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

成釉细胞瘤是一种良性和最常见的牙源性肿瘤，但已有高复发率和可能的恶性发展的报道。在本研究中，我们通过将人端粒酶逆转录酶(HTERT)基因和人乳头状瘤病毒16型(HPV16)E6/E7基因导入滤泡性和结缔组织增生性成釉细胞瘤标本的原代培养细胞，建立了两个永生化细胞系HAM1和HAM2。两株细胞均能在体内生长，无论是原位移植(HAM1,100%；HAM2,100%)还是异位移植(HAM1，33%；HAM2,100%)。组织学观察表明，这些细胞系具有良好的成釉细胞瘤的临床表现。据我们所知，这些细胞系是第一个能够在体内形成可识别的组织结构的体外/体内模型系统，就像人类成釉细胞瘤一样。然后，我们分析了一些肿瘤相关分子在这些细胞系中的表达，并在8例原发成釉细胞瘤的RT-PCR分析中选择了表达频率最高的候选基因(100%)。免疫组织化学研究还显示，在65例原发成釉细胞瘤标本中，34例(52.3%)候选基因的表达显著增加。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株都有显著的抑制作用。我们的研究明确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.