Superinduction of c-fos gene expression by estrogen in cultured guinea-pig endometrial cells requires priming by a cycloheximide-dependent mechanism.
The c-fos gene expression is rapidly induced by various mitogenic agents and protein synthesis inhibitors in many cell types. Estradiol-17 beta can induce c-fos gene expression in breast cancer cell lines and in the uterus in vivo, but not in cultured guinea-pig endometrial cells. Using this model, we investigated whether a protein synthesis inhibitor, cycloheximide, could induce the c-fos gene and permit a superinduction by estrogens. In the presence of cycloheximide (10 micrograms/ml), protein synthesis was inhibited at 95% within the first hour. From 190 min after the addition of estradiol-17 beta or diethylstilbestrol (10(-8) M) and cycloheximide (10 micrograms/ml), there was a significant increase (ranging from 3- to 5-fold) of the c-fos messenger RNA level (2.2 kilobase in size), compared with the level in cells treated with cycloheximide alone. Nonestrogenic steroid hormones and estradiol-17 alpha were unable to induce c-fos gene expression in the presence of cycloheximide. The effect of estradiol-17 beta observed in the presence of cycloheximide was completely abolished by 4-hydroxy-tamoxifen or by Ly 156758 or by ICI 164384 (10(-6) M). The c-fos mRNAs were rather stable in cells treated with cycloheximide for 2 h (half-life = 51 +/- 6 min) and there was no further increase in the c-fos messenger RNA stability after the addition of cycloheximide plus estradiol-17 beta (half-life = 40 +/- 3 min). The overall results suggest a response at the transcriptional level. In conclusion, cycloheximide transmits activating signals to the c-fos gene which act as priming elements to allow the estrogen action in cultured guinea-pig endometrial cells.
Pellerin
I
I
INSERM U 198, Besançon, France.
Vuillermoz
C
C
Jouvenot
M
M
Royez
M
M
Ordener
C
C
Marechal
G
G
Adessi
G
G
D000735:Androstenedione / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology*; D004054:Diethylstilbestrol / Q000494:pharmacology; D004717:Endometrium / Q000187:drug effects / Q000502:physiology*; D004958:Estradiol / Q000494:pharmacology*; D004964:Estriol / Q000494:pharmacology; D004970:Estrone / Q000494:pharmacology; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D016762:Genes, fos; D006168:Guinea Pigs; D006854:Hydrocortisone / Q000494:pharmacology; D007700:Kinetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013629:Tamoxifen / Q000494:pharmacology*; D013739:Testosterone / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects
D012333:RNA, Messenger; D013629:Tamoxifen; D004970:Estrone; D013739:Testosterone; D000735:Androstenedione; D004958:Estradiol; D004054:Diethylstilbestrol; D003513:Cycloheximide; D004964:Estriol; D006854:Hydrocortisone