表皮生长因子受体酪氨酸激酶抑制剂(EGFR-TKIs)的使用为具有EGFR突变的晚期NSCLC患者的生存带来了显着的益处。不幸的是,获得性耐药似乎是不可避免的,限制了EGFR-TKIs在临床实践中的应用。这项研究报道了维持耐药性的共同分子机制和克服EGFR-TKIs耐药性的潜在治疗选择。
建立抗EGFR-TKIs的NSCLC细胞,并通过MTT测定证实。在体内检测胆固醇含量并确定胆固醇对NSCLC生长的促进作用。然后,我们确定ERRα表达是胆固醇介导的耐药的下游因子.剖析监管机制,我们做了实验,包括免疫荧光,免疫共沉淀,荧光素酶报告基因测定和染色质免疫沉淀测定。
长期暴露于EGFR-TKIs会产生耐药性,其特征是胆固醇在脂筏中积累,促进EGFR和Src相互作用并引导EGFR/Src/Erk信号再激活介导的SP1核易位和ERRα再表达。进一步的研究确定ERRα为SP1的靶基因。功能上,ERRα的再表达通过调节ROS解毒过程来维持细胞增殖。洛伐他汀,一种用来降低胆固醇水平的药物,和ERRα的反向激动剂XCT790,在体外和体内克服吉非替尼和奥希替尼耐药。
我们的研究表明,胆固醇/EGFR/Src/Erk/SP1轴诱导的ERRα再表达可促进吉非替尼和奥希替尼耐药癌细胞的存活。此外,我们证明了降低胆固醇和下调ERRα作为NSCLC有效辅助治疗的潜力.
The use of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) brings remarkable benefits for the survival of patients with advanced NSCLC harboring EGFR mutations. Unfortunately, acquired resistance seems to be inevitable and limits the application of EGFR-TKIs in clinical practice. This study reported a common molecular mechanism sustaining resistance and potential treatment options to overcome EGFR-TKIs resistance.
EGFR-TKIs resistant NSCLC cells were established and confirmed by MTT assay. Cholesterol content was detected and the promotional function of cholesterol on NSCLC growth was determined in vivo. Then, we identified ERRα expression as the downstream factor of cholesterol-mediated drug resistance. To dissect the regulatory mechanism, we conducted experiments, including immunofluorescence, co-immunoprecipitation, luciferase reporter assay and chromatin immunoprecipitation assay.
Long-term exposure to EGFR-TKIs generate drug resistance with the characteristic of cholesterol accumulation in lipid rafts, which promotes EGFR and Src to interact and lead EGFR/Src/Erk signaling reactivation-mediated SP1 nuclear translocation and ERRα re-expression. Further investigation identifies ERRα as a target gene of SP1. Functionally, re-expression of ERRα sustains cell proliferation by regulating ROS detoxification process. Lovastatin, a drug used to decrease cholesterol level, and XCT790, an inverse agonist of ERRα, overcome gefitinib and osimertinib resistance both in vitro and in vivo.
Our study indicates that cholesterol/EGFR/Src/Erk/SP1 axis-induced ERRα re-expression promotes survival of gefitinib and osimertinib-resistant cancer cells. Besides, we demonstrate the potential of lowing cholesterol and downregulation of ERRα as effective adjuvant treatment of NSCLC.