探討Slit2的EGF6/LamG Domains 在肺癌細胞株之生長及侵犯能力中所扮演的角色

The Role of EGF6/LamG Domains in Slit2-Mediated Inhibition Growth and Invasion of Lung Cancer Cell Line

蘇商兒(Shang-Er Su)

指導教授 ： 蔡菁華

中山醫學大學/醫學院/醫學研究所/碩士(2012年)

摘要

Slit2是一個分泌型蛋白，過去的研究顯示slit2在許多癌症中扮演著抑癌基因的角色。本實驗室發現，slit2 cDNA具有兩種剪接變異型，slit2-WT、slit2-ΔE15，slit2-WT會抑制癌細胞的侵犯能力，但不會影響癌細胞生長，而slit2-ΔE15則會抑制癌細胞的侵犯力和生長。當slit2-ΔE15上之EGF6/LamG區域被剔除後， slit2-ΔE15-ΔEGF6/LamG失去了抑制癌細胞的生長和侵犯的能力。顯示了EGF6/LamG是slit2-ΔE15抑制癌細胞生長和侵犯所需要的區域。本研究進而將slit2-WT的EGF6/LamG剔除，觀察EGF6/LamG區域是否會影響 slit2-WT抑制細胞侵犯的能力。意外的是，slit2-WT-ΔEGF6/LamG不但仍然會抑制癌細胞的侵襲力，反而會抑制癌細胞的生長。另外，我們發現肺癌病人之正常肺組織中Slit2-ΔE15相對於Slit2-WT的比例非常低或偵測不到，然而在54個氣胸病患組織中，則可看見40.7 %的肺組織中之Slit2-ΔE15的表現等於或高於Slit2-WT的表現，其中甚至於有12.9 %的檢體只表現Slit2-ΔE15。而在老鼠的肺組織和和腦部組織可觀察到，腦部的Slit2多以Slit2-WT的型式表現，而肺部則有較多的老鼠表現Slit2-ΔE15。這些結果都暗示著Slit2的剪接變異型可能是被組織特異性的分子所調控，我們假設肺癌形成的過程可能會改變slit2剪接變異型的表現，由Slit2-ΔE15表現量較高轉為Slit2-WT型，因而使得肺癌細胞的生長不受抑制。

關鍵字

肺癌 ； 剪接變異型

並列摘要

Slit2 is a secreted protein. Previous studies have shown that Slit2 plays a tumor suppressor role in many cancers. Our laboratory identified two splicing variants of slit2, slit2-WT and slit2 ΔE15, Slit2-WT has ability to inhibit cancer cell invasion, while Slit2-ΔE15 possess not only invasion inhibition but also growth inihibition capability in CL1-5 lung cancer cells. When we deleted EGF6/LamG domains of Slit2-ΔE15, Slit2-ΔE15-ΔEGF6/LamG, the ability of growth and invasion inhibition was abolished. This result suggested that the EGF6/LamG domain is required for Slit2-ΔE15-mediated growth and invasion inhibition. In this study, we further deleted EGF6/LamG domain in Slit2-WT, Slit2-WT-ΔEGF6/LamG, to elucidate if EGF6/LamG region affects the ability of Slit2-WT to inhibit cell invasion. Resuts showed that Slit2-WT-ΔEGF6/LamG still inhibited cancer cells invasion, but surprisingly, it gains growth inhibitory capability. Our previous studies also found that the ratio of Slit2-ΔE15 to Slit2-WT expression in normal counterpart of lung cancer pecimen was extremely low. However, in 54 pneumothorax patients’ lung tissues, 40.7% of the lung tissue expressed Slit2-ΔE15 levels equal to or higher than the Slit2-WT. Among them, 12.9% of the samples even expressed slit2-ΔE15 only. We next examined slit2 splicing forms expression in murine brain and lung tissues. Results showed that most of the murine brain and lung expressed either form of slit2. Brain tissues expressed slit2-WT form except for one brain which expressed both slit2-WT and slit2-ΔE15 forms; lung tissues expressed slit2-ΔE15 form more than slit2-WT. These results suggested that Slit2 splicing variants may be regulated by tissue-specific splicing factors. We hypothesized that during lung tumorigenesis, the expression of Slit2 in the tumor microenvironment switch from Slit2-ΔE15 form to Slit2-WT form thus relief growth inhibition of cancer cells.

並列關鍵字

slit2 ； Lung Cancer ； EGF6LamG ； Splicing Forms

參考文獻

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