Regulation of the cholesterol side-chain cleavage cytochrome P-450 and adrenodoxin mRNAs in cultured choriocarcinoma cells.

Abstract

Cytochrome P-450scc (P-450scc) catalyzes the cholesterol side-chain cleavage reaction, a rate-limiting enzymatic step for progesterone synthesis in trophoblastic and other steroidogenic cells. Adrenodoxin is the iron/sulfur protein donating electrons to P-450scc during this reaction. We examined the effects of cholera toxin (CT), an activator of adenylate cyclase, and 12-O-tetradecanoylphorbol acetate (TPA), a phorbol ester protein kinase C activator, on the levels of mRNAs encoding P-450scc and adrenodoxin in JEG-3 choriocarcinoma cells. CT induced in a concentration- and time-dependent manner P-450scc and adrenodoxin mRNA levels to 8-fold and 1.5-fold above that of control, respectively. TPA also increased P-450scc and adrenodoxin mRNA levels about 3-fold and 1.5-fold above that of control, respectively. Epidermal growth factor (EGF) was found to weakly induce P-450scc mRNA accumulation with a maximal 20% stimulation above basal levels. The effects of CT and TPA were apparently additive on both mRNAs. The protein synthesis inhibitor cycloheximide diminished basal, CT-, TPA-, and EGF-stimulated P-450scc mRNA accumulation whereas the opposite was observed for the adrenodoxin mRNA. Insulin-like growth factor I (IGF-I) appeared to have no effect on either mRNA. These data indicate that: (1) the accumulation of P-450scc and adrenodoxin mRNAs is mainly controlled by the cyclic adenosine 3',5'-monophosphate (cAMP)-dependent pathway but their stimulation by TPA- and EGF-induced signals may also play a weaker synergistic role; (2) the protein synthesis inhibitor cycloheximide inhibits basal, CT-, TPA- and EGF-stimulated P-450scc mRNA levels while it increases the expression of adrenodoxin mRNA suggesting that in the malignant trophoblasts these two enzyme mRNAs are differentially controlled.

• Authors: O Ritvos, R Voutilainen
• Journal: Molecular and cellular endocrinology (Mol Cell Endocrinol) Vol. 84 Issue 3 Pg. 195-202 (Apr 1992) ISSN: 0303-7207 [Print] Ireland
• PMID: 1316854 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• RNA, Messenger
• Adrenodoxin
• Epidermal Growth Factor
• Insulin-Like Growth Factor I
• Cholera Toxin
• Cholesterol
• Cycloheximide
• Cyclic AMP
• Cholesterol Side-Chain Cleavage Enzyme
• Tetradecanoylphorbol Acetate

Topics

• Adrenodoxin (biosynthesis, genetics)
• Analysis of Variance
• Blotting, Northern
• Cholera Toxin (pharmacology)
• Cholesterol (metabolism)
• Cholesterol Side-Chain Cleavage Enzyme (biosynthesis, genetics)
• Choriocarcinoma (metabolism)
• Cyclic AMP (metabolism)
• Cycloheximide (pharmacology)
• Epidermal Growth Factor (pharmacology)
• Humans
• Insulin-Like Growth Factor I (pharmacology)
• Nucleic Acid Hybridization
• RNA, Messenger (genetics, metabolism)
• Tetradecanoylphorbol Acetate (pharmacology)
• Tumor Cells, Cultured