探討細胞外基質調控乳腺細胞免疫相關基因表現之機制

在乳腺中，上皮細胞與基底膜(basement membrane)接觸並且形成具空腔的腺體結構。在體外實驗，若是將細胞培養在Matrigel上則能形成相似的結構。反之，若將細胞培養在塑膠盤上則形成單層層狀結構(monolayers)。基於細胞微環境的重要性，我們以微矩陣分析來比較培養在塑膠盤和Matrigel上細胞的基因表現。乳腺細胞培養在Matrigel上時許多免疫相關基因包括了complement component 3 (C3)、CD14、LPS-binding protein (LBP)、growth arrest-specific 6 (GAS6)和milk-fat globulin-E8 (MFG-E8)的表現量會高於培養在塑膠盤上的細胞。由於乳腺腺泡內腔的形成是因細胞聚集後位於內部的細胞死亡並被清除所致，所以我們推測這些基因對於乳腺內腔形成扮演了重要的角色。在本篇研究，我們確認了微矩陣分析之結果並且發現免疫相關基因的表現與腺泡內腔形成的動態變化是一致的，顯示這些基因可能參與乳腺內腔的清除。除了基質的種類，基質的軟硬度、細胞的形狀或是與這些因子相關的訊息途徑（Rho/Rac路徑）會影響不同免疫相關基因的表現。使用cathepsin抑制劑則會阻斷免疫相關基因的表現和乳腺內腔的形成，顯示細胞壞死正向地調控這些現象。因此，我們推測細胞外基質可能藉由改變免疫相關基因的表現來調控組織的構形。

In mammary glands, epithelial cells contact basement membrane (BM) to form glandular structures with a central lumen. In vitro cultures of mammary cells on Matrigel display this morphology. By contrast, cells cultured on tissue culture plastic form monolayers. Owing to the importance of the microenvironment, we compared gene expression in cells cultured on plastic and Matrigel. Many immune-related genes, including complement component 3 (C3), lipopolysaccharide-binding protein (LBP), CD14, growth arrest-specific 6 (GAS6) and milk fat globule-EGF factor 8 (MFG-E8) were upregulated in cells cultured on BM. We speculate that these genes play a role in lumen formation in mammary acini since cell death and the subsequent clearance of the corpses are essential to establish this tissue architecture. Here we have confirmed our microarray data and found that kinetics of gene expression parallels with that of lumen formation, suggesting that these genes might have a role in luminal clearance of the mammary gland. In addition to substratum type, substratum rigidity, cell shape or their related signaling pathways (Rho/Rac pathways) differentially influence the expression of immune-related genes. Necroptosis positively regulates the expression of these genes since inhibition of cathepsin blocks gene expression and lumen formation. Thus, extracellular matrix might control tissue architecture via modulation of immune-related genes.