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CDK4 coexpression with Ras generates malignant human epidermal tumorigenesis

Mirella Lazarov1, Yoshiaki Kubo, Ti Cai

  • 1VAPalo Alto Healthcare System, Palo Alto and the Program in Epithelial Biology, Stanford University School of Medicine, Stanford, California, USA.

Nature Medicine
|October 3, 2002
PubMed

Insights

Oncogenic Ras initially suppresses cell growth by reducing cyclin-dependent kinase (CDK) 4. However, co-expression of CDK4 drives invasive neoplasia, highlighting CDK4

Area of Science:

  • Oncology
  • Cell Biology
  • Molecular Biology

Background:

  • Ras signaling is crucial in neoplasia but can paradoxically suppress normal cell proliferation.
  • Understanding Ras-mediated cell cycle regulation is key to cancer prevention.

Purpose of the Study:

  • To investigate the role of oncogenic Ras in regulating cyclin-dependent kinase (CDK) 4 expression.
  • To determine if CDK4 co-expression can overcome Ras-induced growth suppression and promote tumorigenesis.

Main Methods:

  • Analysis of oncogenic Ras effects on CDK4 expression in primary epidermal cells.
  • Assessment of cell cycle progression and G1 arrest.
  • Evaluation of CDK4 co-expression in inducing invasive human neoplasia and its dependence on kinase function and cyclin D1.

Main Results:

  • Oncogenic Ras transiently decreases CDK4 expression, causing G1 cell cycle arrest.
  • CDK4 co-expression overrides Ras-induced growth suppression, leading to invasive squamous cell carcinoma-like neoplasia.
  • Tumorigenesis is dependent on CDK4 kinase activity and requires cyclin D1.
  • Ras and CDK4 promote resistance to INK4 inhibitors by altering cyclin D/E complex composition.

Conclusions:

  • Oncogenic Ras plays a novel role in regulating CDK4 expression.
  • CDK4 suppression is critical for preventing uncontrolled cell growth.
  • Targeting CDK4 may offer therapeutic strategies against Ras-driven cancers.

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