Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
J Biol Chem. 2011 Jun 3;286(22):19381-91. doi: 10.1074/jbc.M111.218040. Epub 2011 Apr 13.
Testicular cancer is highly curable with cisplatin-based therapy, and testicular cancer-derived human embryonal carcinoma (EC) cells undergo a p53-dominant transcriptional response to cisplatin. In this study, we have discovered that a poorly characterized member of the death-associated protein family of serine/threonine kinases, STK17A (also called DRAK1), is a novel p53 target gene. Cisplatin-mediated induction of STK17A in the EC cell line NT2/D1 was prevented with p53 siRNA. Furthermore, STK17A was induced with cisplatin in HCT116 and MCF10A cells but to a much lesser extent in isogenic p53-suppressed cells. A functional p53 response element that binds endogenous p53 in a cisplatin-dependent manner was identified 5 kb upstream of the first coding exon of STK17A. STK17A is not present in the mouse genome, but the closely related gene STK17B is induced with cisplatin in mouse NIH3T3 cells, although this induction is p53-independent. Interestingly, in human cells containing both STK17A and STK17B, only STK17A is induced with cisplatin. Knockdown of STK17A conferred resistance to cisplatin-induced growth suppression and apoptotic cell death in EC cells. This was associated with the up-regulation of detoxifying and antioxidant genes, including metallothioneins MT1H, MT1M, and MT1X that have previously been implicated in cisplatin resistance. In addition, knockdown of STK17A resulted in decreased cellular reactive oxygen species, whereas STK17A overexpression increased reactive oxygen species. In summary, we have identified STK17A as a novel direct target of p53 and a modulator of cisplatin toxicity and reactive oxygen species in testicular cancer cells.
睾丸癌可以通过顺铂为基础的治疗得到高度治愈，并且睾丸癌来源的人胚癌细胞（EC）细胞对顺铂发生 p53 主导的转录反应。在这项研究中，我们发现丝氨酸/苏氨酸激酶死亡相关蛋白家族的一个特征不明确的成员，STK17A（也称为 DRAK1），是一个新的 p53 靶基因。NT2/D1 EC 细胞系中，p53 siRNA 可以阻止顺铂介导的 STK17A 的诱导。此外，在 HCT116 和 MCF10A 细胞中，顺铂诱导了 STK17A 的表达，但在同源性 p53 抑制细胞中诱导的程度要小得多。在 STK17A 的第一个编码外显子的上游 5kb 处，鉴定到一个顺铂依赖性结合内源性 p53 的功能性 p53 反应元件。STK17A 不存在于小鼠基因组中，但密切相关的基因 STK17B 在顺铂诱导的小鼠 NIH3T3 细胞中被诱导，尽管这种诱导与 p53 无关。有趣的是，在含有 STK17A 和 STK17B 的人类细胞中，只有 STK17A 被顺铂诱导。STK17A 的敲低赋予 EC 细胞对顺铂诱导的生长抑制和凋亡性细胞死亡的抗性。这与解毒和抗氧化基因的上调有关，包括先前被认为与顺铂耐药有关的金属硫蛋白 MT1H、MT1M 和 MT1X。此外，STK17A 的敲低导致细胞内活性氧减少，而 STK17A 的过表达增加活性氧。总之，我们已经确定 STK17A 是 p53 的一个新的直接靶基因，也是睾丸癌细胞中顺铂毒性和活性氧的调节剂。
