Photofrin binds to procaspase-3 and mediates photodynamic treatment-triggered methionine oxidation and inactivation of procaspase-3

Y. J. Hsieh, K. Y. Chien, S. Y. Lin, S. Sabu, R. M. Hsu, L. M. Chi, P. C. Lyu, J. S. Yu*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

5 Scopus citations

Abstract

Diverse death phenotypes of cancer cells can be induced by Photofrin-mediated photodynamic therapy (PDT), which has a decisive role in eliciting a tumor-specific immunity for long-term tumor control. However, the mechanism(s) underlying this diversity remain elusive. Caspase-3 is a critical factor in determining cell death phenotypes in many physiological settings. Here, we report that Photofrin-PDT can modify and inactivate procaspase-3 in cancer cells. In cells exposed to an external apoptotic trigger, high-dose Photofrin-PDT pretreatment blocked the proteolytic activation of procaspase-3 by its upstream caspase. We generated and purified recombinant procaspase-3-D3A (a mutant without autolysis/autoactivation activity) to explore the underlying mechanism(s). Photofrin could bind directly to procaspase-3-D3A, and Photofrin-PDT-triggered inactivation and modification of procaspase-3-D3A was seen in vitro. Mass spectrometry-based quantitative analysis for post-translational modifications using both 16O/18O- and 14N/15N-labeling strategies revealed that Photofrin-PDT triggered a significant oxidation of procaspase-3-D3A (mainly on Met-27, -39 and -44) in a Photofrin dose-dependent manner, whereas the active site Cys-163 remained largely unmodified. Site-directed mutagenesis experiments further showed that Met-44 has an important role in procaspase-3 activation. Collectively, our results reveal that Met oxidation is a novel mechanism for the Photofrin-PDT-mediated inactivation of procaspase-3, potentially explaining at least some of the complicated cell death phenotypes triggered by PDT.

Original languageEnglish
Article numbere347
JournalCell Death and Disease
Volume3
Issue number7
DOIs
StatePublished - 07 2012

Keywords

  • Photofrin
  • cell death
  • mass spectrometry
  • methionine oxidation
  • photodynamic treatment
  • procaspase-3

Fingerprint

Dive into the research topics of 'Photofrin binds to procaspase-3 and mediates photodynamic treatment-triggered methionine oxidation and inactivation of procaspase-3'. Together they form a unique fingerprint.

Cite this