Increased frequency of cancer-initiating cells in arsenic exposed HaCaT cells.

• Main Authors: Yu-Ting Chen, 陳郁婷
• Other Authors: Te-Chang Lee
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/37941869671915591483

碩士 === 國立陽明大學 === 口腔生物研究所 === 98 === Arsenic exposure is still a severe toxicological and pathological problem in humans. Epidemiological evidence has demonstrated that chronic arsenic exposure results in increased incidences of skin, lung, liver, and bladder cancers, but it mechanism of carcinogenesis is still unclear. A human keratinocyte chronically low-dose exposure to inorganic arsenic model has been established in this laboratory. In the tumorigenicity test A0, A2, and T4R2 cells showed different growth rate and tumor sizes in nude mice. These results may be explained by the presence of different frequency of cancer initiating cells (CIC) in A0, A2, and T4R2 cells. This is a question worth of further investigation. In this study, serum-free culture system was established to analyze the effect of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) on cell growth of these cell lines. Under the condition of bFGF defined medium, spheroid formation was observed. The spheroid frequency increases in the cells previously exposed to low dose of arsenic i.e., A1, A2, and T4R2 cells. In low cell density serum-free culture, A0, A1, A2, and T4R2 cells form different types of colony. The cell morphology of typeⅠcolony is typical epithelial cell type, type Π colony a mixed type colony, and type Ш colony composed of small and compact cells. Through single cell colony tracking for 1 month, spheroids are formed from type Π and type Ш colonies, but not typeⅠ. To further characterize these different types of colonies, various types of A2 colonies were individually cloned and amplified in regular medium containing 10% fatal calf serum. In general, type Π and type Ш colonies showed higher spheroid formation ability than typeⅠin serum free medium with bFGF. The tumorigenicity of clones from different type colonies were evaluated by xenografted nude mice model. The preliminary data showed that type Π and type Ш colonies cells may form tumor, but required for further confirmation. Taken together, arsenic exposure to HaCaT cells resulted in increased frequency of spheroid forming cells, which may be considered as cancer initiating cells.