Lens epithelial cell protection by aminothiol WR-1065 and anetholedithiolethione from ionizing radiation

Abstract

SUMMARY Lens epithelium disorganization, glutathione (GSH) depletion, and epithelial cell death have been incriminated in the cytopathogenic mechanisms that lead to cataract formation following UVB and x-ray exposures. The objective of this study was to determine the in vitro capacity of the aminothiol WR-1065, the active metabolite of amifostine, and anetholedithiolethione (ADT or Sulfarlem ) to protect bovine lens epithelial cells against x-ray irradiation. WR-1065 and ADT were used at a concentration of 20 M. A single dose of 10 Gy was delivered at a rate of 2 Gy/min. Fluorimetric assays were then performed using a neutral red probe to evaluate cell viability, a Hoechst 33342 probe (HO) to evaluate nuclear condensation and apoptosis, and a monobromobimane probe to estimate the intracellular GSH pool. Twenty-four hours after x-ray exposure, cells pretreated with WR-1065 showed increased GSH levels, improved cell viability, and decreased HO fluorescence in addition to a lesser proportion of cells with apoptotic nuclear modifications. Between 72 and 120 hr postirradiation, ADT-pretreated cells also showed increased intracellular GSH levels and cell viability and decreased HO fluorescence and apoptotic cell morphology. This in vitro study demonstrates that WR-1065 and ADT protects lens epithelial cells from x-ray injury; thus, ADT and amifostine are appropriate candidates for clinical trials in humans. They are currently used in preventing radiation-induced xerostomia and should be further tested in the prevention of late radiation-induced ocular complications such as sicca syndrome and cataract.

Current Trends in the Pharmacotherapy of Cataracts

“…Amifostine, an organic thiophosphate prodrug, is clinically used as a cytoprotective adjuvant in cancer chemotherapy due to its free radical scavenging capacity and ability to detoxify reactive drug metabolites [92]. Belkacémi et al (2001) reported that the active metabolite of amifostin, aminothiol WR-1065, protected bovine epithelial cells against X-ray radiation of 10 Gy (2 Gy per minute) as evidenced by the elevation of GSH content, enhanced cell viability, and a decrease in both nuclear condensation and epithelial cell apoptosis [93].…”

Antioxidant agents transiently inhibit aneuploidy progression in Li‐Fraumeni cell strains

“…Free radical scavenging activity has been demonstrated by NAC in multiple cell types [21–23] including fibroblasts [24], as well as in amifostine [25] and in genistein [26]. Evidence also demonstrates that NAC [27], amifostine [28–31], genistein [32–34], and oltipraz [35–39] either serve as precursors or induce the presence of cellular defense enzymes that catalyze the reduction of H 2 O 2 , ·OH, and O. Cytoprotection afforded by amifostine includes increased cell viability [28,29,40,41], reduced DNA damage [42–44], and reduced apoptosis [45,46] after irradiation.…”

“…Evidence also demonstrates that NAC [27], amifostine [28–31], genistein [32–34], and oltipraz [35–39] either serve as precursors or induce the presence of cellular defense enzymes that catalyze the reduction of H 2 O 2 , ·OH, and O. Cytoprotection afforded by amifostine includes increased cell viability [28,29,40,41], reduced DNA damage [42–44], and reduced apoptosis [45,46] after irradiation. As a receptor protein tyrosine kinase inhibitor genistein can play an antioxidant role by ameliorating the effects of ROS signal transduction including reducing apoptosis in H 2 O 2 treated fibroblasts [47,48], reducing vascular damage [49], suppressing cyclooxygenase expression [50], and inhibiting the induction of Stat1 activity [51].…”