INFLUENCE OF THE CARCINOGENIC ESTROGEN DIETHYLSTILBESTROL ON THE INTRACELLULAR CALCIUM LEVEL IN C6-RAT GLIOMA-CELLS

The synthetic oestrogen diethylstilboestrol (DES) causes a dose-dependent elevation of the cytoplasmic Ca2+ concentration in C6 rat glioma cells. This Ca2+ rise is caused neither by Ca2+ influx nor by release from the Ca2+ stores of the endoplasmic reticulum. Therefore it seems likely that DES mobilizes Ca2+ from a mitochondrial source. The DES-induced Ca2+ signal is remarkably similar to the one induced by the tumor promoter thapsigargin. As this compound causes leakage of calcium from the endoplasmic reticulum it seems possible that DES induces a similar leakage from mitochondrial Ca2+ stores. It remains to be established whether the DES-mediated rise in intracellular calcium is causally related to the tumor-promoting properties of this compound.