Aberrant hedgehog signaling is responsible for the highly invasive behavior of a subpopulation of hepatoma cells
Aberrant hedgehog signaling is responsible for the highly invasive behavior of a subpopulation of hepatoma cells
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作者：
Fan, Y-H;Ding, J.;Wu, J.
肝癌在细胞表面标志、致瘤性、侵袭和转移能力等方面表现出一系列异质性亚群。我们以前证明了CD 133（-）/EpCAM（-）肝癌亚群比其对应物更具转移性;然而，控制机制尚未探索。本研究的目的是描绘的意义异常刺猬（Hh）信号在介导的转移。富集CD 133（-）/EpCAM（-）的活化细胞分选（双阴性，DN），Huh-7细胞经历转移细胞的transwell选择（transwell选择的，TS）。TS细胞表现出更大的转移活性，如通过增加的侵袭率、与DN和双阳性（DP）亚群相比基质金属蛋白酶（MMP）-1/2/9基因的表达显著上调所证明的。与DP细胞相反，TS细胞失去E-钙粘蛋白，免疫细胞化学显示波形蛋白均呈阳性。从DP、DN到TS亚群，Gli-1/2基因表达水平呈过渡性增加，这与核组分中Gli-1/2或Twist-1蛋白水平升高一致。此外，截短的Gli-1（tGli-1），其反式激活参与转移的分子，在高度侵袭性的Huh-7细胞亚群中检测到，但在转移性较低的肝癌细胞或正常肝细胞中未检测到。增强的转移特征与MMPs的表达增加以及TS Huh-7细胞中扭曲和蜗牛基因的存在被一种有效的Smoothened拮抗剂LDE 225逆转。总之，独特TS亚群的高度转移能力在很大程度上归因于显着的上皮-间充质转化、增强的Hh活性和tGli-1变体的异常发生，这似乎是高度侵袭性行为的原因。
Hepatoma exhibits a series of heterogeneous subpopulations in its cell surface markers, tumorigenicity, invasion and metastatic capability. We previously demonstrated that the CD133(-)/EpCAM(-) hepatoma subpopulation was more metastatic than its counterpart; however, the controlling mechanisms are unexplored. The present study aimed to delineate the significance of aberrant hedgehog (Hh) signaling in the mediation of metastases. Fluorescence-activated cell sorting-enriched CD133(-)/EpCAM(-) (double negative, DN), Huh-7 cells underwent a transwell selection for metastatic cells (transwell-selected, TS). The TS cells displayed much greater metastatic activity as evidenced by an increased invasion rate, extremely upregulated expression of matrix metalloproteinase (MMP)-1/2/9 genes compared with DN and double-positive (DP) subpopulations. In contrast to DP cells, TS cells lost E-cadherin and were all vimentin-positive as shown by immunocytochemistry. There was a transitional increase in Gli-1/2 gene expression levels from DP, DN to TS subpopulations, which was consistent with elevated Gli-1/2 or Twist-1 protein levels in the nuclear fraction. Furthermore, truncated Gli-1 (tGli-1), which transactivates molecules involved in metastasis, was detected in the highly invasive Huh-7 cell subpopulation, but not in less metastatic hepatoma cells or normal hepatocytes. The enhanced metastatic features with increased expression of MMPs as well as the presence of twist and snail genes in TS Huh-7 cells were reversed by LDE225, a potent Smoothened antagonist. In conclusion, the highly metastatic capability of a unique TS subpopulation was highly attributed to significant epithelial-mesenchymal transition, enhanced Hh activity and aberrant occurrence of a tGli-1 variant, which appears to be responsible for the highly invasive behavior.