Treatment-induced tumor dormancy through YAP-mediated transcriptional reprogramming of the apoptotic pathway [YAP1 KO vs CTRL]

Eradicating tumor dormancy that develops following oncogene-targeted therapy, including after epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) treatment of EGFR-mutant non-small cell lung cancer (NSCLC), is an attractive therapeutic strategy but the mechanisms governing the establishment of tumor dormancy are poorly understood. We observe that blockade of ERK1/2 reactivation following EGFR TKI treatment by combined EGFR/MEK inhibition uncovers cells that survive by entering a senescence-like dormant state, characterized by extensive epigenetic remodeling and high YAP/TEAD activity. YAP/TEAD trigger an epithelial-to-mesenchymal transition (EMT) program and engage the EMT transcription factor SLUG to directly repress pro-apoptotic BMF, limiting drug-induced apoptosis. Pharmacological co-inhibition of YAP or TEAD, or genetic deletion of YAP1, all deplete dormant cells by enhancing EGFR/MEK induced apoptosis. Thus, YAP activation can promote the survival of EGFR-mutant NSCLC cells in the chronic absence of EGFR signaling. Eradicating this population enhances the efficacy of targeted therapies which could ultimately lead to prolonged treatment responses in cancer patients. PC-9 and HCC4006 CTRL and YAP1 KO cells were plated into 10 cm dishes at 15 x 104 cells / cm2 in triplicate. The next day, the cells were treated with DMSO or with the combination of 100 nM osimertinib and 30 nM trametinib (OT). After 24 hours, the cells were lysed into TRIzol and RNA extraction was performed according to the manufacturer’s protocol

根除靶向癌基因治疗后诱发的肿瘤休眠，其中包括针对表皮生长因子受体（epidermal growth factor receptor, EGFR）突变非小细胞肺癌（non-small cell lung cancer, NSCLC）施以EGFR酪氨酸激酶抑制剂（tyrosine kinase inhibitor, TKI）治疗后所形成的肿瘤休眠，是一种极具吸引力的治疗策略，但调控肿瘤休眠建立的分子机制目前仍知之甚少。我们观察到，通过联合EGFR/MEK抑制剂阻断EGFR TKI治疗后ERK1/2的重新激活，可使存活的癌细胞进入类似衰老的休眠状态，该状态以广泛的表观遗传重塑及高YAP/TEAD活性为典型特征。YAP/TEAD可触发上皮间质转化（epithelial-to-mesenchymal transition, EMT）程序，并结合EMT转录因子SLUG直接抑制促凋亡蛋白BMF，从而限制药物诱导的细胞凋亡。通过药理学手段共同抑制YAP或TEAD，或是基因敲除YAP1，均可通过增强EGFR/MEK诱导的细胞凋亡来清除休眠的肿瘤细胞。由此可见，在EGFR信号长期缺失的条件下，YAP激活可促进EGFR突变NSCLC细胞的存活。根除这一细胞群可增强靶向治疗的疗效，最终有望延长癌症患者的治疗应答持续时间。
将PC-9与HCC4006的对照（CTRL）及YAP1基因敲除（KO）细胞以15×10⁴个细胞/平方厘米的密度接种于10 cm培养皿中，设置三个复孔。次日，分别用二甲基亚砜（dimethyl sulfoxide, DMSO）或100 nM奥希替尼（osimertinib）联合30 nM曲美替尼（trametinib，OT组合）处理细胞。24小时后，将细胞裂解于TRIzol试剂中，并按照制造商的说明书完成RNA提取。