title: Estrogen receptor beta-mediated nuclear interaction between IRS-1 and Rad51 inhibits homologous recombination directed DNA repair in medulloblastoma.
abstract: In medulloblastomas, which are highly malignant cerebellar tumors of the childhood genotoxic treatments such as cisplatin or gamma-irradiation are frequently associated with DNA damage, which often associates with unfaithful DNA repair, selection of new adaptations and possibly tumor recurrences. Therefore, better understanding of molecular mechanisms which control DNA repair fidelity upon DNA damage is a critical task. Here we demonstrate for the first time that estrogen receptor beta (ERbeta) can contribute to the development of genomic instability in medulloblastomas. Specifically, ERbeta was found highly expressed and active in mouse and human medulloblastoma cell lines. Nuclear ERbeta was also present in human medulloblastoma clinical samples. Expression of ERbeta coincided with nuclear translocation of insulin receptor substrate 1 (IRS-1), which was previously reported to interfere with the faithful component of DNA repair when translocated to the nucleus. We demonstrated that ERbeta and IRS-1 bind each other, and the interaction involves C-terminal domain of IRS-1 (aa 931-1233). Following cisplatin-induced DNA damage, nuclear IRS-1 localized at the sites of damaged DNA, and interacted with Rad51--an enzymatic component of homologous recombination directed DNA repair (HRR). In medulloblastoma cells, engineered to express HRR-DNA reporter plasmid, ER antagonist, ICI 182,780, or IRS mutant (931-1233) significantly increased DNA repair fidelity. These data strongly suggest that both molecular and pharmacological interventions are capable of preventing ERbeta-mediated IRS-1 nuclear translocation, which in turn improves DNA repair fidelity and possibly counteracts accumulation of malignant mutations in actively growing medulloblastomas.
authors.affiliation: Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania 19122, USA.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Urbanska
authors.forename: Paola
authors.initials: P
authors.lastname: Pannizzo
authors.forename: Adam
authors.initials: A
authors.lastname: Lassak
authors.forename: Elisa
authors.initials: E
authors.lastname: Gualco
authors.forename: Eva
authors.initials: E
authors.lastname: Surmacz
authors.forename: Sidney
authors.initials: S
authors.lastname: Croul
authors.forename: Luis
authors.initials: L
authors.lastname: Del Valle
authors.forename: Kamel
authors.initials: K
authors.lastname: Khalili
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Reiss
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D004260:DNA Repair; D047629:Estrogen Receptor beta / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D055504:Insulin Receptor Substrate Proteins / Q000235:genetics / Q000378:metabolism*; D008527:Medulloblastoma / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic
chemical_list: D047629:Estrogen Receptor beta; D055504:Insulin Receptor Substrate Proteins; D051135:Rad51 Recombinase