RFP_（134）对UMR106细胞EGF受体酪氨酸蛋白激酶的调节作用

以大鼠成骨肉瘤细胞（ＵＭＲ１０６）为模型，研究了表皮生长因子（ＥＧＦ）对其受体酪氨酸蛋白激酶（ＴＰＫ）的调节作用。以本实验室从植物中提取纯化的二萜类活性物质（ＲＦＰ１３４）为诱导分化剂，观察了ＲＦＰ１３４对ＵＭＲ１０６细胞ＥＧＦ受体ＴＰＫ的活性和磷酸化作用的影响，并与ＲＡ和ＲＦＰ１３４＋ＲＡ处理细胞做了比较，结果显示ＥＧＦ与其受体结合后能激活ＴＰＫ，使ＴＰＫ活性增加２倍．ＲＦＰ１３４，ＲＡ，ＲＦＰ１３４＋ＲＡ处理细胞后，分别降低ＥＧＦ诱导的受体ＴＰＫ活性５０％，４３％，５５％，降低磷酸化ＴＰＫ含量５５％，３６％，５３％。从结果中发现无ＥＧＦ刺激的细胞也具有受体ＴＰＫ磷酸化作用，用ＲＦＰ１３４，ＲＡ，ＲＦＰ１３４＋ＲＡ处理细胞，分别降低受体磷酸化ＴＰＫ含量５９％，４０％，５７％，而且我们发现用ＥＧＦ诱导的细胞受体ＴＰＫ含量高于无ＥＧＦ作用的细胞．提示ＵＭＲ１０６细胞本身可能具有受体ＴＰＫ活性，能够引起细胞受体自动磷酸化，ＥＧＦ刺激后ＴＰＫ的磷酸化作用增强，可见ＲＦＰ１３４对ＥＧＦ诱导的ＴＰＫ磷酸化和无ＥＧＦ诱导的受体自动磷酸化都具有明显的抑制作用，（并强于ＲＡ）这可能与在第二信使水平上阻抑ＰＴＰＫ活性密切相关

Modulation of RFP_(134) on Tryosine Protein Kinase of Epidermal Growth Factor Receptor in UMR106 Cell

In this study, regulation of epidermal growth factor (EGF) on tyrosine protein kinase (TPK) of its receptor in the rat osteoblastsarcoma UMR106 cell was investigated. The influence of activation and phosphorylation of RFP134 on EGF receptor-specific TPK was studied. RFP134, a diterpen was extracted from the plant, was regarded as an inducer of cell differentiation and its effect was compared with RA or RFP134+RA. The result showed that TPK was activated by EGF binding with its receptor, its activity was increased 2 folds. While UMR106 cells were pre-treated with RFP134, RA or RFP134+RA, the activities of EGF receptor-specific TPK were reduced 50%, 43%,55% respectively and the amount of phosphorylated TPK were decreased 55%,36%,53% respectively.However, we also found that without EGF stimulation, a limited phosphorylation of EGF receptor-specific TPK in UMR106 cells could also appear. When the cells were pre-treated with RFP134, RA, RFP134+RA, the amount of phosphorylated TPK were reduced 59%, 40%, 57% respectivily.In the meantime we also found that the amount of phosphorylated EGFreceptor-specific TPK in UMR106 cell stimulated with EGF was higher than without EGF.These results suggest that UMR106 cell itself possessed the activity of EGF receptorspecific TPK. It can cause initiative phosphorylation in UMR106 cell and the phosphorylation can be improved as stimulated by EGF. The result in this study demonstrated that RFP134 distinctly restrain the phosphoryaltion of EGF receptor-specific TPK induced by EGF and the initiative phosphorylaiton without EGF in UMR106 cell. Therefore RFP134 could be a potential antitumor agent.