Altered cell volume regulation in ras oncogene expressing NIH fibroblasts

Area of Science:

• Cell Biology
• Oncology
• Physiology

Background:

• The Ha-ras oncogene is known to influence ion transport systems.
• These systems, including the Na+/H+ exchanger and Na+,K+,2Cl- cotransporter, are critical for cell volume regulation.
• The precise impact of ras oncogene expression on overall cell volume regulation remains to be fully elucidated.

Purpose of the Study:

• To investigate the effect of Ha-ras oncogene expression on cell volume regulation in NIH 3T3 fibroblasts.
• To compare cell volume and regulatory responses between ras-expressing and non-expressing NIH 3T3 cells.

Main Methods:

• Utilized NIH 3T3 fibroblasts with (+ ras) and without (-ras) Ha-ras oncogene expression.
• Measured cell volumes under isotonic, hypertonic, and hypotonic conditions.
• Assessed the effects of specific inhibitors (quinidine, barium, dimethyl-amiloride, furosemide, bumetanide) on regulatory volume changes.

Main Results:

• + ras cells exhibited significantly larger cell volumes than -ras cells in isotonic conditions.
• Both cell types demonstrated regulatory volume increase in hypertonic and decrease in hypotonic solutions.
• Specific inhibitors differentially affected volume regulation, with furosemide and bumetanide uniquely impacting + ras cells.

Conclusions:

• Ha-ras oncogene expression shifts the set point for cell volume regulation towards larger cell volumes.
• This shift is associated with the activation of the Na+/H+ exchanger and Na+,K+,2Cl- cotransport systems.
• Ras-mediated alterations in cell volume regulation may have implications for cellular function and oncogenesis.