title: Microtubule-targeting agents augment the toxicity of DNA-damaging agents by disrupting intracellular trafficking of DNA repair proteins.
abstract: The paradigm that microtubule-targeting agents (MTAs) cause cell death via mitotic arrest applies to rapidly dividing cells but cannot explain MTA activity in slowly growing human cancers. Many preferred cancer regimens combine a MTA with a DNA-damaging agent (DDA). We hypothesized that MTAs synergize with DDAs by interfering with trafficking of DNA repair proteins on interphase microtubules. We investigated nine proteins involved in DNA repair: ATM, ATR, DNA-PK, Rad50, Mre11, p95/NBS1, p53, 53BP1, and p63. The proteins were sequestered in the cytoplasm by vincristine and paclitaxel but not by an aurora kinase inhibitor, colocalized with tubulin by confocal microscopy and coimmunoprecipitated with the microtubule motor dynein. Furthermore, adding MTAs to radiation, doxorubicin, or etoposide led to more sustained γ-H2AX levels. We conclude DNA damage-repair proteins traffic on microtubules and addition of MTAs sequesters them in the cytoplasm, explaining why MTA/DDA combinations are common anticancer regimens.
authors.affiliation: Center for Cancer Research.
authors.forename: Marianne S
authors.initials: MS
authors.lastname: Poruchynsky
authors.affiliation: Center for Cancer Research.
authors.forename: Edina
authors.initials: E
authors.lastname: Komlodi-Pasztor
authors.affiliation: Center for Cancer Research.
authors.forename: Shana
authors.initials: S
authors.lastname: Trostel
authors.affiliation: Center for Cancer Research.
authors.forename: Julia
authors.initials: J
authors.lastname: Wilkerson
authors.affiliation: National Cancer Institute, Developmental Therapeutics Branch, National Cancer Institute, and.
authors.forename: Marie
authors.initials: M
authors.lastname: Regairaz
authors.affiliation: National Cancer Institute, Developmental Therapeutics Branch, National Cancer Institute, and.
authors.forename: Yves
authors.initials: Y
authors.lastname: Pommier
authors.affiliation: Center for Cancer Research.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Center for Cancer Research.
authors.forename: Tapan
authors.initials: T
authors.lastname: Kumar Maity
authors.affiliation: National Cancer Institute, Developmental Therapeutics Branch, National Cancer Institute, and.
authors.forename: Robert
authors.initials: R
authors.lastname: Robey
authors.affiliation: Center for Cancer Research.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Burotto
authors.affiliation: Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.
authors.forename: Dan
authors.initials: D
authors.lastname: Sackett
authors.affiliation: Center for Cancer Research.
authors.forename: Udayan
authors.initials: U
authors.lastname: Guha
authors.affiliation: Center for Cancer Research, fojot@mail.nih.gov.
authors.forename: Antonio Tito
authors.initials: AT
authors.lastname: Fojo
mesh_terms: D045744:Cell Line, Tumor; D004247:DNA / Q000187:drug effects*; D004249:DNA Damage; D004260:DNA Repair; D005455:Fluorescent Antibody Technique; D006801:Humans; D008870:Microtubules / Q000187:drug effects*
chemical_list: D004247:DNA
keywords: DNA repair protein trafficking; DNA-damaging agents; combination chemotherapy; microtubule targeting agents; targeted therapies