Morphologic change and elevation of cortisol secretion in cultured human normal adrenocortical cells caused by mutant p21K-ras protein.
In our previous study on the tumorigenesis of human functional adrenal tumors, we observed a high frequency of K-ras point mutations in clinical specimens. Furthermore, we cloned the mutated K-ras gene from the tumors and inserted it into vectors to transfect normal bovine adrenocortical cells to express the mutated K-ras gene. The mRNA level of steroidogenic enzymes such as cholesterol sidechain cleavage enzyme (P450SCC), 17alpha-hydroxylase/17,20-lyase (P450c17), and 3beta-hydroxysteroid dehydrogenase (3betaHSD) in the mutant K-ras stably transfected cells were elevated. Cultured normal adrenocortical cells from donors and patients with adrenocortical tumors were then transfected with mutant K-ras expression plasmids constructed from human adrenal tumors. Stable transfectants grew faster than normal cells. Additionally, morphologic change was observed in the transfected cells. Moreover, when the synthesis of hormones was analyzed, the mRNA of P450SCC, P450C17, and 3betaHSD was found to have increased, and the level of cortisol was 18 to 25 times that in control cells. The increased steroid hormone production in mutant K-ras-transfected cells was reversed by lovastatin, a pharmacologic inhibitor of p21ras function. These results, combined with previous reports of steroidogenic K-ras in bovine adrenocortical cells, suggest that the K-ras oncogene is involved in steroidogenesis in human adrenocortical cells.
Wu
Chia-Hung
CH
Graduate Institute of Biochemistry, Kaohsiung Medical University Kaohsiung, Taiwan, ROC.
Lee
Su-Chen
SC
Chiu
Hua-Hsien
HH
Yang
Yuan-Chieh
YC
Lian
Shen-Tsuen
ST
Shin
Shyi-Jang
SJ
Lin
Shiu-Ru
SR
D000302:Adrenal Cortex / Q000378:metabolism* / Q000473:pathology; D000450:Aldosterone / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D002455:Cell Division; D002478:Cells, Cultured; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D006913:Hydroxysteroid Dehydrogenases / Q000235:genetics / Q000378:metabolism; D008148:Lovastatin / Q000494:pharmacology; D017354:Point Mutation; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation
D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D012333:RNA, Messenger; D000450:Aldosterone; D008148:Lovastatin; D006913:Hydroxysteroid Dehydrogenases; D002786:Cholesterol Side-Chain Cleavage Enzyme; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D006854:Hydrocortisone