Epidermal growth factor binding and protein kinase C activities in human breast cancer cell lines: possible quantitative relationship.
Quantitative polyacrylamide gel electrophoresis analysis of Ca2+, phospholipid-dependent protein kinase (PKC) of human mammary tumor cell lines (MCF-7, ZR-75, T-47-D, MDA-MB-231, BT-20, and HBL-100) revealed that 80% of the total cellular PKC resided in the cytosol. The tumor cells with no detectable levels of estrogen receptors (MDA-MB-231, HBL-100, and BT-20 cells) exhibited significantly larger (P less than 0.001) cytosolic PKC activities than those cells that contained estrogen receptors (MCF-7, T-47-D, and ZR-75 cells). In addition, in estrogen receptor-negative cell lines, relatively high levels of specific low-affinity (apparent Kd = 700 pM) epidermal growth factor (EGF) binding activities were found as compared with estrogen receptor-positive cells with significantly (P less than 0.001) lower levels of specific high-affinity (apparent Kd = 90 pM) EGT binding. A significant positive correlation (P less than 0.01) was observed between the number of EGF receptor (Rs = 0.50) and/or the EGF receptor dissociation constants (Rs = 0.78) with the cytosolic PKC activity levels. These data indicate that, in human breast cancer cells, a positive relationship may exist between PKC activity, estrogen, and EGF receptors.
D001943:Breast Neoplasms / Q000032:analysis*; D002460:Cell Line; D002848:Chromatography, DEAE-Cellulose; D003600:Cytosol / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D011493:Protein Kinase C / Q000032:analysis*; D011956:Receptors, Cell Surface / Q000032:analysis*; D011960:Receptors, Estrogen / Q000032:analysis
D007457:Iodine Radioisotopes; D011956:Receptors, Cell Surface; D011960:Receptors, Estrogen; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D011493:Protein Kinase C