ERβ调控胶质母细胞瘤DNA损伤应答的作用及机制研究

Glioblastoma (GBM) is the most common and aggressive form of primary malignant brain tumor with very low 5-year survival rates. PAPR inhibitors have shown significant anti-tumor effects in patients with BRCA/IDH mutations which leads to defects in homologous recombination repair, whereas wild-type patients are less effective. Our group found that high expression of ERβ can inhibit the proliferation and induce apoptosis of GBM cells. RNA sequencing revealed that ERβ regulates DNA damage response, homologous recombination repair, ATM signaling and G2M checkpoints in transcriptional level, and western blot showed that ERβ can inhibit phosphorylation of ATM and Chk2 thus leading to the homologous recombination defects. Based on these findings, the applicant proposes that ERβ inhibits the homologous recombination repair in GBM through inhibiting the ATM/Chk2/Rad51 signaling pathway and the combination therapy of ERβ agonists and PAPP inhibitors would result in synthetic lethality. The objective of this project is to study the effect of GBM sensitization to PARP inhibitors modulated by ERβ in vitro and in vivo, to elucidate the mechanism of DNA damage response modulated by ERβ, and to explore the synthetic lethal effect of ERβ agonists combined with PARP inhibitors, which will provide new targets and treatments for GBM.

胶质母细胞瘤（GBM）是最常见且恶性程度最高的原发性恶性脑肿瘤，5年生存率极低。研究表明PARP抑制剂对存在BRCA/IDH基因突变导致同源重组修复缺陷的患者具有显著抗肿瘤效应，而无突变患者效果较差。本课题组发现高表达ERβ可抑制GBM细胞增殖并诱导其凋亡，RNA测序发现ERβ在转录水平调控DNA损伤反应、同源重组修复、ATM信号及G2M检查点等相关基因，蛋白免疫印迹发现ERβ可抑制ATM和Chk2蛋白磷酸化进而抑制同源重组修复通路。申请人据此提出假说：ERβ通过抑制ATM/Chk2/Rad51信号通路抑制GBM细胞同源重组修复途径，联合ERβ激动剂和PAPP抑制剂可产生协同治疗作用。本项目将以细胞和动物模型为对象，研究ERβ对PARP抑制剂的增敏作用，明确ERβ调控DNA损伤应答的机制，探索ERβ激动剂联合PARP抑制剂对GBM的合成致死效应，为GBM患者提供新的治疗靶点和方法。

胶质母细胞瘤（GBM）是最常见且恶性程度最高的原发性恶性脑肿瘤，手术和放化疗是主要治疗手段，但复发率高，且放疗可导致患者脑损伤及认知功能障碍和运气记忆损伤。雌激素受体β被证明在多种肿瘤中呈抑癌作用。在研究中，我们通过构建细胞模型发现ERβ可以通过调控DNA损伤应答和同源重组修复通路影响化疗药物的敏感性，但使用雌激素受体β激动剂可抑制胶质母细胞瘤细胞模型的增殖，但并未明显增加PARPi的杀伤效应。研究发现在敲除小鼠大脑中神经特异性芳香化酶（ARO）后，小鼠大脑产生的雌激素合成受到限制，小鼠的空间记忆、识别记忆等有所下降，外源性补充雌激素后相应的上述记忆功能可得到恢复，并探索了认知功能障碍和铁死亡以及细胞损伤修复的关系，通过大鼠模型证明铁死亡抑制剂Fer-1通过抑制海马神经元铁死亡改善大鼠的认知功能。本研究验证了ERβ调控DNA损伤修复通路并且可增加化疗药物敏感性以及雌激素对认识功能的保护作用。