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A Ca2(+)-activated K+ current in ras-transformed fibroblasts is absent from nontransformed cells

S G Rane1

  • 1Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907.

The American Journal of Physiology
|January 1, 1991
PubMed

Insights

Ras proteins, involved in cell transformation, may alter ion channel activity. Researchers found a specific calcium-activated potassium channel significantly increased in ras-transformed cells, suggesting a role in cancer development.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biophysics

Background:

  • Ras proteins share similarities with GTP-binding proteins.
  • Ras-induced cell transformation correlates with altered transmembrane cation fluxes.
  • Ras proteins may modulate ion channel activity.

Purpose of the Study:

  • To investigate the hypothesis that ras proteins modulate ion channel activity.
  • To compare ion channel currents in ras-transformed and non-transformed fibroblasts.

Main Methods:

  • Whole-cell, tight-seal, patch-clamp recording.
  • Comparison of macroscopic currents in ras-transformed and nontransformed fibroblasts.
  • Pharmacological characterization of ion currents using charybdotoxin, tetraethylammonium, and apamin.

Main Results:

  • A prominent calcium-activated, voltage-independent potassium current was found in 83-100% of ras-transformed cells, versus 0-15% of nontransformed cells.
  • This potassium current is blocked by charybdotoxin and high tetraethylammonium concentrations.
  • Ras-transformed cells exhibit altered ion channel activity, specifically a type of calcium-activated potassium channel.

Conclusions:

  • Ras-mediated cell transformation may involve alterations in ion channel number or activity.
  • A specific calcium-activated potassium channel is significantly upregulated in ras-transformed cells.
  • These findings suggest a potential role for ion channels in ras-driven oncogenesis.

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