title: Cathepsin D by western blotting and immunohistochemistry: failure to confirm correlations with prognosis in node-negative breast cancer.
abstract: OBJECTIVE
  We attempted to replicate and improve on our previous study (N Engl J Med 322:297-302, 1990) that showed that 34-kd cathepsin D levels as determined by Western blotting strongly correlated with disease-free survival (DFS) and overall survival (OS) of axillary node-negative (N-) breast cancer patients. We also examined the prognostic significance of cathepsin D measured by immunohistochemistry (IHC) in these patients.
  
  
  METHODS
  Western blotting was performed on cytosols from frozen tumor specimens of 927 N- breast cancer patients in the San Antonio Breast Tumor Bank. The monoclonal antibody M1G8 was used to detect cathepsin D (in previous study, a polyclonal antiserum had been used). The same monoclonal antibody was also used for frozen-section IHC staining of tumor specimens from 562 N- patients from the same tumor bank. Levels of cathepsin D expression were then correlated with DFS and OS.
  
  
  RESULTS
  Although the levels of cathepsin D expression as measured by Western blotting and IHC correlated with each other and with levels of cathepsin D measured in previous work using Western blotting with the polyclonal antiserum, in this present study, using the monoclonal antibody M1G8, we were unable to demonstrate that cathepsin D expression (measured by either Western blotting or by IHC) correlates with DFS or OS.
  
  
  CONCLUSIONS
  In this study, cathepsin D expression as determined by either Western blotting or IHC using the monoclonal antibody M1G8 failed to improve the prognostic evaluation of N- breast cancer patients. The role of cathepsin D expression as a prognostic factor is still not precisely defined, raising questions about its use in the routine evaluation of N- breast cancer patients.
authors.affiliation: Department of Medicine, University of Texas Health Science Center, San Antonio 78284.
authors.forename: P M
authors.initials: PM
authors.lastname: Ravdin
authors.forename: A K
authors.initials: AK
authors.lastname: Tandon
authors.forename: D C
authors.initials: DC
authors.lastname: Allred
authors.forename: G M
authors.initials: GM
authors.lastname: Clark
authors.forename: S A
authors.initials: SA
authors.lastname: Fuqua
authors.forename: S H
authors.initials: SH
authors.lastname: Hilsenbeck
authors.forename: G C
authors.initials: GC
authors.lastname: Chamness
authors.forename: C K
authors.initials: CK
authors.lastname: Osborne
mesh_terms: D000704:Analysis of Variance; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000201:enzymology* / Q000401:mortality / Q000473:pathology; D002402:Cathepsin D / Q000032:analysis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008207:Lymphatic Metastasis; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D016019:Survival Analysis
chemical_list: D002402:Cathepsin D