Prrx2在人類乳腺細胞中調控TGF-β引發的腫瘤侵犯

Abstract

轉化生長因子-β (TGF-β)是一種多功能的細胞激素，它可以調控細胞生長、細胞譜系決定、細胞分化、細胞凋亡、細胞移動以及細胞貼附。它也可以引發細胞上皮-間質轉型和轉移，在腫瘤進程中扮演重要角色。在本篇實驗中，我們使用人類乳腺上皮細胞株MCF10A來探討轉化生長因子-β如何去引發細胞侵犯。我們發現在MCF10A細胞株中，轉化生長因子-β可以促進paired related homeobox 2 (Prrx2)的表現，此促進是經由依賴smad和不依賴smad途徑。讓MCF10A細胞株穩定表現Prrx2會增加細胞侵犯以及惡性轉化的能力。利用微陣列基因表現分析，我們發現當穩定表現Prrx2時，tissue plasminogen activator (tPA)的表現量也會跟著上升。根據螢光素酶報告基因檢測系統，Prrx2可以激活tPA啟動子的活性。染色質免疫沉澱實驗證明Prrx2可以直接結合在tPA的啟動子上。我們的實驗顯示，Prrx2在人類乳腺細胞中可能藉由tPA來調控轉化生長因子-β引發的腫瘤侵犯。

Transforming growth factor-β (TGF-β) is a multifunctional cytokine which controls cell proliferation, lineage determination, differentiation, apoptosis, motility, and adhesion. It also can induce epithelial-mesenchymal transition and metastasis, and is important in cancer progression. In this study, we used human mammary epithelial cell line MCF10A to investigate how TGF-β induces cell invasion. We found that TGF-β induces expression of paired related homeobox 2 (Prrx2) through both Smad-dependent and Smad-independent pathways in MCF10A. MCF10A stably transfected with Prrx2-expressing plasmid (MCF10A-Prrx2) had enhanced invasion and malignant transformation as compared to vector control. Using microarray analysis, we found that expression of tissue plasminogen activator (tPA) was induced in MCF10A-Prrx2, compared to vector control. Cotransfection of Prrx2-expressing plasmid and tPA reporter in Human Embryonic Kidney (HEK) 293T showed that tPA promoter activity was increased as evidenced by luciferase reporter assay. Chromatin immunoprecipitation assay showed that tPA is a direct target for Prrx2. Our study suggests that Prrx2 mediates TGF-β-induced cell invasion, possibly involving tPA, in human mammary epithelial cells.