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LKB1 interacts with and phosphorylates PTEN: a functional link between two proteins involved in cancer predisposing

Hamid Mehenni1, Nathalie Lin-Marq, Karine Buchet-Poyau

  • 1Département de Biologie Cellulaire, Université de Genève, 1211 Genève 4, Switzerland.

Human Molecular Genetics
|July 1, 2005
PubMed

Insights

Germline mutations in the LKB1 gene cause Peutz-Jeghers syndrome (PJS). This study reveals PTEN interacts with LKB1, and disrupted interaction contributes to PJS and cancer predisposition.

Area of Science:

  • Molecular Biology
  • Genetics
  • Oncology

Background:

  • Germline mutations in the LKB1 (STK11) tumor suppressor gene are linked to Peutz-Jeghers syndrome (PJS), a condition predisposing individuals to cancer.
  • LKB1, a serine/threonine kinase, is frequently inactivated in PJS patients.

Purpose of the Study:

  • To investigate the functional relationship between LKB1 and PTEN, a known tumor suppressor.
  • To determine if the interaction between LKB1 and PTEN is disrupted in Peutz-Jeghers syndrome.

Main Methods:

  • Protein-protein interaction assays to identify LKB1-interacting partners.
  • Analysis of LKB1 mutations found in PJS patients to assess their impact on PTEN interaction.
  • In vitro kinase assays to determine if PTEN is a substrate of LKB1.

Main Results:

  • The dual phosphatase and tumor suppressor PTEN was identified as an LKB1-interacting protein.
  • Several LKB1 point mutations associated with PJS were found to disrupt the interaction with PTEN.
  • PTEN was confirmed as a substrate of LKB1 kinase in vitro.
  • The interaction between PTEN and LKB1 promotes cytoplasmic relocalization of LKB1.

Conclusions:

  • The disruption of the LKB1-PTEN interaction may contribute to the pathogenesis of Peutz-Jeghers syndrome.
  • This study suggests a functional link between LKB1 and PTEN in hamartomatous polyposis syndromes.
  • LKB1 plays a crucial role as a tumor suppressor, particularly in the small intestine.

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