Zhao Y L, Piao C Q, Wu L J, Suzuki M, Hei T K
Center for Radiological Research, College of Physicians & Surgeons of Columbia University, VC11-218, 630 West 168th Street, New York, NY 10032, USA.
Carcinogenesis. 2000 Nov;21(11):2005-10. doi: 10.1093/carcin/21.11.2005.
Although exposure to asbestos fibers is associated with the development of lung cancer, the underlying mechanism(s) remains unclear. Using human papillomavirus-immortalized human bronchial epithelial (BEP2D) cells, we previously showed that UICC chrysotiles can malignantly transform these cells in a stepwise fashion before they become tumorigenic in nude mice. In the present study we used cDNA expression arrays to screen differentially expressed genes among the tumorigenic cells. A total of 15 genes were identified, 11 of which were further confirmed by northern blot. Expression levels of these genes were then determined among transformed BEP2D cells at different stages of the neoplastic process, including non-tumorigenic cells that were resistant to serum-induced terminal differentiation, early and late passage transformed BEP2D cells, five representative tumor cell lines and fused tumorigenic-control cell lines which were no longer tumorigenic. A consistent 2- to 3-fold down-regulation of the DCC (deleted in colon cancer), Ku70 and heat shock protein 27 genes were detected in all the independently generated tumor cell lines while expression levels in early transformants as well as in the fusion cell lines remained normal. In contrast, all the tumor cell lines examined demonstrated 2- to 4-fold overexpression of the insulin receptor and its signal transduction genes. Differential expression of these genes was completely restored in the fusion cell lines examined. No alteration in c-jun or EGF receptor expression was found in any of the cell lines. Our data suggest that activation of the insulin receptor pathway and inactivation of DCC and Ku70 may cooperate in malignant transformation of BEP2D cells induced by asbestos.
尽管接触石棉纤维与肺癌的发生有关，但其潜在机制仍不清楚。我们先前使用人乳头瘤病毒永生化的人支气管上皮（BEP2D）细胞，证明国际癌症控制联盟（UICC）温石棉可以在这些细胞在裸鼠中具有致瘤性之前，以逐步的方式使其发生恶性转化。在本研究中，我们使用cDNA表达阵列筛选致瘤细胞中差异表达的基因。共鉴定出15个基因，其中11个通过Northern印迹进一步证实。然后在肿瘤形成过程的不同阶段的转化BEP2D细胞中测定这些基因的表达水平，包括对血清诱导的终末分化有抗性的非致瘤细胞、早代和晚代传代的转化BEP2D细胞、五个代表性肿瘤细胞系以及不再具有致瘤性的融合致瘤-对照细胞系。在所有独立产生的肿瘤细胞系中均检测到结肠癌缺失基因（DCC）、Ku70和热休克蛋白27基因一致下调2至3倍，而早期转化体以及融合细胞系中的表达水平保持正常。相反，所有检测的肿瘤细胞系均显示胰岛素受体及其信号转导基因过表达2至4倍。在检测的融合细胞系中，这些基因的差异表达完全恢复。在任何细胞系中均未发现c-jun或表皮生长因子受体表达的改变。我们的数据表明，胰岛素受体途径的激活以及DCC和Ku70的失活可能共同作用于石棉诱导的BEP2D细胞的恶性转化。
