Xu Lei, Hazard Florette K, Zmoos Anne-Flore, Jahchan Nadine, Chaib Hassan, Garfin Phillip M, Rangaswami Arun, Snyder Michael P, Sage Julien
Department of Pediatrics Department of Genetics and.
Department of Pediatrics Department of Pathology, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA.
Hum Mol Genet. 2015 Jan 1;24(1):50-63. doi: 10.1093/hmg/ddu418. Epub 2014 Aug 13.
Pediatric tumors are relatively infrequent, but are often associated with significant lethality and lifelong morbidity. A major goal of pediatric cancer research has been to identify key drivers of tumorigenesis to eventually develop targeted therapies to enhance cure rate and minimize acute and long-term toxic effects. Here, we used genomic approaches to identify biomarkers and candidate drivers for fibrolamellar hepatocellular carcinoma (FL-HCC), a very rare subtype of pediatric liver cancer for which limited therapeutic options exist. In-depth genomic analyses of one tumor followed by immunohistochemistry validation on seven other tumors showed expression of neuroendocrine markers in FL-HCC. DNA and RNA sequencing data further showed that common cancer pathways are not visibly altered in FL-HCC but identified two novel structural variants, both resulting in fusion transcripts. The first, a 400 kb deletion, results in a DNAJB1-PRKCA fusion transcript, which leads to increased cAMP-dependent protein kinase (PKA) activity in the index tumor case and other FL-HCC cases compared with normal liver. This PKA fusion protein is oncogenic in HCC cells. The second gene fusion event, a translocation between the CLPTM1L and GLIS3 genes, generates a transcript whose product also promotes cancer phenotypes in HCC cell lines. These experiments further highlight the tumorigenic role of gene fusions in the etiology of pediatric solid tumors and identify both candidate biomarkers and possible therapeutic targets for this lethal pediatric disease.
儿童肿瘤相对少见,但往往与显著的致死率和终身发病相关。儿童癌症研究的一个主要目标是确定肿瘤发生的关键驱动因素,最终开发靶向治疗方法,以提高治愈率并将急性和长期毒性作用降至最低。在此,我们采用基因组学方法来鉴定纤维板层状肝细胞癌(FL-HCC)的生物标志物和候选驱动因素,FL-HCC是一种非常罕见的儿童肝癌亚型,其治疗选择有限。对一个肿瘤进行深入的基因组分析,随后对其他七个肿瘤进行免疫组化验证,结果显示FL-HCC中存在神经内分泌标志物的表达。DNA和RNA测序数据进一步表明,常见的癌症通路在FL-HCC中没有明显改变,但鉴定出两个新的结构变异,均导致融合转录本。第一个变异是400 kb的缺失,导致DNAJB1-PRKCA融合转录本,与正常肝脏相比,该转录本在索引肿瘤病例和其他FL-HCC病例中导致cAMP依赖性蛋白激酶(PKA)活性增加。这种PKA融合蛋白在肝癌细胞中具有致癌性。第二个基因融合事件是CLPTM1L和GLIS3基因之间的易位,产生一种转录本,其产物在肝癌细胞系中也促进癌症表型。这些实验进一步突出了基因融合在儿童实体瘤病因中的致瘤作用,并确定了这种致命儿童疾病的候选生物标志物和可能的治疗靶点。