Genotoxicity of gliotoxin on epithelial (A549, Hep G-2, CHO), monocyte (THP-1) cell lines and human peripheral blood leukocytes using alkaline comet assay

Abstract

Gliotoxin is a potent immunosuppressive and cytotoxic myctoxin from the epidithiodioxopiperazine group of secondary metabolites. Its production in situ by medically important molds Asperegillus fumigatus Fres. and A. terreus Thom contribute to invasive apergillosis of mammals. Our previous research found potent cytotoxic effects on epithelial, fibroblast-like, and monocyte cell lines (with IC50 from 2 to 11 microM). In this study we analysed in vitro genotoxicity of gliotoxin (CAS 67-99-2) on epithelial (A549, Hep G-2, CHO), fibroblast-like (COS-7), and monocyte (THP-1) cell lines as well as on human leukocytes ex situ using alkaline comet assay (single cell gel electrophoresis). After 18h-exposure of cells to the gliotoxin, comet tail length (TL, in micrometers), tail intensity (DNA%) and tail moment (TM) were recorded using fluorescence microscope and Comet Assay II software. At 2 microM gliotoxin expresses genotoxic effects with the most differences noted in THP-1 cell line (p<0.001), followed by epithelial A549, Hep G-2, CHO cell lines and leukocytes (p<0.05). Gliotoxin exhibited dose-depended genotoxic effect on human leukocytes ex situ from concentrations 0.5 to 2 microM. Sub-IC50 concentration of gliotoxin (0.5 and 1 microM) showed TL (21.04 ; 23.48 micrometer, respectively) ; tail intensity (3.79% ; 4.84%, respectively) and TM (0.61 ; 0.91 respectively) with statistically higher values than in control (TL 14.14 ; tail intensity 0.64% ; TM 0.08). At higher concentrations of gliotoxin, from 2 to 4 microM, apoptotic effect has been noted. Our results indicate that gliotoxin was genotoxic in concentration bellow cytotoxic IC50 concentrations in epithelial cell lines, and this effect is dose-depended in human peripheral blood leukocytes.