GADD45a调控APE1内质网应激介导宫颈癌放疗抵抗及其机制研究

As one of a number of p53-regulated genes, Gadd45a (growth arrest and DNA damage inducible gene) has been shown to radiosensitization and delay carcinogenesis. But so far, the main interpretation mechanisms due to the cell cycle regulation point function, while the other mechanism reported less at home and abroad. APE1 is a DNA damage repair and REDOX double function of the gene, is a key molecule of regulating tumor cell radiation sensitive. We found that the GADD45a and cytoplasm APE1 expression was negatively correlated，their role in promoting tumor cell apoptosis opposite function，According to the results of our previous studies and the latest literature, we suppose that GADD45a may regulat cytoplasm APE1 localizating in endoplasmic reticulum, which may play an important role in the oxidative stress in endoplasmic reticulum stress，and subsequently may be involved in the resistance to radiotherapy in cancer cells.To test this possibility，by means of gene transfection, RNAi, WB and Co-IP .etc, we intend to reveal the relationship between Gadd45a and/or cytoplasm APE1 and the radioresistance of cervical cancer. We further confirm the effect of Gadd45a on cytoplasm APE1 and the mechanism of action in inhibiting endoplasmic reticulum-mediated apoptosis. The present study will not only provide experimental foundation for research on the mechanism of radioresistance of cervical but also provide new research ideas for individualized treatment of cervical cancer with different types of GADD45a. This study not only creatively elucidates biological significance of APE1 subcellular localization but also provide new research ideas for revealing the mechanism of resistance to radiotherapy and exploring the molecular targets for the enhancement of sensitivity of radiotherapy.

GADD45a可通过细胞周期检查点和促凋亡功能调控肿瘤放射敏感性，近年有研究表明GADD45a缺失可导致双功能基因APE1蛋白胞浆表达升高；而我们前期研究发现APE1胞浆异位高表达与宫颈癌细胞的放疗抵抗密切相关，但具体机制尚不清楚。据此我们提出：GADD45a可能对APE1胞浆移位具有负向调控作用，而胞浆APE1可作用于内质网，通过氧化还原和RNA酶功能，增强放疗诱导的内质网氧化应激耐受性，进而决定肿瘤放疗抵抗。本课题拟采用基因转染、RNAi、蛋白印迹等手段，确定GADD45a/胞浆APE1与宫颈癌放疗抵抗的关系；揭示Gadd45a调控APE1胞浆异位，以及APE1作用内质网应激的分子机制。该项目不仅有助于阐明GADD45a与放疗敏感的新机制，而且拓展研究胞浆APE1的内质网应激新功能，对阐明宫颈癌放疗抵抗的机制，提高临床治疗效果具有重要意义。