Functional characterization of the chromosome 8p tumor suppressor gene interaction with tumor microenvironment in human hepatocellular carcinoma

肝癌是全球第三大癌症死亡原因，超过85%的肝癌病例是肝细胞癌。肝细胞癌的高死亡率主要是由肝内转移或新生的多灶性肿瘤形成所致。在之前使用基因组和转录学方法的研究中，我已经证明了在45%的患者中观察到8p染色体的丢失，并与不良预后相关。预测肝细胞癌预后的10个基因“驱动”信号包含位于染色体8p上的6个潜在的肿瘤抑制基因(TSG)、真正的TSG DLC1和两个新的TSG，即SORBS3和SH2D4A。克隆形成实验、细胞迁移实验和异种移植小鼠模型均证实了SH2D4A和SORBS3的肿瘤抑制作用。因此，这种无偏见的方法在识别一个预后基因签名和两个新的TSG方面是有效的。我未发表的研究表明，染色体8p缺失患者的基因表达谱表现出白细胞介素6(IL-6)信号抑制的特征。此外，我还能够证明SH2D4A通过抑制STAT3信号发挥作用，而SORBS3通过增加雌激素受体α(ERAlpha)信号来抑制IL-6信号。因此，这个应用的第一个目标是阐明最近发现的TSGs SORBS3和SH2D4A在IL-6信号转导中的作用。IL-6信号已被证明在炎症，特别是在肝细胞癌的发生和转移中起重要作用，提示SORBS3和SH2D4A可能在功能上协同抑制IL-6信号。为此，将从功能上分析8p TSGs SORBS3和SH2D4A是如何调节IL-6信号的。此外，我将调查单个TSG丢失与多个TSG丢失的影响，并确定丢失多个TSG的功能后果。为了阐明SORBS3和SH2D4A对肿瘤微环境的影响，我们将从肿瘤细胞生长、免疫细胞浸润和细胞因子谱方面研究SORBS3和SH2D4A对原位小鼠模型和肝癌患者样本的影响。这些发现可能导致针对SORBS3和SH2D4A表达降低的肝细胞癌患者的新方法的开发，从而改善肝细胞癌的治疗和患者的生存。

Liver cancer is the third leading cause of cancer death worldwide and more than 85% of all liver cancer cases are hepatocellular carcinoma (HCC). The high mortality rate of HCC is mainly caused by metastasis or by de novo multifocal tumor formation in the diseased liver. In previous work using an integrative genomic and transcriptomic approach, I have shown that loss of chromosome 8p is observed in 45% of patients and is associated with poor outcome. A 10-gene 'driver' signature that predicts outcome in HCC contains six potential tumor suppressor genes (TSGs) on chromosome 8p, the bona fide TSG DLC1 and two novel TSGs, namely SORBS3 and SH2D4A. Clonogenicity assays, cell migration assays and xenograft mouse models confirmed the tumor suppressor function of SH2D4A and SORBS3. Therefore, this unbiased approach was effective in identifying a prognostic gene signature and two novel TSGs. My unpublished studies show that the gene expression profiles of patients with chromosome 8p deletion exhibit expression patterns characteristic of inhibition of interleukin-6 (IL-6) signaling. In addition, I was able to show that SH2D4A functions by repressing STAT3 signaling, whereas, SORBS3 inhibits IL-6 signaling through increase of estrogen receptor alpha (ERalpha) signaling. Thus, the first objective of this application is to elucidate the role of the recently identified TSGs SORBS3 and SH2D4A in IL-6 signaling. IL-6 signaling has been shown to be critically involved in inflammation, and especially in tumorigenesis and metastasis of HCC suggesting that SORBS3 and SH2D4A may functionally collaborate to inhibit IL-6 signaling. To this end, it will be functionally analyzed how chromosome 8p TSGs SORBS3 and SH2D4A modulate IL-6 signaling. In addition, I will investigate the effect of loss of a single versus multiple TSGs and determine the functional consequence of the loss of multiple TSGs. To elucidate the influence of SORBS3 and SH2D4A on the tumor microenvironment, an orthotopic mouse model and HCC patient samples will be studied in regard to tumor cell growth, immune cell infiltration and cytokine profiles. These findings may lead to the development of novel approaches for HCC patients with reduced SORBS3 and SH2D4A expression, thus, leading to improved HCC treatment and patient survival.