CD90為免疫球蛋白超家族(immunoglobulin superfamily)的一員，是一種藉由醣練鑲嵌於細胞膜上脂筏區(lipid rafts)的醣磷脂醯肌醇錨定醣蛋白(GPI-anchored protein)。過去的研究發現， CD90可作為一個肝癌的腫瘤幹細胞標誌(cancer stem cell maker)，並具有參與細胞之間、細胞與基質之間訊息調節的功能，更可藉由整合蛋白(integrin)調控細胞的生理功能，如細胞黏著(cell adhesion)、細胞遷移(migration) 及纖維化(fibrosis)等，但是目前對於 CD90是否會影響肝癌的細胞遷移能力仍然沒有明確的研究報導。因此，在本篇研究中，我們想瞭解 CD90在肝癌中，是否會影響肝癌細胞的遷移能力？並嘗試瞭解 CD90在這過程中是扮演什麼樣的角色？為此，我們使用會穩定表現 CD90的肝癌細胞株，進行傷口癒合爬行能力分析(wound-healing assay)及細胞爬行能力分析(Boyden chamber assay)，結果發現於肝癌細胞 Hep3B中表現 CD90時，有增進肝癌細胞 Hep3B之細胞遷移行為的現象。進一步以西方墨點法(western blot assay)來觀察細胞內部分子機制的變化，根據實驗的結果，我們發現於肝癌細胞 Hep3B中表現 CD90時，其磷脂醯肌醇-3激酶(phosphoinositide 3-kinase, PI3K)與粘著斑激酶(focal adhesion kinase, FAK)分子表現量有減少的傾向，另外也發現，於肝癌細胞 Hep3B中表現 CD90時，其鈣黏著素E (E-cadherin)表現量有減少的傾向，而鈣黏著素N (N-cadherin)表現量有增加的傾向。本篇研究發現 CD90在肝癌細胞 Hep3B中會降低細胞粘著的能力，產生表皮-間質轉換 (epithelial-mesenchymal transition, EMT)的現象，並增進肝癌細胞 Hep3B的細胞遷移能力，具有造成癌症轉移的風險。

CD90 is a member of immunoglobulin supergene family, and is a glycosylphosphatidylinositol-anchored glycoprotein, which localizies at cell lipid rafts on the outer surface of the lipid bilayer. Previous studies have suggested that CD90 could be a liver cancer stem cell marker, and it is play an important role in cell-cell and cell-matrix interactions via integrin signaling pathway, and also affects a lot of biological processes, including cellular adhesion, migration and fibrosis, but it is unclear whether CD90 will affect liver cancer migration. In this study, we want to investigate the role of CD90 in cancer cell migration and whether CD90 affect signal transduction in other pathway. For this reason, we analyzed the cell migration of stable cells expressing exogenous CD90 with wound healing assay and Boyden chamber assay. The result showed that ectopic expression of CD90 enhanced cell migration in Hep3B hepatoma cell line. By western bolt assay, we also found that ectopic expression of CD90 decreased the level of phosphoinositide 3-kinase, focal adhesion kinase and E-cadherin, but increased the level of N-cadherin in Hep3B cell. Our results suggested that CD90 facilitated Hep3B hepatoma cell migration and epithelial-mesenchymal transition, reduced ability of cell adhesion, and had high chance to cause cancer metastasis.

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