Study on development, proliferation and differentiation of ameloblastoma

为明确成釉细胞瘤的增殖特点，将其分为立方细胞型、柱状细胞型和基底细胞型。增殖细胞核抗原（PCNA）在成釉细胞瘤中的表达，基底细胞型的PCNA标记指数高于立方细胞型和柱状细胞型。该结果表明，在基底细胞中具有强的细胞增殖活性。根据造袋术前后囊性成釉细胞瘤生长特点的临床和组织病理学研究，造袋术前以立方细胞型的扩张型为主，而造袋术后许多病例由扩张型转为柱状或基底细胞型的浸润型。认为囊内压力的缓解可能潜在地激活肿瘤细胞的增殖。使用抗人bcl-2癌蛋白的单克隆抗体，对25例成釉细胞瘤进行了bcl-2蛋白表达的免疫组织化学评价，该蛋白可防止细胞凋亡。bcl-2蛋白主要表达于肿瘤细胞的外层，内层细胞均为阴性。因此，bcl-2蛋白被认为在维持肿瘤巢周围层中的蒸汽细胞群中起作用，增殖细胞可以从肿瘤巢中募集。该细胞系保持了spithelian细胞的形态，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凝胶。由于细胞系AM-1的行为模拟成釉细胞瘤的行为，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.