title: A Peptide mimicking a region in proliferating cell nuclear antigen specific to key protein interactions is cytotoxic to breast cancer.
abstract: Proliferating cell nuclear antigen (PCNA) is a highly conserved protein necessary for proper component loading during the DNA replication and repair process. Proteins make a connection within the interdomain connector loop of PCNA, and much of the regulation is a result of the inherent competition for this docking site. If this target region of PCNA is modified, the DNA replication and repair process in cancer cells is potentially altered. Exploitation of this cancer-associated region has implications for targeted breast cancer therapy. In the present communication, we characterize a novel peptide (caPeptide) that has been synthesized to mimic the sequence identified as critical to the cancer-associated isoform of PCNA. This peptide is delivered into cells using a nine-arginine linking mechanism, and the resulting peptide (R9-cc-caPeptide) exhibits cytotoxicity in a triple-negative breast cancer cell line, MDA-MB-436, while having less of an effect on the normal counterparts (MCF10A and primary breast epithelial cells). The novel peptide was then evaluated for cytotoxicity using various in vivo techniques, including ATP activity assays, flow cytometry, and clonogenetic assays. This cytotoxicity has been observed in other breast cancer cell lines (MCF7 and HCC1937) and other forms of cancer (pancreatic and lymphoma). R9-cc-caPeptide has also been shown to block the association of PCNA with chromatin. Alanine scanning of the peptide sequence, combined with preliminary in silico modeling, gives insight to the disruptive ability and the molecular mechanism of action of the therapeutic peptide in vivo.
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.).
authors.forename: Shanna J
authors.initials: SJ
authors.lastname: Smith
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.).
authors.forename: Long
authors.initials: L
authors.lastname: Gu
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.).
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Phipps
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.).
authors.forename: Lacey E
authors.initials: LE
authors.lastname: Dobrolecki
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.).
authors.forename: Karla S
authors.initials: KS
authors.lastname: Mabrey
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.).
authors.forename: Pattie
authors.initials: P
authors.lastname: Gulley
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.).
authors.forename: Kelsey L
authors.initials: KL
authors.lastname: Dillehay
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.).
authors.forename: Zhongyun
authors.initials: Z
authors.lastname: Dong
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.).
authors.forename: Gregg B
authors.initials: GB
authors.lastname: Fields
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.).
authors.forename: Yun-Ru
authors.initials: YR
authors.lastname: Chen
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.).
authors.forename: David
authors.initials: D
authors.lastname: Ann
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.).
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hickey
authors.affiliation: Department of Molecular and Cellular Biology (S.J.S., L.G., L.H.M.), Department of Molecular Medicine (R.J.H.), and Department of Diabetes and Metabolic Diseases Research (Y.-R.C., D.A.), Beckman Research Institute at City of Hope, Duarte, California; Department of Medical and Molecular Genetics (E.A.P.) and Department of Medicine (K.S.M., P.G.), Indiana University School of Medicine, Indianapolis, Indiana; Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas (L.E.D.); Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio (K.L.D., Z.D.); and Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida (G.B.F.) lmalkas@coh.org.
authors.forename: Linda H
authors.initials: LH
authors.lastname: Malkas
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D003603:Cytotoxins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D016688:Mice, Inbred NOD; D018345:Mice, Knockout; D016513:Mice, SCID; D018716:Molecular Mimicry / Q000502:physiology*; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism*; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011817:Rabbits; D011897:Random Allocation
chemical_list: D003603:Cytotoxins; D010446:Peptide Fragments; D018809:Proliferating Cell Nuclear Antigen