lysine) was left virtually un-ubiquitinated and was refractory to hyperthermia-triggered degradation, and thus partially blocked the synergistic effect of Mapa and hyperthermia. Our observations reveal that hyperthermia transiently reduced c-FLIPL by proteolysis linked to K195 ubiquitination, which contributed to the synergistic effect between Mapa and hyperthermia. This study supports the application of hyperthermia combined with other regimens to treat colorectal hepatic metastases.

Original languageEnglish (US)
Article numbere577
JournalCell Death and Disease
Volume4
Issue number4
DOIs
StatePublished - Apr 2013

Funding

Acknowledgements. We thank Dr. Patrick Kaminker from Human Genome Sciences who provided us with mapatumumab. This work was supported by the following Grants: NCI Grant R01 CA140554 (YJ L), R01 HL083365 (YTK) and R01 DK085711 (EL), DOD-CDMRP Grant BC103217:W81XWH-11-1-0128 (YJL), and World Class University R31-2008-000-10103-0 (YTK). This project used the UPCI Core Facility and was supported in part by award P30CA047904.

Keywords

  • C-FLIP
  • Hyperthermia
  • Mapatumumab
  • Mitochondria-independent pathway
  • Ubiquitination

ASJC Scopus subject areas

  • Immunology
  • Cellular and Molecular Neuroscience
  • Cell Biology
  • Cancer Research

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