SENP6通过与GPX4结合抑制铁死亡促进小细胞肺癌耐药的功能和机制研究

Reversing the chemoresistance of Small Cell Lung Cancer（SCLC）is a critical step to improve the prognosis of SCLC patients. Using the technologies such as CRISPR/Cas9-sgRNA for whole genome knockout, high content screening and whole exome sequencing, we found that small ubiquitin-related modifier （SUMO）specific protease 6（SENP6）could promoted the chemoresistance of SCLC by inhibiting the ferroptosis. Besides, we found that SENP6 could bind to the iron death protein glutathione peroxidase（GPX4）. Suppression of SENP6 increased the SUMO2 level of GPX4, but decreased the protein expression of GPX4. In addition, inhibition of ubiquitin degradation could repress the effect of SENP6 on GPX4 protein. Thus, we propose a hypothesis that SENP6 promotes the chemoresistance of SCLC by inhibiting the ferroptosis through GPX4. To test our hypothesis, we formulate the following studies. Firstly, the relationship between SENP6 and chemoresistance is to be verified by clinical samples, SCLC chemoresistance cells and animal models. Secondly, the experiments such as co-immunoprecipitation and construction of SENP6 mutants are performed to investigate whether SENP6 promotes the chemoresistance of SCLC by inhibiting the ferroptosis through GPX4. The specific way that SENP6 affection on GPX4 may be like this: SENP6 suppressed the SUMO2 level of GPX4, so reducing the GPX4 ubiquitination degradation. We may provide a new method to reverse the chemoresistance of SCLC by targeting the expression of SENP6.

逆转化疗耐药是改善小细胞肺癌（SCLC）患者预后的关键。我们前期利用CRISPR/Cas9-sgRNA全基因组敲除、高内涵功能筛选、全外显子测序等技术发现类泛素化特异性蛋白酶SENP6可抑制铁死亡促进化疗耐药。还发现SENP6可与铁死亡蛋白GPX4结合，下调SENP6可提高GPX4的类泛素化（Sumo2），同时降低GPX4蛋白表达，而抑制泛素化降解则可回复SENP6对GPX4蛋白的影响。据此，我们提出假设：SENP6与GPX4结合抑制铁死亡，促进SCLC耐药。为验证假说，拟开展以下研究：<1>、利用临床样本、细胞和动物模型确证SENP6通过调节铁死亡促进SCLC耐药；<2>、机制探讨：通过CoIP、构建SENP6突变体等验证：SENP6互作于GPX4，通过降低GPX4蛋白Sumo2化，以减少GPX4蛋白泛素化降解，进而抑制铁死亡促进SCLC耐药。本项目有望为逆转SCLC耐药研究提供新靶点。

逆转化疗耐药是改善小细胞肺癌（SCLC）患者预后的关键。已有研究提示血红素加氧酶1（HMOX1）可以通过提高细胞内铁离子含量影响铁代谢进而促进铁死亡，且有报道提示HMOX1参与了肝癌的化疗耐药机制。然而，并未有研究提示HMOX1可以通过铁死亡影响小细胞肺癌的化疗耐药。我们前期首次发现：HMOX1在SCLC肿瘤组织和化疗耐药细胞系中低表达，且与SCLC患者的预后密切相关；调控HMOX1蛋白的表达可以影响铁死亡相关标志分子的表达。据此，我们认为HMOX1有可能通过促进铁死亡，进而逆转SCLC化疗耐药。为验证假设，本项目进一步利用SCLC敏感和耐药细胞系明确HMOX1可以影响SCLC化疗耐药；然后明确HMOX1的表达可促进SCLC细胞系发生铁死亡；最后，通过实时荧光定量PCR，探讨了HMOX1通过调控MICOS复合体促进铁死亡进而逆转SCLC化疗耐药的机制。本项目有望为临床逆转SCLC化疗耐药提供新的指导方向。