Progestin Increases Gene Transcription and Messenger Ribonucleic Acid Stability of Fatty Acid Synthetase in Breast Cancer Cells

Abstract

The cDNA clone (Pg8) corresponding to the 3'-end of fatty acid synthetase (FAS) mRNA is one of the few probes to study in cell lines the mechanism by which an endogenous gene is regulated by progestins. The steady-state level of FAS mRNA is known to be increased by the synthetic progestin R5020 in the human breast cancer cell line MCF7. We show here that it is also increased in another progesterone-receptor-positive cell line T47D but not in progesterone-receptor-negative cell lines BT20, MDA-MB231, and HBL100. In R5020-treated MCF7 cells, the FAS mRNA concentration increased with cell density. Protein synthesis inhibitors did not abolish progestin induction of FAS suggesting a primary effect of the hormone. In vitro nuclear run-on transcription assays showed that the FAS gene transcription rate was increased about 4-fold by progestin. This stimulation of transcription was detectable 30 min after addition of R5020 and was maximal after 4 h, but could not totally account for the total increase in the mRNA steady state level. Chase experiments in the presence of Actinomycin D or Cordycepin showed that progestin also increased the half-life of FAS mRNA from 6-9 h to 24-33 h. We conclude that progestin stimulates the FAS concentration both by increasing the transcription rate of the gene and by stabilizing the mRNA.

TReP-132 Is a Novel Progesterone Receptor Coactivator Required for the Inhibition of Breast Cancer Cell Growth and Enhancement of Differentiation by Progesterone

“…7A). Moreover, concurring with previous data (16,35), progesterone increased the expression of FAS and ALP, which are markers of differentiation correlating with lipid storage in breast cancer cells (9,15) (Fig. 7B).…”

“…Therefore, we tested whether siRNA silencing of TReP-132 also influences the effects of progesterone on T47D cell differentiation. To this end, the expression levels of a panel of previously identified markers of early and terminal differentiation in breast cancer cells (15,35,37) were analyzed ( Fig. 7A and B).…”

Inhibition of tumor-associated fatty acid synthase activity antagonizes estradiol- and tamoxifen-induced agonist transactivation of estrogen receptor (ER) in human endometrial adenocarcinoma cells

“…Under the same conditions, high concentrations of cerulenin and C75 (45 mg/ml) completely inhibited endometrial adenocarcinoma cell growth. Early studies previously demonstrated that in hormone-responsive human breast cancer cells (MCF-7 and T47-D), E 2 stimulates cell growth and concomitant FAS expression (Joyeux et al, 1989;Chalbos et al, 1992;Kalkhoven et al, 1994). Corroborating these observations in endometrial adenocarcinoma cells, we found that E 2 stimulation significantly upregulated FAS expression in Ishikawa cells, while the pure antiestrogen ICI 182,780 significantly abolished this effect, as revealed by Western blotting analyses (Figure 3b).…”

“…Thus, FAS expression is part of the E 2 -driven cellular response that leads to proliferation in hormone-dependent endometrial carcinoma cells and associated with higher endometrial tumor grades (Pizer et al, 1998b). E 2 , progesterone, and synthetic progestins also stimulate cell growth and concomitant FAS expression in hormone-dependent human breast cancer cells such as MCF-7 and T47-D (Joyeux et al, 1989;Chalbos et al, 1992;Kalkhoven et al, 1994). In the androgendependent prostate cancer cell line LNCaP, androgens have been shown to stimulate coordinate expression of FAS and enzymes involved in cholesterol synthesis (Swinnen et al, 1997;Heemers et al, 2001).…”

Essential Amino Acids Regulate Fatty Acid Synthase Expression through an Uncharged Transfer RNA-dependent Mechanism

“…Triiodothyronine stimulates FAS gene transcription in cultured chick embryo hepatocytes (7) and mouse 3T3-L1 adipocytes (8). Progesterone stabilizes FAS mRNA levels (9).…”