| Co-Investigator(Kenkyū-buntansha) |
NAGAI Masazumi ibib. Assistant, 歯学部, 助手 (00217960)
KYAKUMOTO Seiko ibib. Assistant, 歯学部, 助手 (90118274)
KUROKAWA Riki ibib. Assistant, 歯学部, 助手 (70170107)
NEMOTO Takayuki ibib. Assistant, 歯学部, 講師 (90164665)
SATO Nobuko Iwata Medical University School of Dentistry Department of Biochemistry Instruct, 歯学部, 助教授 (00048399)
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| Research Abstract |
The human salivary gland adenocarcinoma cell line HSG proliferates autonomously, with the proliferation mediated by an autocrine growth factor, a Mr.46K epidrmal growth factor(EGF)-like molecule. In this project, the mechanism of autocrine growth of HSG by EGF-like molecule was investigated. Firstly, the expression of the intuitive candidates for the receptor, EGF receptor (EGF-R) and c-erbB2 protooncogene product, p185^<erbB2>, which closely resembles EGF-R and seems also to be a cell surface receptor, was examined. Immunoprecipitation and immunoblotting analyzes using the antibody specific to each protein revealed the expression of both EGF-R and p185^<erbB2> in HSG cells. Northern blotting analyzes also revealed the expression of 5.6 kb EGF-R mRNA and 4.6 kb c-erbB2 mRNA.The co-expression of EGF-R and p185^<erbB2> was also confirmed by immunohistochemical analyzes. When EGF-like molecule was added to the HSG cell cultures, only 170K EGF-R was autophosphorylated, and p185^<erbB2> was not. These result suggested that, although both EGF-R and p185^<erbB2> are co-expressed in HSG cells, the EGF-R is the genuine receptor for the EGF-like molecule. However, there is a possibility that p185^<erbB2> is involved in the signal transduction system. This was examined by using specific antibodies to hEGF-R, p185^<erbB2>, and EGF to inhibit the functions of these molecules. Addition of these three antibodies to the cultures inhibited the growth of HSG cells. Particularly, the effect of the anti-p185^<erbB2> antibody was the strongest in three antibodies. Moreover, the antibodies to EGF-R and p185^<erbB2> caused morphological changes such as disturbances of the plasma membrane, and some cell death. Thus, p185^<erbB2> expressed in EGF as well as EGF-R has an important function in the signal transduction of HSG cell growth.
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