Guangdong Provincial Key Laboratory of Regional Immunity and Diseases, Cancer Research Center, Department of Pharmacology, Shenzhen University Health Science Center, Shenzhen 518055, China.
Department of Physiology, School of Medicine, Health Science Center, Shenzhen University, Shenzhen 518060, China.
Theranostics. 2021 Mar 4;11(9):4421-4435. doi: 10.7150/thno.53901. eCollection 2021.
Amino-terminal enhancer of split (AES) has been identified as a tumor and metastasis suppressor in some cancers including colorectal cancer (CRC), but very little is known about the regulation of AES expression. Bioinformatics analysis was used to investigate the expression patterns of AES, CK1δ and CK1ε. The co-immunoprecipitation, GST pull-down, Western Blot, real-time PCR and immunohistochemistry were performed to study the mechanism underlying the regulation of AES expression by CK1δ/ε. The biological function was assessed by colony formation, transwell, sphere formation, tumor organoids, tumor metastasis model and patient-derived colorectal tumor xenografts (PDTX) model. A strong inverse relationship was observed between the expression of AES and the expression of CK1δ/ε. Mechanically, AES could interact with CK1δ/ε and SKP2 using its Q domain. SKP2 mediated the ubiquitination and degradation of AES in a CK1δ/ε-dependent manner. CK1δ/ε phosphorylated AES at Ser121 and accelerated the SKP2-mediated ubiquitination and degradation of AES. In colon cancer cells, CK1δ/ε antagonized the effect of wild-type AES but not that of its mutant (S121A) on Wnt and Notch signaling, leading to an increase in the expression of Wnt target genes and Notch target genes. By downregulating the expression of AES, CK1δ/ε enhanced anchorage-independent growth, migration, invasion and sphere formation in colon cancer cells. CK1δ/ε also promoted the growth of APC colorectal tumor organoids and liver metastasis in colon cancer mouse models through the regulation of AES degradation. Furthermore, CK1 inhibitor SR3029 treatment suppressed tumor growth via stabilizing AES in APC colorectal tumor organoids and patient-derived colorectal tumor xenografts (PDTX). Our results revealed that the CK1δ/ε-AES axis is important for CRC tumorigenesis and metastasis, and targeted inhibition of this axis may be a potential therapeutic strategy for CRC.
氨基末端分裂增强子（AES）已被确定为包括结直肠癌（CRC）在内的一些癌症中的肿瘤和转移抑制因子，但对 AES 表达的调控知之甚少。使用生物信息学分析来研究 AES、CK1δ 和 CK1ε 的表达模式。通过共免疫沉淀、GST 下拉、Western Blot、实时 PCR 和免疫组织化学来研究 CK1δ/ε 调节 AES 表达的机制。通过集落形成、Transwell、球体形成、肿瘤类器官、肿瘤转移模型和患者来源的结直肠肿瘤异种移植（PDTX）模型评估其生物学功能。观察到 AES 的表达与 CK1δ/ε 的表达之间存在强烈的负相关关系。从机制上讲，AES 可以使用其 Q 结构域与 CK1δ/ε 和 SKP2 相互作用。SKP2 介导 CK1δ/ε 依赖性 AES 的泛素化和降解。CK1δ/ε 在 Ser121 处磷酸化 AES，并加速 SKP2 介导的 AES 泛素化和降解。在结肠癌细胞中，CK1δ/ε 拮抗野生型 AES 的作用，但不拮抗其突变体（S121A）对 Wnt 和 Notch 信号的作用，导致 Wnt 靶基因和 Notch 靶基因的表达增加。通过下调 AES 的表达，CK1δ/ε 增强了结肠癌细胞的无锚定生长、迁移、侵袭和球体形成。CK1δ/ε 还通过调节 AES 降解促进 APC 结直肠肿瘤类器官和结直肠癌小鼠模型中的肝脏转移。此外，CK1 抑制剂 SR3029 通过稳定 APC 结直肠肿瘤类器官和患者来源的结直肠肿瘤异种移植（PDTX）中的 AES 来抑制肿瘤生长。我们的结果表明，CK1δ/ε-AES 轴对于 CRC 肿瘤发生和转移很重要，靶向抑制该轴可能是 CRC 的一种潜在治疗策略。
