Expression of Polo-Like Kinase (PLK1) in Thin Melanomas: A Novel Marker of Metastatic Disease

J Cutan Pathol. 2002 Jul;29(6):354-8. doi: 10.1034/j.1600-0560.2002.290605.x.


Background: The maximum thickness of a primary malignant melanoma as measured by Breslow's method is currently the most important prognostic factor. However, some thin melanomas (< or= 0.75 mm), which should have an excellent prognosis according to Breslow, can be lethal due to their ability to metastasize.

Methods: In our study, thin malignant melanomas (< or= 0.75 mm) from 36 patients were analyzed with immunohistochemical techniques using monoclonal antibodies directed against PLK1 and Ki-67. The immunoreactivity of 22 melanomas which developed metastases within 5 years of follow-up was compared with a group of 14 non-metastasized melanomas. Two independent investigators evaluated stained sections. Differences of PLK1 and Ki-67 indices between melanomas with and without metastases were tested statistically using the Mann-Whitney U-test.

Results: Malignant melanomas with metastases expressed PLK1 at markedly elevated levels compared to melanomas without metastases (median, 60.00% vs. 37.98%; p = 0.000053). The difference of the Ki-67 index between both groups was not significant (median, 6.35% vs. 4.53%; p = 0.150473).

Conclusions: Our results suggest that PLK1 expression in thin melanomas is a reliable marker to identify patients at high risk for metastases.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins
  • Female
  • Humans
  • Immunohistochemistry
  • Ki-67 Antigen / metabolism
  • Male
  • Melanoma / enzymology*
  • Melanoma / secondary
  • Melanoma / surgery
  • Middle Aged
  • Neoplasm Recurrence, Local
  • Prognosis
  • Protein Kinases / metabolism*
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins
  • Skin Neoplasms / enzymology*
  • Skin Neoplasms / pathology
  • Skin Neoplasms / surgery


  • Cell Cycle Proteins
  • Ki-67 Antigen
  • Proto-Oncogene Proteins
  • Protein Kinases
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1