Proteomic analysis of the tumorigenic human prostate cell line M12 after microcell-mediated transfer of chromosome 19 demonstrates reduction of vimentin

Critical alterations in proteins that accompany or control the aggressiveness of human prostate cancers remain poorly defined. Previously we demonstrated that the highly tumorigenic, metastatic human prostate cell line M12 was converted to a slow growing, poorly tumorigenic cell line by introduction of an intact human chromosome 19, generating the M12 (F6) hybrid cells. The objective of this report was to identify changes in the protein profile of these M12(F6) microcell hybrid cells. A combination of two‐dimensional gel electrophoresis and matrix assisted laser desorption‐time of flight‐mass spectroscopy was used to compare proteins made by these two cell lines. No consistently increased proteins were identified. However, seven proteins were reproducibly reduced more than twofold: vimentin, hsp90, ATP synthase, 26S protease regulatory subunit, heterogeneous nuclear ribonucleoprotein, T‐Complex protein 1 β, and α‐1 tubulin. The striking reduction in vimentin protein was accompanied by significantly decreased vimentin mRNA, revealed by Northern blotting. Our findings implicate reduced vimentin in the conversion of these tumorigenic prostate epithelial cells into slow growing, less aggressive cells. These studies demonstrate that application of proteomic analysis to specific problems in an experimental context can yield biologically relevant information about the prostate cancer cell phenotype.