子宮肌瘤是好發於生殖年齡女性的良性腫瘤，它是由子宮平滑肌細胞衍生而來。相較於正常的子宮平滑肌組織，子宮肌瘤含有較多的細胞外基質，包含膠原蛋白(collagen)及纖維連接蛋白(fibronectin)。Integrins是細胞表面上最主要與細胞外基質作用的黏著分子，而syndecans則是一種穿透細胞膜的蛋白聚糖，可幫助integrin的作用。Integrin和syndecans與細胞基質間的相互作用會調控細胞貼附、分化及移動等行為。本研究的重點在於探討integrin β1與syndecan-4在子宮肌瘤細胞的貼附能力上所扮演的角色。我們所使用的細胞是由病人的子宮肌瘤組織所分離培養出來的。首先我們將integrin β1的siRNA送入細胞中並以scramble siRNA作為控制組，接著將細胞種在有纖維連接蛋白或是膠原蛋白覆蓋的基質上測試細胞貼附的能力。實驗結果顯示integrin β1的siRNA 可以降低integrin β1的表現量，但是卻不會減低細胞貼附的能力。肌瘤細胞貼附在纖維連接蛋白上可以引發focal adhesion kinase (FAK)的磷酸化，而抑制integrin β1表現量只些微地減少FAK磷酸化的反應。我們接著利用含有RGD序列的蛋白來阻礙integrin與細胞外基質間的相互作用，並發現它可以抑制細胞貼附能力。另外我們發現子宮肌瘤細胞亦有表現integrin α5及β3。為了研究syndecan-4對細胞貼附能力的影響，我們利用帶有syndecan-4的shRNA的慢病毒(lentivirus)感染細胞，我們的結果顯示shRNA能減少syndecan-4的表現量，但是並沒有減少細胞的貼附能力。另外我們也探討長期缺乏integrin β1對於細胞生長的影響，發現抑制integrin β1的表現會減緩細胞生長速度。綜合而言，單獨抑制integrin β1或syndecan-4的表現並不會影響子宮肌瘤細胞的貼附能力。細胞所表現的其他的黏著分子可能足以支持細胞進行貼附。Integrin β1可能在長期的細胞生長扮演重要的角色，其作用機制則有待進一步的研究。

Uterine leiomyoma is a benign tumor that originates from myometrium in women of the reproductive age. Compared to myometrium, leiomyoma contains excessive extracellular matrix (ECM). Integrins are the major adhesion molecules on cell surface to interact with ECM. Syndecans (SDCs) are transmembrane proteoglycans that cooperate with integrins in focal adhesion formation. The interactions of ECM with integrins and syndecans regulate cell adhesion and initiate signals for cell growth, differentiation and migration. My study focused on the role of integrin β1 and syndecan-4 in leiomyomal cell adhesion. Leiomyomal cells were isolated from leiomyomal tissues obtained from patients who underwent hysterectomy. Cells were transfected with siRNA of integrin β1 or scramble control and their adhesive ability were evaluated on fibronectin- or collagen-coated wells. Integrin β1-specific siRNA suppressed integrin expression, but did not significantly reduce cell adhesion. Cell adhesion to fibronectin induced phosphorylaltion of focal adhesion knase (FAK). Integrin β1 knockdown slightly decreased phosphorylation of FAK. An RGD sequence-containing protein, which blocks the interaction of integrins with matrix, decreased cell adhesion. We found that leiomyomal cells also expressed integrin α5 and β3. To study the role of syndecan-4, we infected cells with lentivirus carrying shRNA of syndecan-4 (shSDC4). Although syndecan-4 expression was decreased by shSDC4, cell adhesion was not reduced. We further investigated the long-term effect of lacking of integrin β1. Compared with control group, cell growth rate in integrin β1-specific siRNA-treated group was reduced. All together, knockdown of integrin β1 and syndecan-4 alone did not affect cell adhesion, suggesting that redundant expression of integrin subtypes may be sufficient for cell adhesion. The role of integirn β1 in long-term regulation of cell growth remains to be investigated.

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