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Published on: December 11, 2017

P27(kip1) down-regulation is associated with trastuzumab resistance in breast cancer cells

Rita Nahta1, Takeshi Takahashi, Naoto T Ueno

  • 1Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030-4009, USA.

Cancer Research
|June 3, 2004
PubMed

Insights

Trastuzumab resistance in breast cancer may stem from reduced p27(kip1) levels. Restoring p27(kip1) or using proteasome inhibitors like MG132 could overcome this resistance.

Area of Science:

  • Oncology
  • Molecular Biology
  • Pharmacology

Background:

  • Trastuzumab (Herceptin) targets HER-2 in breast cancer.
  • Resistance to trastuzumab limits its long-term efficacy.
  • Mechanisms of trastuzumab resistance require further investigation.

Purpose of the Study:

  • To investigate the molecular mechanisms underlying trastuzumab resistance in HER-2-overexpressing breast cancer.
  • To identify potential therapeutic strategies to overcome trastuzumab resistance.

Main Methods:

  • Developed trastuzumab-resistant (TR) SKBR3 breast cancer cell line pools.
  • Analyzed cell proliferation, cell cycle (S-phase fraction), and protein levels (p27(kip1)).
  • Assessed the impact of p27(kip1) repletion and proteasome inhibition (MG132) on trastuzumab sensitivity.

Main Results:

  • TR cells maintained HER-2 amplification but exhibited faster proliferation.
  • Resistant cells showed decreased p27(kip1) and increased CDK2 activity.
  • Exogenous p27(kip1) restored trastuzumab sensitivity; MG132 increased p27(kip1) and sensitivity.

Conclusions:

  • Trastuzumab resistance is associated with diminished p27(kip1) levels.
  • Therapies that induce p27(kip1) expression may overcome trastuzumab resistance.
  • Proteasome inhibitors represent a potential strategy to re-sensitize resistant breast cancer cells.

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