title: Inhibition of heat shock protein 27-mediated resistance to DNA damaging agents by a novel PKC delta-V5 heptapeptide.
abstract: Heat shock protein 27 (HSP27), which is highly expressed in human lung and breast cancer tissues, induced resistance to cell death against various stimuli. Treatment of NCI-H1299 cells, which express a high level of HSP27, with small interference RNA specifically targeting HSP27 resulted in inhibition of their resistance to radiation or cisplatin, suggesting that HSP27 contributed to cellular resistance in these lung cancer cells. Furthermore, because HSP27 interacts directly with the COOH terminus of the protein kinase C delta (PKC delta)-V5 region with ensuing inhibition of PKC delta activity and PKC delta-mediated cell death, we wished to determine amino acid residues in the V5 region that mediate its interaction with HSP27. Investigation with various deletion mutants of the region revealed that amino acid residues 668 to 674 of the V5 region mediate its interaction with HSP27. When NCI-H1299 cells were treated with biotin or with FITC-tagged heptapeptide of the residues 668 to 674 (E-F-Q-F-L-D-I), the cells exhibited dramatically increased cisplatin or radiation-induced cell death with the heptapeptide having efficient interaction with HSP27, which in turn restored the PKC delta activity that had been inhibited by HSP27. In vivo nude mice grafting data also suggested that NCI-H1299 cells were sensitized by this heptapeptide. The above data strongly show that the heptapeptide of the PKC delta-V5 region sensitized human cancer cells through its interaction with HSP27, thereby sequestering HSP27. The heptapeptide may provide a novel strategy for selective neutralization of HSP27.
authors.affiliation: Laboratory of Radiation Effect, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
authors.forename: Eun-Ho
authors.initials: EH
authors.lastname: Kim
authors.forename: Hae-June
authors.initials: HJ
authors.lastname: Lee
authors.forename: Dae-Hoon
authors.initials: DH
authors.lastname: Lee
authors.forename: Sangwoo
authors.initials: S
authors.lastname: Bae
authors.forename: Jae-Won
authors.initials: JW
authors.lastname: Soh
authors.forename: Dooil
authors.initials: D
authors.lastname: Jeoung
authors.forename: Joon
authors.initials: J
authors.lastname: Kim
authors.forename: Chul-Koo
authors.initials: CK
authors.lastname: Cho
authors.forename: Yoon-Jin
authors.initials: YJ
authors.lastname: Lee
authors.forename: Yun-Sil
authors.initials: YS
authors.lastname: Lee
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004249:DNA Damage; D019008:Drug Resistance, Neoplasm; D015972:Gene Expression Regulation, Neoplastic; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D051379:Mice; D018832:Molecular Chaperones; D009363:Neoplasm Proteins / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology*; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D051745:Protein Kinase C-delta / Q000378:metabolism*; D014162:Transfection
chemical_list: D000596:Amino Acids; D000970:Antineoplastic Agents; D055551:HSP27 Heat-Shock Proteins; C057725:HSPB1 protein, human; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D009842:Oligopeptides; D010455:Peptides; C509183:Val-Pro-Met-Leu-Lys; D051745:Protein Kinase C-delta