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Role of p12(CDK2-AP1) in transforming growth factor-beta1-mediated growth suppression

Miaofen G Hu1, Guo-Fu Hu, Yong Kim

  • 1Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.

Cancer Research
|January 28, 2004
PubMed

Insights

p12, a growth suppressor, mediates TGF-beta1

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cancer Research

Background:

  • p12 (CDK2-AP1) is a known growth suppressor in normal keratinocytes.
  • Ectopic p12 expression reverses malignant phenotypes in squamous carcinoma cells by inhibiting DNA polymerase alpha/primase and CDK2.
  • Transforming growth factor beta1 (TGF-beta1) is a key regulator of cell growth and differentiation.

Purpose of the Study:

  • To investigate the role of p12 in TGF-beta1-mediated growth suppression in normal epithelial cells.
  • To elucidate the molecular mechanisms by which p12 mediates TGF-beta1's inhibitory effects.
  • To analyze the impact of p12 deficiency on cell cycle regulation and TGF-beta1 response.

Main Methods:

  • Creation of inducible p12 antisense HaCaT cell lines (ip12(-) HaCaT).
  • Generation of p12-deficient mouse oral keratinocytes (MOK(p12-/-)) and comparison with wild-type (MOK(WT)).
  • Assays for CDK2-associated kinase activity, retinoblastoma (pRB) phosphorylation, and DNA synthesis ([(3)H]thymidine incorporation).

Main Results:

  • Selective reduction of p12 in ip12(-) HaCaT cells increased CDK2 activity, pRB phosphorylation, and [(3)H]thymidine incorporation.
  • p12 deficiency in MOK(p12-/-) cells led to increased S phase, decreased G2 phase, elevated CDK2 activity, and compromised TGF-beta1-mediated growth suppression.
  • p12 mediates TGF-beta1's inhibitory effects on CDK2 activity, pRB phosphorylation, and cell proliferation.

Conclusions:

  • p12 is a critical mediator of TGF-beta1's growth inhibitory activity in epithelial cells.
  • p12 functions by modulating CDK2 activity and pRB phosphorylation.
  • p12 plays a significant role in regulating cell proliferation and response to growth factors.

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