Summary: | 碩士 === 國立陽明大學 === 臨床醫學研究所 === 100 === Over-expression and mutations of epidermal growth factor receptor (EGFR) has been wildly addressed in most lung adenocarcinoma. The tumorigenicity of oncogenic EGFR has been justified in vitro and in transgenic mice, but the mechanism and process of transformation have not been fully elucidated. Here, we established cancer cell lines from non-tumoral human bronchiolar epithelial cells and mouse fibroblasts in vitro using a piggyBac transposon expressing oncogenic EGFRs. Transformed cancer cells showed morphological alternations, loss of contact inhibition, anchorage-independent growth, enhanced migration and invasion ability. Intriguingly, these properties were maintained in the re-transformed cells after complete removal of the transposon, suggesting that after completion of oncogenic transformation, the causative oncogene is no longer indispensable for tumor growth. Addition of TSA (HDAC inhibitor) and 5’-AZC (methylation inhibitor) severely blocked cell colony formation and growth during the transformation and re-transformation process, but not affected in EGFR-transformed and -removed stable cells, suggesting that epigenetic modification is a critical step for EGFR-mediated transformation and -removed re-transformation. Stemness genes including Oct4 and Bmi-1 were found to be overexpressed in EGFR-transformed cells, while Oct4 was further enhanced after removal of the transposon, suggesting a role of stemness genes in oncogenic transformation. Finally, gene expression profiles were analyzed and compared between normal and transformed cells using microarray. In conclusion, our study provides an experimental platform to uncover and determine novel and important genetic/epigenetic alternations in the process of oncogenic transformation.
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