title: Serum protein kinase Cα as a diagnostic biomarker of cancers.
abstract: BACKGROUND
  Several serum biomarkers such as antigens, soluble proteins, metabolites, and genes have been identified for the diagnosis of cancers and for monitoring the recurrence after cancer treatment.
  
  
  METHODS
  In the present study, a protein kinase C (PKC) α-specific peptide substrate was phosphorylated with serum samples collected from cancer-bearing mice (U87, A431, HepG2, and A549) and the phosphorylation ratio was detected by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS).
  
  
  RESULTS
  The phosphorylation ratio for peptide substrates significantly increased in the serum of cancer-bearing mice compared with the ratio found in control mice. The addition of a PKCα inhibitor induced a concentration-dependent decrease in phosphorylation ratios, but the non-PKCα inhibitors, rottlerin and H-89, did not significantly effect phosphorylation ratios.
  
  
  CONCLUSIONS
  These results suggest that serum activated PKCα is a good biomarker applicable to cancer diagnosis.
authors.affiliation: Department of Applied Chemistry, Faculty of Engineering, Kyushu University, Nishi-Ku, Fukuoka, Japan. jrjhkang@ncvc.go.jp
authors.forename: Jeong-Hun
authors.initials: JH
authors.lastname: Kang
authors.forename: Takeshi
authors.initials: T
authors.lastname: Mori
authors.forename: Hirotaro
authors.initials: H
authors.lastname: Kitazaki
authors.forename: Takuro
authors.initials: T
authors.lastname: Niidome
authors.forename: Koichi
authors.initials: K
authors.lastname: Takayama
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Nakanishi
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Katayama
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000097:blood*; D045744:Cell Line, Tumor; D006801:Humans; D008297:Male; D051379:Mice; D009369:Neoplasms / Q000097:blood* / Q000175:diagnosis*; D010455:Peptides / Q000378:metabolism; D010766:Phosphorylation; D051571:Protein Kinase C-alpha / Q000097:blood* / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity
chemical_list: D014408:Biomarkers, Tumor; D010455:Peptides; D051571:Protein Kinase C-alpha