Impairment of clathrin-mediated endocytosis via cytoskeletal change by epithelial to fibroblastoid conversion in HepG2 cells: A possible mechanism of des-γ-carboxy prothrombin production in hepatocellular carcinoma
Impairment of clathrin-mediated endocytosis via cytoskeletal change by epithelial to fibroblastoid conversion in HepG2 cells: A possible mechanism of des-γ-carboxy prothrombin production in hepatocellular carcinoma
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DOI：
10.3892/ijo_00000104
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发表时间：
2008-12-01
影响因子：
5.2
通讯作者：
Sakamoto, Atsushi
中科院分区：
文献类型：
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作者：
Murata, Kazumoto;Sakamoto, Atsushi
des - γ -羧基凝血酶原（DCP）已被确定为肝细胞癌（HCC）的肿瘤标志物。然而，HCC细胞产生DCP的确切机制尚不清楚。重要的是，DCP不是HCC特异性的。例如，维生素K缺乏或摄入维生素K拮抗剂（华法林）也会导致DCP的产生。此外，HCC患者补充维生素K2类似物可降低血清DCP水平。根据这些观察，我们假设DCP可能是由维生素K摄取功能受损的HCC细胞产生的。因为，如前所述。肝细胞癌患者e -钙粘蛋白下调或血清DCP升高与血管侵犯的高风险相关。肝内转移和肿瘤复发，我们研究了HCC细胞是否可能通过上皮细胞到成纤维细胞样细胞的转化（EFC）在体外产生DCP。肿瘤启动子12- o -四烯酰基磷酸-13-乙酸酯（TPA）诱导HepG2细胞EFC。在失去E-cadherin表达的HepG2细胞中，以tpa剂量依赖性的方式观察到DCP的产生。在处理细胞中引入额外的维生素K2可以抑制DCP的产生。此外，在tpa处理的HepG2细胞中，LDL摄取作为维生素K摄取的替代品显著受损。LDL摄取受损的细胞产生DCP。脂溶性维生素通过网格蛋白介导的内吞作用进入细胞，其中f -肌动蛋白的动态聚合起着至关重要的作用。我们发现f -肌动蛋白重排的HepG2细胞产生DCP。此外，肌动蛋白解聚剂latrunculin A诱导幼稚HepG2细胞产生DCP，证实F-actin聚合损伤是DCP产生的关键机制。我们在体外实验中发现EFC引起的细胞骨架丝的改变对HepG2细胞产生DCP至关重要。
Des-gamma-carboxy prothrombin (DCP) has been well established as a hepatocellular carcinoma (HCC) tumor marker. However, the precise mechanism by which HCC cells produce DCP remains unknown. Importantly, DCP is not specific for HCC. For example, vitamin K-deficiency or ingestion of a vitamin K antagonist (warfarin) also leads to DCP production. In addition, supplementary administration of vitamin K2 analogues to HCC patients has led to reduce serum DCP levels. From these observations, we hypothesize that DCP might be produced from HCC cells with functional impairment of vitamin K uptake. Because, as previously reported. the down-regulation of E-cadherin or high serum DCP in HCC patients is associated with a high risk of vascular invasion. intra-hepatic metastasis and tumor recurrence, we examined if HCC cells might produce DCP by epithelial to fibroblastoid conversion (EFC) in vitro. HepG2 cells were induced EFC by tumor promoter, 12-O-tetracanoylphorbol-13-acetate (TPA). DCP production was observed in HepG2 cells that had lost E-cadherin expression in a TPA-dose-dependent manner. The DCP production was inhibited by introducing additional vitamin K2 into the treated cells. In addition, LDL uptake as a surrogate of vitamin K uptake was significantly impaired in TPA-treated HepG2 cells. The cells with impairment of LDL uptake produced DCP. Fat soluble vitamins are taken up into cells through clathrin-mediated endocytosis, in which the dynamic polymerization of F-actin plays a crucial role. We found that HepG2 cells with F-actin rearrangement produced DCP. In addition, latrunculin A, an actin depolymerizer, induced naive HepG2 cells to produce DCP, confirming that impairment of F-actin polymerization is a key mechanism of DCP production. We showed ill vitro that cytoskeletal filament change by EFC is Crucial for DCP production in HepG2 cells.