Local renin-angiotensin system is involved in K+-induced aldosterone secretion from human adrenocortical NCI-H295 cells.
NCI-H295, a human adrenocarcinoma cell line, has been proposed as a model system to define the role of the renin-angiotensin system in the regulation of aldosterone production in humans. Because the precise cellular localization of the components of the renin-angiotensin system in human adrenal cortical cells remains unclear, we investigated their localization in this defined cell system. NCI-H295 cells expressed both angiotensinogen and renin as shown by reverse transcriptase polymerase chain reaction and immunohistochemistry. Human angiotensin-converting enzyme (ACE) was not detectable by immunocytochemistry, ACE binding, or reverse transcriptase polymerase chain reaction. However, 3.5 mmol/L K+ stimulated the formation of both angiotensin I and angiotensin II 1. 9- and 2.5-fold, respectively, and increased aldosterone release 3. 0-fold. The K+-induced stimulation of aldosterone release was decreased by captopril and enalaprilat (24% and 26%, respectively) and by the angiotensin type 1 (AT1)-receptor antagonist losartan (28%). Angiotensin II-induced stimulation of aldosterone release was abolished by losartan treatment. Specific [125I]Sar1-angiotensin II binding was detected by receptor autoradiography. The binding of [125I]Sar1-angiotensin II was completely displaced by the AT1 antagonist losartan but not by the AT2 receptor ligand PD 123319, confirming the expression of angiotensin II AT1 receptors in NCI-H295 cells. Our results demonstrate that NCI-H295 cells express most of the components of the renin-angiotensin system. Our failure to detect ACE, however, suggests that the production of angiotensin II in NCI-H295 cells may be ACE independent. NCI-H295 cells are able to produce angiotensin II, and K+ increases aldosterone secretion in part through an angiotensin-mediated pathway. The production of angiotensin II in NCI-H295 cells demonstrates that this human cell line can be useful to characterize the role of locally produced angiotensin II in the regulation of aldosterone release.
Hilbers
U
U
Department of Internal Medicine III, University of Leipzig, Germany.
Peters
J
J
Bornstein
S R
SR
Correa
F M
FM
Jöhren
O
O
Saavedra
J M
JM
Ehrhart-Bornstein
M
M
D000302:Adrenal Cortex / Q000378:metabolism*; D000450:Aldosterone / Q000378:metabolism*; D000808:Angiotensinogen / Q000032:analysis; D002216:Captopril / Q000494:pharmacology; D002478:Cells, Cultured; D006801:Humans; D019808:Losartan / Q000494:pharmacology; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology*; D012083:Renin / Q000378:metabolism; D012084:Renin-Angiotensin System / Q000502:physiology*
D000808:Angiotensinogen; D000450:Aldosterone; D002216:Captopril; D007703:Peptidyl-Dipeptidase A; D012083:Renin; D019808:Losartan; D011188:Potassium