ALTERATION OF INTRACELLULAR FREE CALCIUM AND ACYLPHOSPHATASE LEVELS IN DIFFERENTIATING SH-SY5Y NEUROBLASTOMA CELLS

Levels of acylphosphatase isoenzymes and free intracellular calcium have been investigated in cultured SH-SY5Y human neuroblastoma cells under stimulation with all-trans retinoic acid and phorbol-12-myristate-13-acetate. Under these conditions morphological and functional characteristics demonstrated the differentiation of SH-SY5Y cells towards neuronal phenotype. Retinoic acid treatment caused a progressive and synchronous increase of the organ common-type acylphosphatase and of free intracellular calcium but not of the muscle-type acylphosphatase. Phorbol-12-myristate-13-acetate treatment gave rise to a peak of the muscle-type acylphosphatase levels during the early differentiation stage whereas organ common-type isoenzyme and free calcium levels show a pattern similar to that observed in retinoic acid-treated cells. These evidences indicate that the two acylphosphatase isoenzymes play different roles in SH-SY5Y differentiation and that during this process the expression of organ common-type acylphosphatase increases in a synchronous way with intracellular free calcium concentration.