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

采用免疫组织化学方法对牙胚和牙源性肿瘤中釉基质蛋白（amelogenin）和基底膜成分进行定位，以评价肿瘤细胞的功能分化。免疫组化结果提示釉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类似成釉细胞，但大多数成釉细胞瘤的分化程度不高，不能合成釉原蛋白。成釉细胞纤维瘤不合成釉原蛋白。免疫组化检测PCNA的分布、阳性率及c-myc、ras、p53蛋白的定位。增殖细胞核抗原（PCNA）免疫组化染色显示滤泡型和丛状型成釉细胞瘤中增殖细胞的分布模式不同。成釉细胞瘤复发时细胞增殖能力增强。PCNA阳性率 ...更多信息 恶性成釉细胞瘤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p53蛋白分布异常，2例良性成釉细胞瘤PCNA阳性率较高。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。结果表明，免疫组化检测上述蛋白质的含量和定位变化反映了成釉细胞瘤的分化、增殖和分化情况，并应用原位杂交技术观察了大鼠切牙和人牙源性肿瘤中釉原蛋白mRNA的信号。探针由人丛状型成釉细胞瘤组织制成，地高辛标记。釉原蛋白mRNA主要表达于滤泡周围的柱状细胞中。釉原蛋白mRNA在牙源性腺样瘤的肿瘤细胞中普遍存在，同时也存在釉原蛋白蛋白。从这些研究结果可以得出结论，腺样牙源性肿瘤更好地分化成釉细胞瘤方面的釉原蛋白蛋白和mRNA的合成。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