鉴定Nrf1α/TCF11作为癌症化学预防的一个新策略靶点并阐明抗氧化-内质网应激的防御机制

The fact that loss or get of the water-soluble Nrf2, though it was accepted as a master regulator of genes about antioxidant, detoxification and cytoprotection mainly against various cellular stress , does not prevent carcinogenesis. By contrast, the transmembrane-bound Nrf1 transcription factor is essential for maintaining cellular redox, lipid and protein homeostasis, organ integrity, and/or endoplasmic reticulum (ER)- and continuous nuclear envelope membranes-associated quality-control systems, through regulating constitutive and inducible expression of the antioxidant response element (ARE)-battery genes against various stresses. However, recover Nrf1α and TCF11 respectively in Talens-based genome-editing Nrf1α/TCF11 specific knockdown cell line shown weak malignancy. It is interesting to note that the tumor hardly to growth in subcutaneous carcinoma xenograft of nude mice with TCF11 recovered cell line. In light of this, we are trying to 1) address whether Nrf1α/TCF11 in a bona find cancer suppressor gene; 2) identify whether can improve the cancer prevention ability through increase the constitutive expression of Nrf1α/TCF11; 3) elucidate whether Nrf1u/TCF11u as a molecule switch to regulate carcinogenesis; 4) determine the pathophysiological mechanism(s) whereby Nrf1α and/or TCF11 (alone or together with Nrf2) maintains cellular homeostasis and developmental organ integrity during the resistance to stress but its loss-of-function enables it to switch into robust stress imbalance resulting in siginificant pathology. Collectively, the proposal study will facilitate to identify whether Nrf1α/TCF11 will be a new potent cancer chemoprevention target, thus allowing a novel anti-cancer strategy to be developed for chemical intervention and prevention against inflammatory carcinogenesis.

尽管Nrf2作为最大的抗氧化调控开关，主要管控细胞应激条件下抗氧化解毒及保护基因的诱导表达，但是Nrf2具防癌促癌发生的两面性。然而，Nrf1是一个不可或缺的抗氧化解毒转录因子，其独特地调控生理学稳态基因的基础构成性表达，能够确保氧化还原稳态、细胞功能稳态、器官完整性生理发育、预防疾病发生。其缺失导致肿瘤发生，裸鼠荷瘤恶化，但是是再恢复Nrf1α/TCF11后肿瘤几乎完全被抑制。鉴于此，本课题着力解决1) Nrf1α/TCF11是否是抑癌基因; 2) 提高Nrf1α/TCF11基础构成性表达水平能否增加肿瘤预防能力; 3) 阐明Nrf1u/TCF11u是否为癌病理生理分子开关; 4）Nrf1α/TCF11与Nrf2协同或拮抗管控细胞氧化还原稳态及其抗氧化解毒的保护效应及化学预防机制。力证Nrf1α/TCF11是否作为癌症化学预防的一个新靶点，为抗癌化学干预与防治新技术研发新策略奠定基础。

Nrf1是一个至关重要的转录因子，调控氧化还原稳态、脂肪和蛋白质稳态平衡，发挥其抗氧化、抗凋亡及抗癌变的细胞保护作用。然而，恢复或过表达是否能够缓解或抵抗上述症状仍有待阐明，尤其是Nrf1α/TCF11独特的跨膜生物学特性在细胞应激、衰老、炎癌转变的生理过程中作用机制也需深入探讨。为此，本项目按预期目标完成以下研究内容, 其主要亮点：（1）建立人Nrf1α/TCF11特异敲除细胞株系且进行了荷瘤动物实验，且该基因的缺失可导致荷瘤恶性增殖，且该技术位定点敲除，并不影响Nrf1其他亚型的正常表达，具有独创性；（2）阐明Nrf1α/TCF11各自与Nrf2如何协同或拮抗管控细胞稳态平衡及器官发育完整性的生理学防御保护机制、及其功能缺失所致鲁棒性失衡而诱发炎症癌变的病理生理学调控网络和分子基础，该结果有助于筛选针对Nrf1/TCF11的激活剂和失活剂，并利于化学干预等技术研发;（3）鉴定了Nrf1转录本内上游开放阅读框(uORF)及翻译产物Nrf1u/TCF11u为一个病理生理学的分子开关，尤其在病理生理学细胞应激反应下，uORF是否调控其mORF所翻译产物Nrf1及靶基因谱系的表达变化。这项研究提升了Nrf1α/TCF11在癌症化学防治策略中的影响，并为后续靶向制剂的探索开辟了新思路。此外，详细解释了Nrf1α/TCF11与Nrf2在细胞内环境稳态方面的协同/差异调控。