Perra Maria Teresa, Maxia Cristina, Corbu Arianna, Minerba Luigi, Demurtas Paolo, Colombari Romano, Murtas Daniela, Bravo Sonia, Piras Franca, Sirigu Paola
Department of Cytomorphology, University of Cagliari, Monserrato, Italy.
Mol Vis. 2006 Sep 30;12:1136-42.
Ultraviolet (UV) radiation is known to cause oxidative DNA damage and is thought to be a major factor implicated in the pathogenesis of pterygium, a benign invasive lesion of the bulbar conjunctiva. Among all the photooxidative DNA products, 8-hydroxydeoxyguanosine (8-OHdG) is regarded as a sensitive and stable biomarker for evaluating the degree of DNA damage. The protein p53 is a major cell stress regulator that acts to integrate signals from a wide range of cellular stresses. UV radiation can cause mutations in the p53 tumor suppressor gene that, when inactivated through mutation and loss of heterozygosity, can lead to cell proliferation and genomic instability. In many types of UV-radiation damaged cells, p53 is overexpressed and immunohistochemically detectable. Recent data on tissues exposed to factors inducing oxidative stress have provided evidence of the concomitant presence of increased levels of 8-OHdG and protein p53. To verify a possible significant association between p53 and 8-OHdG, we examined a series of 31 Ecuadorian pterygia for the expression of the two markers. Moreover, we evaluated if clinical variables such as patient's age, gender, geographic location, and disease stage, might play a role affecting the 8-OHdG and p53 immunohistochemical staining results.
Primary pterygium samples were treated for immunohistochemical evaluations of 8-OHdG and p53 protein. Mouse monoclonal antibodies to 8-OHdG and p53 were used. Statistical analyses were performed using the SPSS 12 statistical software package.
In our study, 21 (67.74%) pterygial samples were positive for 8-OHdG staining, 11 (35.48%) specimens were positive for p53 expression, and all negative control samples showed no staining. The staining for 8-OHdG was limited to the nuclei of the epithelial layer. No substantial staining was visible in the subepithelial fibrovascular layers. No differences in the pattern of staining between 8-OHdG and p53 were observed. All samples positive for p53 (11/31, 35.48%) were also positive for 8-OHdG immunostaining, and all specimens negative for 8-OHdG (10/31, 32.26%) were also negative for p53. When analyzed by Fisher's exact test, 8-OHdG expression was significantly associated with p53 positivity (p=0.0049). Student's t-test demonstrated statistically significant association between the expression of p53 and age (p=0.02). The correlation between the two markers and the other clinical variables revealed no statistically significant association.
Although pterygium is a lesion with limited local invasion and an inability to metastasize, the concomitant presence of altered p53 in 8-OHdG-immunoreactive cells could provide evidence of apparent genetic instability, which is in contrast to its benign clinical course.
已知紫外线（UV）辐射会导致氧化性DNA损伤，并且被认为是翼状胬肉发病机制中的一个主要因素，翼状胬肉是一种球结膜的良性侵袭性病变。在所有光氧化DNA产物中，8-羟基脱氧鸟苷（8-OHdG）被视为评估DNA损伤程度的一种敏感且稳定的生物标志物。蛋白质p53是一种主要的细胞应激调节因子，其作用是整合来自多种细胞应激的信号。紫外线辐射可导致p53肿瘤抑制基因突变，当该基因通过突变和杂合性缺失而失活时，可导致细胞增殖和基因组不稳定。在许多类型的紫外线辐射损伤细胞中，p53会过度表达且可通过免疫组织化学检测到。最近关于暴露于诱导氧化应激因素的组织的数据提供了8-OHdG水平升高与蛋白质p53同时存在的证据。为了验证p53与8-OHdG之间可能存在的显著关联，我们检查了31例厄瓜多尔翼状胬肉样本中这两种标志物的表达情况。此外，我们评估了患者年龄、性别、地理位置和疾病分期等临床变量是否可能影响8-OHdG和p53免疫组织化学染色结果。
对原发性翼状胬肉样本进行8-OHdG和p53蛋白的免疫组织化学评估。使用针对8-OHdG和p53的小鼠单克隆抗体。使用SPSS 12统计软件包进行统计分析。
在我们的研究中，21例（67.74%）翼状胬肉样本8-OHdG染色呈阳性，11例（35.48%）标本p53表达呈阳性，所有阴性对照样本均未显示染色。8-OHdG染色仅限于上皮层细胞核。上皮下纤维血管层未见明显染色。未观察到8-OHdG和p53染色模式的差异。所有p53阳性样本（11/31，35.48%）8-OHdG免疫染色也呈阳性，所有8-OHdG阴性标本（10/31，32.26%）p53也呈阴性。通过Fisher精确检验分析，8-OHdG表达与p53阳性显著相关（p = 0.0049）。Student t检验显示p53表达与年龄之间存在统计学显著关联（p = 0.02）。两种标志物与其他临床变量之间的相关性未显示统计学显著关联。
尽管翼状胬肉是一种局部侵袭有限且无法转移的病变，但8-OHdG免疫反应性细胞中p53改变的同时存在可能提供明显遗传不稳定的证据，这与其良性临床病程形成对比。
