TGF-β1 promotes epithelial-to-mesenchymal transition and stemness of prostate cancer cells by inducing PCBP1 degradation and alternative splicing of CD44
TGF-β1 promotes epithelial-to-mesenchymal transition and stemness of prostate cancer cells by inducing PCBP1 degradation and alternative splicing of CD44
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TGF-β1通过诱导PCBP1降解和CD44选择性剪接促进前列腺癌细胞的上皮间质转化和干性
DOI：
10.1007/s00018-020-03544-5
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发表时间：
2020-05-21
影响因子：
8
通讯作者：
Wang, Zhong
中科院分区：
文献类型：
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作者：
Chen, Qi;Gu, Meng;Wang, Zhong
CD44是多种肿瘤中肿瘤干细胞（CSC）的标志物。其20个外显子的选择性剪接产生各种具有不同组织特异性表达和功能的CD44亚型，包括由恒定外显子编码的CD44标准亚型（CD44s）和具有变异外显子插入的CD44变异亚型（CD44v）。CD44v和CD44s亚型之间的切换在肿瘤进展中起着关键作用。在这里，我们报道了tgf - β 1诱导CD44选择性剪接的新机制及其与人前列腺癌细胞上皮-间质转化（EMT）和干细胞增强的联系。tgf - β 1处理增加了DU-145前列腺癌细胞中CD44s和N-cadherin的表达，而降低了CD44v和E-cadherin的表达。tgf - β 1治疗后，其他EMT标志物和癌症干细胞标志物也上调。RNAi敲低CD44可逆转这种表型，可通过过表达CD44s而非CD44v来挽救这种表型，这表明CD44s的选择性剪接介导了tgf - β 1治疗的活性。从机制上讲，tgf - β 1处理诱导了PCBP1的磷酸化、多泛素化和降解，PCBP1是一种众所周知的调节CD44剪接的RNA结合蛋白。RNAi敲低PCBP1能够模拟tgf - β 1治疗，以增加cd44的表达，以及EMT和癌症干细胞标记物。体外和体内实验表明，CD44s促进前列腺癌细胞的迁移、侵袭和肿瘤发生。综上所述，我们确定了tgf - β 1诱导CD44选择性剪接并促进前列腺癌进展的机制。
CD44 is a marker of cancer stem cell (CSC) in many types of tumors. Alternative splicing of its 20 exons generates various CD44 isoforms that have different tissue specific expression and functions, including the CD44 standard isoform (CD44s) encoded by the constant exons and the CD44 variant isoforms (CD44v) with variant exon insertions. Switching between the CD44v and CD44s isoforms plays pivotal roles in tumor progression. Here we reported a novel mechanism of CD44 alternative splicing induced by TGF-beta 1 and its connection to enhanced epithelial-to-mesenchymal transition (EMT) and stemness in human prostate cancer cells. TGF-beta 1 treatment increased the expression of CD44s and N-cadherin while decreased the expression of CD44v and E-cadherin in DU-145 prostate cancer cells. Other EMT markers and cancer stem cell markers were also upregulated after TGF-beta 1 treatment. RNAi knockdown of CD44 reversed the phenotype, which could be rescued by overexpressing CD44s but not CD44v, indicating the alternatively spliced isoform CD44s mediated the activity of TGF-beta 1 treatment. Mechanistically, TGF-beta 1 treatment induced the phosphorylation, poly-ubiquitination, and degradation of PCBP1, a well-characterized RNA binding protein known to regulate CD44 splicing. RNAi knockdown of PCBP1 was able to mimic TGF-beta 1 treatment to increase the expression of CD44s, as well as the EMT and cancer stem cell markers. In vitro and in vivo experiments were performed to show that CD44s promoted prostate cancer cell migration, invasion, and tumor initiation. Taken together, we defined a mechanism by which TGF-beta 1 induces CD44 alternative splicing and promotes prostate cancer progression.