title: Estrogen treatment induces MLL aberrations in human lymphoblastoid cells.
abstract: Epidemiological data indicates increased risk of infant acute leukemia involving MLL gene aberrations with use of oral contraceptives. To determine whether estrogens might be implicated, we examined the effect of estradiol (E2) or 4-OH-E2 in an in vitro model of translocation susceptibility. Genomic DNA from the TK6 human lymphoblastoid cell line was screened by ligation mediated PCR and inverse PCR at a rearrangement hot spot within the MLL breakpoint cluster region to detect DNA aberrations. An increase in DNA double strand breaks was observed within this region after exposure to either E2 or 4-OH-E2. An increase in the frequency of MLL translocations was only found after exposure to E2. Induction of cleavage due to increased activation of apoptotic nucleases was excluded by pre-treatment with the pan-caspase inhibitor, zVAD.fmk. We conclude that concentrations of E2 and 4-OH-E2 that may occur during pregnancy, or during use of oral contraceptives, can cause aberrations of the MLL gene and could thus be a factor in the early events of leukemogenesis occurring in utero.
authors.affiliation: Department of Radiation Oncology, 4501 X Street, University of California Davis, Sacramento, CA 95817, USA.
authors.forename: Sabine
authors.initials: S
authors.lastname: Schnyder
authors.forename: Nga T
authors.initials: NT
authors.lastname: Du
authors.forename: Hongan B
authors.initials: HB
authors.lastname: Le
authors.forename: Sheetal
authors.initials: S
authors.lastname: Singh
authors.forename: Grace A
authors.initials: GA
authors.lastname: Loredo
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Vaughan
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor / Q000187:drug effects; D002648:Child; D002869:Chromosome Aberrations / Q000187:drug effects*; D003001:Cloning, Molecular; D065633:Cytochrome P-450 CYP1B1; D004264:DNA Topoisomerases, Type I / Q000235:genetics; D004958:Estradiol / Q000031:analogs & derivatives / Q000627:therapeutic use; D004967:Estrogens / Q000627:therapeutic use*; D002393:Estrogens, Catechol; D005260:Female; D005434:Flow Cytometry; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D007223:Infant; D051788:Myeloid-Lymphoid Leukemia Protein / Q000235:genetics*; D016133:Polymerase Chain Reaction; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy* / Q000196:embryology; D011247:Pregnancy; D011960:Receptors, Estrogen / Q000235:genetics
chemical_list: D017304:Annexin A5; D000970:Antineoplastic Agents; D004967:Estrogens; D002393:Estrogens, Catechol; C497422:KMT2A protein, human; D011960:Receptors, Estrogen; D051788:Myeloid-Lymphoid Leukemia Protein; D004958:Estradiol; C014036:4-hydroxyestradiol; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D065633:Cytochrome P-450 CYP1B1; D011495:Histone-Lysine N-Methyltransferase; D004264:DNA Topoisomerases, Type I