Establishment and characterization of immortalized human ameloblastoma cell lines, HAM1 and 2

成釉细胞瘤是一种最常见的良性牙源性肿瘤，然而高复发率和可能的恶性发展已被报道。在本研究中，我们通过转染人端粒酶逆转录酶（hTERT）基因和人乳头瘤病毒-16 (HPV16) E6/E7基因，建立了两种永生化细胞系HAM1和ham2，分别来自滤泡和结缔组织增生成釉细胞瘤标本。这两种细胞系不仅可以通过原位（HAM1, 100%; HAM2, 100%）植入，也可以通过异位（HAM1, 33%; HAM2, 100%）植入在体内生长。接种组织的组织学结果显示，这些细胞系很好地保留了成釉细胞瘤的临床表现。据我们所知，这些细胞系是第一个体外/体内模型系统，可以在体内形成可识别的人体成釉细胞瘤组织结构。然后，我们分析了这些细胞系中一些癌症相关分子的表达，并在8例原发性成釉细胞瘤的RT-PCR分析中选择了一个表达频率最高的候选基因（100%）。一项免疫组织化学研究也表明，在65例原发性成釉细胞瘤标本中，34例（52.3%）的候选基因的产生显著增加。此外，该候选基因的选择性抑制剂在体外和体内对这些细胞系表现出显著的抑制作用。我们的研究清楚地支持该候选基因的产物可以成为治疗成釉细胞瘤的分子靶点之一。

Ameloblastoma is a benign and the most common odontogenic neoplasm, whereas high recurrence rates and possible malignant development have been reported. In the present study, we established two immortalized cell lines, termed HAM1 and 2, by transfecting of human telomerase reverse transcriptase (hTERT) gene and human papillomavirus-16 (HPV16) E6/E7 genes into primary in vitro outgrowths from follicular and desmoplastic ameloblastoma specimens. Both lines could growth in vivo not only as a result of orthotopic (HAM1, 100% ; HAM2, 100%) but also of ectopic (HAM1, 33% ; HAM2, 100%) implantation. The histological findings of these inoculated tissues showed that these cell lines retained the clinical manifestations of ameloblastoma well. These cell lines are, to the best of our knowledge, the first in vitro / in vivo model system that can form recognizable tissue structures as human ameloblastoma in vivo. Then, we analyzed expression of some cancer-related molecules in these cell lines, and selected a candidate gene showed the highest expression frequency (100%) in RT-PCR analysis of eight primary ameloblastoma cases. An immunohistochemical study also demonstrated that the production of the candidate gene was considerably increased in 34 of 65 primary ameloblastoma specimens (52.3%). Moreover, a selective inhibitor for this candidate gene showed significant inhibitory effects on these cell lines in vitro and in vivo. Our study clearly supports that products of this candidate gene can make one of the molecular targets in treatment of ameloblastoma.