STUDIES ON MECHANISM OF AUTOCRINE GROWTH OF A HUMAN SALIVARY GLAND ADENOCARCINOMA BY EPIDERMAL GROWTH FACTOR

人涎腺腺癌细胞系HSG在自分泌生长因子的介导下自主增殖，这种生长因子是一种类似于硬膜外生长因子(EGF)的分子。本课题研究了类EGF分子对HSG细胞自分泌生长的作用机制。首先，研究了EGF受体(EGF-R)和c-erbB2原癌基因产物p185^&lt；erbB2&gt；这两个与EGF-R极为相似的受体的表达情况。免疫沉淀和免疫印迹分析表明，在HSG细胞中有EGF-R和p185^-lt；erbB2&gt；Northern blotting检测到5.6kb的EGF-R mRNA和4.6kb的c-erbB2mRNAs的表达，免疫组织化学分析证实EGF-R与p185^&lt；erbB2&gt；在HSG细胞中加入EGF样分子后，仅有170K的EGF-R被自动磷酸化，而p185^&lt；erbB2&gt；这些结果表明，虽然在HSG细胞中EGF-R和P185^-lt；erbB2&gt；共表达，但EGF-R是EGF样分子的真正受体。然而，有一种可能性是p185^；lt；erbB2；gt；参与信号转导系统。这是通过使用针对hEGF-R、p185^和lt；erbB2和gt；以及EGF的特异性抗体来抑制这些分子的功能来进行的。加入这三种抗体可抑制HSG细胞的生长。在三种抗体中，以抗p185；lt；erbB2&gt；抗体的效果最强。此外，抗EGF-R和p185的抗体可引起细胞质膜紊乱和部分细胞死亡等形态改变。因此，在HSG细胞生长的信号转导中，表达在EGF和EGF-R中的p185^&lt；erbB2&gt；在HSG细胞生长中具有重要作用。

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.