Proteomic analysis of laser capture microdissected human prostate cancer and in vitro prostate cell lines

Specific populations of normal and malignant epithelium from three radical prostatectomy tissue specimes were procured by laser capture microdissectio n (LCM) and analyzed by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). Six proteins that were only seen in malignant cells and two pro teins that were only seen in benign epithelium were reproducibly observed i n two of two cases examined. Furthermore, these proteins were not observed in the 2-D PAGE profiles from the patient-matched microdissected stromal ce ll populations, but were seen in the protein profiles from the undissected whole cryostat Sections. One of these proteins was determined to be prostat e-specific antigen (PSA) by Western blot analysis, and intriguingly the rem aining protein candidates were found to be at least as abundant as the PSA protein. Comparison of 2-D PAGE profiles of microdissected cell with matche d in vitro cell lines from the same patient, and metastatic prostate cancer cell lines (LnCaP and PC3) showed striking differences between prostate ce lls in vivo and in vitro with less than 20% shared proteins. The data demon strate that 2-D PAGE analysis of LCM-derived cells can reliably detect alte rations in protein expression associated with prostate cancer, and that the se differentially expressed proteins are produced in high enough levels whi ch could allow for their clinical utility as new targets for therapeutic in tervention, serum markers, and/or imaging markers.