Detection of p53 expression and S-phase cell fraction in paraffin-embedded tissue by a double-labeling technique

E. Benini, R. Silvestrini, M. G. Daidone, S. Canova

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TP53 is a gene that normally regulates cell growth and division. Alterations to it may induce a proliferative advantage and confer an aggressive phenotype. In breast cancer, we observed a poor correlation (t(s) = 0.17) between P53 expression and proliferative activity evaluated as [3H]- thymidine ([3H]-dT) labeling index and an independent prognostic relevance of the two variables. We used a double-labeling technique to simultaneously evaluate the fraction of P53-positive and [3H]-dT-labeled cells to analyze the degree of association between the two markers on individual cells in order to understand their biological significance. The study was performed on a series of 44 P53-positive (P53+) breast cancers. Histological sections were immunostained for P53 with monoclonal antibody (MAb) PAb1801 and then processed for autoradiography. A weak direct relation between P53 positivity and [3H]-dT incorporation (t(s) = 0.4) was observed on the overall series of P53+ tumors and was maintained in subgroups defined by several biological and pathological features, except for estrogen receptor-negative tumors. The simultaneous presence of P53 expression and [3H]-dT incorporation was directly and significantly proportional to the fraction of S-phase cells of the tumor (t(s) = 0.7). Conversely, the fraction of cells expressing only P53 was inversely related to cell proliferation (t(s) = -0.66). These findings support the hypothesis that P53 has biological functions other than cell cycle regulation.

Original languageEnglish
Pages (from-to)999-1003
Number of pages5
JournalJournal of Histochemistry and Cytochemistry
Issue number10
Publication statusPublished - 1995


  • Cell proliferation
  • Double labeling
  • Human breast cancer
  • P53 expression

ASJC Scopus subject areas

  • Cell Biology
  • Anatomy


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