Lee Ming-Shyue, Igawa Tsukasa, Lin Ming-Fong
Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, 984525 Nebraska Medical Center, Omaha, NE 68198-4525, USA.
Oncogene. 2004 Apr 15;23(17):3048-58. doi: 10.1038/sj.onc.1207451.
The involvement of tyrosine phosphorylation signaling pathways in steroid-induced cell proliferation has received much attention. However, the adaptor molecule that mediates this interaction remains to be identified. In this communication, we identify p52(Shc) as the mediator between tyrosine phosphorylation signaling and steroid signaling in steroid-responsive cell proliferation. Although the different LNCaP prostate cancer cells, C-33, C-51 and C-81, express similar levels of functional androgen receptor (AR), they exhibit different levels of androgen sensitivity. C-33 cell proliferation is highly responsive to the presence of androgens, whereas C-51 cell proliferation is comparatively less responsive to androgens. In contrast, C-81 cell proliferation is independent of androgens. In these cells, tyrosine phosphorylation levels of both p52(Shc) and ErbB-2 were greatest in C-81 cells, comparatively less in C-51 cells and weaker in C-33 cells. The levels and activity of protein tyrosine phosphatase, cellular prostatic acid phosphatase, decreased correspondingly in those cells. In both androgen-independent, rapidly growing C-81 and ErbB-2 cDNA-transfected C-33 cells, p52(Shc) was hyperphosphorylated at Tyr317 (Y317). Conversely, p52(Shc) tyrophosphorylation was decreased in prostatic acid phosphatase cDNA-transfected stable subclones of C-81 cells, which restore androgen-sensitive proliferation and leads to slow growth rates. In C-33 cells, androgen-stimulated cell proliferation correlated with tyrophosphorylation of ErbB-2 and increased phosphorylation of p52(Shc) at Y317, but not at Y239, differing from phosphorylation patterns associated with epidermal growth factor (EGF) stimulation. Furthermore, overexpression of a mutant of p52(Shc), that is Y317F, blocks Y317 phosphorylation of endogenous p52(Shc) and abolishes androgen-stimulated proliferation, but not EGF-stimulated proliferation. Thus, Y317 of p52(Shc) serves as an important regulatory site that allows tyrosine phosphorylation pathways to moderate androgen sensitivity in human prostate cancer cells.
酪氨酸磷酸化信号通路在类固醇诱导的细胞增殖中的作用已备受关注。然而，介导这种相互作用的衔接分子仍有待确定。在本通讯中，我们确定p52(Shc)是类固醇反应性细胞增殖中酪氨酸磷酸化信号与类固醇信号之间的介质。尽管不同的LNCaP前列腺癌细胞、C-33、C-51和C-81表达相似水平的功能性雄激素受体(AR)，但它们表现出不同程度的雄激素敏感性。C-33细胞增殖对雄激素的存在高度敏感，而C-51细胞增殖对雄激素的反应相对较弱。相比之下，C-81细胞增殖与雄激素无关。在这些细胞中，p52(Shc)和ErbB-2的酪氨酸磷酸化水平在C-81细胞中最高，在C-51细胞中相对较低，在C-33细胞中较弱。那些细胞中蛋白质酪氨酸磷酸酶（细胞前列腺酸性磷酸酶）的水平和活性相应降低。在雄激素非依赖性、快速生长的C-81细胞和ErbB-2 cDNA转染的C-33细胞中，p52(Shc)在Tyr317 (Y317)处发生过度磷酸化。相反，在前列腺酸性磷酸酶cDNA转染的C-81细胞稳定亚克隆中，p52(Shc)的酪氨酸磷酸化降低，该亚克隆恢复了雄激素敏感性增殖并导致生长速率减慢。在C-33细胞中，雄激素刺激的细胞增殖与ErbB-2的酪氨酸磷酸化以及p52(Shc)在Y317而非Y239处磷酸化增加相关，这与表皮生长因子(EGF)刺激相关的磷酸化模式不同。此外，p52(Shc)的Y317F突变体的过表达阻断了内源性p52(Shc)的Y317磷酸化并消除了雄激素刺激的增殖，但不影响EGF刺激的增殖。因此，p52(Shc)的Y317作为一个重要的调节位点，使酪氨酸磷酸化途径能够调节人前列腺癌细胞中的雄激素敏感性。
