Downregulation of human polo-like kinase activity by antisense oligonucleotides induces growth inhibition in cancer cells

Oncogene. 2002 May 9;21(20):3162-71. doi: 10.1038/sj.onc.1205412.


A central role for polo-like kinases (PLK) in regulating several stages of mitotic progression has been born out in several species. Overexpression of PLK1 is observed in the majority of hitherto analysed human tumors. PLK1 overexpression is a negative prognostic factor in patients suffering from non-small cell lung cancer, head and neck tumors, esophageal carcinomas and melanomas. In order to define the role of PLK1 for mitotic progression of human cells and for neoplastic cell growth, phosphorothioate antisense oligonucleotides (ASOs) were tested to selectively downregulate PLK1 expression in MDA-MB-435 (breast cancer), HeLa S3 (cervical carcinoma) and A549 (non-small cell lung cancer) cells. ASOs were identified which suppress PLK1 mRNA and protein in a dose-dependent and sequence-specific manner. This approach also led to reduced PLK1 serine/threonine kinase activity. Downregulation of cellular PLK1 levels in cancer cells altered cell cycle progression moderately with an elevated percentage (20-30%) of cells in G(2)/M. Furthermore, cells with reduced PLK1 protein gained a rounded phenotype with multiple centrosomes. Moreover, ASO treatment resulted in potent antiproliferative effects in cell culture. Considerable antitumor activity was observed in vivo against A549 cells. This study suggests that antisense inhibitors targeted against PLK1 at well tolerated doses may be considered as a cancer therapeutic agent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / enzymology
  • Adenocarcinoma / pathology
  • Antineoplastic Agents / pharmacology*
  • Breast Neoplasms / enzymology
  • Breast Neoplasms / pathology
  • Carcinoma, Non-Small-Cell Lung / enzymology
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Cell Cycle / drug effects
  • Cell Cycle Proteins
  • Cell Division
  • Dose-Response Relationship, Drug
  • Enzyme Induction
  • Gene Expression Regulation, Enzymologic / drug effects*
  • Gene Expression Regulation, Neoplastic / drug effects*
  • HeLa Cells / drug effects
  • HeLa Cells / enzymology
  • Humans
  • Lung Neoplasms / enzymology
  • Lung Neoplasms / pathology
  • Mitosis / drug effects
  • Neoplasm Proteins / biosynthesis
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / physiology*
  • Oligonucleotides, Antisense / administration & dosage
  • Oligonucleotides, Antisense / pharmacology*
  • Protein Kinases / biosynthesis
  • Protein Kinases / genetics
  • Protein Kinases / physiology*
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins
  • RNA, Messenger / biosynthesis
  • RNA, Neoplasm / biosynthesis
  • Thionucleotides / administration & dosage
  • Thionucleotides / pharmacology*
  • Tumor Cells, Cultured / drug effects
  • Tumor Cells, Cultured / enzymology


  • Antineoplastic Agents
  • Cell Cycle Proteins
  • Neoplasm Proteins
  • Oligonucleotides, Antisense
  • Proto-Oncogene Proteins
  • RNA, Messenger
  • RNA, Neoplasm
  • Thionucleotides
  • Protein Kinases
  • Protein Serine-Threonine Kinases
  • polo-like kinase 1