Isolation of normal epithelial cells adapted to grow at nonphysiological concentration of magnesium

Extracellular magnesium (Mg) depletion inhibits the growth of the HC11 norm al mammary epithelial cells. In this study we found that an acute increase in extracellular Mg generally exerts a positive effect on the growth of the se cells. We also isolated and characterized two derivatives adapted to gro w and proliferate at nonphysiological concentration of Mg. The growth prope rties of the HC-LMg cells at 25 muM Mg were comparable to those of the pare ntal HC11 cells in the regular medium (0.5 mM Mg) despite an increased expr ession of the CDK inhibitor p27(Kip1). They also showed a reduced dependenc e from serum to grow. The HC-HMg cells have been adapted to grow and prolif erate at an increased (45 mM) Mg concentration. Cell total Mg content was 1 9.6, 9.7, and 20.1 nmol/mg protein in the HC11, HC-LMg, and HC-HMg cells, r espectively. Thus, we have isolated derivatives of normal epithelial cells which are able to maintain Mg content in a physiological range in the face of different extracellular concentration gradients and will be a valuable t ool for further studies on the regulation of Mg homeostasis in eukaryotic c ells. (C) 2001 Academic Press.