The Calcium-binding Protein S100B Down-regulates p53 and Apoptosis in Malignant Melanoma
The Calcium-binding Protein S100B Down-regulates p53 and Apoptosis in Malignant Melanoma
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DOI：
10.1074/jbc.m110.155382
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发表时间：
2010-08-27
影响因子：
4.8
通讯作者：
Weber, David J.
中科院分区：
文献类型：
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作者：
Lin, Jing;Yang, Qingyuan;Weber, David J.
S100B-p53 蛋白复合物是在 C8146A 恶性黑色素瘤中发现的，但这种相互作用的后果需要进一步研究。当 siRNA (siRNA(S100B)) 抑制 C8146A 中的 S100B 表达时，wt p53 mRNA 水平不变，但 p53 蛋白、磷酸化 p53 和 p53 基因产物（即 p21 和 PIDD）增加。 siRNAS100B 转染还恢复了 C8146A 中 p53 依赖性细胞凋亡，根据聚（ADP-核糖）聚合酶切割、DNA 梯形成、半胱天冬酶 3 和 8 激活以及 Fas 死亡受体 (+UV) 的聚集来判断；然而，siRNA(S100B)对含有升高的S100B和失活的p53（p53R145L突变体）的SK-MEL-28细胞没有影响。 siRNA(S100B) 介导的细胞凋亡独立于线粒体，因为未观察到线粒体膜电位、细胞色素 c 释放、caspase 9 激活或促凋亡蛋白和抗凋亡蛋白（BAX、Bcl-2 和 Bcl-X-L）的比率发生变化。正如预期的那样，缺乏 S100B (LOX-IM VI) 的细胞不受 siRNA(S100B) 的影响，并且引入 S100B 将其 UV 诱导的细胞凋亡活性降低了 7 倍，进一步证明 S100B 抑制含有 p53 的细胞的细胞凋亡活性。在其他野生型 p53 细胞（即 C8146A、UACC-2571 和 UACC-62）中，S100B 被发现有助于 UV 处理后的细胞存活，而对于 C8146A，siRNAS100B 转染（+UV）后存活率的下降可以通过 p53 抑制剂 Pifithrin-α 逆转。总之，用 siRNA 减少 S100B 表达足以激活 p53、其转录激活活性以及涉及 Fas 死亡受体和可能 PIDD 的黑色素瘤中 p53 依赖性凋亡途径。因此，众所周知的恶性黑色素瘤标志物 S100B 可能通过下调肿瘤抑制蛋白 p53 来促进癌症进展。
The S100B-p53 protein complex was discovered in C8146A malignant melanoma, but the consequences of this interaction required further study. When S100B expression was inhibited in C8146As by siRNA (siRNA(S100B)), wt p53 mRNA levels were unchanged, but p53 protein, phosphorylated p53, and p53 gene products (i.e. p21 and PIDD) were increased. siRNAS100B transfections also restored p53-dependent apoptosis in C8146As as judged by poly (ADP-ribose) polymerase cleavage, DNA ladder formation, caspase 3 and 8 activation, and aggregation of the Fas death receptor (+UV); whereas, siRNA(S100B) had no effect in SK-MEL-28 cells containing elevated S100B and inactive p53 (p53R145L mutant). siRNA(S100B)-mediated apoptosis was independent of the mitochondria, because no changes were observed in mitochondrial membrane potential, cytochrome c release, caspase 9 activation, or ratios of pro- and anti-apoptotic proteins (BAX, Bcl-2, and Bcl-X-L). As expected, cells lacking S100B (LOX-IM VI) were not affected by siRNA(S100B), and introduction of S100B reduced their UV-induced apoptosis activity by 7-fold, further demonstrating that S100B inhibits apoptosis activities in p53-containing cells. In other wild-type p53 cells (i.e. C8146A, UACC-2571, and UACC-62), S100B was found to contribute to cell survival after UV treatment, and for C8146As, the decrease in survival after siRNAS100B transfection (+UV) could be reversed by the p53 inhibitor, pifithrin-alpha. In summary, reducing S100B expression with siRNA was sufficient to activate p53, its transcriptional activation activities, and p53-dependent apoptosis pathway(s) in melanoma involving the Fas death receptor and perhaps PIDD. Thus, a well known marker for malignant melanoma, S100B, likely contributes to cancer progression by down-regulating the tumor suppressor protein, p53.