Linking chronic inflammation with tumor suppressor gene inactivation in liver cancer

在先前使用基因组学和转录组学综合方法的工作中，我们发现在HCC中，45%的肿瘤中观察到8p染色体的缺失，并且与不良的患者预后相关。此外，我们发现SORBS3和SH2D4A是8p染色体上的两个新的肿瘤抑制基因，它们与白细胞介素-6 （IL-6）信号传导减少的表达模式有关。IL-6信号通路在炎症，尤其是肝癌的肿瘤发生和转移中起着至关重要的作用，这表明SORBS3和SH2D4A可能调节免疫细胞诱导的肝癌细胞中IL-6/STAT3信号通路。最近，我们证明了SH2D4A和SORBS3在功能上协同抑制IL-6/STAT3信号传导和HCC细胞生长。此外，我们证明SH2D4A直接与线粒体蛋白禁止蛋白1 （PHB1）相互作用，而SH2D4A的敲低改变了线粒体基础呼吸和线粒体ATP的产生。选择性PHB抑制剂FL3的使用导致这些作用的抑制，这表明SH2D4A可能参与线粒体功能，FL3的抑制可能挽救肿瘤细胞中SH2D4A丢失的作用。因此，我们能够功能表征和分子解剖染色体8p肿瘤抑制基因SH2D4A的作用。在该项目的下一阶段，我们的目标是通过鉴定染色体8p缺失的hcc中与肿瘤进展和对肿瘤微环境的反应相关的必要基因来扩大项目。为此，我们已经确定FOXM1在具有野生型染色体8p的HCC细胞中是必需的，而PARD3/PARD6B在具有染色体8p缺失的HCC细胞中是必需的。在这里提出的项目中，我们的目标是解剖具有或不具有染色体8p缺失的HCC中与炎症IL-6信号传导有关的必要基因。因此，我们将从功能上剖析FOXM1 （Aim 1）和PARD3/PARD6B （Aim 2）在有或没有8p染色体缺失的hcc中的作用。此外，我们将使用我们的工程染色体8p缺失和相应的野生型细胞（有或没有IL-6暴露）来鉴定染色体8p相关的必要基因，并对染色体8p缺失和STAT3激活的HCC必需候选基因进行功能解剖。

In previous work using an integrative genomic and transcriptomic approach, we showed that in HCC loss of chromosome 8p is observed in 45% of tumors and associated with poor patient outcome. In addition, we identified SORBS3 and SH2D4A as two novel tumor suppressor genes on chromosome 8p, which are associated with expression patterns characteristic of reduced interleukin-6 (IL-6) signaling. IL-6 signaling is critically involved in inflammation, and especially in tumorigenesis and metastasis of HCC suggesting that SORBS3 and SH2D4A may modulate the immune cell induced IL-6/STAT3 signaling in liver cancer cells. Recently, we demonstrated that SH2D4A and SORBS3 functionally cooperate to inhibit IL-6/STAT3 signaling and HCC cell growth. In addition, we demonstrated that SH2D4A directly interacts with the mitochondrial protein prohibitin 1 (PHB1) and SH2D4A knockdown alters basal mitochondrial respiration and mitochondrial ATP production. The usage of the selective PHB inhibitor FL3 led to a repression of these effects suggesting that SH2D4A may be involved in mitochondrial function and inhibition by FL3 may rescue the effects of SH2D4A loss in tumor cells. Thus, we were able to functionally characterize and molecularly dissect the role of the chromosome 8p tumor suppressor gene SH2D4A. In the next stage of the project, we aim to broaden the project by identification of genes essential in chromosome 8p deleted HCCs which are associated with tumor progression and response to the tumor microenvironment. To this end, we have identified FOXM1 to be essential in HCC cells with wildtype chromosome 8p, whereas PARD3/PARD6B were essential in HCC cells with chromosome 8p deletion. In the here proposed project, we aim to dissect essential genes in HCC with or without chromosome 8p deletion in regard to inflammatory IL-6 signaling. Thus, we will functionally dissect the role of FOXM1 (Aim 1) and of PARD3/PARD6B (Aim 2) in HCCs with or without chromosome 8p deletion. Furthermore, we will identify chromosome 8p associated essential genes using our engineered chromosome 8p deleted and corresponding wildtype cells with or without IL-6 exposure (Aim 3) and functionally dissect candidate genes essential in HCC with chromosome 8p deletion and STAT3 activation.