利用人類臍靜脈內皮細胞探討 LPLs調控VEGF-C及淋巴標記表現機制之研究

The signaling mechanism of lysophospholipids-regulated vascular endothelial growth factor-C and lymphatic marker expressions in human umbilical cord vein endothelial cells

林芷歆(chihi hsin lin)

指導教授 ： 李心予

國立臺灣大學/生命科學院/動物學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.00607

摘要

Lysophosphatidic acid (LPA) 和 sphingosine 1 phosphate (S1P) 都是一種構造簡單的小分子水解磷酸脂 (lysophospholipids, LPLs)，其藉由結合至專一的G蛋白接合型的接受器 (G protein-coupled receptor)，進而活化下游的分子機制，調控許多細胞內的功能。在本實驗室的研究中首次發現在人類臍靜脈內皮細胞(human umbilical vein endothelial cells, HUVECs)中LPA對於調控淋巴管生成(lymphangiogenesis)的作用。Interleukin (IL)-1β為一重要的促發炎細胞激素(cytokine)，已知和血管硬化、血管新生、淋巴管生成及腫瘤轉移有很重要的關係。本研究中，利用流式細胞儀及管狀結構的生成分析等實驗方法，探討IL-1β在LPA調控淋巴管生成的機制中所扮演之角色。經由實驗結果發現在人類臍靜脈內皮細胞中，IL-1β 為LPA調控淋巴管生成中必要之分子。此外，我們觀察到IL-1β蛋白質濃度會受到LPA的誘導而增加，並且是藉由一種endothelial growth factor receptor (EGFR) transactivation的機制所調控。另一方面，本實驗室先前的研究指出在人類臍靜脈內皮細胞中LPA調控管狀結構的生成是經由EGFR transactivation；然而有趣的是S1P卻不是經由EGFR transactivation的機制所調控。最近的研究指出，纖維母細胞生長因子(fibroblast growth factor, FGF) 亦可促進淋巴管生成的作用，故我們假設S1P可能是經由和FGFR結合進而調控淋巴管生成之機制。藉由real-time polymerase chain reaction我們發現 S1P是經由FGFR之調控去誘導血管內皮細胞生長因子(vascular endothelial growth factor-C, VEGF-C)和淋巴管標記因子(lymphatic marker)之mRNA表現。接下來，我們更進一步研究發現S1P亦是藉由FGFR去誘導人類內皮細胞中管狀結構之生成。經由以上的實驗結果發現，LPLs在人類臍靜脈內皮細胞中調控淋巴管生成之機制扮演一重要之角色。

關鍵字

水解磷酸脂 ； 淋巴管新生

並列摘要

Lysophosphatidic acid (LPA) and sphingosine 1 phosphate (S1P) are both low-molecular-weight lysophospholipids (LPLs) ligands which bind to G-protein-coupled receptors and activate a variety of cellular functions. LPA was reported to regulate vessel formation by modulating the lymphangiogenesis process, but the molecular mechanisms largely remain unknown. In this study, we show that LPA upregulated vascular endothelial growth factor (VEGF)-C and subsequent lymphatic markers, including Prox-1, LYVE-1, and podoplanin, the protein expressions of which are mediated through an interleukin(IL)-1 receptor-dependent manner in human umbilical vein endothelial cells (HUVECs). In addition, we demonstrate that LPA-induced endothelial cell tube formation is also mediated through an IL-1 receptor in vitro. Furthermore, we also show that LPA-induced IL-1β expression is mediated through an EGFR transactivation-dependent mechanism. On the other hand, we found that S1P induced VEGF-C and subsequent lymphatic marker expressions via the fibroblast growth factor (FGF) receptor (FGFR) pathway. Moreover, we demonstrated that S1P induced endothelial cell tube formation in vitro. These enhancement effects were suppressed by the inhibition of FGFR. This study demonstrates the signaling mechanism of LPLs-regulated expressions of VEGF-C and lymphatic markers in endothelial cells; the results suggest that LPLs may be a suitable target for generating therapeutic agents against lymphangiogenesis and tumor metastasis.

並列關鍵字

LPL ； lymphangiogenesis ； HUVECs

參考文獻

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