肝星型细胞分泌 collagen I 激活盘状结构域受体DDR1-STAT3信号轴促进葡萄膜黑色素瘤肝转移的研究

Hepatic metastasis is the major and direct cause of death in uveal melanoma (UM) patients with no effective treatments. Mechanism exploration and improved treatments for hepatic metastatic patients with UM were urgently needed. Because discoidin domain recptor 1 (DDR1) was identified to be overexpressed in UM cell lines and specimens, and abundant pathological deposition of collagen, a specific type of DDR1 ligand, was noted in the microenvironment of liver in metastatic patients with UM, we postulated hypothesis that DDR1 and its ligand might bridge the interaction between UM cells and their surrounding niche of liver thereby conferring strengthened survival, proliferation, stemness and eventually promoting metastatic colonization in liver. Based on the previous research, we further confirmed the role of DDR1 in regulating the malignant phenotypes such as proliferation, migration, invasion, tumor stem cells and liver metastasis activated by microenvironment derived collagen I. Our study may provide theoretical and experimental basis for the application of DDR1 inhibitor 7rh in the treatment of liver metastases in UM.

葡萄膜黑色素瘤（uveal melanoma，UM）是一种常见的成人原发性眼内肿瘤，恶性程度高且易发生肝转移，一旦发生肝转移则无有效的治疗手段，是导致UM病人死亡的主要原因。所以，开发出新型靶向治疗UM尤其是靶向转移性UM的药物显得尤为重要。我们前期研究发现盘状结构域DDR1在UM细胞系与UM病人标本中高表达，且DDR1特异性配体胶原在UM病人的肝脏转移灶也大存在大量沉积，因此我们提出假设：DDR1是否通过与胶原相互作用介导UM细胞与肝脏肿瘤微环境的相互作用，促进UM细胞在肝脏中的恶性克隆增殖并发生转移。本课题在前期研究基础上，进一步通过细胞系，病人标本及体内动物实验，明确微环境来源的胶原激活DDR1后对UM恶性表型如增殖、迁移、侵袭、肿瘤干细胞及肝转移的调控作用和分子机制，拟为DDR1抑制剂7rh应用于UM肝转移治疗提供理论与实验依据。

定植被认为是转移级联的限速步骤。然而，其根本机制尚不清楚。以单器官肝转移为特征的葡萄膜黑色素瘤（UM）可能为实现这一目标提供了一个简化的模型复杂的殖民过程。因为DDR1被鉴定为在UM细胞系和标本中过度表达细胞外基质胶原（一种DDR1配体）在小鼠肝脏微环境中发生病理性沉积转移性UM患者，我们假设DDR1及其配体可能点燃UM细胞之间的相互作用以及它们周围的肝脏生态位，从而增强了生存、增殖、干细胞，并最终促进肝转移定植。我们检验了这一假设，发现DDR1促进了这些恶性细胞表型促进UM在肝脏中的转移定植。机制上，UM细胞分泌TGF-β1，诱导静止的肝星状细胞细胞（qHSCs）转化为分泌I型胶原的活化HSCs（aHSCs）。这种细胞外基质的重塑反过来激活DDR1，通过上调STAT3依赖性Mcl-1表达增强生存，通过上调STAT3依赖性SOX2和促进癌细胞克隆形成。通过使用7rh（一种特异性抑制剂）靶向DDR1体外和体内生长的增殖和存活。更重要的是，通过药物灭活靶向癌细胞DDR1或靶向微环境TGF-β。总之，本研究获得抑制 DDR1 能够抑制 UM 细胞生长、迁移侵袭、消除 UM 肿瘤干细胞及干预微环境从而抑制 UM 细胞肝转移的有力证据，建立动物模型明确干预 DDR1对体内肿瘤生长及肝转移的影响，为治疗原发灶及转移灶 UM 提供转化医学依据。