Galectin-1(Gal-1)屬β-galactoside-binding animal lectins家族的一員，已知參與腫瘤細胞的轉型、附著、遷移及避開免疫攻擊等反應，Gal-1在口腔癌前期會大量表現在腫瘤附近的間質組織(tumor-associated stroma)及侵犯前緣與轉移至淋巴結的腫瘤細胞，並與前期口腔癌的預後有關。基於這些和腫瘤生物息息相關的反應，本研究利用基因沉默(gene silencing)的方法去探討細胞裡內生性Gal-1對於口腔癌的發展過程及其生物活性，發現抑制細胞體內的Gal-1會促進口腔癌細胞的生長、增加細胞週期S期的量、抑制細胞的遷移、及降低MMP-2及MMP-9蛋白活性的表現；且降低Gal-1的表現量可減少small GTPase cdc42的活化而明顯改變細胞表面filopodia的形態與數量進而抑制細胞的遷移。接著利用Tandem affinity purification (TAP)純化策略與質譜學(mass spectrometry, MS)的方法找出和Gal-1有交互作用的蛋白質Disheveled-associated activator of morphogenesis 1 (Daam1)和histone H4，雖然免疫共沉澱法(Coimmunoprecipitation)及哺乳動物雙雜交系統(mammalian two-hybrid)未能證明Gal-1和histone H4及Daam1有交互作用，但我們的結果卻發現到Gal-1和Daam1蛋白在細胞內的表現量是有正相關，且免疫螢光染色法(Immunocytometry)也指出Gal-1及Daam1在細胞內有colocalized，顯示Gal-1和Daam1之間的互動和口腔癌的發展過程有關聯，釐清細胞內Gal-1和Daam1的蛋白質聯絡網絡將有助於定位Gal-1於口腔癌細胞的增生及細胞遷移所扮演的角色。

Galectin-1(Gal-1) is a β-galactoside-binding lectin and involved in multiple biological functions, such as cell adhesion, proliferation, migration, apoptosis, inflammation, tumor progression and metastasis. Our previous investigations have shown that Gal-1 was overexpressed in the tumor-associated stroma as well as the invasion front during early oral carcinogenesis and correlated with worse prognosis of oral cancer. In this study we used siRNA of Gal-1 to determine the function of intracellular Gal-1. We found that silencing Gal-1 stimulates proliferation, increases cell cycle S phase, inhibits cell migration, and decreases the expression of MMP-2 and MMP-9. The migration inhibition of silencing Gal-1 might be due to the inhibition of small GTPase cdc42 activity and cytoskeleton rearrangement and significant decrease in the length and number of filopodia. Next, using a tandem affinity purification (TAP) method to purify the protein complex of Gal-1 and subsequent mass spectrometry to identify the associated proteins. Disheveled-associated activator of morphogenesis 1 (Daam1) and Histone H4 proteins were first identified as Gal-1 associated proteins by such approaches. Co-immunoprecipitation and mammalian two-hybrid analysis did not demonstrate that Gal-1 interacted with histone H4 and Daam1. However, Gal-1 was strongly sub-cellular colocalized with Daam1, and the expression of Daam1 was significantly decreased while gal-1 was silencing. These results implied that Daam1 might have a role in Gal-1-regulated cell functions. To further clarify the interacting network of Gal-1 and Daam1 might help to gain insight into the Gal-1 functions in oral carcinogenesis.

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