Ca(2+) and Na(+) contribute to the swelling of differentiated neuroblastoma cells induced by equinatoxin-II.

Abstract

Equinatoxin-II (EqTx-II), a cytotoxic protein (mol.wt 20 kDa) isolated from the sea anemone Actinia equina, was found to consistently increase the three-dimensional projected area of differentiated neuroblastoma (NG108-15) cells provided Ca(2+) was present in the medium. No swelling was detected when external NaCl was replaced by sucrose, but replacement of NaCl by Na-isethionate did not prevent the swelling, as revealed by confocal laser scanning microscopy. In addition, microspectrofluorometric measurements in cells preloaded with the Ca(2+) indicator fura-2/AM revealed that EqTx-II (100 nM) markedly increased the fluorescence (F(340)/F(380)) ratio indicating a rise of intracellular Ca(2+) concentration ([Ca(2+)](i)). The elevation of [Ca(2+)](i) exhibited two components that seem to be related to the kinetics of EqTx-II-induced Ca(2+) entry since pretreatment of cells with Ca(2+)-ATPase inhibitors (thapsigargin), Ca(2+) channel blockers (nifedipine and Gd(3+)) or prolonged exposure to a high K(+) (75 mM) medium did not alter EqTx-II-induced Ca(2+) signals. As far as we know, this is the first demonstration that EqTx-II causes swelling of neuroblastoma cells and that this effect is correlated both with an increase of [Ca(2+)](i) and needs the presence of extracellular Na(+). It is suggested that EqTx-II has the ability to insert into the plasma membrane of neuroblastoma cells and to form pores altering the membrane permeability and the intracellular osmolality, inducing a marked influx of water into the cells.

• Authors: F A Meunier, R Frangez, E Benoit, G Ouanounou, B Rouzaire-Dubois, D Suput, J Molgó
• Journal: Toxicon : official journal of the International Society on Toxinology (Toxicon) Vol. 38 Issue 11 Pg. 1547-60 (Nov 2000) ISSN: 0041-0101 [Print] England
• PMID: 10775755 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Calcium Channel Blockers
• Cnidarian Venoms
• Cytotoxins
• Enzyme Inhibitors
• equinatoxin
• Sodium
• Calcium-Transporting ATPases
• Calcium

Topics

• Animals
• Calcium (metabolism)
• Calcium Channel Blockers (pharmacology)
• Calcium Signaling (drug effects)
• Calcium-Transporting ATPases (antagonists & inhibitors)
• Cell Differentiation
• Cnidarian Venoms (toxicity)
• Cytotoxins (toxicity)
• Enzyme Inhibitors (pharmacology)
• Membrane Potentials (drug effects)
• Mice
• Microscopy, Confocal (methods)
• Neuroblastoma (pathology)
• Rats
• Sea Anemones (chemistry)
• Sodium (metabolism)
• Tumor Cells, Cultured