Noninvasive Imaging of Cell Death Using an Hsp90 Ligand

Abstract

Cell death plays a central role in normal physiology and in disease. Common to apoptotic and necrotic cell death is the eventual loss of plasma membrane integrity. We have produced a small organoarsenical compound, 4-(N-(S-glutathionylacetyl)amino)phenylarsonous acid, that rapidly accumulates in the cytosol of dying cells coincident with loss of plasma membrane integrity. The compound is retained in the cytosol predominantly by covalent reaction with the 90 kDa heat shock protein (Hsp90), the most abundant molecular chaperone of the eukaryotic cytoplasm. The organoarsenical was tagged with either optical or radioisotope reporting groups to image cell death in cultured cells and in murine tumors ex vivo and in situ. Tumor cell death in mice was noninvasively imaged by SPECT/CT using an (111)In-tagged compound. This versatile compound should enable the imaging of cell death in most experimental settings.

Necrotic platelets provide a procoagulant surface during thrombosis

“…Rationale for the platelet necrosis marker GSAO is a tripeptide trivalent arsenical that has recently been characterized as an imaging agent for necrotic and late apoptotic nucleated cells [15][16][17] ( Figure 1A). When tagged with a reporter compound at the g-glutamyl residue of the glutathione moiety, the compound is unable to cross the plasma membrane of viable cells.…”

“…However, when plasma membrane permeability changes in necrosis or late apoptosis, GSAO enters the cell and is retained in the cytoplasm by covalent bonding to proteins containing closely spaced cysteine thiols. 15 The intracellular protein targets for trivalent arsenicals vastly outnumber the extracellular targets. For instance, the intensity of GSAO labeling of dying/dead nucleated cells is at least 1000-fold higher than labeling of viable cells.…”

“…GSAO and GSCA were produced and conjugated to Alexa Fluor 647, as described previously. 15,16,18 On some occasions, washed platelets were also labeled with annexin V-Pacific Blue (5% vol/vol; Life Technologies).…”

“…Traditional markers of loss of membrane integrity that bind to nuclear material such as propidium iodide or Sytox dyes cannot be used in the anucleate platelet. Thus, we investigated the use of a cell death imaging agent that complexes with cytoplasmic ligands, 4-[N-(S-glutathionylacetyl) amino] phenylarsonous acid (GSAO), [15][16][17] to determine whether we could identify the procoagulant platelet in vitro and in vivo. Using GSAO, we show that necrotic platelets are generated within a few seconds of agonist stimulation in vitro and are procoagulant.…”

Improvement in the Anticancer Activity of 6-Mercaptopurine <i>via</i> Combination with Bismuth(III)

“…11) Recently, many proteinlabeling agents have been already explored based on the high affinity of trivalent arsenicals with vicinal dithiols. [12][13][14][15] Therefore, bismuth(III) (Bi(III)), particularly the organometallic Bi(III) complexes, was assumed to have the same quality of anticancer in this work. In addition, the bioactivity of Bi(III) containing complexes like treatment of a variety of gastrointestinal disorders, antitumor, antimicrobial, and antibacterial activities have been reported.…”