Study on development, proliferation and differentiation of ameloblastoma

为了阐明成釉细胞瘤的增殖特征，将肿瘤分为3种类型：立方细胞型、柱状细胞型和基底细胞型。对成釉细胞瘤中增殖细胞核抗原（PCNA）表达的免疫组织化学评估显示，基底细胞类型的PCNA标记指数高于立方细胞和柱状细胞类型。该结果表明基底细胞具有很强的细胞增殖活性。根据对囊性成釉细胞瘤有袋化前后生长特征的临床和组织病理学研究，有袋化前以立方细胞型的扩张型为主，而有袋化后许多病例已由扩张型转变为柱状细胞或基底细胞型的侵袭型。人们认为，缓解囊内压力可能会激活肿瘤细胞增殖。使用抗人 bcl-2 癌蛋白的单克隆抗体，对 25 个成釉细胞瘤中防止细胞凋亡的 bcl-2 蛋白的表达进行了免疫组织化学评估。在所有病例中，bcl-2蛋白主要存在于肿瘤细胞的外层，而内层细胞呈阴性。因此，bcl-2 蛋白被认为在维持肿瘤巢外周层的蒸汽细胞群中发挥着作用，从中可以招募增殖的细胞。我们使用 16 型人乳头瘤病毒产生了成釉细胞瘤细胞系 (AM-1) 的永生化克隆。该细胞系保持了尖峰细胞形态并表达细胞角蛋白 K14、K18、K19 和 bcl-2 蛋白。这些细胞可以侵入胶原蛋白凝胶。由于细胞系 AM-1 的行为模仿成釉细胞瘤的行为，因此它似乎是研究这些肿瘤的合适模型。

On the purpose of clarification of characteristics of proliferation of ameloblastoma, the tumor was classified into 3 types : cubiodal cell, columnar cell, and basal cell type. Immunohistochemical evaluation on expression of proliferating cell nuclear antigen (PCNA) in ameloblastoma revealed that PCNA labelling index was higher in the basal cell type than the cuboidal and the columnar cell type. This results suggested strong cell proliferation activity in the basal cell. According to the clinical and histopathological study on the growth characteristics before and after marsupialization of cystic ameloblasoma, the expansive pattern with the cuboidal cell type was dominant premarsupialization, whereas for postmarsupialization many cases that had been expansive changed to an invasive type showing columnar or basal cell types. It is thought that relief of the intracystic pressure may potentially activate tumor cell proliferation.Immunohistochemical evaluation of the expression of bcl-2 protein, which prevents apoptosis, was performed in 25 ameloblastomas using a monoclonal antibody against anti-human bcl-2 oncoprotein. In all cases, bcl-2 protein was found mainly in the outer layr of tumor cells, whereas the inner cells were negative. The bcl-2 protein is therefore thought to play a role in maintaining the steam-cell population in the perpheral layrs of the tumor nests from which proliferating ells can be recruited.We produced an immortalized clones of ameloblastoma cell line (AM-1) using human pappiloma-virus type-16. This cell line maintains spithelian cell morphology and expressed cyto-keratines K14, K18, K19 and bcl-2 protein. These cells could invade athe collargen gel. Since the behavior of cell line AM-1 mimics the behavior of ameloblastoma, it appears to be an appropriate model for the study of these neoplasms.