Identification of Radioprotectors in Human Hepatocellular Carcinoma by Genome-Wide RNAi Screening

• Main Authors: Wei-Hsiao Li, 李偉孝
• Other Authors: 林育誼
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/v458jn

碩士 === 國立臺灣大學 === 生物化學暨分子生物學研究所 === 101 === Hepatocellular carcinoma (HCC), the third most prevalent malignant tumor in Taiwan, has a poor prognosis due to high rates of recurrence and metastasis. Radiotherapy is one of the modalities in cancer treatments. With the recent development of stereotactic radiosurgery technology, physicians can deliver precise doses of energy to an exact location (i.e. the tumor) and thus limit collateral damage to surrounding normal tissues. Despite such an advanced technology, radiotherapy has not yet been incorporated into standard management guidelines of HCC because of the unsatisfactory clinical outcomes. In order to improve the efficacy of radiotherapy in treating HCC, we carried out a genome-wide RNA-interference (RNAi) screen in Huh7 cells (a human HCC cell line) and identified many genes as radiation protector candidates (i.e. knockdown of such genes increases the sensitivity of Huh7 cells to a predetermined dose of radiation) which might be used as potential targets for drug design to enhance radiation sensitivity of HCC. We identified twenty-one candidates from the screening results, including sixteen radioprotectors and five radiosensitizers. All of the candidates were validated by colony formation assay. Among these candidates, clusterin is the most significant radio-protector. Here we demonstrated that suppression of clusterin expression enhances the radiation-mediated cell death. Furthermore, the phenomenon caused by clusterin suppression is specific for ionizing radiation, but not for ultraviolet (UV) radiation. However, the detailed mechanisms and functions of clusterin need to be further studied and elucidated in the future.