Malignant transformation of mammalian cells initiated by constitutive expression of the polo-like kinase

Biochem Biophys Res Commun. 1997 May 19;234(2):397-405. doi: 10.1006/bbrc.1997.6633.


Polo-like kinase (Plk) is the mammalian homologue of the Drosophila polo and Saccharomyces cerevisiae CDC5 genes, which are thought to be involved in regulating chromosomal segregation. Previously, we showed that transient ectopic expression of Plk could induce DNA synthesis in quiescent NIH 3T3 cells, suggesting that Plk might also have a function during G1 or S phase. Here we report that microinjection of Plk mRNA is sufficient to drive quiescent cells into mitosis and that constitutive expression of Plk in NIH 3T3 cells causes oncogenic focus formation. These transformed cells grow in soft agar and form tumors in nude mice. Because Plk expression has been shown to be high in various human tumors, we suggest that Plk may contribute to the promotion and/or progression of human cancers.

MeSH terms

  • 3T3 Cells
  • Animals
  • Cell Cycle
  • Cell Cycle Proteins
  • Cell Division
  • Cell Transformation, Neoplastic*
  • DNA / biosynthesis
  • Drosophila / enzymology
  • Drosophila / genetics
  • Gene Expression
  • Humans
  • Mice
  • Mice, Nude
  • Microinjections
  • Mitosis
  • Neoplasms, Experimental / enzymology
  • Neoplasms, Experimental / etiology
  • Neoplasms, Experimental / genetics
  • Protein Kinases / genetics*
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins
  • RNA, Messenger / administration & dosage
  • RNA, Messenger / genetics
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics
  • Transfection


  • Cell Cycle Proteins
  • Proto-Oncogene Proteins
  • RNA, Messenger
  • DNA
  • Protein Kinases
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1