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DOI: 10.1055/s-2006-933017
The influence of DHEA on NGF-induced differentiation of pheochromocytoma PC12 cells
Adrenocortical androgens, including dehydroepiandrosterone (DHEA), are produced in the inner zone of the adrenal cortex which is in direct contact to the neural crest-derived catecholamine-producing chromaffin cells. DHEA has recently been identified as a crucial regulator in neural stem cell proliferation. Thus, DHEA might play a hitherto unknown intra-adrenal role in adrenal tissue formation and/or tumorigenesis. The rat pheochromocytoma cell line PC12 is a well established model for proliferation- and mitotic competent chromaffin cells. In the present study we examined the influence of DHEA on nerve growth factor (NGF)-induced morphological changes, proliferation and signalling pathways in PC12 cells. NGF, in a dose dependent manner, promoted cell survival in serum deprived PC12 cells. This effect was lessened by DHEA (10–5–10–8 Mol). The influence of DHEA on NGF-induced differentiation was characterized by Western blotting and immunohistochemistry, using the neuroendocrine markers SNAP 25 and VAMP-2. Both are known to promote in PC12 cells morphological changes like, neurite elongation or neurite sprouting, respectively. NGF promoted the upregulation of SNAP 25 and VAMP-2, an effect reduced by DHEA in a dose dependent manner (10–5–10–8 Mol). In a next step, we explored the possible molecular mechanisms of DHEA and NGF interaction in more detail. It is well accepted that steroid hormones like DHEA can induce rapid (“non-genomic“) effects by interfering within e.g. intracellular second messenger generation, pH regulation or signalling cascades like the mitogen-activated protein kinases (MAPK) ERK 1/2. Differentiation as well as proliferation processes in PC12 cells are accompanied by ERK 1/2 activation. Phospho-specific ELISA and Western blotting showed that NGF-induced ERK 1/2 activation (2–10min) in PC12 cells was significantly inhibited by DHEA in a time- and dose dependent manner. In summary, the data shows that DHEA influences differentiation processes in pheochromocytoma cells.