Co-expression of epidermal growth factor-receptor and c-erb B-2 proto-oncogene product in human salivary-gland adenocarcinoma cell line HSG and the implications for HSG cell autocrine growth.
The autonomous proliferation of HSG cells is mediated by an autocrine growth factor, a 46K epidermal growth factor (EGF)-like molecule. The receptor for this molecule was investigated. Immunoprecipitation and immunoblotting revealed the expression of two possible receptor molecules, EGF-R and p185erbB-2, in HSG cells. Northern blotting also revealed the co-expression of 5.6-kb EGF-R mRNA and 4.6-kb c-erb B-2 mRNA. When the purified EGF-like molecule was added to the cultures, EGF-R but not p185erbB-2 was autophosphorylated. These results suggest that, although both EGF-R and p185erbB-2 are co-expressed in HSG cells, the EGF-R is the genuine receptor for the EGF-like molecule. However, there is a possibility that p185erB-2 is involved in the signal transduction system. This possibility was examined by using specific antibodies to human EGF-R (hEGF-R), p185erbB-2, and EGF to inhibit the functions of these molecules. Addition of these three antibodies to the cultures inhibited the growth of HSG cells. The antibodies to EGF-R and p185erbB-2 also caused morphological changes such as disturbances of the plasma membrane, and some cell death. Surprisingly, the effect of the anti-p185erbB-2 antibody on growth inhibition and morphology was stronger than that of the anti-hEGF-R antibody. Thus, p185erB-2 expressed in HSG cells has an important function in the signal transduction of HSG cell growth.
Kyakumoto
S
S
Department of Biochemistry, Iwate Medical University School of Dentistry, Morioka, Japan.
Kurokawa
R
R
Hoshino
M
M
Ota
M
M
D000818:Animals; D016923:Cell Death; D002462:Cell Membrane / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004815:Epidermal Growth Factor / Q000502:physiology; D066246:ErbB Receptors / Q000096:biosynthesis*; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger / Q000032:analysis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis*; D011956:Receptors, Cell Surface; D012469:Salivary Glands / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D015398:Signal Transduction; D014407:Tumor Cells, Cultured / Q000378:metabolism
D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D006023:Glycoproteins; D011505:Protein-Tyrosine Kinases; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases; D011956:Receptors, Cell Surface; C000715470:MAS1 protein, human