A Role for the Novel HAF-NFkappaB Axis in Driving Obesity-Associated Liver Cancer

肝细胞癌是肝脏的主要原发癌，是第四大致癌原因。 死亡，以及美国增长最快的恶性肿瘤。晚期肝癌基本上仍无法治愈，因为 不良反应率(&lt；20%)和治疗抵抗。目前的肥胖症流行与 代谢(功能障碍)相关性脂肪性肝病(MAFLD)及其炎症性疾病的发病率不断上升 成分，非酒精性脂肪性肝炎(NASH)，可导致肝细胞癌。MAFLD-肝癌的发病率正在上升 戏剧性地，突显了对新的诊断和治疗战略的未得到满足的医疗需求。在这里，我们 描述低氧相关因子HAF在MAFLD-肝癌中的一种新的肿瘤抑制作用。两者都是全球性的 HAF单倍体功能不全和肝细胞特异性缺失导致伴有NASH特征的肝细胞癌 包括严重的脂肪变性并伴有肝细胞变性(肝细胞气球)、纤维化和 炎性细胞浸润。HAF在两种小鼠模型中的丢失或在肝癌细胞中通过siRNA转染而丢失相关 随着p65/p50核因子-κB转录亚单位的活性降低，其 上游监管机构TAK1和NEMO。内源性HAF与NEMO和TAK1形成复合体，提示 HAF通过直接调节这些蛋白质的稳定性来调节NF-κB途径，可能是通过 HAF的E3泛素连接酶活性。HAF基因敲除与自发性细胞凋亡增加有关， 而hAf的过表达保护细胞免受肿瘤坏死因子诱导的细胞死亡，提示hAf可能在 通过保护细胞免受与肝脏炎症(肝炎)相关的死亡而发挥肿瘤抑制作用 会导致肝细胞癌。事实上，肝炎期间流行的疾病，如缺氧和缺氧，会抑制HAF的水平。 升高的肿瘤坏死因子或转化生长因子-β，而hAf是通过dna损伤而增加，提示hAf可能参与了 核因子-κB的激活对癌前肝细胞基因组不稳定性的反应。值得注意的是，HAF是高度 在大多数人类肝炎病例中表达，但在所检查的94%的人肝细胞癌中未检测到(65例)。 因此，我们的假设是HAF通过促进核因子-κB的激活在肝细胞癌中发挥新的肿瘤抑制作用。 这促进了肝炎期间肝细胞的存活。缺氧或炎症对HAF的抑制作用 肝炎期间的细胞因子导致细胞周转增加，从而推动NASH和肝细胞癌的进展。我们的 总体目标是确定新的肝癌预测/预后生物标志物或治疗靶点，特别是那些 与MAFLD-HCC相关。在目标1中，我们将检验HAF通过以下方式激活NF-κB途径的假设 调节TAK1和NEMO的稳定性，从而确定调控HAF-1的分子机制。 核因子-κB轴。在目标2中，我们将测试HAF保护细胞免受肝炎期间细胞过度死亡的假设， 从而防止进展为NASH和肝细胞癌。在目标3中，我们将检验放松管制是 通过研究HAF在500名患者样本中的表达，确定HAF与肝癌进展的关系 HAF及其下游靶点与肝细胞癌的发生、发展或治疗反应的关系。

Hepatocellular carcinoma (HCC), the predominant primary cancer of the liver, is 4th leading cause of cancer deaths, and the fastest growing malignancy in the US. Advanced-stage HCC remains largely incurable due to a dismal response rate (<20%) and therapeutic resistance. The current obesity epidemic has been associated with the rising prevalence of metabolic (dysfunction) associated fatty liver disease (MAFLD) and its inflammatory component, non-alcoholic steatohepatitis (NASH), which can lead to HCC. MAFLD-HCC incidence is increasing dramatically, underscoring an unmet medical need for new diagnostic and treatment strategies. Here, we describe a novel tumor suppressor role of the Hypoxia-Associated Factor, HAF, in MAFLD-HCC. Both global haploinsufficiency and hepatocyte-specific deletion of HAF in mice result in HCC with hallmarks of NASH including severe steatosis with hepatocyte degeneration (hepatocyte ballooning), fibrosis, and increased inflammatory cell infiltration. HAF loss in both mouse models or by siRNA transfection in HCC cells is associated with decreased activation of the p65/p50 NF-κB transcriptional subunits, and in decreased levels of their upstream regulators, TAK1 and NEMO. Endogenous HAF forms a complex with NEMO and TAK1, suggesting that HAF modulates the NF-κB pathway by directly modulating the stability of these proteins, potentially through HAF’s E3 ubiquitin ligase activity. HAF knockdown was associated with increased spontaneous apoptosis, whereas HAF overexpression protected cells against TNF-induced cell death, suggesting that HAF may play a tumor suppressor role by protecting cells against death associated with liver inflammation (hepatitis) that can lead to HCC. Indeed, HAF levels are suppressed by conditions prevalent during hepatitis such as hypoxia and elevated TNF or TGF-β, whereas HAF are increased by DNA damage, suggesting that HAF may contribute to NF-κB activation in response to genomic instability in pre-neoplastic hepatocytes. Significantly, HAF was highly expressed in most cases of human hepatitis but was undetectable in 94% of human HCCs examined (65 cases). Thus, our hypothesis is that HAF plays a novel tumor suppressor role in HCC by facilitating NF-κB activation that promotes the survival of hepatocytes during hepatitis. Suppression of HAF by hypoxia or inflammatory cytokines during hepatitis results in increased cellular turnover that drives progression to NASH and HCC. Our overall goal is to identify new predictive/prognostic biomarkers or therapeutic targets for HCC, particularly those relevant to MAFLD-HCC. In Aim 1, we will test the hypothesis that HAF activates the NF-κB pathway by modulating the stability of TAK1 and NEMO, and thus identify the molecular mechanisms regulating the HAF- NF-κB axis. In Aim 2, we will test the hypothesis that HAF protects cells from excessive cell death during hepatitis, thus preventing progression to NASH and HCC. In Aim 3, we will test the hypothesis that HAF deregulation is associated with progression to HCC by investigating HAF expression in > 500 patient samples, to determine the association of HAF and its downstream targets to HCC initiation and progression or to treatment response.