Cell transformation induces a cytoplasmic Ca2+ oscillator in Madin-Darby canine kidney cells.
Alkaline stress transforms Madin-Darby canine kidney (MDCK) cells as indicated by loss of epithelial structure, multilayer cell growth and formation of foci. In the present study we report that transformed MDCK cells (MDCK-F cells) exhibit spontaneous and lasting oscillations of intracellular Ca2+ concentration ([Ca2+]i), which are absent in non-transformed cells. Oscillations, as revealed by Fura-2 video imaging, were due to the activity of an inositol 1,4,5-trisphosphate-(InsP3)-sensitive Ca2+ store since their frequency was dependent on bradykinin concentration and they were abolished by the phosphoinositidase C inhibitor U73122. Moreover, blockers of the cytoplasmic Ca(2+)-ATPase, thapsigargin and 2,5-di-(tetr-butyl)-1,4-benzohydroquinone inhibited oscillatory activity. In contrast, neither injection of ruthenium red, ryanodine nor caffeine had any effect on oscillations. Analysis of the spatial distribution of [Ca2+]i showed that Ca2+ transients originated from an initiation site constant for a given cell and spread through the cell as an advancing Ca2+ wave. Oscillations started in a random manner from single cells and spread over neighbouring cells, suggesting a kind of intercellular communication. We conclude that MDCK-F cells have acquired the ability for endogenous Ca2+ release through transformation. Oscillations are primarily due to the activity of an InsP3-sensitive cytosolic Ca2+ oscillator.
Wojnowski
L
L
Department of Physiology, University of Würzburg, Germany.
Hoyland
J
J
Mason
W T
WT
Schwab
A
A
Westphale
H J
HJ
Oberleithner
H
H
D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology*; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002450:Cell Communication; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004285:Dogs; D004963:Estrenes / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D004963:Estrenes; D011760:Pyrrolidinones; D013729:Terpenes; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D015759:Ionomycin; D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate; D010738:Type C Phospholipases; D000252:Calcium-Transporting ATPases; D001920:Bradykinin; D002118:Calcium