Department of Infectious Diseases, the First Affiliated Hospital of Xi'an Jiaotong University, No. 277 Yanta West Road, Xi'an 710061, China.
Department of Hepatobiliary Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, No. 277 Yanta West Road, Xi'an 710061, China.
Theranostics. 2020 Apr 27;10(13):5790-5801. doi: 10.7150/thno.44789. eCollection 2020.
: Increasing evidence indicates that the physical environment is a critical mediator of tumor behavior. Hepatocellular carcinoma (HCC) develops in an altered biomechanical environment, and increased matrix stiffness is a strong predictor of HCC development. C-X-C chemokine receptor type 4 (CXCR4) is known to trigger HCC progression. However, CXCR4 as a mediator of mechanical cues in HCC is not well characterized. : qRT-PCR, Western blot and IHC were used to detect the CXCR4 expression in different matrix stiffness gels. MTT was used to measure the cell proliferation of HCC cells. Immunoblotting was used for detection of epithelial-to-mesenchymal transition (EMT) and stemness on the matrix stiffness. Immunofluorescence (IF) was used to detect the nuclear location in HCC cells. IP was used to show the interaction between YAP, UbcH5c and β-TrCP. : We identified CXCR4 as a critical intracellular signal transducer that relays matrix stiffness signals to control mechano-sensitive cellular activities through ubiquitin domain-containing protein 1 (UBTD1)-mediated YAP signaling pathway. We found that CXCR4 expression was remarkably up-regulated in HCC cells with increasing matrix stiffness and mediated proliferation, epithelial to mesenchymal transition, and stemness. Mechanistically, matrix stiffness acts through CXCR4 to decrease the levels of UBTD1, which is involved in the proteasome-dependent degradation of YAP, a major cell mechano-transducer. UBTD1 interacted with components of the YAP degradation complex and promoted the interaction between YAP and its E3 ubiquitin ligase β-TrCP. UBTD1 knockdown decreased YAP ubiquitylation and resulted in the activation of YAP-targeted genes and YAP downstream signaling. Downregulation of UBTD1 in HCC tissues correlated with malignant prognostic features and overall survival. Finally, luteolin, a natural product, suppressed matrix stiffness-induced biological effects and CXCR4-mediated YAP signaling pathway in HCC cells. : Our findings reveal CXCR4 as a molecular switch in mechano-transduction, thereby defining a mechano-signaling pathway from matrix stiffness to the nucleus.
越来越多的证据表明，物理环境是肿瘤行为的一个关键介质。肝细胞癌 (HCC) 发生在改变的生物力学环境中，基质硬度增加是 HCC 发展的一个强有力预测因子。已知 C-X-C 趋化因子受体 4 (CXCR4) 触发 HCC 进展。然而，CXCR4 作为 HCC 中机械线索的介质尚未得到很好的描述。 ：qRT-PCR、Western blot 和 IHC 用于检测不同基质硬度凝胶中 CXCR4 的表达。MTT 用于测量 HCC 细胞的增殖。免疫印迹用于检测基质硬度上的上皮-间充质转化 (EMT) 和干性。免疫荧光 (IF) 用于检测 HCC 细胞的核定位。IP 用于显示 YAP、UbcH5c 和 β-TrCP 之间的相互作用。 ：我们确定 CXCR4 是一种关键的细胞内信号转导蛋白，它通过泛素结构域蛋白 1 (UBTD1) 介导的 YAP 信号通路将基质硬度信号传递到控制机械敏感细胞活动。我们发现，随着基质硬度的增加，CXCR4 在 HCC 细胞中的表达显著上调，并介导增殖、上皮-间充质转化和干性。在机制上，基质硬度通过 CXCR4 作用降低 UBTD1 的水平，UBTD1 参与 YAP 的蛋白酶体依赖性降解，YAP 是主要的细胞机械转导物。UBTD1 与 YAP 降解复合物的成分相互作用，并促进 YAP 与其 E3 泛素连接酶 β-TrCP 的相互作用。UBTD1 敲低降低了 YAP 的泛素化，导致 YAP 靶向基因和 YAP 下游信号的激活。HCC 组织中 UBTD1 的下调与恶性预后特征和总生存期相关。最后，木犀草素，一种天然产物，抑制基质硬度诱导的生物效应和 HCC 细胞中的 CXCR4 介导的 YAP 信号通路。 ：我们的研究结果揭示了 CXCR4 作为机械转导中的分子开关，从而定义了从基质硬度到细胞核的机械信号通路。
