WAF1/CIP1 protein expression in human breast tumors

S. G. Diab, Y. Y. Yu, S. G. Hilsenbeck, D. C. Allred, R. M. Elledge

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


WAF1/CIP1 is a cyclin-dependent kinase inhibitor which is directly induced by p53 and negatively controls cell proliferation. To test the hypothesis that increased levels of WAF1 would be associated with a lower S-phase fraction and better prognosis, WAF1 protein was assessed by immunohistochemistry (IHC) in 115 node-negative human breast tumors, and results were correlated with established prognostic factors and clinical outcome. Nuclear staining was observed in malignant cells in 43% of tumors. In most (90%) of the positive tumors, the proportion of cells staining for WAF1 was low (< 10%). WAF1 was not detected in the cytoplasm, or in non-malignant epithelium. Contrary to expectations, the accumulation of p53 protein, a surrogate marker of p53 inactivation, was weakly but positively associated with WAF1 expression (p = 0.05). Surprisingly, there was no significant correlation with S-phase fraction, ER or PgR status, tumor size, age, ploidy, nuclear grade, or survival. Conclusion: WAF1 expression is found in the nuclei of a small fraction of cells in human breast tumors. WAF1 status is not significantly associated with cell proliferation, other established prognostic factors, or clinical outcome.

Original languageEnglish (US)
Pages (from-to)99-103
Number of pages5
JournalBreast Cancer Research and Treatment
Issue number2
StatePublished - 1997
Externally publishedYes


  • Breast cancer
  • Immunohistochemistry
  • WAF1/CIP1 protein
  • p53 protein

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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