Oncogenic ETS proteins replace activated Ras/MAPK signaling in prostate cells.

Approximately 50% of prostate cancers have chromosomal translocations resulting in the over-expression one of four ETS family transcription factors. However, it is not known why these four four family members are selected for oncogenic roles, while other ETS proteins are not. We found that the four oncogenic ETS family members have a specific role in prostate cell migration. Using chromatin immunoprecipitation coupled with next-generation sequencing, this specific biological function was matched to a specific set of genomic targets highlighted by the presence of an AP-1 binding site. ETS/AP-1 binding sites are prototypical Ras-responsive elements, but oncogenic ETS proteins could activate a Ras/MAPK transcriptional program in the absence of MAPK activation. These findings indicate that the specific function of ETS proteins over-expressed in prostate cancer is the activation of a Ras/MAPK gene expression program in the absence of signaling pathway mutations. Overall design: ChIP sequencing two transcription factors in PC3 cells, four transcription factors plus a FLAG control in RWPE-1 cells and input DNA sequencing from each cell line.

约50%的前列腺癌存在染色体易位，导致4个ETS家族转录因子(ETS family transcription factors)之一过表达。然而，目前尚不明确为何这4个家族成员会被选择发挥致癌作用，而其他ETS蛋白则无此功能。本研究发现，这4种致癌性ETS家族成员在前列腺细胞迁移中具有特异性功能。本研究通过染色质免疫共沉淀(chromatin immunoprecipitation, ChIP)结合下一代测序(next-generation sequencing, NGS)技术，将这一特异性生物学功能与一组特定的基因组靶标相匹配，这类靶标以存在AP-1结合位点(AP-1 binding site)为特征。ETS/AP-1结合位点是典型的Ras应答元件，但致癌性ETS蛋白可在丝裂原活化蛋白激酶(Mitogen-Activated Protein Kinase, MAPK)未被激活的情况下，激活Ras/MAPK转录程序。上述研究结果表明，前列腺癌中过表达的ETS蛋白的特异性功能，是在信号通路未发生突变的情况下激活Ras/MAPK基因表达程序。整体实验设计：在PC3细胞中对2种转录因子进行ChIP测序；在RWPE-1细胞中对4种转录因子以及FLAG标签对照进行ChIP测序，并对每个细胞系的输入DNA进行测序。