Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway.
Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
J Cell Biol. 2020 Aug 3;219(8). doi: 10.1083/jcb.202003063.
Cancer cells break tissue barriers by use of small actin-rich membrane protrusions called invadopodia. Complete invadopodia maturation depends on protrusion outgrowth and the targeted delivery of the matrix metalloproteinase MT1-MMP via endosomal transport by mechanisms that are not known. Here, we show that the ER protein Protrudin orchestrates invadopodia maturation and function. Protrudin formed contact sites with MT1-MMP-positive endosomes that contained the RAB7-binding Kinesin-1 adaptor FYCO1, and depletion of RAB7, FYCO1, or Protrudin inhibited MT1-MMP-dependent extracellular matrix degradation and cancer cell invasion by preventing anterograde translocation and exocytosis of MT1-MMP. Moreover, when endosome translocation or exocytosis was inhibited by depletion of Protrudin or Synaptotagmin VII, respectively, invadopodia were unable to expand and elongate. Conversely, when Protrudin was overexpressed, noncancerous cells developed prominent invadopodia-like protrusions and showed increased matrix degradation and invasion. Thus, Protrudin-mediated ER-endosome contact sites promote cell invasion by facilitating translocation of MT1-MMP-laden endosomes to the plasma membrane, enabling both invadopodia outgrowth and MT1-MMP exocytosis.
癌细胞通过使用称为侵袭伪足的富含小肌动蛋白的小膜突起来破坏组织屏障。完整的侵袭伪足成熟取决于突起的生长和基质金属蛋白酶 MT1-MMP 通过内体运输的靶向递送，其机制尚不清楚。在这里，我们表明 ER 蛋白 Protrudin 协调侵袭伪足的成熟和功能。Protrudin 与含有 RAB7 结合的 Kinesin-1 衔接蛋白 FYCO1 的 MT1-MMP 阳性内体形成接触位点，并且 RAB7、FYCO1 或 Protrudin 的耗竭抑制了 MT1-MMP 依赖性细胞外基质降解和癌细胞侵袭，通过防止 MT1-MMP 的正向易位和胞吐作用。此外，当通过耗尽 Protrudin 或突触结合蛋白 VII 分别抑制内体易位或胞吐作用时，侵袭伪足无法扩展和伸长。相反，当过表达 Protrudin 时，非癌细胞形成明显的侵袭伪足样突起，并表现出增加的基质降解和侵袭。因此，Protrudin 介导的 ER-内体接触位点通过促进载有 MT1-MMP 的内体向质膜的易位，促进侵袭伪足的生长和 MT1-MMP 的胞吐作用，从而促进细胞侵袭。
