S100A2是屬於S100鈣離子結合蛋白質家族中的一員，S100A2分子能透過其2個EF-hand鈣離子蛋白結合區域，自我結合形成同型二聚體結合蛋白。在我們先前研究已證實細胞核內S100A2的喪失，可提供早期口腔癌病人高危險復發的診斷標記。為了找出S100A2抑制腫瘤的分子機轉，我們最近利用並列親和層析法(Tandem Affinity Purification) 、二維凝膠電泳(2D-GE)及MOLTI-TOF質譜儀，去找尋可以與S100A2作用的新穎蛋白質。其中我們發現Enolase 1是可以與S100A2作用的新穎蛋白質，並利用免疫共沈澱法及免疫螢光顯微鏡，再次證明S100A2與Enolase 1之間的結合。目前已知Enolase 1是參與醣類代謝的酵素之一，Enolase 1可將2-phosho-D-glycerate轉換成phosphoenopyruvate。我們利用Enolase 1截短型(truncation mutants)及pull down assay，發現S100A2可與Enolase 1的N端和C端區域結合。值得注意地，在人類許多癌症腫瘤中發現Enolase 1蛋白表現是呈現上升的。我們建立增加ENO1表現和降低ENO1表現的穩定轉染細胞株，藉由細胞生長速率、傷口癒合實驗、侵襲能力測試、集落培養及腫瘤新生分析，去找出Enolase 1 在口腔癌細胞株中所扮演的角色為何。當ENO1表現增加時，則會促進口腔癌細胞的生長速率、移動能力、侵襲能力、集落形成能力及腫瘤新生能力；若降低ENO1的表現，則會抑制口腔癌細胞的生長速率、移動能力、侵襲能力及集落形成能力。為了更進一步研究口腔癌病人的Enolase 1表現情況，目前我們收集45個口腔癌病人檢體，利用RT-PCR技術去分析Enolase 1 mRNA表現情形。我們發現Enolase 1 mRNA表現量是隨著口腔腫瘤癌化程度而上升。綜合以上的結果，認為在人類口腔癌Enolase 1可能扮演腫瘤基因的角色。未來我們還需要更進一步研究，去釐清口腔癌細胞中Enolase 1所扮演的角色及其與S100A2作用的分子機轉。

S100A2 is a member of S100 calcium-binding protein family and can form homodimer via two EF-hand calcium-binding motif in each molecule. Our previous studies demonstrated that the loss of nuclear S100A2 may serve as an independent prognostic marker for early-stage oral cancer patients at high risk of recurrence. To clarify whereby S100A2 mediated anti-tumor effect, we recently used tandem affinity purification (TAP), 2D-GE and MOLTI-TOF mass spectrometry to identify that Enolase 1 was the interacting partner of S100A2, which was later confirmed by co-immunoprecipitation and immunofluoresence microscopy. Enolase 1 is a glycolytic enzyme catalyzing the conversion of 2-phospho-D-glycerate to phosphoenolpyruvate. Using Enolase 1 truncation mutants and pull down assay, we have identified that S100A2 interacted with both N- and C-terminal of Enolase 1. Upregulation of Enolase 1 has been detected in many types of human cancer. We established stable ENO1-expressing and ENO1-knocking down clones followed by the use of growth rate, wound healing, invasion, colony formation, and in vivo tumorigenesis assays to study the role of ENO1 in cancer cells. Knocking down the expression of Enolase 1 slowed down the growth, migration, invasion and colony formation of oral cancer growth while overexpression of Enolase 1 enhanced the the cell growth, migration, invasion, colony formation and tumorgenesis. To further study the clinical implication of Enolase 1 expression in oral cancer patients, we collected 45 oral cancer specimens for measuring Enolase 1 mRNA expression by RT-PCR. We found that Enolase 1 mRNA expression increased with clinical progression of oral cancer. Together, Enolase 1 may act as an oncogenic role in human oral squamous cell carcinoma. More studies will be needed to address the role and molecular mechanism of Enolase 1 in the anti-tumor effect of S100A2.

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