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[The effect of retinoic acid on primary cultures of human pheochromocytoma cells].

INTRODUCTION
Retinoic acid is a regulator of gene expression which, by binding to its nuclear receptor, determines the degree of differentiation in multiple cancer cell types. On the basis of this capability it was introduced, e.g. in the therapy of neuroblastoma. In cells derived from neural crest, such as neuroblastoma cells, retinoic acid initiates differentiation into neurons. This substance acts in a similar way on a rat pheochromocytoma cell line PC12. The aim of our work was to examine the influence of retinoic acid on the phenotype of human pheochromocytoma cells in primary culture.


MATERIAL AND METHODS
Observations were made on two primary cultures isolated from human pheochromocytoma. Cells were grown in RPMI1640 medium supplemented with 10% foetal bovine serum. Subsequently, the cultures were treated with 100 mMol retinoic acid for three-days. An evaluation of the phenotype change was performed by estimating the expression levels of F-actin, MAP-2 protein, and chromogranin, with the use of a confocal microscopy.


RESULTS
The introduction of retinoic acid into the culture caused an increase in the F-actin level and its redistribution in the form of stress fibers. Simultaneously, the cells changed their shape, generating more processes. No change was detected in the expression level of neuroendocrine markers: MAP-2 and chromogranin.


CONCLUSIONS
Retinoic acid appears to have an influence on some phenotype parameters of human pheochromocytoma cells. Further work is needed to determine the molecular mechanisms of this process, and to evaluate thoroughly the benefits of introducing retinoic acid into therapy of pheochromocytoma tumors.