沉默AKR1C3基因逆转食管癌放射抵抗性作用机制的研究

Radiotherapy has been widely recognized as one of the important treatments for Esophagus Cancer, but significant fraction of tumors recurs after such treatment and becomes to radioresistant. Therefore, it is crucial to characterize genetic alterations that affect esophageal cancer resistant to radiotherapy. Our previous study found the overexpression of AKR1C3 (Aldo-keto reductase 1C3) contributes to the radioresistance of esophageal cancer and knockdown of AKR1C3 could improve the radiosensitization of esophageal cancer cells. Given that the clearance of ROS (reactive oxygen species) and DNA repair which are major factors associated with radioresistance. So we speculated that AKR1C3 probably play a vital role in those factors regulatiing radioresistance in esophageal cancer. In this study, we aim to analyze the effects of AKR1C3 knock-down or inactivation on ROS level ，DNA repair of esophageal cancer cells respectively. In addition, the signaling pathways involved in those factors which mediated by AKR1C3 will be studied. Our studies will contribute to further understanding of tumor therapeutic resistance and will provide targets for cancer therapy.

放射抵抗是放疗失败的重要原因，探索放射抵抗相关基因并阐明其机制至关重要。前期课题组应用人类全基因组RNA芯片筛选发现AKR1C3 (Aldo-keto reductase 1C3)基因与食管癌放射抵抗相关。克隆形成实验提示沉默AKR1C3基因克隆形成数减少放射敏感性增加；过表达该基因克隆形成数增多放射敏感性降低，裸鼠成瘤实验得到相同结果。故推测AKR1C3基因为食管癌放射抵抗基因，但其具体作用机理不明。同时课题组观察到沉默AKR1C3基因可改变放射后细胞内ROS(reactive oxygen species)水平及DNA损伤情况，而放射后ROS清除及DNA损伤修复是放射抵抗产生的重要机制。本研究拟应用沉默及过表达AKR1C3基因的细胞系，从ROS清除及DNA损伤修复入手，探讨AKR1C3基因参与放射抵抗的分子机制。本课题将为AKR1C3作为潜在放射增敏分子靶标提供实验基础及理论依据。

放射抵抗是放疗失败的重要原因，探索放射抵抗相关基因并阐明其机制至关重要。前期课题发现AKR1C3基因为食管癌放射抵抗基因，但其具体作用机理不明。同时课题组观察到沉默AKR1C3基因可改变放射后细胞内ROS(reactive oxygen species)水平及DNA损伤情况，而放射后ROS清除及DNA损伤修复是放射抵抗产生的重要机制。本研究应用高表达AKR1C3的食管癌放射抵抗细胞系KY170R及稳定沉默AKR1C3基因的细胞系KY170R-AKR1C3（sh-KY170R），从ROS清除及DNA损伤修复入手，探讨AKR1C3基因参与放射抵抗的分子机制。.研究发现在接受照射后MAPK及AKT信号通路在放射敏感细胞中较抵抗细胞系均存在不同程度的活化。通过茉莉酸甲酯（mej，AKR1C3的小分子抑制剂）抑制KY170R细胞中AKR1C3的表达及活性可激活PPAR通路，从而抑制细胞内ROS的清除，引起细胞放射敏感性增加；而在低表达AKR1C3的sh-KY170R细胞系中，茉莉酸甲酯未起到放射增敏作用。同时，课题组还观察到，在高表达AKR1C3的放射抵抗细胞系KY170R中，同时存在着经典Wnt通路的异常活化，但是高表达AKR1C3与Wnt通路活化的相关性有待进一步研究。.综上，AKR1C3可能通过PPAR通路调控细胞内ROS清除，从而发挥放射抵抗作用；AKR1C3的小分子抑制剂茉莉酸甲酯可逆转高表达AKR1C3的食管癌细胞的放射抵抗性，有望成为新型的放疗增敏药物。高表达AKR1C3的食管癌放射抵抗细胞系中存在Wnt通路异常活化；低表达AKR1C3的放射敏感细胞系中存在MAPK通路、AKT通路的活化，但其具体机制待进一步探讨。