去泛素化酶PSMD14调控肿瘤干性促进肺腺癌EGFR-TKIs耐药机制研究

EGFR-TKIs have been the first-line drug for advanced lung adenocarcinoma patients with EGFR mutation. The mechanism of EGFR-TKIs resistance and coping strategies are urgent to be solved. It has been confirmed that the drug-resistant tumor cells showed cancer stem cell-like properties with high PSMD14 expression by RNA Seq. Knock-down of PSMD14 impeded the forming of tumor spheres, enhanced sensitivity to EGFR-TKIs and MS analysis showed that PSMD14 could bind Notch2, which is one of the stem cell signal molecule. Thus, we proposed that PSMD14 may regulate cancer stem cell-like properties via deubiquitination of Notch2 to promote EGFR-TKIs resistance in lung adenocarcinoma.This project aims to identify the biological functions of PSMD14 in EGFR-TKIs resistance by molecular cytology combined with experimental animal models and clinical tissue specimens; exploring the regulatory effects of PSMD14 deubiquitination modification in regulating cancer stem cell-like properties and illustrating the molecular mechanism of PSMD14 in drug resistance. We will provide new target and new idea for exploring the mechanism of EGFR-TKIs resistance from the new perspective of deubiquitination modification.

EGFR-TKIs已经成为EGFR突变型晚期肺腺癌患者的一线用药，其耐药机制和应对策略亟需解决。我们前期通过表达谱测序发现去泛素酶PSMD14在EGFR-TKIs耐药细胞较敏感细胞中显著高表达，且耐药的肿瘤细胞表现出肿瘤干细胞样特性。敲除PSMD14可以抑制细胞成球能力；增加EGFR-TKIs的药物敏感性；且质谱发现PSMD14与干细胞信号分子Notch2存在着相互作用。所以我们推测PSMD14通过去泛素化修饰Notch2调控肿瘤干细胞样特性促进肺腺癌的EGFR-TKIs耐药。本项目拟采用分子细胞学方法结合实验动物模型及临床组织标本，研究PSMD14在EGFR-TKIs耐药中发挥的生物学功能；探讨PSMD14去泛素化修饰Notch2对肿瘤干细胞样特性的调控作用，阐明其调控耐药的分子机制。本研究将从去泛素化修饰的新视点，为揭示肺腺癌EGFR-TKIs耐药机制提供新靶点和新思路。

表皮生长因子受体酪氨酸激酶抑制剂（EGFR-TKIs）是EGFR敏感突变的非小细胞肺癌（NSCLC）患者的一线首选用药，但仍有部分患者在治疗中出现耐药，影响患者生存。然而，其耐药机制仍不明确。申请人在针对EGFR-TKIs耐药机制研究中，发现去泛素化酶PSMD14是调控EGFR-TKIs耐药重要因子，PSMD14在EGFR-TKIs耐药细胞中高表达，在耐药细胞株PC9/GR中沉默PSMD14后，显著降低其干细胞特性，细胞对吉非替尼的敏感性增加；相反，在敏感细胞株PC9中过表达PSMD14后，细胞干性特征明显增强，对吉非替尼的敏感性显著降低。PSMD14可能通过调控肿瘤细胞干性特征，进而诱导肿瘤细胞对EGFR-TKIs的耐药性，本研究将为逆转EGFR-TKIs耐药提供新的理论基础，为临床患者的个体化治疗提供新的思路。同时，在此过程中发现了泛素化酶家族另一因子UBE2T与非小细胞肺癌患者不良预后相关以此作为横向课题进行研究，体内体外实验证实UBE2T促进肺癌细胞增殖、迁移、侵袭和放疗抵抗。机制上UBE2T通过靶向泛素化修饰FOXO1促进肺癌细胞上皮间质转化（EMT）并调控Wnt信号通路促进NSCLC细胞增殖和放疗抵抗。本研究通过上述研究深入的揭示并拓宽了非小细胞肺癌进展及耐药的调控机制，为以后探索非小细胞肺癌的治疗提供了宝贵的经验。