Department of Pediatrics and Pharmacology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
Hepatology. 2010 Sep;52(3):945-53. doi: 10.1002/hep.23748.
Epithelial-to-mesenchymal transition (EMT) is predicted to play a critical role in metastatic disease in hepatocellular carcinoma. In this study, we used a novel murine model of EMT to elucidate a mechanism of tumor progression and metastasis. A total of 2 x 10(6) liver cells isolated from Pten(loxp/loxp)/Alb-Cre(+) mice, expanded from a single CD133(+)CD45(-) cell clone, passage 0 (P0), were sequentially transplanted to obtain two passages of tumor cells, P1 and P2. Cells were analyzed for gene expression using microarray and real-time polymerase chain reaction. Functional analysis included cell proliferation, migration, and invasion in vitro and orthotopic tumor metastasis assays in vivo. Although P0, P1, and P2 each formed tumors consistent with mixed liver epithelium, within the P2 cells, two distinct cell types were clearly visible: cells with epithelial morphology similar to P0 cells and cells with fibroblastoid morphology. These P2 mesenchymal cells demonstrated increased locomotion on wound healing; increased cell invasion on Matrigel basement membrane; increased EMT-associated gene expression of Snail1, Zeb1, and Zeb2; and down-regulated E-cadherin. P2 mesenchymal cells demonstrated significantly faster tumor growth in vivo compared with P2 epithelial counterparts, with invasion of intestine, pancreas, spleen, and lymph nodes. Furthermore, P2 mesenchymal cells secreted high levels of hepatocyte growth factor (HGF), which we propose acts in a paracrine fashion to drive epithelial cells to undergo EMT. In addition, a second murine liver cancer stem cell line with methionine adenosyltransferase 1a deficiency acquired EMT after sequential transplantations, indicating that EMT was not restricted to Pten-deleted tumors.
EMT is associated with a high rate of liver tumor proliferation, invasion, and metastasis in vivo, which is driven by HGF secreted from mesenchymal tumor cells in a feed-forward mechanism.
上皮-间充质转化（EMT）被预测在肝细胞癌的转移疾病中发挥关键作用。在这项研究中，我们使用了一种新的 EMT 小鼠模型来阐明肿瘤进展和转移的机制。总共从 Pten(loxp/loxp)/Alb-Cre(+) 小鼠分离的 2 x 10(6) 个肝细胞，从单个 CD133(+)CD45(-) 细胞克隆扩展而来，传代 0（P0），被连续移植以获得两批肿瘤细胞，P1 和 P2。使用微阵列和实时聚合酶链反应分析细胞的基因表达。功能分析包括体外细胞增殖、迁移和侵袭以及体内原位肿瘤转移测定。尽管 P0、P1 和 P2 各自形成的肿瘤与混合肝上皮一致，但在 P2 细胞中，两种明显不同的细胞类型清晰可见：具有类似于 P0 细胞的上皮形态的细胞和具有成纤维细胞形态的细胞。这些 P2 间充质细胞在伤口愈合时表现出更强的运动性；在 Matrigel 基底膜上的细胞侵袭性增加；EMT 相关基因 Snail1、Zeb1 和 Zeb2 的表达增加；E-钙黏蛋白表达下调。与 P2 上皮细胞相比，P2 间充质细胞在体内显示出明显更快的肿瘤生长速度，侵犯肠、胰腺、脾脏和淋巴结。此外，P2 间充质细胞分泌高水平的肝细胞生长因子（HGF），我们提出 HGF 以旁分泌方式作用于上皮细胞使其发生 EMT。此外，另一种具有蛋氨酸腺苷转移酶 1a 缺陷的小鼠肝癌干细胞系在连续移植后获得 EMT，表明 EMT 不仅限于 Pten 缺失的肿瘤。
EMT 与体内肝肿瘤增殖、侵袭和转移的高发生率相关，这是由间充质肿瘤细胞分泌的 HGF 以正反馈机制驱动的。
