title: Alpha(2) macroglobulin, a PSA binding protein, is expressed in human prostate stroma.
abstract: BACKGROUND
  Benign prostatic hyperplasia (BPH) is characterized as a stromal process. The stroma smooth muscle (SM) may alter its phenotype during the progression of BPH. We have identified gene transcripts that may be differentially expressed in BPH using a differential display method. Among the fragments isolated, alpha(2) macroglobulin (alpha(2)-M) is one of the most interesting. alpha(2)-M is a binding protein of a variety of proteinases, including prostatic specific antigen (PSA). It also plays roles in molecular trapping and targeting. In this study, we characterized alpha(2)-M expression in the human prostate.
  
  
  METHODS
  Differential display was used to identify and isolate the differentially expressed transcripts between normal prostate and BPH tissues. RT-PCR, Western blot, in situ hybridization, and immunohistochemistry were utilized to confirm and characterize alpha(2)-M expression in the prostate.
  
  
  RESULTS
  Real-time RT-PCR results revealed that a 3.2-fold increase in alpha(2)-M mRNA expression is observed in BPH compared with normal prostate tissue. A 1.9-fold increase at protein level was also observed. In situ hybridization and immunohistochemistry showed that alpha(2)-M expression is primarily localized to the stromal compartment. Cultured primary stroma cells maintained alpha(2)-M expression, while prostate epithelial cells had a significantly lower level of alpha(2)-M expression. Furthermore, stromal cells in culture produce and secrete alpha(2)-M in the medium.
  
  
  CONCLUSIONS
  We identified alpha(2)-M expression in the human prostate. An increased alpha(2)-M expression appears to be associated with BPH. Considering the unique features of its protein binding and targeting properties, alpha(2)-M expressed in the prostate may play an important role in regulating benign and malignant prostatic growth.
authors.affiliation: Department of Urology, The University of Texas, Southwestern Medical Center, Dallas, Texas, USA. victor.lin@utsouthwestern.edu
authors.forename: Victor K
authors.initials: VK
authors.lastname: Lin
authors.forename: Shih-Ya
authors.initials: SY
authors.lastname: Wang
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Boetticher
authors.forename: Dolores V
authors.initials: DV
authors.lastname: Vazquez
authors.forename: Hossein
authors.initials: H
authors.lastname: Saboorian
authors.forename: John D
authors.initials: JD
authors.lastname: McConnell
authors.forename: Claus G
authors.initials: CG
authors.lastname: Roehrborn
mesh_terms: D015153:Blotting, Western; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D004591:Electrophoresis, Polyacrylamide Gel; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D011467:Prostate / Q000378:metabolism*; D011470:Prostatic Hyperplasia / Q000378:metabolism*; D012333:RNA, Messenger / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000378:metabolism; D046509:Tissue Culture Techniques; D000511:alpha-Macroglobulins / Q000235:genetics*
chemical_list: D017077:Culture Media, Conditioned; D012333:RNA, Messenger; D000511:alpha-Macroglobulins