School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, Guangdong, China.
Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Las Vegas, NV, 89154-4003, USA.
Sci Rep. 2019 Feb 13;9(1):1988. doi: 10.1038/s41598-018-36963-3.
The proto-oncoprotein MET is a receptor tyrosine kinase that plays a key role in cancer cell growth and invasion. We have used fluorescence-tagged antibodies to activate MET in live serum-starved glioblastoma cells and monitor the fate of antibody-bound MET receptor in single cell-based assays. We found that the antibodies induced rapid and transient formation of highly polarized MET clusters on the plasma membrane and promoted the activation of MET, resembling the initial effects of binding to its ligand, HGF. However, the antibody-induced clustering and activation of MET led to the rapid removal of the receptor from cell surface and altered its intracellular processing, resulted in rapid degradation of the receptor. Consequently, while cells pre-treated with HGF remain competent to respond to further HGF stimulation, cells pre-treated with antibodies are refractory to further HGF stimulation due to antibody-mediated MET depletion. Removal of MET by sustained treatment of antibodies blocked cancer cell migration and invasion. Our studies reveal a novel mechanism to alter the recycling process of MET in glioblastoma cancer cells by promoting the receptor degradation through a proteasome-sensitive and lysosome-dependent pathway through the ligand-independent activation of MET using anti-MET antibodies.
原癌蛋白 MET 是一种受体酪氨酸激酶，在癌细胞生长和侵袭中发挥关键作用。我们使用荧光标记的抗体在活的血清饥饿的神经胶质瘤细胞中激活 MET，并在单细胞基础测定中监测抗体结合的 MET 受体的命运。我们发现，抗体诱导质膜上高度极化的 MET 簇的快速和瞬时形成，并促进 MET 的激活，类似于与配体 HGF 结合的初始效应。然而，抗体诱导的 MET 聚类和激活导致受体从细胞表面迅速去除，并改变其细胞内处理，导致受体的快速降解。因此，虽然用 HGF 预处理的细胞仍然能够对进一步的 HGF 刺激作出反应，但由于抗体介导的 MET 耗竭，用抗体预处理的细胞对进一步的 HGF 刺激无反应。通过持续用抗体去除 MET 阻断了癌细胞的迁移和侵袭。我们的研究揭示了一种通过使用抗-MET 抗体通过配体非依赖性激活 MET 来促进通过蛋白酶体敏感和溶酶体依赖性途径的受体降解，从而改变神经胶质瘤癌细胞中 MET 循环过程的新机制。
