Cancer cell exosomes depend on cell-surface heparan sulfate proteoglycans for their internalization and functional activity
Cancer cell exosomes depend on cell-surface heparan sulfate proteoglycans for their internalization and functional activity
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DOI：
10.1073/pnas.1304266110
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发表时间：
2013-10-22
影响因子：
11.1
通讯作者：
Belting, Mattias
中科院分区：
文献类型：
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作者：
Christianson, Helena C.;Svensson, Katrin J.;Belting, Mattias
细胞外小泡(EV)介导的信号蛋白和核酸的细胞间转移最近被认为与癌症和其他病理疾病的发生有关；然而，EV摄取的机制和如何靶向仍然是重要的问题。在这里，我们提供的证据表明，硫酸乙酰肝素蛋白多糖(PGs；HSPGs)作为具有外切体样特征的癌细胞来源的EV的内化受体发挥作用。内化的外切体与细胞表面的合并型和Glypican型HSPG共定位，外切体的摄取被游离的HS链特异性地抑制，而与之密切相关的硫酸软骨素则没有作用。通过使用几个细胞突变体，我们提供了HSPG在外切体摄取中的受体功能的遗传学证据，该功能依赖于完整的HS，特别是2-O和N-硫酸基团。此外，木糖苷对细胞表面HSPG的酶促耗竭或对内源性PG生物合成的药理抑制显著地减弱了外切体的摄取。我们提供了HSPG被分类并与外切体相关的生化证据；然而，与外切体相关的HSPG似乎在外切体内化中没有直接作用。在功能水平上，在PG缺陷突变细胞和木糖苷处理的WT细胞中，Exosome诱导的ERK1/2信号激活被减弱。重要的是，在PG缺乏的突变细胞中，外切体对癌细胞迁移的刺激作用显著减少，或者通过肝素或木糖苷处理WT细胞。我们的结论是，癌细胞来源的外切体利用HSPGs进行内化和功能活性，这显著扩展了HSPGs作为大分子货物关键受体的新兴作用。
Extracellular vesicle (EV)-mediated intercellular transfer of signaling proteins and nucleic acids has recently been implicated in the development of cancer and other pathological conditions; however, the mechanism of EV uptake and how this may be targeted remain as important questions. Here, we provide evidence that heparan sulfate (HS) proteoglycans (PGs; HSPGs) function as internalizing receptors of cancer cell-derived EVs with exosome-like characteristics. Internalized exosomes colocalized with cell-surface HSPGs of the syndecan and glypican type, and exosome uptake was specifically inhibited by free HS chains, whereas closely related chondroitin sulfate had no effect. By using several cell mutants, we provide genetic evidence of a receptor function of HSPG in exosome uptake, which was dependent on intact HS, specifically on the 2-O and N-sulfation groups. Further, enzymatic depletion of cell-surface HSPG or pharmacological inhibition of endogenous PG biosynthesis by xyloside significantly attenuated exosome uptake. We provide biochemical evidence that HSPGs are sorted to and associate with exosomes; however, exosome-associated HSPGs appear to have no direct role in exosome internalization. On a functional level, exosome-induced ERK1/2 signaling activation was attenuated in PG-deficient mutant cells as well as in WT cells treated with xyloside. Importantly, exosome-mediated stimulation of cancer cell migration was significantly reduced in PG-deficient mutant cells, or by treatment of WT cells with heparin or xyloside. We conclude that cancer cell-derived exosomes use HSPGs for their internalization and functional activity, which significantly extends the emerging role of HSPGs as key receptors of macromolecular cargo.