c-myc、p53和p16的表达及GNAS1基因突变在骨的纤维结构不良中的意义

Abnormal expression of c-myc, p53, p16 protein and GNAS1 gene mutation in fibrous dysplasia

目的检测c-myc、p53和p16蛋白在骨的纤维结构不良（FD）中的表达及其意义，检测FD中GNAS1基因第8外显子突变，探讨FD的病变性质。方法采用免疫组织化学SP法检测35例FD（包括1例FD恶变，1例Mazabraud综合征）及20例对照组（10例骨痂、10例骨肉瘤）中c-myc、p53和p16蛋白表达。采用基因组DNA抽提、PCR扩增及基因测序的方法检测35例FD中GNAS1基因第8外显子突变情况。结果91％（32／35）FD中检测到c-myc蛋白表达，与阴性对照组相比差异具有统计学意义（P=0．001）。p53阳性表达仅出现于1例FD合并骨肉瘤变病例中。p16蛋白在34例FD中阳性，与阳性对照组相比差异具有统计学意义（P=0．001）。35例FD中，12例GNAS1基因第8外显子DNA扩增成功，其中2例（1例Mazabraud综合征的FD；1例单骨性FD）检测到GNAS1基因突变。结论c-myc可能是除c-fos外的又一FD相关的原癌基因，p16基因的异常表达在FD的形成过程中可能起重要作用，p53蛋白过表达有助于FD恶变的预测及预后的判断。FD中存在有GNAS1的基因突变。FD是多种因素共同作用导致的骨成熟障碍的肿瘤性病变。

Objective To study the significance of c-myc,p53 and p16 protein expression in fibrous dysplasia, to detect the GNAS1 gene mutation in fibrous dysplasia, and to explore the property of fibrous dysplasia. Methods The expression of c-myc,p53 and p16 protein was evaluated by immunohistochemistry SP method in 35 cases of fibrous dysplasia including 1 FD with malignancy, 1 Mazabraud syndrome and 20 control cases （10 cases of bony callus, 10 cases of osteosarcoma）. Genomic DNA extraction, PCR amplification and gene sequencing were used to detect GNAS1 gene mutation in 35 cases of fibrous dysplasia. Results C-myc protein immunoreactivity was detected in 91 percentage of FD （ P = 0. 001 ）. Compared with the negative control group, the difference was significant. P16 positive was detected in 34 FD cases（P =0. 001 ）. The difference was significant as compared with the positive control group. Positive p53 protein expression was detected in the only 1 case of fibrous dysplasia with malignant transformation. PCR amplification was successful in 12 of 35 FD cases. Two of the 12 FD cases were detected to have GNAS1 gene mutation, in which 1 case was FD of Mazabraud syndrome, 1 case was a monostotic lesion. Conclusions C-myc could be another protooncogene in addition to c-fos in the fibrous dysplasia disease. P53 protein overexpression could be useful in the diagnosis of FD malignancy and in the prediction of the prognosis of FD. The abnormal expression of the gene p16 might play an important role in the formation of FD. The GNAS1 mutation exist in FD. All of the results indicate that FD could be a neoplasia disease, caused by multiple factors leading to a dysfunction of bone development.