Identification of Novel Androgen-Regulated Pathways and mRNA Isoforms through Genome-Wide Exon-Specific Profiling of the LNCaP Transcriptome
Identification of Novel Androgen-Regulated Pathways and mRNA Isoforms through Genome-Wide Exon-Specific Profiling of the LNCaP Transcriptome
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DOI：
10.1371/journal.pone.0029088
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发表时间：
2011-12-14
期刊：
影响因子：
3.7
通讯作者：
Elliott, David J.
中科院分区：
文献类型：
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作者：
Rajan, Prabhakar;Dalgliesh, Caroline;Elliott, David J.
雄激素通过调节雄激素受体（AR）转录活性来驱动前列腺癌（PCa）的发生和进展。虽然几个基于微阵列的研究已经确定了雄激素调控的基因，在这里，我们确定在平行的全球雄激素依赖性的变化，基因和替代mRNA亚型表达的外显子水平分析的LNCaP转录组。虽然全基因组基因表达变化与先前发表的研究相关性很好，但我们还发现了226个新的雄激素调节基因的子集。该亚组的基因表达途径分析揭示了与酪氨酸激酶林恩相关并包括酪氨酸激酶的基因簇，以及mTOR（雷帕霉素的哺乳动物靶）途径的组分，其通常在癌症中失调。我们还确定了1279个假定的雄激素调节的替代事件，其中325个（类似于25%）映射到已知的选择性剪接事件或替代第一/最后一个外显子。我们选择了30个雄激素依赖的替代事件进行RT-PCR验证，包括来自编码肿瘤抑制因子和细胞周期调节因子的基因的mRNA。在7个阳性验证事件（类似于23%）中，5个事件涉及来自已知AR基因靶标的替代启动子的转录物。特别是，我们发现了一种新的雄激素依赖性mRNA亚型，来源于TSC 2肿瘤抑制基因内的替代内部启动子，预计该基因编码的蛋白质缺乏mTOR抑制所需的相互作用结构域。我们证实，这种替代TSC 2 mRNA亚型的表达直接受雄激素调节，染色质免疫沉淀表明，在雄激素刺激后的早期时间点，AR募集到替代启动子区域，这与替代转录本的表达相关。总之，我们的数据表明，替代mRNA亚型表达可能介导细胞对雄激素的反应，并可能在临床PCa中发挥作用。
Androgens drive the onset and progression of prostate cancer (PCa) by modulating androgen receptor (AR) transcriptional activity. Although several microarray-based studies have identified androgen-regulated genes, here we identify in-parallel global androgen-dependent changes in both gene and alternative mRNA isoform expression by exon-level analyses of the LNCaP transcriptome. While genome-wide gene expression changes correlated well with previously-published studies, we additionally uncovered a subset of 226 novel androgen-regulated genes. Gene expression pathway analysis of this subset revealed gene clusters associated with, and including the tyrosine kinase LYN, as well as components of the mTOR (mammalian target of rapamycin) pathway, which is commonly dysregulated in cancer. We also identified 1279 putative androgen-regulated alternative events, of which 325 (similar to 25%) mapped to known alternative splicing events or alternative first/last exons. We selected 30 androgen-dependent alternative events for RT-PCR validation, including mRNAs derived from genes encoding tumour suppressors and cell cycle regulators. Of seven positively-validating events (similar to 23%), five events involved transcripts derived from alternative promoters of known AR gene targets. In particular, we found a novel androgen-dependent mRNA isoform derived from an alternative internal promoter within the TSC2 tumour suppressor gene, which is predicted to encode a protein lacking an interaction domain required for mTOR inhibition. We confirmed that expression of this alternative TSC2 mRNA isoform was directly regulated by androgens, and chromatin immunoprecipitation indicated recruitment of AR to the alternative promoter region at early timepoints following androgen stimulation, which correlated with expression of alternative transcripts. Together, our data suggest that alternative mRNA isoform expression might mediate the cellular response to androgens, and may have roles in clinical PCa.