title: Identification, validation, and targeting of the mutant p53-PARP-MCM chromatin axis in triple negative breast cancer.
abstract: Over 80% of triple negative breast cancers express mutant p53. Mutant p53 often gains oncogenic function suggesting that triple negative breast cancers may be driven by p53 protein type. To determine the chromatin targets of this gain-of-function mutant p53 we used inducible knockdown of endogenous gain-of-function mtp53 in MDA-MB-468 cells in conjunction with stable isotope labeling with amino acids in cell culture and subcellular fractionation. We sequenced over 70,000 total peptides for each corresponding reciprocal data set and were able to identify 3010 unique cytoplasmic fraction proteins and 3403 unique chromatin fraction proteins. The present proteomics experiment corroborated our previous experiment-based results that poly ADP-ribose polymerase has a positive association with mutant p53 on the chromatin. Here, for the first time we report that the heterohexomeric minichromosome maintenance complex that participates in DNA replication initiation ranked as a high mutant p53-chromatin associated pathway. Enrichment analysis identified the minichromosome maintenance members 2-7. To validate this mutant p53- poly ADP-ribose polymerase-minichromosome maintenance functional axis, we experimentally depleted R273H mutant p53 and found a large reduction of the amount of minichromosome maintenance complex proteins on the chromatin. Furthermore a mutant p53-minichromosome maintenance 2 direct interaction was detected. Overexpressed mutant p53, but not wild type p53, showed a protein-protein interaction with minichromosome maintenance 2 and minichromosome maintenance 4. To target the mutant p53- poly ADP-ribose polymerase-minichromosome maintenance axis we treated cells with the poly ADP-ribose polymerase inhibitor talazoparib and the alkylating agent temozolomide and detected synergistic activation of apoptosis only in the presence of mutant p53. Furthermore when minichromosome maintenance 2-7 activity was inhibited the synergistic activation of apoptosis was blocked. This mutant p53- poly ADP-ribose polymerase -minichromosome maintenance axis may be useful for theranostics.
authors.affiliation: The Department of Biological Sciences Hunter College, City University of New York, Hunter College-Weill Cornell Belfer Research Building, 413 East 69th, New York, NY 10065, USA; The Graduate Center PhD Program in Biology, City University of New York, New York, NY 10016, USA; Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY 10065, USA.
authors.forename: Wei-Gang
authors.initials: WG
authors.lastname: Qiu
authors.affiliation: The Department of Biological Sciences Hunter College, City University of New York, Hunter College-Weill Cornell Belfer Research Building, 413 East 69th, New York, NY 10065, USA.
authors.forename: Alla
authors.initials: A
authors.lastname: Polotskaia
authors.affiliation: The Department of Biological Sciences Hunter College, City University of New York, Hunter College-Weill Cornell Belfer Research Building, 413 East 69th, New York, NY 10065, USA.
authors.forename: Gu
authors.initials: G
authors.lastname: Xiao
authors.affiliation: The Department of Biological Sciences Hunter College, City University of New York, Hunter College-Weill Cornell Belfer Research Building, 413 East 69th, New York, NY 10065, USA.
authors.forename: Lia
authors.initials: L
authors.lastname: Di
authors.affiliation: Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA.
authors.forename: Yuhan
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA.
authors.forename: Wenwei
authors.initials: W
authors.lastname: Hu
authors.affiliation: Proteomics Core Facility, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: John
authors.initials: J
authors.lastname: Philip
authors.affiliation: Proteomics Core Facility, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Hendrickson
authors.affiliation: The Department of Biological Sciences Hunter College, City University of New York, Hunter College-Weill Cornell Belfer Research Building, 413 East 69th, New York, NY 10065, USA; The Graduate Center PhD Programs in Biology and Biochemistry, City University of New York, New York, NY 10016, USA; Department of Cell and Developmental Biology, Weill Cornell Medical College of Cornell University, New York, NY 10065, USA.
authors.forename: Jill
authors.initials: J
authors.lastname: Bargonetti