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Down-regulation of bcl-2 is associated with p16INK4-mediated apoptosis in non-small cell lung cancer cells

M Kataoka1, S Wiehle, F Spitz

  • 1Department of Thoracic and Cardiovascular Surgery, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Blvd, Box 13, Houston, TX 77030, USA.

Oncogene
|March 29, 2000
PubMed

Insights

Introducing functional p16 via adenovirus into non-small cell lung cancer cells induced cell cycle arrest and apoptosis, particularly in cells with functional p53. This suggests p16

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Genetics

Background:

  • Non-small cell lung cancer (NSCLC) is a major cause of cancer-related deaths.
  • The p16, p53, and Rb tumor suppressor genes play critical roles in cell cycle regulation and are frequently altered in NSCLC.
  • Understanding the interplay of these genes is crucial for developing effective cancer therapies.

Purpose of the Study:

  • To investigate the effect of exogenous p16 expression on cell growth and apoptosis in NSCLC cell lines.
  • To elucidate the role of functional p53 and Rb in p16-mediated apoptosis.
  • To determine the molecular mechanisms underlying p16-induced cell death in NSCLC.

Main Methods:

  • Recombinant adenovirus (Adv) was used to deliver functional p16 cDNA into NSCLC cell lines with varying p16, p53, and Rb gene status.
  • Cell growth, cell cycle progression (G0-G1 arrest), and apoptosis were analyzed post-infection.
  • Expression levels of p16, Rb, bcl-2, and Bax proteins were assessed using Western blotting or similar techniques.

Main Results:

  • Exogenous p16 expression induced G0-G1 cell cycle arrest in p16-deficient NSCLC cells.
  • Apoptosis was observed by day 5 post-Adv/p16 infection, correlating with increased p16 and hypophosphorylated Rb, but only in cells with functional p53.
  • p16-mediated apoptosis involved down-regulation of the anti-apoptotic protein bcl-2, particularly in cells with wild-type p53 and Rb. Restoration of Rb expression counteracted p16-induced apoptosis and increased bcl-2 levels.

Conclusions:

  • p16 can induce apoptosis in NSCLC cell lines expressing wild-type p53.
  • p16-mediated apoptosis is dependent on functional p53 and involves direct down-regulation of Rb and indirect down-regulation of bcl-2.
  • These findings highlight the potential of p16 as a therapeutic agent for NSCLC, especially in tumors with specific genetic profiles.

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