Distinct signaling pathways mediate stimulation of cell cycle progression and prevention of apoptotic cell death by estrogen in rat pituitary tumor PR1 cells.
Estrogens control cell growth and viability in target cells via an interplay of genomic and extragenomic pathways not yet elucidated. Here, we show evidence that cell proliferation and survival are differentially regulated by estrogen in rat pituitary tumor PR1 cells. Pico- to femtomolar concentrations of 17beta-estradiol (E2) are sufficient to foster PR1 cell proliferation, whereas nanomolar concentrations of the same are needed to prevent cell death that occurs at a high rate in these cells in the absence of hormone. Activation of endogenous (PRL) or transfected estrogen-responsive genes occurs at the same, higher concentrations of E2 required to promote cell survival, whereas stimulation of cyclin D3 expression and DNA synthesis occur at lower E2 concentrations. Similarly, the pure antiestrogen ICI 182,780 inhibits estrogen response element-dependent trans-activation and cell death more effectively than cyclin-cdk activity, G1-S transition, or DNA synthesis rate. In antiestrogen-treated and/or estrogen-deprived cells, death is due predominantly to apoptosis. Estrogen-induced cell survival, but not E2-dependent cell cycle progression, can be prevented by an inhibitor of c-Src kinase or by blockade of the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase signaling pathway. These data indicate the coexistence of two distinguishable estrogen signaling pathways in PR1 cells, characterized by different functions and sensitivity to hormones and antihormones.
Caporali
Simona
S
Dipartimento di Patologia generale, Seconda Università degli Studi di Napoli, 80138 Napoli, Italy.
Imai
Manami
M
Altucci
Lucia
L
Cancemi
Massimo
M
Caristi
Silvana
S
Cicatiello
Luigi
L
Matarese
Filomena
F
Penta
Roberta
R
Sarkar
Dipak K
DK
Bresciani
Francesco
F
Weisz
Alessandro
A
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D000081247:CSK Tyrosine-Protein Kinase; D002455:Cell Division / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D056743:Cyclin D3; D016213:Cyclins / Q000378:metabolism; D004261:DNA Replication / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D004967:Estrogens / Q000378:metabolism*; D005260:Female; D000077267:Fulvestrant; D005786:Gene Expression Regulation / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000502:physiology; D019061:src-Family Kinases
C534698:Ccnd3 protein, rat; D056743:Cyclin D3; D016213:Cyclins; D004791:Enzyme Inhibitors; D004965:Estrogen Antagonists; D004967:Estrogens; D000077267:Fulvestrant; D004958:Estradiol; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; D020928:Mitogen-Activated Protein Kinases