Glucocorticoid hormone renders rat glioma cells dependent on high concentrations of external Ca2+ for growth.
C6 rat glioma cells, like other tumor cells, grow optimally in Ca2+-or Mg2+-depleted 5% serum medium. However, the glucocorticoid hormone hydrocortisone renders these cells dependent on high concentrations of external Ca2+ for growth. Upon Ca2+ deprivation (30-80 microM Ca2+ medium) hydrocortisone-treated C6 cells undergo reversible cell-cycle arrest at G0/G1 phase. This effect is specific for glucocorticoid hormones and occurs at physiological concentrations. Growth restimulation of Ca2+-deprived, hydrocortisone-treated C6 cells by bovine pituitary growth factors or serum growth factors only takes place if the external Ca2+ concentration is increased. On the other hand, C6 cell growth requirement for external Mg2+ was not increased by the glucocorticoid hormone treatment. A minimum of 80 microM of external Mg2+ is required to keep cells adhered and spread in Ca2+-depleted (30 microM) 5% serum medium; in high Ca2+ concentration (1.8 mM), Mg2+ is not required for adhesion or spreading. Thus, the hormone hydrocortisone renders the cell cycle of C6 glioma cells controllable by the levels of external Ca2+, a minimal external Mg2+ being necessary to warrant normal adhesion.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D005910:Glioma / Q000378:metabolism*; D006854:Hydrocortisone / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology; D051379:Mice; D011247:Pregnancy
D008274:Magnesium; D002118:Calcium; D006854:Hydrocortisone