title: Heat shock protein 27-targeted heptapeptide of the PKCΔ catalytic V5 region sensitizes tumors with radio- and chemoresistance.
abstract: OBJECTIVE
  Previous data suggest that the PKCδ catalytic V5 (PKCδ-V5) heptapeptide (HEPT) (FEQFLDI) binds HSP27 and blocks HSP27-mediated radio- or chemoresistance. Here we investigated further the in vivo function of the PKCδ-V5 HEPT.
  
  
  METHODS
  Labeling of HEPT with Cy5.5 or fluorescein isothiocyanate was performed to evaluate in vitro or in vivo distribution of HEPT. A clonogenic survival assay, flow cytometry, and Western blotting of cleaved caspase-3 were performed to determine in vitro sensitization effects of HEPT plus ionizing radiation (IR) versus IR alone or those of HEPT plus cisplatin(Cis) versus Cis alone. A nude mouse xenografting system was also applied to detect in vivo sensitizing effects of HEPT.
  
  
  RESULTS
  HEPT efficiently bound to HSP27 and showed sensitization after combined treatment with IR versus treatment with Cis alone in NCI-H1299 lung carcinoma cells, with higher HSP27 expression, which was similar to that of combined treatment with IR or with Cis alone in NCI-H460 lung carcinoma cells with lower HSP27 expression. In vivo image analysis using Cy5.5-labeled HEPT showed that HEPT was retained in HSP27-overexpressing cancer cells after xenografting to nude mice. Combined treatment of HEPT with IR versus that with Cis alone in xenografted mice showed that HEPT increased radio- or chemosensitization in NCI-H1299 cells compared to that in mice xenografted with NCI-H460 cells.
  
  
  CONCLUSIONS
  The novel PKCδ-V5 HEPT may help overcome HSP27-mediated radio- or chemoresistance.
authors.affiliation: Division of Radiation Effects, Korea Institute of Radiological and Medical Sciences, Seoul 136-706, Korea.
authors.forename: Hae-June
authors.initials: HJ
authors.lastname: Lee
authors.forename: Eun-Ho
authors.initials: EH
authors.lastname: Kim
authors.forename: Woo Duck
authors.initials: WD
authors.lastname: Seo
authors.forename: Tae Hyun
authors.initials: TH
authors.lastname: Choi
authors.forename: Gi-Jeong
authors.initials: GJ
authors.lastname: Cheon
authors.forename: Yoon-Jin
authors.initials: YJ
authors.lastname: Lee
authors.forename: Yun-Sil
authors.initials: YS
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000378:metabolism / Q000532:radiotherapy; D053148:Caspase 3 / Q000378:metabolism; D020134:Catalytic Domain; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000502:physiology; D005434:Flow Cytometry; D055551:HSP27 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000532:radiotherapy; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology*; D051745:Protein Kinase C-delta / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011836:Radiation Tolerance / Q000187:drug effects* / Q000502:physiology; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
chemical_list: D055551:HSP27 Heat-Shock Proteins; D009363:Neoplasm Proteins; D010446:Peptide Fragments; D047428:Protein Kinase Inhibitors; D011838:Radiation-Sensitizing Agents; C558800:phenylalanyl-glutamyl-glutaminyl-phenylalanyl-leucyl-aspartyl-isoleucine; D051745:Protein Kinase C-delta; D053148:Caspase 3; D002945:Cisplatin