利用女性X染色体失活嵌合性磷酸甘油酸激酶及雄激素受体位点多态性检测骨纤维结构不良的克隆性

Fibrous dysplasia:molecular clonality analysis of 21 cases

目的利用基于女性体细胞构成组织内 X 染色体失活嵌合性的磷酸甘油酸激酶(PGK)及雄激素受体(AR)基因位点的克隆性检测,探讨骨的纤维结构不良的克隆性,以进一步阐明它的本质。方法 21例女性纤维结构不良手术切除标本,均经4%甲醛固定,石蜡包埋,HE 染色后应用显微切割技术分离病变及病变周围软组织,提取基因组 DNA,经甲基化敏感的限制性内切酶 HpaⅡ或 Hha Ⅰ消化,套式聚合酶链反应(nested-PCR)扩增 PGK 和 AR 基因。通过 Bst Ⅺ消化和琼脂糖电泳显示 PGK 基因单核苷酸多态性;应用变性聚丙烯酰胺凝胶电泳显示 AR 基因 CAG 重复序列长度多态性。结果 21例纤维结构不良,光镜下均表现其组织学典型特征,即病变主要由梭形纤维样细胞和不成熟骨小梁组成,两者比例各例不一。在梭形细胞间由胶原纤维和鱼钩状或逗点状的不成熟骨小梁,梭形细胞与骨小梁直接移行,小梁周围大多没有骨母细胞围绕。克隆性检测结果表明,2例纤维结构不良在 PGK 和 AR 位点均不具有多态性,不能用于分析。其余15例和4例分别在 AR 和 PGK 基因位点显示多态性,并均表现为单克隆性,表明其肿瘤性本质。结论纤维结构不良不是一种反应性增生,而是一种真性肿瘤,但还需更多的病例证实。

Objective To investigate the neoplastic nature of fibrous dysplasia by molecular clonality approaches. Methods Twenty-one cases of fibrous dysplasia were examined by clonality assays based on X-chromosomal inactivation mosiacism. Lesional and non-lesional tissues were microdissected from paraffin sections followed by DNA extraction. The DNA was predigested by Hpa Ⅱ or Hha I , and then amplified by nested PCR targeting phosphoglycerate kinase （ PGK ） and androgen receptor （ AR ） genes. Single nucleotide polymorphism （SNP） at the PGK locus was identified by incubation of the PCR products with Bst XI and agarose gel electrophoresis, and CAG repeat length polymorphism at AR locus was determined by denaturing polyacrylamide gel electrophoresis and visualized by silver staining. Results Microscopically, all 21 cases showed characteristic features of fibrous dysplasia, including spindle fibrous cell proliferation and immature bone trabeculae at various proportions. DNA polymorphisms at AR locus and SNP of PGK gene were found in 15 of 21, and 4 of 21 cases, respectively. All 19 cases were monoclonal in nature. Two cases showed no polymorphism at either AR or PGK gene locus. Conclusions Fibrous dysplasia is likely a clonal, neoplastic process. Additional studies of larger number of cases are needed for a definitive conclusion.