A Novel Method for Imaging Apoptosis Using a Caspase-1 Near-Infrared Fluorescent Probe

Shanta M. Messerli, Shilpa Prabhakar, Yi Tang, Khalid Shah, Maria L. Cortes, Vidya Murthy, Ralph Weissleder, Xandra O. Breakefield, Ching Hsuan Tung

Research output: Contribution to journalArticlepeer-review

101 Scopus citations

Abstract

Here we describe a novel method for imaging apoptosis In cells using a near-infrared fluorescent (NIRF) probe selective for caspase-1 (interleukin 1β-converting enzyme, ICE). This biocompatible, optically quenched ICE-NIRF probe incorporates a peptide substrate, which can be selectively cleaved by caspase-1, resulting in the release of fluorescence signal. The specificity of this probe for caspase-11 is supported by various lines of evidence: 1) activation by purified caspase-1, but not another caspase in vitro; 2) activation of the probe by infection of cells with a herpes simplex virus amplicon vector (HGC-ICE-lacZ) expressing a catalytically active caspase-1-lacZ fusion protein; 3) Inhibition of HGC-ICE-lacZ vector-induced activation of the probe by coincubation with the caspase-1 inhibitor YVAD-cmk, but not with a caspase-3 inhibitor; and 4) activation of the probe following standard methods of inducing apoptosis with staurosporine, ganciclovir, or ionizing radiation in culture. These results indicate that this novel ICE-NIRF probe can be used in monitoring endogenous and vector-expressed caspase-1 activity in cells. Furthermore, tumor implant experiments indicate that this ICE-NIRF probe can be used to detect caspase-1 activity in living animals. This novel ICE-NIRF probe should prove useful in monitoring endogenous and vector-expressed caspase-1 activity, and potentially apoptosis in cell culture and in vivo.

Original languageEnglish (US)
Pages (from-to)95-105
Number of pages11
JournalNeoplasia
Volume6
Issue number2
DOIs
StatePublished - 2004
Externally publishedYes

Keywords

  • Apoptosis
  • Brain tumors
  • Caspase-1
  • HSV
  • Near-infrared fluorescence (NIRF)

ASJC Scopus subject areas

  • Cancer Research

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