肝癌細胞的細胞形態與正常細胞之形態有所不同，過去的研究發現這可能與細胞骨架的組合和聯結的改變有關，也因為細胞的形態不穩定，所以造成細胞移行能力的增加。在細胞骨架中，中間絲(intermediate filament)、微小管(microtubule)跟微細絲(microfilament)是主要的三種細胞骨架，而plectin，為一種多功能的細胞質聯結蛋白質為連接中間絲跟微細絲的蛋白質，因此plectin蛋白質的穩定對於細胞移行扮演重要的角色。在我們之前的研究當中，發現肝細胞株Chang cell的plectin被降解後會影響CK18的表現和結構改變，進而造成肝細胞形態改變並引起肝細胞多形性的轉化。而在我們最近的研究進一步發現plectin的缺失會影響細胞附著分子激酶(focal adhesion kinase，FAK)表現，而促進細胞移行。為了進一步在活體中證明plectin在肝癌所扮演的角色，我們以異體細胞移植老鼠模式探討肝細胞在plectin缺乏的狀態下的癌細胞生長以及擴散情形，並同時觀察integrin以及FAK的表現和分布。另外一方面，我們從第一部分的實驗結果中發現plectin的缺失會提高FAK的活化並促使細胞的移行能力增加。在肝癌的臨床用藥中有一種tyrosine kinase inhibitor–sorafenib，目前研究指出sorafenib可以透過抑制VEGFR、PDGFR、Raf等分子的活化去抑制腫瘤的增生以及血管新生，並促使細胞凋亡，而FAK也是一種tyrosine kinase，因此我們想要知道sorafenib的藥性是否跟plectin的表達量有所關聯，所以我們利用細胞實驗以及皮下注射的方式測試sorafenib這個藥物對於plectin表達量不同的肝細胞株是否存在不同的敏感性。目前在細胞實驗中的結果顯示sorafenib在plectin表達量較低的肝細胞株中有較高的敏感性，而在活體實驗的部分我們將會利用Chang、PLC、HepG2這三株肝細胞在活體中確認細胞實驗的結果，希望將來可以透過plectin的表達量作為sorafenib使用的依據。 The morphology of hepatoma cells is different from that of normal liver cells; it might be related to disorganization of the hepatic cytoskeletal network and resulting in liver cell transformation and migration. Intermediate filament, microtubule and microfilament are three major cytoskeletons in the cell. Plectin, a versatile cytoplasmic cross-linking protein, which connects intermediate filaments to microfilaments was shown to play important role in cell migration. Our previous studies have shown that the deficiency of plectin in Chang liver cell, affected CK18 expression and distribution, and induced pleomorphic changes of Chang liver cells. In our recent study also found plectin deficiency affected focal adhesion kinase (FAK) expression and distribution and further improved cell migration. To further investigate the role of plectin in vivo, this study established xenograft mouse model to investigate the effect of plectin deficiency in liver cell migration and the tumor invasion of hepatoma cells. Control and plectin knockdown human liver cell line, Chang cells were injected into immune deficient mice by portal vein injection. After 28 days, mice were sacrificed for tumor analysis. The expression and distribution of focal adhesion kinase and integrin will also be monitored.In other side, we found that plectin deficiency increases FAK activity and cell migration. We found a clinical drug, sorafenib which is a tyrosine kinase inhibitor and can inhibit tumor proliferation, and angiogenesis. FAK is a tyrosine kinase, so we want to know whether the drug efficacy of sorafenib is related to plectin deficiency. The current results showed that low expression of plectin is sensitive to sorafenib. Next, we will confirm the results by in vivo mouse model and hope that plectin can be a biomarker of sorafenib treatment in the future.
