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Signal transduction by the CEACAM1 tumor suppressor. Phosphorylation of serine 503 is required for growth-inhibitory

V T Estrera1, D T Chen, W Luo

  • 1Department of Molecular Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.

The Journal of Biological Chemistry
|March 30, 2001
PubMed

Insights

Phosphorylation of serine 503 in CEACAM1 is crucial for its tumor-suppressive activity. This finding is vital for understanding CEACAM1

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cancer Research

Background:

  • CEACAM1 is a cell-cell adhesion molecule with demonstrated tumor-suppressive roles in prostate, breast, and colon cancers.
  • CEACAM1's extracellular domain mediates adhesion, while its cytoplasmic domain is key for growth inhibition.
  • The precise signaling pathways underlying CEACAM1's tumor suppression remain largely unknown.

Purpose of the Study:

  • To investigate the role of serine 503 phosphorylation in the growth-inhibitory signaling pathway of CEACAM1.
  • To determine the significance of tyrosine 488 and serine 503 phosphorylation for CEACAM1's tumor-suppressive function.

Main Methods:

  • Analysis of in vivo phosphorylation of full-length CEACAM1 at tyrosine and serine residues.
  • Site-directed mutagenesis of tyrosine 488 to phenylalanine and serine 503 to alanine or aspartic acid.
  • Assessment of the impact of these mutations on CEACAM1's growth-inhibitory activity in DU145 prostate cancer cells.

Main Results:

  • CEACAM1 is phosphorylated on both tyrosine and serine residues in vivo.
  • Mutation of tyrosine 488 did not affect CEACAM1's tumor-suppressive activity.
  • Mutation of serine 503 to alanine abolished growth inhibition, while mutation to aspartic acid mimicked wild-type activity.

Conclusions:

  • Phosphorylation at serine 503 is essential for the in vivo tumor-suppressive function of CEACAM1.
  • Tyrosine 488 phosphorylation is not critical for CEACAM1's growth-inhibitory role.
  • These findings elucidate a key mechanism in CEACAM1-mediated cancer growth suppression.

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