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p27Kip1 is inactivated in human colorectal cancer by cytoplasmic localization associated with activation of Akt/PKB

C Bottini1, F Platini, M Rinaldi

  • 1Department of Food, Chemical, Pharmaceutical and Pharmacological Sciences (DISCAFF), University of East Piedmont 'A. Avogadro', 28100 Novara, Italy.

International Journal of Oncology
|December 17, 2008
PubMed

Insights

Reduced levels of p27Kip1, a cell cycle regulator, are common in colorectal cancers. Cytoplasmic p27Kip1 accumulation correlates with poorer patient outcomes, suggesting its role in tumor progression and as a prognostic factor.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Cycle Regulation

Background:

  • p27Kip1 is a cyclin-dependent kinase inhibitor and tumor suppressor.
  • Reduced p27Kip1 levels are linked to poor prognosis in human cancers.
  • Investigating p27Kip1 expression and localization in colorectal cancer is crucial.

Purpose of the Study:

  • To analyze p27Kip1 expression and intracellular localization in colorectal cancers.
  • To correlate p27Kip1 status with Akt expression and clinicopathological parameters.
  • To determine the prognostic value of p27Kip1 in colorectal cancer patients.

Main Methods:

  • Western blotting to assess p27Kip1 and phosphorylated Akt protein levels.
  • Immunohistochemistry to evaluate p27Kip1 intracellular localization.
  • Analysis of 70 human colorectal cancer samples and correlation with clinical data.

Main Results:

  • p27Kip1 was absent or reduced in 63% of colorectal cancers compared to normal tissue.
  • Cytoplasmic p27Kip1 was detected in 30% of cases, suggesting inactivation via translocation.
  • Cytoplasmic p27Kip1, with or without Akt activation, was associated with poorer relapse-free survival and overall survival.

Conclusions:

  • Cytoplasmic p27Kip1 localization may contribute to colorectal tumorigenesis and metastasis.
  • p27Kip1 inactivation through cytoplasmic translocation is a potential mechanism in colorectal cancer.
  • Cytoplasmic p27Kip1 serves as a negative prognostic factor for colorectal cancer patients.

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