Wang Yaohui, Zhang Xi, Wang Weimin, Xing Xiaoxia, Wu Sifan, Dong Yinying, You Yang, Chen Rongxin, Ren Zhenggang, Guo Weijian, Cui Jiefeng, Li Wentao
Department of Interventional Radiology, Fudan University Shanghai Cancer Center Shanghai 200032, People's Republic of China.
Department of Medical Oncology, Fudan University Shanghai Cancer Center Shanghai 200032, People's Republic of China.
Am J Cancer Res. 2020 Aug 1;10(8):2635-2648. eCollection 2020.
Our previous study has validated that higher matrix stiffness obviously improves vascular endothelial growth factor (VEGF) expression in HCC cells, highlighting a linkage between matrix stiffness and HCC angiogenesis. However, the effects of matrix stiffness on vascular endothelial cells in HCC and its underlying mechanism remain largely uncharacterized. Here we further analyzed the expression of vascular endothelial growth factor receptor 2 (VEGFR2) in human umbilical vein endothelial cells (HUVECs) grown on different stiffness substrates and explored its regulatory mechanism for better understanding matrix stiffness-regulated angiogenesis in HCC. Our results revealed that increased matrix stiffness significantly upregulated the expression of VEGFR2 in HUVECs, and the expression level of VEGFR2 was positively correlated with the expression levels of COL1 and lysyl oxidase in human HCC tissues and rat HCC tissue, moreover VEGFR2 and CD34 were co-localized at blood vessel of HCC tissues, indicating an obvious regulation role of matrix stiffness in VEGFR2 expression. Simultaneously, increased matrix stiffness also elevated the phosphorylation level of Akt and the expressions of integrin αV/β5 and nuclear Sp1 in HUVECs. Inhibition of integrin αVβ5 remarkably reversed the expression of VEGFR2 and phosphorylation level of Akt in HUVECs grown on higher stiffness substrate. Except that, PI3K inhibitor also suppressed the phosphorylation level of Akt and the expressions of VEGFR2 and nuclear Sp1 evidently. Taken together, higher matrix stiffness increased VEGFR2 expression in HUVECs, and integrin αVβ5/Akt/Sp1 pathway participated in stiffness-mediated effects on VEGFR2 upregulation. This study combining with our previous report discloses a new paradigm in which higher matrix stiffness as an initiator drives HCC angiogenesis via upregulating both VEGFR2 expression in vascular endothelial cells and VEGF expression in HCC cells.
我们之前的研究已经证实，较高的基质硬度明显提高肝癌细胞中血管内皮生长因子（VEGF）的表达，突出了基质硬度与肝癌血管生成之间的联系。然而，基质硬度对肝癌中血管内皮细胞的影响及其潜在机制在很大程度上仍未明确。在此，我们进一步分析了在不同硬度底物上生长的人脐静脉内皮细胞（HUVECs）中血管内皮生长因子受体2（VEGFR2）的表达，并探索其调节机制，以更好地理解基质硬度调节的肝癌血管生成。我们的结果显示，增加的基质硬度显著上调了HUVECs中VEGFR2的表达，并且VEGFR2的表达水平与人肝癌组织和大鼠肝癌组织中COL1和赖氨酰氧化酶的表达水平呈正相关，此外VEGFR2和CD34在肝癌组织血管处共定位，表明基质硬度对VEGFR2表达具有明显的调节作用。同时，增加的基质硬度也提高了HUVECs中Akt的磷酸化水平以及整合素αV/β5和核Sp1的表达。抑制整合素αVβ5可显著逆转在较高硬度底物上生长的HUVECs中VEGFR2的表达和Akt的磷酸化水平。除此之外，PI3K抑制剂也明显抑制了Akt的磷酸化水平以及VEGFR2和核Sp1的表达。综上所述，较高的基质硬度增加了HUVECs中VEGFR2的表达，并且整合素αVβ5/Akt/Sp1途径参与了硬度介导的对VEGFR2上调的影响。本研究与我们之前的报告相结合，揭示了一种新的模式，即较高的基质硬度作为启动因素，通过上调血管内皮细胞中的VEGFR2表达和肝癌细胞中的VEGF表达来驱动肝癌血管生成。
