molecular biology study on odontogenic and osteogenic tumors with respect to application in differentiation diagnosis

采用免疫组化方法对牙胚和牙源性肿瘤的牙釉质基质蛋白（amelogenin）和基底膜组分进行定位，评价肿瘤细胞的功能分化情况。免疫组化结果表明，淀粉原蛋白和基底膜物质在牙胚硬组织形成过程中起重要作用。成釉细胞瘤的肿瘤细胞与非成釉细胞相似，但多数成釉细胞瘤分化程度不足以合成成釉原蛋白。成釉纤维瘤完全不合成淀粉蛋白。免疫组化检测PCNA的分布规律、阳性率及c-myc蛋白、ras蛋白、p53蛋白的定位。PCNA免疫染色发现滤泡型和丛状型成釉细胞瘤的增殖细胞分布模式不同。成釉细胞瘤复发后，细胞增殖能力增强。PCNA在恶性成釉细胞瘤中的阳性率明显高于良性成釉细胞瘤。在成釉细胞瘤中，c-myc蛋白的定位随细胞周期的变化而变化，并与细胞增殖有关。Ras蛋白定位于分化的肿瘤细胞，与细胞增殖无直接关系。2例恶性成釉细胞瘤和2例良性成釉细胞瘤中p53蛋白分布异常，PCNA阳性率较高。此外，c-myc和ras蛋白在p53异常成釉细胞瘤中的分布模式与恶性成釉细胞瘤相似。上述蛋白在数量和定位上的差异反映了成釉细胞瘤的分化、增殖和恶性程度。采用原位杂交技术观察大鼠门牙和人牙源性肿瘤中淀粉原蛋白mRNA的表达。探针取材于人丛状型成釉细胞瘤，用地高辛标记。淀粉原蛋白mRNA主要存在于卵泡周围的柱状细胞中。在腺样牙源性肿瘤的肿瘤细胞中普遍存在淀粉原蛋白mRNA，同时也存在淀粉原蛋白。由此可见，腺样体牙源性肿瘤在淀粉原蛋白和mRNA的合成方面优于成釉细胞瘤。少

Immunohistochemistry was adopted to localize enamel matrix protein (amelogenin) and basement membrane components in tooth germ and odontogenic tumors as to evaluate the functional differentiation of tumor cells. The immunohistochemical results indicated that amelogenin and basement membrane substance playd important roles during hard tissue formation in tooth germ. The tumor cells in ameloblastomas resemble amoblasts but majority of ameloblastomas were not so differentiated as to synthesize amelogenin protein. Ameloblastic fibromas did not synthesize amelogeinin protein at all. Immunohistochemistry was also used to evaluate the distribution pattern and positive rate of PCNA and the localization of c-myc protein, ras protein, and p53 protein. Different distribution patterns of proliferation cells were found between follicular type and plexiform type ameloblastomas by PCNA immunostaining. In addition, the proliferation ability was increased when ameloblastomas recured. PCNA positive rate … More in malignant ameloblastomas was significantly higher than that in benign ameloblastomas. In ameloblastomas the localization of c-myc protein varied with cell circle and showed relationship to cell proliferation. ras protein was localized in differentiated tumor cells showing no direct ralationship to cell proliferation. The abnormal distribution of p53 protein was found in 2 cases of malignant ameloblastomas and 2 cases of benign ameloblastomas showing higher PCNA positive rate. Furthermore, the distribution pattern of c-myc and ras protein in p53 abnormal ameloblastomas were similar to those in malignant ameloblastomas. These results indicated that the immunodetection of above-mentioned proteins varying in quantity and localization reflected differentiation, proliferation and malignance of ameloblastomas.In addition in situ hybridization was performed to observe amelogenin mRNA signals in rat incisors and in human odontogenic tumors. The probe was made from human plexiform type ameloblastoma and labeled by Digoxigenin. Amelogenin mRNA was mainly present in columnar cells located in the periphery of the folicles. Amelogenin mRNA was commonly observed in the tumor cells of adenoid odontogenic tumors, which also showed presence of amelogenin protein. From these findings it is concluded that adenoid odontogenic tumors were better differentiated than ameloblastomas in respect to the synthesis of amelogenin protein and mRNA. Less