2,6-Dithiopurine, a nucleophilic scavenger, protects against mutagenesis in mouse skin treated in vivo with 2-(chloroethyl) ethyl sulfide, a mustard gas analog

Abstract

Sulfur mustard [bis(2-chloroethyl)sulfide, SM] is a well-known DNA-damaging agent that has been used in chemical warfare since World War I, and is a weapon that could potentially be used in a terrorist attack on a civilian population. Dermal exposure to high concentrations of SM produces severe, long-lasting burns. Topical exposure to high concentrations of 2-(chloroethyl) ethyl sulfide (CEES), a monofunctional analog of SM, also produces severe skin lesions in mice. Utilizing a genetically engineered mouse strain, Big Blue, that allows measurement of mutation frequencies in mouse tissues, we now show that topical treatment with much lower concentrations of CEES induces significant dose- and time-dependent increases in mutation frequency in mouse skin; the mutagenic exposures produce minimal toxicity as determined by standard histopathology and immunohistochemical analysis for cytokeratin 6 and the DNA-damage induced phosphorylation of histone H2AX (γ-H2AX). We attempted to develop a therapeutic that would inhibit the CEES-induced increase in mutation frequency in the skin. We observe that multi-dose, topical treatment with 2,6-dithiopurine (DTP), a known chemical scavenger of CEES, beginning 1 hour post-exposure to CEES, completely abolishes the CEES-induced increase in mutation frequency. These findings suggest the possibility that DTP, previously shown to be non-toxic in mice, may be useful as a therapeutic agent in accidental or malicious human exposures to SM.

Identification of an Allosteric Binding Site on Human Lysosomal Alpha-Galactosidase Opens the Way to New Pharmacological Chaperones for Fabry Disease

“…As a second choice we selected DTP, which is not an approved drug, but is a good candidate because it is safe when tested on human skin cells [25] and on mice [24] [26]. Even if the docking simulations started at GAL site DTP contacted the allosteric site.…”

“…Some molecules resulting from our virtual screening bind better to the allosteric site than to the active site. One of these molecules, a chemopreventive 2,6-dithiopurine DTP, appeared particularly promising because it is actively transported into mammalian cells where it accumulates at millimolar concentration [25] and it is safe [24] [26]. …”

“…Among the top ranking hits we found one molecule, 2,6-dithiopurine (DTP). This molecule was chosen for further studies since it has already passed some safety tests, is a known chemiopreventive agent [24] [25] and it is safe when administered to mice [26]. DTP is able to stabilize AGAL against thermal and urea-induced denaturation and is able to rescue a mutant that is not sensitive to DGJ.…”

Sulfur and nitrogen mustards induce characteristic poly(ADP-ribosyl)ation responses in HaCaT keratinocytes with distinctive cellular consequences

“…While mustards are not thought to produce DNA strand breaks by direct reaction with DNA, both DNA single as well as double strand breaks are introduced during subsequent DNA repair processes and potentially by secondary ROS formation (Debiak et al, 2011;Inturi et al, 2011;Jain et al, 2011). If persistent, mustard induced DNA damage can cause genetic mutations during cell division or induce cell death via apoptosis and necrosis (Boulware et al, 2012;Kehe et al, 2008;Matijasevic and Volkert, 2007;Powell et al, 2010).…”

Sulforaphane induces phase II detoxication enzymes in mouse skin and prevents mutagenesis induced by a mustard gas analog

“…Despite recent progress in identifying agents that ameliorate some of the effects of mustards (Anumolu et al , 2010; Gordon et al , 2010; O'Neill et al , 2010; Anumolu et al , 2011), there are currently no effective therapies for the acute effects of dermal exposure. Mustard gas and a less toxic analog, 2-(chloroethyl) ethyl sulfide (CEES), induce DNA damage through structurally analogous electrophilic intermediates and are mutagenic (Ogston et al , 1946; Fox and Scott, 1980; Liu et al , 2010; Boulware et al , 2012). Epidemiological evidence suggests that chronic SM exposure leads to increased risk for respiratory malignancies (Wada et al.…”