Hepatic Stellate Cells and Liver Cancer

描述（由申请人提供）：80%的肝细胞癌（HCC）发生在纤维化肝脏中。值得注意的是，慢性损伤、炎症和纤维化足以在小鼠中触发HCC，这表明HCC真正代表“不愈合的伤口”，并且肝脏微环境发挥了深刻的促肿瘤影响。与其他器官相比，肌成纤维细胞（MF）在肝脏中的积累不仅是对已建立的肿瘤的促纤维增生反应，伴随着癌症相关成纤维细胞（CAF）的积累，而且在癌前肝脏中也有大量的MF。因此，HCC可能在不同阶段受到不同MF子集（即组织纤维化相关MF和CAF）的影响。尽管纤维化和HCC之间存在很强的相关性，但目前尚不清楚纤维化是否促进HCC的发展，或者纤维化和肝癌发生是否代表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，其中肝MF激活可以选择性地调节，而不会对伴随所有当前模型的炎症和上皮细胞区室产生混淆效应。在这里，我们试图测试的假设，肝MF和CAF是肝癌发生的重要贡献者。为此，我们将采用一种新的Cre转基因小鼠，不仅标记了99%的肝星状细胞（HSC），肝脏中MF的前体，而且还使我们能够选择性地增加或减少肝脏中激活的MF的数量。在本提案的目的1中，我们试图通过LratCre使用命运追踪来检验HSC是纤维化相关肝癌发生中纤维化相关MF和CAF的关键来源的假设。我们将进一步确定HSC衍生的MF的功能贡献，分别采用LratCre与Cre诱导的白喉受体和活化的PDGFR β组合来遗传地消耗或活化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衍生的MF促进HCC的时间点，并分析MF激活或消融如何改变肿瘤增殖、凋亡和肿瘤激酶组。此外，我们试图比较高纯度的MF和CAF之间的基因表达，并调查参与候选介质MF和CAF在肝癌发生。在目标3中，我们将采用一种新型高效的抗纤维化、HSC靶向IFNγ，以确定抑制MF活化和肝纤维化是否会减少HCC的发展。我们还试图确定是否HSC靶向IFNγ，无论是作为单一疗法还是与索拉非尼联合，抑制HCC进展。这些研究不仅将揭示MF在肝癌发生中的起源和功能，而且可能为靶向MF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 PDGFRß, 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.