微型核醣核酸221及200a在翼狀贅片致病過程中所扮演的角色

翼狀贅片(pterygium)是一種古老而常見的眼部疾病，亦稱之為「眼翼」。至今仍未知道其確切的發病原因。一般認為和長期紫外線的曝曬，刺激結膜細胞增生有強烈的相關性。翼狀贅片在結膜表面不正常細胞增生之特性與腫瘤細胞極為相似，組織中p53基因的變化及蛋白表現異常亦與腫瘤組織極為類似。近年來發現與腫瘤形成有關的microRNAs的變化可能也參與了翼狀贅片疾病的發展。microRNA是小的非編碼RNA，過去的研究指出microRNA經由表現量的差異調控細胞週期的進行，亦調控許多與細胞不正常增生相關的基因表現而參與細胞的癌化，例如ras、Rb、 p53、p21及myc等。但至今仍沒有確切的研究結果證實microRNA與翼狀贅片形成的相關性，因此本研究收集了120個翼狀贅片組織及120個正常的結膜組織，使用免疫組織染色法、及時定量PCR (real-time RT-PCR) 及翼狀贅片細胞株模型來確認監測β-catenin蛋白的位置、miR-221、p27Kip1、p53、p53下游的EMT相關蛋白及miR-200a基因表現。研究結果顯示miR-221的表達在翼狀贅片組有60.0％（72 of 120）顯著高於對照組10.8％（13 of 120，p<0.0001）；miR-221表達在β-catenin-nuclear/cytoplasmic-陽性組顯著比β-catenin membrane-陽性和陰性組（p=0.001）高。並且發現p27Kip1的基因表達與miR-221表達呈現負相關（p=0.002）。另外，miR-200a的表達在翼狀贅片組顯著低於對照組（Ratio＜0.5；p =0.015）。miR-200a的表現量與p53蛋白的表達呈正相關（p <0.001），但與下游基因ZEB1和ZEB2的表達呈負相關（ZEB1 p<0.001; ZEB2 p <0.001;）。本研究證實miR-221 / p27Kip1參與翼狀贅片的細胞增殖。並且證明p53失去活性可導致miR-200a在翼狀贅片的表現量增加，造成下游基因ZEB1 / ZEB2上升及上皮細胞間質轉化，促進翼狀贅片的發病機制。

Pterygium is a common ocular disease of which the exact pathogenesis is still unclear. In general, pterygium has a strong correlation with UV exposure. The characteristics of pterygium are very similar to the proliferation of tumor cells, and the abnormalities in p53 gene and protein expression in pterygia tissues is also very similar to tumor tissues. Changes of microRNAs in tumor formation may also be involved in the development of pterygium. MicroRNAs are small non coding RNAs that have been implicated in tumor development. Previous studies show that microRNAs can regulate the expression of cell cycles and the associate genes of cancerous cells, including ras、Rb、 p53、p21 and myc. We collected 120 pterygial and 120 normal conjunctival samples for this study.Immunohistochemistry, real-time reverse transcription (RT)–PCR, and pterygium cell line (PECs) cell models were performed to determine and confirm the effect of β-catenin protein localization, miR-221, p27Kip1 gene expression, p53, p53 down-stream EMT associated protein and miR-200a. Seventy-two (60.0%) pterygial specimens showed high miR-221 expression levels, which was significantly higher than the control groups (13 of 120, 10.8%, p<0.0001). MiR-221 expression was significantly higher in the β-catenin-nuclear/cytoplasmic-positive groups than in the β-catenin membrane-positive and negative groups (p=0.001). We also found that p27Kip1 gene expression in pterygium correlated negatively with miR-221 expression (p=0.002). The expression of miR-200a in pterygium tissues was significantly lower than in the conjunctiva controls (Ratio＜0.5,p =0.015). Up-regulated miR-200a levels correlated positively with p53 protein expression (p <0.001). MiR-200a downstream ZEB1/ZEB1 protein expression correlated negatively with miR-200a expression. Cell model studies demonstrated that miR-200a controlled the EMT of PECs through up-regulated ZEB1, ZEB2 and Snail gene expression. Our study demonstrated that activation of β-catenin in pterygium may interact with miR-221, resulting in p27Kip1 gene downregulation that influences pterygium pathogenesis, and the expression of miR-200a plays an important role in EMT processing.