Submitted on December 28, 2005
Accepted on June 29, 2006
Regulation of steroid hormone biosynthesis enzymes and organic anion transporters by forskolin and DHEAS treatment in adrenocortical cells
Abdul R Asif1, Marija Ljubojevic2, Ivan Sabolic2, Vladimir Shnitsar3, Maria Metten4, Naohiko Anzai5, Gerhard A Mueller6, Gerhard Burckhardt7, and Yohannes Hagos7*
1 Nephrologie und Rheumatologie, University, Goettingen, Germany; Vegetative Physiologie und Pathophysiologie, University, Goettingen, Germany
2 Unit of Molecular Toxicology, Medical Research and Occupational Health, Zagreb, Croatia
3 University, Vegetative Physiologie und Pathophysiologie, Germany
4 Klinische und Experimentelle Endokrinologie, University, Goettingen, Germany
5 Department of Pharmacology and Toxicology, University, Tokyo, Japan
6 Nephrologie und Rheumatologie, University, Goettingen, Germany
7 Vegetative Physiologie und Pathophysiologie, University, Goettingen, Germany
* To whom correspondence should be addressed. E-mail: Hagos{at}physiol.med.uni-goettingen.de.
Several important physiological functions are regulated by cortisol. Previously, we demonstrated the involvement of human organic anion transporter (OAT3) in cortisol release. In the present study we investigated the influence of DHEAS and estrone sulfate on cortisol release in a human adrenocortical cell line (NCI-H295R cells) in comparison to forskolin stimulation. Additionally we examined the impact of forskolin and DHEAS on the expression of key enzymes in steroid biosynthesis and expression of organic anion transporter 3 and 4 in NCI-H295R cells. The cortisol release was increased by 10 fold after 24 h incubation with DHEAS, but incubation with estrone sulfate did not show any significant change in cortisol release. When cells were incubated with DHEAS in the presence of forskolin, an additive influence of DHEAS stimulation of cortisol was recorded over forskolin alone. The 24 h stimulation of NCI-H295R cells with forskolin increased the expression of StAR, CYP17, CYP21A2 and CYP11A1, whereas only steroidogenic acute regulatory protein (StAR) mRNA expression was increased significantly by incubation with DHEAS. Immunofluorescence analyses revealed strongly elevated expression of hOAT3 by forskolin as well as by DHEAS stimulation. We conclude that the observed increased cortisol release of adrenocortical cells by DHEAS and forskolin stimulation is probably due to high expression of the key enzymes of steroid biosynthesis and human organic anion transporter 3.
