Innate Immune Signaling in Fibrolamellar Carcinoma

纤维板细胞癌（FLC）是一种罕见的肝癌，困扰儿童和年轻人。当时 在诊断时，约60%的患者的癌症是IV期，没有有效的治疗选择。对其余 40%，肝移植是唯一的治愈性治疗，只要能及时找到合适的供体， 然后，有短期和长期并发症的重大风险。 事实上，所有FLC患者在第19染色体上都有基因组改变，导致FLC的DNAJB 1外显子1融合。 Hsp 40家族与PKA的催化亚基PRKACA的外显子2-10。得到的DNAJB 1-PRKACA融合物 基因编码具有保留的催化活性的Dnajb 1-Prkaca蛋白。使用CRISPR/Cas9技术 结合流体动力学尾静脉注射，我们和其他人已经得出结论，一个同线Dnajb 1- 小鼠第8染色体上的Prkaca融合基因足以引发具有FLC特征的肝癌。 FLC被认为是由肝干细胞引起的，但Dnajb 1-Prkaca促进致癌的机制 转型还没有被很好地理解。为了在与发育相关的背景下进行功能研究，我们 使用CRISPR/Cas9技术在小鼠肝脏类器官中工程化同线Dnajb 1-Prkaca。我们发现 表达Dnajb 1-Prkaca的肝类器官易于发生裂解性细胞死亡。接下来，我们表演了 广泛的转录组分析揭示了一种先天免疫特征， NLRC 4炎性小体此外，我们确定表达Dnajb 1-Prkaca的肝类器官表现出 切割的半胱天冬酶-8水平显著升高，与其有效活化一致。 在这项工作中，我们将首先测试NLRC 4炎性体是否被小鼠肝脏类器官中的Dnajb 1-Prkaca激活。 并确定其在溶解性细胞死亡中的作用。然后我们将确定Nlrc 4和/或Casp-8基因是否是必需的 用于通过在小鼠肝脏中工程化Dnajb 1-Prkaca融合基因引起的肿瘤发生。后者将 代表了对FLC发病机制理解的重大突破。

Fibrolammellar Carcinoma (FLC) is a rare form of liver cancer that afflicts children and young adults. At the time of diagnosis, the cancer is stage IV in ~60% of patients without effective treatment option. For the remaining 40%, liver transplantation is the only curative therapy, providing a suitable donor can be found in time and even then, with significant risks for short- and long-term complications. Virtually all patients with FLC have a genomic alteration on Chr. 19 resulting in fusion of exon 1 of DNAJB1 of the Hsp40 family to exons 2-10 of PRKACA, a catalytic subunit of PKA. The resulting DNAJB1-PRKACA fusion gene encodes a Dnajb1-Prkaca protein with preserved catalytic activity. Using CRISPR/Cas9 technology combined with hydrodynamic tail vein injection, we and others have shown conclusively that a syntenic Dnajb1- Prkaca fusion gene on mouse Chr. 8 is sufficient to elicit liver cancer with hallmarks of FLC. FLC is thought to arise from liver stem cells, but the mechanisms whereby Dnajb1-Prkaca promotes oncogenic transformation are not well understood. To permit functional studies in a developmentally relevant context, we used CRISPR/Cas9 technology to engineer syntenic Dnajb1-Prkaca in mouse liver organoids. We discovered that liver organoids expressing Dnajb1-Prkaca are prone to undergoing lytic cell death. Next, we performed extensive transcriptome analyses that revealed an innate immune signature prominently featuring constituents of the NLRC4 inflammasome. We moreover determined that Dnajb1-Prkaca expressing liver organoids exhibit significantly elevated levels of cleaved caspase-8 consistent with its potent activation. In this work, we will first test if the NLRC4 inflammasome is activated by Dnajb1-Prkaca in mouse liver organoids and establish its role in lytic cell death. We will then determine if the Nlrc4 and/or Casp-8 genes are necessary for tumorigenesis elicited by engineering of the Dnajb1-Prkaca fusion gene in the mouse liver. The latter would represent a major breakthrough in understanding the pathogenesis of FLC.