Dai Yuyuan, Kyoyama Hiroyuki, Yang Yi-Lin, Wang Yucheng, Liu Shu, Wang Yinghao, Mao Jian-Hua, Xu Zhidong, Uematsu Kazutsugu, Jablons David M, You Liang
Thoracic Oncology Laboratory, Department of Surgery, Comprehensive Cancer Center, University of California, San Francisco, CA, USA.
Model Animal Research Center of Nanjing University, Nanjing, Jiangsu, China.
Oncotarget. 2021 Feb 2;12(3):173-184. doi: 10.18632/oncotarget.27871.
Homeodomain-interacting protein kinase-2 (HIPK2) can either promote or inhibit transcription depending on cellular context. In this study, we show that a new HIPK2 isoform increases TEAD reporter activity in NSCLC cells. We detected HIPK2 copy number gain in 5/6 (83.3%) NSCLC cell lines. In NSCLC patients with high HIPK2 mRNA expression in the Human Protein Atlas, the five-year survival rate is significantly lower than in patients with low expression (38% vs 47%; = 0.047). We also found that 70/78 (89.7%) of NSCLC tissues have moderate to strong expression of the N-terminal HIPK2 protein. We detected and cloned a novel HIPK2 isoform 3 and found that its forced overexpression promotes TEAD reporter activity in NSCLC cells. Expressing HIPK2 isoform 3_K228A kinase-dead plasmid failed to increase TEAD reporter activity in NSCLC cells. Next, we showed that two siRNAs targeting HIPK2 decreased HIPK2 isoform 3 and YAP protein levels in NSCLC cells. Degradation of the YAP protein was accelerated after HIPK2 knockdown in NSCLC cells. Inhibition of HIPK2 isoform 3 decreased the mRNA expression of YAP downstream gene CTGF. The specific HIPK2 kinase inhibitor TBID decreased TEAD reporter activity, reduced cancer side populations, and inhibited tumorsphere formation of NSCLC cells. In summary, this study indicates that HIPK2 isoform 3, the main HIPK2 isoform expressed in NSCLC, promotes YAP/TEAD transcriptional activity in NSCLC cells. Our results suggest that HIPK2 isoform 3 may be a potential therapeutic target for NSCLC.
同源结构域相互作用蛋白激酶2（HIPK2）可根据细胞环境促进或抑制转录。在本研究中，我们发现一种新的HIPK2异构体可增加非小细胞肺癌（NSCLC）细胞中的TEAD报告基因活性。我们在6个NSCLC细胞系中的5个（83.3%）检测到HIPK2拷贝数增加。在人类蛋白质图谱中HIPK2 mRNA高表达的NSCLC患者中，五年生存率显著低于低表达患者（38%对47%；P = 0.047）。我们还发现，78个NSCLC组织中的70个（89.7%）N端HIPK2蛋白呈中度至强表达。我们检测并克隆了一种新的HIPK2异构体3，发现其强制过表达可促进NSCLC细胞中的TEAD报告基因活性。表达HIPK2异构体3_K228A激酶失活质粒未能增加NSCLC细胞中的TEAD报告基因活性。接下来，我们表明，两种靶向HIPK2的小干扰RNA降低了NSCLC细胞中HIPK2异构体3和YAP蛋白水平。在NSCLC细胞中敲低HIPK2后，YAP蛋白的降解加速。抑制HIPK2异构体3降低了YAP下游基因CTGF的mRNA表达。特异性HIPK2激酶抑制剂TBID降低了TEAD报告基因活性，减少了癌症侧群细胞，并抑制了NSCLC细胞的肿瘤球形成。总之，本研究表明，HIPK2异构体3是NSCLC中主要表达的HIPK2异构体，可促进NSCLC细胞中的YAP/TEAD转录活性。我们的结果表明，HIPK2异构体3可能是NSCLC的一个潜在治疗靶点。
