Mollerup S, Rivedal E, Mæhle L, Haugen A
Department of Toxicology, National Institute of Occupational Health, Norway.
Carcinogenesis. 1996 Feb;17(2):361-7. doi: 10.1093/carcin/17.2.361.
We have previously described immortalization of normal human kidney epithelial cells by nickel(II) and the subsequent tumorigenic conversion by v-Ha-ras transfection. We report here that nickel(II) induces alterations in growth regulatory control. Normal human kidney epithelial cells (NHKE) were growth inhibited by transforming growth factor beta 1 (TGF-beta 1). This effect was abrogated in both the immortalized (IHKE) and transformed (THKE) cells. NHKE expressed approximately 4700 high-affinity binding sites/cell for TGF-beta 1. IHKE and THKE showed reduced binding of 47% and 44% relative to NHKE respectively. On the other hand, expression of epidermal growth factor (EGF) receptors was elevated in IHKE (260%) and THKE (236%) relative to NHKE, which expressed 1.5 x 10(5) receptors/cell. Preincubation of IHKE and THKE with TGF-beta 1 resulted in reduced EGF binding, whereas this binding was unaltered in NHKE. Exposure of human kidney epithelial cells to EGF led to tyrosine phosphorylation of the EGF receptor and other cellular proteins in the mol. wt range from 42 to > 300 kDa. The level of receptor phosphorylation induced by EGF reflected receptor expression. Tyrosine phosphorylated proteins appear to be identical in all three cell lines, and reach phosphorylation maxima independently of EGF receptor expression. These studies indicate that nickel carcinogenesis may involve changes in sets of genes important in normal growth regulation.
我们之前已经描述过通过镍（II）使正常人肾上皮细胞永生化以及随后通过v-Ha-ras转染实现致瘤性转化的过程。我们在此报告，镍（II）会诱导生长调节控制的改变。正常人肾上皮细胞（NHKE）受到转化生长因子β1（TGF-β1）的生长抑制。在永生化细胞（IHKE）和转化细胞（THKE）中这种效应均被消除。NHKE细胞对TGF-β1的高亲和力结合位点约为4700个/细胞。相对于NHKE，IHKE和THKE的结合分别减少了47%和44%。另一方面，相对于每个细胞表达1.5×10⁵个受体的NHKE，表皮生长因子（EGF）受体在IHKE（增加260%）和THKE（增加236%）中的表达有所升高。用TGF-β1预孵育IHKE和THKE会导致EGF结合减少，而在NHKE中这种结合未改变。将人肾上皮细胞暴露于EGF会导致EGF受体和分子量范围从42至>300 kDa的其他细胞蛋白发生酪氨酸磷酸化。由EGF诱导的受体磷酸化水平反映了受体表达情况。酪氨酸磷酸化蛋白在所有三种细胞系中似乎是相同的，并且在不依赖于EGF受体表达的情况下达到磷酸化最大值。这些研究表明镍致癌作用可能涉及正常生长调节中重要的基因集的变化。
