Vacuolar-type H+-ATPases are functionally expressed in plasma membranes of human tumor cells

R. Martinez-Zaguilan, Ron Lynch, G. M. Martinez, R. J. Gillies

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Abstract

Mammalian cells generally regulate their intracellular pH (pH(i)) via collaboration between Na+-H+ exchanger and HCO3/- transport. In addition, a number of normal mammalian cells have been identified that express H+- adenosinetriphosphatases (ATPases) in their plasma membranes. Because tumor cells often maintain a high pH(i), we hypothesized that they might functionally express H+-ATPases in their plasma membranes. In the first phase of the present study, we screened 19 normal and tumorigenic human cell lines for the presence of plasmalemmal H+-ATPase activity using bafilomycin A1 to inhibit V-type H+-ATPase and Sch-28080 to inhibit P-type H+-K+- ATPase. Bafilomycin A1 decreased pH(i) in the six tumor cell lines with the highest resting pH(i) in the absence of HCO3/-. Sch-28080 did not affect pH(i) in any of the human cells. Simultaneous measurement of pH in the cytoplasm and in the endosomes/lysosomes localized the activity of bafilomycin to the plasma membrane in three cell lines. In the second phase of this study, these three cell lines were shown to recover from NH4/+- induced acid loads in the absence of Na+. This recovery was inhibited by N- ethylmaleimide, bafilomycin A1, and ATP depletion and was not significantly affected by vanadate, Sch-28080, or hexamethyl amiloride. These results indicate that a vacuolar type H+-ATPase is expressed in the plasma membrane of some tumor cells.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume265
Issue number4 34-4
StatePublished - 1993

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Cell membranes
Adenosine Triphosphatases
Tumors
Cells
Cell Membrane
Proton-Translocating ATPases
Neoplasms
Vacuolar Proton-Translocating ATPases
Cell Line
Sodium-Hydrogen Antiporter
Ethylmaleimide
Vanadates
Amiloride
Endosomes
Lysosomes
Tumor Cell Line
Cytoplasm
Adenosine Triphosphate
Acids
Recovery

Keywords

  • bafilomycin
  • carboxyseminaphtorhodofluor
  • coumarin- dextran
  • endosomes
  • fluorescence
  • glycolysis
  • intracellular pH
  • lysosomes
  • proton-adenosinetriphosphatases
  • Sch- 28080

ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Physiology

Cite this

Vacuolar-type H+-ATPases are functionally expressed in plasma membranes of human tumor cells. / Martinez-Zaguilan, R.; Lynch, Ron; Martinez, G. M.; Gillies, R. J.

In: American Journal of Physiology - Cell Physiology, Vol. 265, No. 4 34-4, 1993.

Research output: Contribution to journalArticle

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