title: Exploiting altered patterns of choline kinase-alpha expression on human prostate tissue to prognosticate prostate cancer.
abstract: OBJECTIVE
  Malignant transformation results in overexpression of choline-kinase (CHK) and altered choline metabolism, which is potentially detectable by immunohistochemistry (IHC). We investigated the utility of CHK-alpha (CHKA) IHC as a complement to current diagnostic investigation of prostate cancer by analysing expression patterns in normal (no evidence of malignancy) and malignant human prostate tissue samples.
  
  
  METHODS
  As an initial validation, paraffin-embedded prostatectomy specimen blocks with both normal and malignant prostate tissue were analysed for CHKA protein and mRNA expression by western blot and quantitative reverse transcriptase PCR (qRT-PCR), respectively. Subsequently, 100 paraffin-embedded malignant prostate tumour and 25 normal prostate cores were stained for both Ki67 (labelling-index: LI) and CHKA expression.
  
  
  RESULTS
  The validity of CHKA-antibody was verified using CHKA-transfected cells and siRNA knockdown. Immunoblotting of tissues showed good resolution of CHKA protein in malignant prostate, verifying use of the antibody for IHC. There was minimal qRT-PCR detectable CHKA mRNA in normal tissue, and conversely high expression in malignant prostate tissues. IHC of normal prostate cores showed mild (intensity) CHKA expression in only 28% (7/25) of samples with no Ki67 expression. In contrast, CHKA was expressed in all malignant prostate cores along with characteristically low proliferation (median 2% Ki67-LI; range 1-17%). Stratification of survival according to CHK intensity showed a trend towards lower progression-free survival with CHK score of 3.
  
  
  CONCLUSIONS
  Increased expression of CHKA, detectable by IHC, is seen in malignant lesions. This relatively simple cost-effective technique (IHC) could complement current diagnostic procedures for prostate cancer and, therefore, warrants further investigation.
authors.affiliation: Department of Surgery and Cancer, Imperial College London, London, UK.
authors.forename: Amarnath
authors.initials: A
authors.lastname: Challapalli
authors.affiliation: Department of Surgery and Cancer, Imperial College London, London, UK.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Trousil
authors.affiliation: Department of Pathology, Imperial College London/ Imperial College Healthcare NHS Trust, London, UK.
authors.forename: Steve
authors.initials: S
authors.lastname: Hazell
authors.affiliation: Department of Surgery and Cancer, Imperial College London, London, UK.
authors.forename: Kasia
authors.initials: K
authors.lastname: Kozlowski
authors.affiliation: Department of Pathology, Imperial College London/ Imperial College Healthcare NHS Trust, London, UK.
authors.forename: Mihir
authors.initials: M
authors.lastname: Gudi
authors.affiliation: Department of Surgery and Cancer, Imperial College London, London, UK.
authors.forename: Eric O
authors.initials: EO
authors.lastname: Aboagye
authors.affiliation: Department of Surgery and Cancer, Imperial College London, London, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Mangar
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D015153:Blotting, Western; D002797:Choline Kinase / Q000032:analysis / Q000096:biosynthesis*; D018572:Disease-Free Survival; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008297:Male; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000401:mortality; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D014408:Biomarkers, Tumor; C517212:CHKA protein, human; D002797:Choline Kinase
keywords: IMMUNOHISTOCHEMISTRY; ONCOLOGY; PROSTATE