探討IGFBP5 基因在人類纖維母細胞造成之效應

Abstract

放射治療已被應用於治療多種癌症，視網膜母細胞瘤就是其中之一。然而，罹患遺傳性視網膜母細胞瘤的孩童其外表正常的雙親之皮膚纖維母細胞會對游離放射線產生預期外的高敏感性(hypersensitivity)現象。Dr. Chuang 等人於2006 年利用 DNA 微陣列晶片技術分析並挑選出42 個與游離輻射誘發細胞敏感度改變有關之基因。IGFBP5 (insulin-like growth factor binding protein 5)是42 個游離輻射敏感性相關的基因之一，此基因被選出並探討其在人類纖維母細胞中造成之細胞輻射敏感度效應。此外，IGFBP5 已被證實與內皮細胞之老化有關。因此，本論文之主題為研究IGFBP5 基因在人類纖維母細胞中造成的游離輻射敏感性及細胞老化之效應。 本篇研究顯示，IGFBP5 與人類纖維母細胞老化有關，此結果是經由老化相關特定酵素染色(SA-β-gal staining)、細胞增生分析、以及分析微陣列實驗數據得到與抗細胞增生、細胞週期中止以及細胞老化之相關基因得知。此外，IGFBP5 與人類纖維母細胞之游離輻射敏感度有關：經由細胞聚落形成分析(colony formation assay)得知，大量表現IGFBP5 之人類纖維母細胞 Hs68 其對於2 Gy 到4 Gy 的游離輻射有較高的耐受性。本篇實驗結果顯示，IGFBP5 造成人類纖維母細胞對輻射耐受性增加，是因為此基因使得細胞增生速率變慢，以及從微陣列實驗數據分析得知其間接活化PI3K-AKT 細胞訊息傳遞路徑有關。

Radiotherapy is commonly used for the treatment of many kinds of cancer such as retinoblastoma. However, an unexpected hypersensitivity to ionizing radiation in skin fibroblasts derived from unaffected parents of children with hereditary retinoblastoma was observed. The results from Dr. Chuang et al. used DNA microarray technology to select the 42 significantly differential expressed genes and identified as radiosensitive genes were observed in 2006. IGFBP5 (insulin-like growth factor binding protein 5), one of these 42 genes, was chosen to further investigate the role in radiosensitivity in fibroblast cells. In addition, IGFBP5 was reported that it was involved in the cellular senescence in endothelial cells. As the result, the topic of this thesis was to evaluate the role of IGFBP5 in radiosensitivity and cellular senescence in human fibroblast cells. The results of this study showed IGFBP5 was involved in senescence by the method of SA-β-gal staining, cell proliferation assays, and the identification of genes related to anti-proliferation, cell-cycle arrest and senescence by the analysis of array data. Also, IGFBP5 played a role in radiosensitivity: Hs68 IGFBP5-overexpressed cells were more resistant to radiation at 2-4 Gy verified by colony formation assays. The radioresistace of IGFBP5 might be the lower proliferation rate of Hs68 IGFBP5-overexpressed cells and the up-regulation of PI3K-AKT pathway found from the analysis of array data.