血管新生(angiogenesis)和癌症的發展有密切的關係，當腫瘤尺寸大於2-3立方厘米時需要靠新生血管供給養分。又內皮細胞的增生與移動是形成新生血管時兩個很重要的步驟，為了了解內皮細胞的關鍵功能是如何被調控，我們利用生物資訊方法尋找會影響血管新生的基因。而藉由serial analysis of gene expression (SAGE)這個功能強大的生物資訊方法可以篩選出跟內皮細胞生長相關的新穎蛋白質，跟cDNA資料庫不同的是即使缺乏已知的相關資訊，SAGE仍可以分析完整的基因表現。我們則利用SAGE找到了一個在靜脈具有高度表現的新穎蛋白質-胎盤內皮細胞蛋白1(PEP1)。
PEP1中包括了許多凝血酶敏感蛋白-1 Thrombospondin type-1 (TSP-1)重複，TSP-1已知會抑制內皮細胞的移動能力，所以我們猜測PEP1可能也具有影響內皮細胞移動能力之特性。為了解PEP1是否會在體外影響內皮細胞移動，我們挑選了兩個片段為優先研究目標：第一個片段為C端尾端胜肽片段－c terminal end (CTE)；另一個片段為介於第八與第九個TSP-1之間的胜肽片段－inter TSP-1 domain sequence 8 (IDS8)。
如預期結果顯示，CTE和 IDS8兩段胜肽片段會在體外促使人類臍帶靜脈內皮細胞移動能力，但不會影響其生長繁殖能力。總結我們的結果，證明了PEP1可能在血管新生扮演一定的角色，而且經由更多有關分子機制的調查，將可提供血管功能不全以及癌症更深層的研究。

Angiogenesis is known to play a critical role in cancer development. When tumor grows larger than 2-3 mm3, cancer mass needs to induce angiogenesis to sustain its nutrition needs. During the angiogenesis process, proliferation and migration of endothelial cells (ECs) are two important steps. In order to understand the transcript regulation governing these critical EC functions, we took the bioinformatic approach to identify genes that are involved in angiogenesis. Serial analysis of gene expression (SAGE) is a powerful bioinformatic tool to screen for novel proteins related to ECs growth. Unlike cDNA microarray, SAGE allows in silico analysis of overall gene expression with no need for preexisting sequence information. A novel protein, Placenta Endothelial Protein1 (PEP1) is found highly expressed in vein, was identified by SAGE.
PEP1 comprises of several thrombospondin type-1 (TSP-1) repeats. Since TSP-1 inhibits ECs migration, we hypothesize PEP1 may also involve in regulating similar EC function. Two regions of PEP1 are selected to test whether PEP1 could affect EC migration in vitro. The first one is the C Terminal End (CTE) of PEP1, and the other is an inter-TSP1-domain-sequence (IDS8).
As expected, the CTE and IDS8 of PEP1 promote the migration of Human Umbilical Vein Endothelial Cells (HUVECs) in vitro. In conclusion, our results demonstrate PEP1 is likely to play a role in angiogenesis and further study on the underlying mechanism may provide insight in vascular dysfunction and cancer research.

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