Korc M
Department of Medicine, University of California, Irvine 92717.
Int J Pancreatol. 1990 Aug-Nov;7(1-3):71-81. doi: 10.1007/BF02924222.
The epidermal growth factor (EGF) receptor is a transmembrane protein that has tyrosine kinase activity. It is activated by both EGF and transforming growth factor-alpha (TGF-alpha). Human pancreatic cancer cells overexpress the EGF receptor and exhibit a parallel increase in EGF receptor mRNA without a detectable increase in the number of gene copies coding for the receptor. These cells also produce TGF-alpha and are capable of binding exogenous TGF-alpha. They often recycle EGF, but markedly and rapidly degrade TGF-alpha. However, TGF-alpha is 10-100-fold more potent than EGF in enhancing their anchorage-independent growth. Both growth factors induce EGF receptor down-regulation, but EGF is more efficient than TGF-alpha in this regard. The concomitant overexpression of the EGF receptor and production of TGF-alpha, the recycling of EGF, and the attenuated ability of TGF-alpha to down-regulate the EGF receptor may combine to provide a distinct growth advantage to human pancreatic cancer cells.
表皮生长因子（EGF）受体是一种具有酪氨酸激酶活性的跨膜蛋白。它可被表皮生长因子（EGF）和转化生长因子-α（TGF-α）激活。人胰腺癌细胞过度表达EGF受体，且EGF受体mRNA水平相应升高，但编码该受体的基因拷贝数并未显著增加。这些细胞还能产生TGF-α，并能够结合外源性TGF-α。它们常常循环利用EGF，但能显著且迅速地降解TGF-α。然而，在促进其非锚定依赖性生长方面，TGF-α的效力比EGF强10至100倍。两种生长因子均可诱导EGF受体下调，但在这方面EGF比TGF-α更有效。EGF受体的过度表达与TGF-α的产生、EGF的循环利用以及TGF-α下调EGF受体能力的减弱，可能共同赋予人胰腺癌细胞独特的生长优势。
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