Huang Tonghai, Yang Lin, Wang Guangsuo, Ding Guanggui, Peng Bin, Wen Yuxin, Wang Zheng
Department of Thoracic Surgery, Shenzhen People's Hospital, Shenzhen, Guangdong Province, People's Republic of China.
Onco Targets Ther. 2017 Jan 18;10:439-446. doi: 10.2147/OTT.S125789. eCollection 2017.
S-phase kinase-associated protein 2 (Skp2) is an E3 ubiquitin ligase and plays an important role in the control of cell cycle progression. Skp2 is upregulated in several cancers, including lung cancers, but the role of Skp2 in the tumorigenesis and anticancer drug resistance in human lung cancer remains to be determined. We report here that Skp2 positively regulated mitotic arrest deficient 2 (MAD2) expression and that inhibition of Skp2 sensitizes human lung cancer cells to paclitaxel. Knockdown of Skp2 by small interfering RNA (siRNA) decreased Mad2 messenger RNA (mRNA) and protein levels in A549 and NCI-H1975 cells, accompanied with upregulation of p27 but decrease of the phosphorylation of retinoblastoma (Rb). In contrast, ectopic overexpression of Skp2 increased Mad2 mRNA and protein levels and phosphorylation of Rb, while it decreased p27. Pharmacological inhibition of CDK1/2 by flavopiridol or E2F1 with HLM006474 led to downregulation of Mad2 expression and prevented the increase of Mad2 expression by Skp2. Most importantly, pharmacological inhibition of Skp2 sensitized A549 and NCI-H1299 cells to paclitaxel. Our results demonstrated that SKP2 positively regulates the gene expression of MAD2 through p27-CDKs-E2F1 signaling pathway and that inhibition of Skp2 sensitizes A549 and NCI-H1299 cells to paclitaxel, suggesting that small molecule inhibitors of Skp2 are potential agents for the treatment of lung cancer with upregulation of Skp2.
S期激酶相关蛋白2（Skp2）是一种E3泛素连接酶，在细胞周期进程的调控中发挥重要作用。Skp2在包括肺癌在内的多种癌症中上调，但其在人肺癌发生和抗癌药物耐药性中的作用仍有待确定。我们在此报告，Skp2正向调节有丝分裂阻滞缺陷蛋白2（MAD2）的表达，并且抑制Skp2可使人肺癌细胞对紫杉醇敏感。用小干扰RNA（siRNA）敲低Skp2可降低A549和NCI-H1975细胞中Mad2信使核糖核酸（mRNA）和蛋白水平，同时伴随p27上调但视网膜母细胞瘤（Rb）磷酸化水平降低。相反，Skp2的异位过表达增加了Mad2 mRNA和蛋白水平以及Rb的磷酸化，同时降低了p27。用黄酮哌醇或HLM006474对CDK1/2进行药理学抑制导致Mad2表达下调，并阻止Skp2介导的Mad2表达增加。最重要的是，对Skp2进行药理学抑制可使A549和NCI-H1299细胞对紫杉醇敏感。我们的结果表明，SKP2通过p27-CDKs-E2F1信号通路正向调节MAD2的基因表达，并且抑制Skp2可使A549和NCI-H1299细胞对紫杉醇敏感，这表明Skp2的小分子抑制剂是治疗Skp2上调的肺癌的潜在药物。
