title: Differential percentage of serum prostate-specific antigen subforms suggests a new way to improve prostate cancer diagnosis.
abstract: BACKGROUND
  Prostate-specific antigen (PSA) is the tumor marker currently used for prostate cancer (PCa) screening and diagnosis. However, its use is controversial as serum PSA levels are also increased in other non-malignant prostatic diseases such as benign prostatic hyperplasia (BPH). PSA sialic acid content is altered in tumor situation and modifies PSA's isoelectric point (pI). Our goal has been to evaluate serum PSA subforms from PCa and BPH patients by two-dimensional electrophoresis (2-DE) and to investigate whether they could be used to improve PCa diagnosis.
  
  
  METHODS
  PSA from 20 PCa and 20 BPH patients' sera was subjected to a four-step method to obtain serum PSA 2-DE subforms from free PSA (fPSA) plus PSA released from the complex with alpha-1-antichymotrypsin. Relative percentages of PSA spots were quantified and subjected to statistical analysis.
  
  
  RESULTS
  Five PSA subforms (F1, F2, F3, F4, and F5) of different pI were obtained. Relative percentages of F3 (%F3) and F4 (%F4) were different between PCa and BPH groups. %F3 decreased in cancers and this decrease correlated with the cancer stage, while F4 behaved oppositely. These observations were also found when only focusing on the patients within the low total PSA (tPSA) range 2-20 ng/ml.
  
  
  CONCLUSIONS
  %F3 showed a tendency of higher sensitivity and specificity than the currently used tPSA and %fPSA tests. Therefore, %F3 measurement should be investigated in a larger cohort of patients to study whether it could be introduced to improve PCa diagnosis.
authors: Unitat de Bioquímica i Biologia Molecular, Departament de Biologia, Universitat de Girona, Campus de Montilivi, Girona, Spain.
authors: Ariadna
authors: A
authors: Sarrats
authors: Josep
authors: J
authors: Comet
authors: Glòria
authors: G
authors: Tabarés
authors: Manel
authors: M
authors: Ramírez
authors: R Núria
authors: RN
authors: Aleixandre
authors: Rafael
authors: R
authors: de Llorens
authors: Rosa
authors: R
authors: Peracaula
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D003955:Diagnostic Tests, Routine / Q000592:standards*; D005500:Follow-Up Studies; D006801:Humans; D007527:Isoenzymes / Q000097:blood / Q000145:classification; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood* / Q000145:classification; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000201:enzymology*; D015203:Reproducibility of Results
chemical_list: D014408:Biomarkers, Tumor; D007527:Isoenzymes; D017430:Prostate-Specific Antigen