Polo-like kinase: a novel marker of proliferation: correlation with estrogen-receptor expression in human breast cancer

Pathol Res Pract. 2000;196(11):753-9. doi: 10.1016/S0344-0338(00)80107-7.


Previous data have shown that the mRNA-expression of the serin/threonine-kinase polo-like kinase (PLK) is closely correlated with the survival of patients suffering from a subset of malignant tumors. PLK-mRNA and protein-expression are restricted to cells in the cell cycle. PLK-mRNA-transcripts are highly abundant in proliferating cells; no gene expression is found in G0-phase cells. Here we investigated the mRNA- and protein-expression of PLK- and estrogen-receptor (ER) in human breast-carcinoma by northern-blotting, RT-PCR and immunohistochemistry. The expression of MIB-I was determined on serial sections. Analysis of the immunohistochemical data revealed a close correlation between the ER and PLK-expression (r = 0.677; p = 0.001, n = 30). No relationship between the mRNA-expression of ER and PLK was found. Furthermore, no correlation for the protein expression of PLK and MIB-I exists. The influence of estrogen (ES) is known to have proliferative potential. The expression of ER correlates with the ES-plasma-level. In addition, the hormone cycle of premenopausal women undergoes rapid vacillations with varying effects on the proliferating tumor cells, e.g., growth induction. Our results therefore show that ER-expression is not only of therapeutic value for the clinician, but it may also be a tool for determining the tumor proliferation index more precisely by integrating the hormone-mediated proliferation stimulus.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antigens, Nuclear
  • Biomarkers, Tumor / analysis
  • Blotting, Northern
  • Breast Neoplasms / chemistry
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology
  • Carcinoma, Ductal, Breast / chemistry
  • Carcinoma, Ductal, Breast / genetics
  • Carcinoma, Ductal, Breast / metabolism*
  • Carcinoma, Ductal, Breast / secondary
  • Carcinoma, Lobular / chemistry
  • Carcinoma, Lobular / genetics
  • Carcinoma, Lobular / metabolism*
  • Carcinoma, Lobular / secondary
  • Cell Cycle Proteins
  • Cell Division
  • Female
  • Fluorescent Antibody Technique, Direct
  • Humans
  • Middle Aged
  • Nuclear Proteins / metabolism
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins
  • RNA, Messenger / metabolism
  • RNA, Neoplasm / analysis
  • Receptors, Estrogen / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction


  • Antigens, Nuclear
  • Biomarkers, Tumor
  • Cell Cycle Proteins
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • RNA, Messenger
  • RNA, Neoplasm
  • Receptors, Estrogen
  • Protein Kinases
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1