Intersex-like (IXL) is a cell survival regulator in pancreatic cancer with 19q13 amplification
Intersex-like (IXL) is a cell survival regulator in pancreatic cancer with 19q13 amplification
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DOI：
10.1158/0008-5472.can-06-3387
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发表时间：
2007-03-01
期刊：
影响因子：
11.2
通讯作者：
Kallioniemi, Anne
中科院分区：
文献类型：
--
作者：
Kuuselo, Riina;Savinainen, Kimmo;Kallioniemi, Anne
胰腺癌是一种侵袭性很强的疾病，预后差，遗传不稳定。最近基于微阵列的全基因组调查已经确定了胰腺癌中多个复发性拷贝数畸变；然而，靶基因在很大程度上是未知的。在此，我们对胰腺癌中的19q13扩增子进行了表征，以确定可能的新药物靶点。应用荧光原位杂交技术，对16株胰腺癌细胞系和31例原发肿瘤中19q13拷贝数的增加进行了定量分析。细胞系拷贝数数据描绘了一个1.1 Mb的扩增子，在10%的原发性胰腺肿瘤中也证实了该扩增子的存在。实时定量逆转录- pcr综合表达分析表明，该区域的7个转录本在扩增细胞系与非扩增细胞系中表达水平持续升高。通过RNA干扰的高通量功能丧失筛选在扩增子上应用，以鉴定下调影响细胞活力的基因。该筛选结果显示，在扩增的PANC-1细胞中，有5个基因的下调导致细胞活力显著降低，而在未扩增的MiaPaca-2细胞中则没有，这表明该区域存在多个生物学上有趣的基因。其中，转录调节因子intersex-like （IXL）在扩增细胞中持续过表达，并对细胞活力产生最显著的影响。IXL沉默也会导致GO-G、细胞周期阻滞和PANC-1细胞凋亡增加。这些发现提示IXL在胰腺癌中是一个新的扩增靶基因，并提示在19q13扩增的肿瘤中，IXL是癌细胞存活所必需的。
Pancreatic cancer is a highly aggressive disease characterized by poor prognosis and vast genetic instability. Recent micro-array-based, genome-wide surveys have identified multiple recurrent copy number aberrations in pancreatic cancer; however, the target genes are, for the most part, unknown. Here, we characterized the 19q13 amplicon in pancreatic cancer to identify putative new drug targets. Copy number increases at 19q13 were quantitated in 16 pancreatic cancer cell lines and 31 primary tumors by fluorescence in situ hybridization. Cell line copy number data delineated a 1.1 Mb amplicon, the presence of which was also validated in 10% of primary pancreatic tumors. Comprehensive expression analysis by quantitative real-time reverse transcription-PCR indicated that seven transcripts within this region had consistently elevated expression levels in the amplified versus nonamplified cell lines. High-throughput loss-of-function screen by RNA interference was applied across the amplicon to identify genes whose down-regulation affected cell viability. This screen revealed five genes whose down-regulation led to significantly decreased cell viability in the amplified PANC-1 cells but not in the nonamplified MiaPaca-2 cells, suggesting the presence of multiple biologically interesting genes in this region. Of these, the transcriptional regulator intersex-like (IXL) was consistently overexpressed in amplified cells and had the most dramatic effect on cell viability. IXL silencing also resulted in GO-G, cell cycle arrest and increased apoptosis in PANC-1 cells. These findings implicate IXL as a novel amplification target gene in pancreatic cancer and suggest that IXL is required for cancer cell survival in 19q13-amplified tumors.