Protein kinase C is differentially regulated by thrombin, insulin, and epidermal growth factor in human mammary tumor cells.
The exposure of serum-deprived mammary tumor cells MCF-7 and T-47D to insulin, thrombin, and epidermal growth factor (EGF) resulted in dramatic modifications in the activity and in the translocation capacity of protein kinase C from cytosol to membrane fractions. Insulin induces a 600% activation of the enzyme after 5 h of exposure to the hormone in MCF-7 cells; thrombin either activates (200% in MCF-7) or down-regulates (in T-47D), and EGF exerts only a moderate effect. Thus, the growth factors studied modulate differentially the protein kinase C activity in human mammary tumor cells. The physiological significance of the results obtained are discussed in terms of the growth response elicited by insulin, thrombin, and EGF.
Gomez
M L
ML
Instituto de Ingeniería Genética y Biología Molecular (INGEBI, CONICET, Buenos Aires, Argentina.
Medrano
E E
EE
Cafferatta
E G
EG
Tellez-Inon
M T
MT
D001943:Breast Neoplasms / Q000201:enzymology; D002455:Cell Division; D002462:Cell Membrane / Q000201:enzymology; D003593:Cytoplasm / Q000201:enzymology; D004815:Epidermal Growth Factor / Q000502:physiology*; D006801:Humans; D007328:Insulin / Q000502:physiology*; D011493:Protein Kinase C / Q000502:physiology*; D013917:Thrombin / Q000502:physiology*; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000201:enzymology
D007328:Insulin; D004815:Epidermal Growth Factor; D011493:Protein Kinase C; D013917:Thrombin