Anti-MSMB monoclonal antibody, clone 3F8

Background: Most biomarkers in prostate cancer have only been evaluated in surgical cohorts. The value of these biomarkers in a different therapy context remains unclear. Our objective was to test a panel of surgical biomarkers for prognostic value in men treated by external beam radiotherapy (EBRT) and primary androgen deprivation therapy (PADT). Methods: The Fluidigm (R) PCR array was used for multi-transcript profiling of laser microdissected tumours from archival formalin-fixed diagnostic biopsies of patients treated by EBRT or PADT. Cases were matched for disease characteristics and had known 5 year biochemical relapse outcomes (n = 60). Results were validated by immunohistochemistry in a custom needle biopsy tissue microarray. Six biomarkers previously tested only in surgical cohorts were analysed (PTEN, E-Cadherin, EGFR, EZH2, PSMA, MSMB). Transcript and protein expression was correlated with clinical outcome analysed using Kruskal Wallis, Fisher's test and Cox proportional hazard model. Results: Altered expression of E-Cadherin (p = 0.008) was associated with early relapse after EBRT. In PADT treated men however only altered MSMB transcript was prognostic for early relapse (p = 0.001). The remaining biomarkers however did not demonstrate prognostic ability in either cohort. In a separate tissue array we validated altered E-Cadherin protein as a predictor of early relapse after EBRT (n = 47) (HR 0.34, CI p = 0.02) but not in PADT treated men (n = 63). Conclusion: We demonstrate proof of principle of multiple transcript profiling in archival diagnostic biopsies of non-surgically treated men for biomarker discovery. We identify a role for E-Cadherin as a novel biomarker of early relapse following EBRT.

The mukB gene codes for a 177 kDa protein, which might be a candidate for a force-generating enzyme in chromosome positioning in Escherichia coli. The mukB106 mutant produces normal-sized, anucleate cells and shows a temperature-sensitive colony formation. To identify proteins interacting with the MukB protein, we isolated three multicopy suppressors (msmA, msmB, and msmC) to the temperature-sensitive colony formation of the mukB106 mutation. The msmA gene, which could not suppress the production of anucleate cells, was found to be identical to the dksA gene. The msmB and msmC genes suppressed the production of anucleate cells as well as the temperature-sensitive colony formation. However, none of them could suppress both phenotypes in a mukB null mutation. DNA sequencing revealed that the msmS gene was identical to the cspC gene and that the msmC gene had not been described before. A homology search revealed that the amino acid sequences of both MsmB and MsmC possessed high similarity to proteins containing the cold-shock domain, such as CspA of E. coli and the Y-box binding proteins of eukaryotes; this suggests that MsmB and MsmC might be DNA-binding proteins that recognize the CCAAT sequence. Hence, the msmB and msmC genes were renamed cspC and cspE, respectively. Possible mechanisms for suppression of the mukB106 mutation are discussed.