Identification of both Myt-1 and Wee-1 as necessary mediators of the p21-independent inactivation of the cdc-2/cyclin B1 complex and growth inhibition of TRAMP cancer cells by genistein

Prostate. 2006 Oct 1;66(14):1542-55. doi: 10.1002/pros.20495.

Abstract

Background: The G2/M cell-cycle arrest is one mechanism by which genistein exerts its anti-proliferative effects, and the proposed underlying causes encompass the transcriptional repression of cyclin B1 and the activation of p21. However, the involvement of upstream kinases Myt-1 and Wee-1 in this arrest remains to be elucidated.

Methods: Myt-1 and Wee-1 modulation by genistein was examined via Western blot analysis and the effect of their inhibition by siRNA on cyclin B1 levels/localization, cdc2 kinase activity, and cellular proliferation of genistein-treated TRAMP-C2 cells was determined.

Results: The sustained G2/M arrest by genistein in TRAMP-C2 cells is associated with increased phospho-cdc2(Tyr15), decreased cdc2 protein, and cytoplasmic retention of cyclinB1, resulting in decreased cdc2 kinase activity independently of p21. Genistein treatment increased Myt-1 levels and decreased Wee-1 phosphorylation. Downregulation of Myt-1 and Wee-1 by siRNA restored cdc2 levels, its kinase activity, cyclinB1 nuclear localization, and partially restored cell proliferation of genistein-treated cells.

Conclusions: Myt-1 and Wee-1 rather than p21 are necessary for genistein-induced G2/M arrest in TRAMP-C2 cells and their inhibition partially restores proliferation of TRAMP-C2 cells in the presence of genistein.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenocarcinoma / drug therapy*
  • Adenocarcinoma / metabolism
  • Adenocarcinoma / pathology
  • Animals
  • Anticarcinogenic Agents / pharmacology*
  • Apoptosis / drug effects
  • Aurora Kinases
  • CDC2 Protein Kinase / antagonists & inhibitors*
  • CDC2 Protein Kinase / metabolism
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Division / drug effects
  • Cell Nucleus / metabolism
  • Cyclin B / metabolism
  • Cyclin B1
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Dose-Response Relationship, Drug
  • G2 Phase / drug effects
  • Genistein / pharmacology*
  • Male
  • Mice
  • Mice, Transgenic
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Prostatic Neoplasms / drug therapy*
  • Prostatic Neoplasms / metabolism
  • Prostatic Neoplasms / pathology
  • Protein-Serine-Threonine Kinases / metabolism
  • Protein-Tyrosine Kinases / genetics
  • Protein-Tyrosine Kinases / metabolism*
  • RNA, Small Interfering
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • Anticarcinogenic Agents
  • Ccnb1 protein, mouse
  • Cell Cycle Proteins
  • Cyclin B
  • Cyclin B1
  • Cyclin-Dependent Kinase Inhibitor p21
  • DNA-Binding Proteins
  • Myt1 protein, mouse
  • Nuclear Proteins
  • RNA, Small Interfering
  • Transcription Factors
  • Genistein
  • Protein-Tyrosine Kinases
  • Wee1 protein, mouse
  • Aurora Kinases
  • Protein-Serine-Threonine Kinases
  • CDC2 Protein Kinase