Increased capacity of lymphocytes from hereditary hemochromatosis patients homozygous for the C282Y HFE mutation to respond to the genotoxic effect of diepoxybutane.
Hereditary hemochromatosis (HH) is a common autosomal recessive disorder characterized by systemic iron overload with consequent tissue damage. The vast majority of HH patients are homozygous for the C282Y mutation in HFE, a non-classical MHC class-I gene located in chromosome 6, whose role in the regulation of systemic iron metabolism is still not completely understood. Iron enhances the formation of reactive oxygen species, with increasing risk of DNA damage induced by oxidative stress, and consequently an increased susceptibility to chromosome instability. In the present work we examined spontaneous and diepoxybutane (DEB)-induced chromosome instability in PHA-stimulated lymphocyte cultures from 23 HH patients, all homozygous for the C282Y HFE mutation, in comparison to 29 normal controls. In addition, three patients with secondary forms of iron overload, not related to HFE, were studied as controls to test the role of iron overload on DEB-induced chromosome instability. Our results show a significantly higher frequency of spontaneous chromosome breaks in lymphocytes from the HH patients, when compared with lymphocytes from normal controls (p<0.0001). In addition, there is a significant correlation between the percentage of cells with spontaneous chromosomal breaks and the transferrin saturation (r=0.53, p=0.0041) or serum-ferritin levels (r=0.66, p=0.0001) in patients. Surprisingly, the frequency of DEB-induced chromosome breaks was significantly lower in lymphocytes from HH patients than in lymphocytes from both controls and patients with secondary forms of hemochromatosis (p=0.0029). No correlation was observed between the percentage of cells with DEB-induced chromosome breaks and the transferrin saturation or serum-ferritin values. These results suggest that lymphocytes from HH patients may have an increased capacity to respond to DEB-induced chromosome breakage, and that this capacity is somehow related to the presence of the C282Y HFE mutation.
Porto
Beatriz
B
ICBAS-Instituto Ciências Biomédicas Abel Salazar, Laboratory of Cytogenetics, Universidade do Porto, Largo do Prof. Abel Salazar 2, 4099-003 Porto, Portugal. bporto@icbas.up.pt
Vieira
Raquel
R
Porto
Graça
G
D000328:Adult; D000368:Aged; D002478:Cells, Cultured; D043171:Chromosomal Instability / Q000187:drug effects / Q000235:genetics; D019457:Chromosome Breakage / Q000187:drug effects; D004852:Epoxy Compounds / Q000494:pharmacology*; D005260:Female; D006432:Hemochromatosis / Q000235:genetics*; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D019190:Iron Overload / Q000503:physiopathology; D008214:Lymphocytes / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008875:Middle Aged; D055815:Young Adult
D004852:Epoxy Compounds; C103673:HFE protein, human; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; C007366:diepoxybutane