Hepatic Stellate Cells and Liver Cancer

描述(申请人提供)：80%的肝细胞癌(HCC)发生在纤维化的肝脏。值得注意的是，慢性损伤、炎症和纤维化足以引发肝癌I小鼠，这表明肝癌确实代表了一个无法愈合的伤口，肝脏微环境对促进肿瘤产生了深远的影响。与其他器官不同的是，肌成纤维细胞(MF)在肝脏中的积聚不仅是对已建立的肿瘤的一种促结缔组织反应，伴随着癌症相关成纤维细胞(CAF)的积聚，而且在癌前肝脏中也有大量的MF。因此，在不同的阶段，肝细胞癌可能受到不同的间质纤维化亚群，即组织纤维化相关的间质纤维化和CAF的影响。尽管肝纤维化与肝细胞癌之间有很强的相关性，但目前尚不清楚肝纤维化是否促进了肝细胞癌的发展，或者肝纤维化和肝癌的发生是否代表了两种平行但功能独立的反应。这在很大程度上是由于缺乏模型，在这些模型中，可以选择性地调节肝脏MF的激活，而不会混淆所有现有模型所伴随的炎症和上皮细胞间隔的影响。在这里，我们试图检验这一假设，即肝脏的MF和CAF是肝癌发生的重要贡献者。为此，我们将使用一种新型的Cre转基因小鼠，它不仅可以标记99%的肝星状细胞(HSC)，也可以选择性地增加或减少肝脏中活化的MF的数量。在这项建议的目标1中，我们试图通过LratCre命运追踪来检验这一假设，即HSC是纤维化相关MF和CAF在纤维化相关肝癌发生中的关键来源。我们将进一步确定HSC来源的MF的功能贡献，分别使用LratCre与CRE诱导的白喉受体和激活的PDGFR？结合在基因上耗尽或激活HSC。在目标2中，我们试图确定MF促进肝脏癌变的机制。为此，我们将确定HSC来源的MF促进肝癌的时间点，并分析MF的激活或消融如何改变肿瘤的增殖、凋亡和肿瘤基因组。此外，我们试图比较高纯度的MF和CAF的基因表达，并研究来自MF和CAF的候选介质在肝癌发生中的作用。在目标3中，我们将使用一种新型高效的抗纤维化、肝星状细胞靶向干扰素γ，以确定抑制MF激活和肝纤维化是否减少肝癌的发生。我们还试图确定以肝星状细胞为靶点的干扰素γ，无论是作为单一疗法还是与索拉非尼联合治疗，是否可以抑制肝癌的进展。这些研究不仅将揭示MF在肝癌发生中的起源和作用，而且可能为以MF为靶点预防或治疗肝癌提供依据。

DESCRIPTION (provided by applicant): 80% of hepatocellular carcinomas (HCC) arise in fibrotic livers. Notably, chronic injury, inflammation and fibrosis are sufficient to trigger HCC i mice, suggesting that HCC truly represents "a wound that does not heal" and that the hepatic microenvironment exerts a profound tumor-promoting influence. In contrast to other organs, myofibroblast (MF) accumulation in the liver occurs not only as a desmoplastic response to established tumors with accumulation of cancer-associated fibroblasts (CAF), but there is also an abundance of MF in the precancerous liver. Thus, HCC may be affected by different MF subsets, namely tissue fibrosis-associated MF and CAF, at different stages. Despite the strong association between fibrosis and HCC, it is currently not known whether fibrosis promotes HCC development, or whether fibrosis and hepatocarcinogenesis represent two parallel but functionally independent responses. This is largely due to the lack of models, in which hepatic MF activation can be selectively modulated without confounding effects on the inflammatory and epithelial cell compartments that accompany all current models. Here, we seek to test the hypothesis that hepatic MF and CAF are important contributors to hepatocarcinogenesis. For this purpose, we will employ a novel Cre-transgenic mouse that not only marks 99% of hepatic stellate cells (HSC), the precursors of MF in the liver, but also enables us to selectively increas or decrease the number of activated MF in the liver. In Aim 1 of this proposal, we seek to test the hypothesis that HSC are the key source of fibrosis-associated MF and CAF in fibrosis-associated hepatocarcinogenesis using fate tracing via LratCre. We will furthermore establish the functional contribution of HSC-derived MF, employing LratCre to genetically deplete or activate HSC in combination with Cre-inducible diphtheria receptor and activated PDGFR?, respectively. In Aim 2, we seek to determine mechanisms by which MF promote carcinogenesis in the liver. For this purpose, we will determine time points at which HSC-derived MF promote HCC and analyze how MF activation or ablation change tumor proliferation, apoptosis and the tumor kinome. In addition, we seek to compare gene expression between highly-purified MF and CAF, and to investigate the involvement of candidate mediators from MF and CAF in hepatocarcinogenesis. In Aim 3, we will employ a novel and highly efficient anti-fibrotic, HSC-targeted IFNγ, to determine whether inhibiting MF activation and liver fibrosis reduces HCC development. We also seek to determine whether HSC-targeted IFNγ, either as monotherapy or in combination with sorafenib, inhibits HCC progression. The proposed studies will not only reveal origin and functions of MF in hepatocarcinogenesis, but may provide a basis for targeting MF for HCC prevention or therapy.