Tyrosine kinase/p21ras/MAP-kinase pathway activation by estradiol-receptor complex in MCF-7 cells.
The mechanism by which estradiol acts on cell multiplication is still unclear. Under conditions of estradiol-dependent growth, estradiol treatment of human mammary cancer MCF-7 cells triggers rapid and transient activation of the mitogen-activated (MAP) kinases, erk-1 and erk-2, increases the active form of p21ras, tyrosine phosphorylation of Shc and p190 protein and induces association of p190 to p21ras-GAP. Both Shc and p190 are substrates of activated src and once phosphorylated, they interact with other proteins and upregulate p21ras. Estradiol activates the tyrosine kinase/p21ras/MAP-kinase pathway in MCF-7 cells with kinetics which are similar to those of peptide mitogens. It is only after introduction of the human wild-type 67 kDa estradiol receptor cDNA that Cos cells become estradiol-responsive in terms of erk-2 activity. This finding, together with the inhibition by the pure anti-estrogen ICI 182 780 of the stimulatory effect of estradiol on each step of the pathway in MCF-7 cells proves that the classic estradiol receptor is responsible for the transduction pathway activation. Transfection experiments of Cos cells with the estradiol receptor cDNA and in vitro experiments with c-src show that the estradiol receptor activates c-src and this activation requires occupancy of the receptor by hormone. Our experiments suggest that c-src is an initial and integral part of the signaling events mediated by the estradiol receptor.
Migliaccio
A
A
Istituto di Patologia Generale e Oncologia, Facoltà di Medicina e Chirurgia, Napoli, Italia.
Di Domenico
M
M
Castoria
G
G
de Falco
A
A
Bontempo
P
P
Nola
E
E
Auricchio
F
F
D001943:Breast Neoplasms / Q000378:metabolism*; D000081247:CSK Tyrosine-Protein Kinase; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D020662:Guanine Nucleotide Exchange Factors; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009687:Nuclear Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism; D011959:Receptors, Estradiol / Q000378:metabolism*; D012097:Repressor Proteins; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D020666:ras-GRF1; D018909:src Homology Domains; D019061:src-Family Kinases
C074560:ARHGAP35 protein, human; D020662:Guanine Nucleotide Exchange Factors; D009687:Nuclear Proteins; D010750:Phosphoproteins; C513039:RASGRF1 protein, human; D011959:Receptors, Estradiol; D012097:Repressor Proteins; D020666:ras-GRF1; D004958:Estradiol; D006160:Guanosine Triphosphate; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D016392:Proto-Oncogene Proteins pp60(c-src); D019061:src-Family Kinases; C000631346:CSK protein, human; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)