Taylor Jack, Azimi Iman, Monteith Gregory, Bebawy Mary
Discipline of Pharmacy, Graduate School of Health, The University of Technology Sydney, Australia.
Division of Pharmacy, College of Health and Medicine, University of Tasmania, Australia.
J Extracell Vesicles. 2020 Mar 3;9(1):1734326. doi: 10.1080/20013078.2020.1734326. eCollection 2020.
Extracellular vesicles (EVs) are small extracellular membrane vesicles that serve as important intercellular signalling intermediaries in both malignant and non-malignant cells. For EVs formed by the plasma membrane, their biogenesis is characterized by an increase in intracellular calcium followed by successive membrane and cytoskeletal changes. EV production is significantly higher in malignant cells relative to non-malignant cells and previous work suggests this is dependent on increased calcium mobilization and activity of calpain. However, differences in calcium-signalling pathways in the context of malignant and non-malignant EV biogenesis remain unexplored. Here, we demonstrate vesiculation is greater in malignant MCF-7 cells relative to non-malignant hCMEC-D3 cells, increases in free cytosolic Ca via endoplasmic reticulum (ER) Ca store depletion with thapsigargin increases EV biogenesis in both cell types, and vesicular induction is abolished by the intracellular Ca chelator BAPTA-AM. Store-operated calcium entry (SOCE) plays an essential role in the maintenance of EV biogenesis after store depletion. These findings contribute to furthering our understanding of extracellular vesicle biogenesis. Furthermore, since EVs are key mediators in the intercellular transfer of deleterious cancer traits such as cancer multidrug resistance (MDR), understanding the molecular mechanisms governing their biogenesis in cancer is the crucial first step in finding novel therapeutic targets that circumvent EV-mediated MDR.
细胞外囊泡（EVs）是小的细胞外膜囊泡，在恶性和非恶性细胞中均作为重要的细胞间信号传导介质。对于由质膜形成的细胞外囊泡，其生物发生的特征是细胞内钙增加，随后是连续的膜和细胞骨架变化。相对于非恶性细胞，恶性细胞中的细胞外囊泡产生显著更高，先前的研究表明这取决于钙动员增加和钙蛋白酶的活性。然而，在恶性和非恶性细胞外囊泡生物发生背景下钙信号通路的差异仍未得到探索。在这里，我们证明，相对于非恶性的hCMEC-D3细胞，恶性MCF-7细胞中的囊泡形成更多，用毒胡萝卜素通过内质网（ER）钙库耗竭使游离胞质钙增加会增加两种细胞类型中的细胞外囊泡生物发生，并且细胞内钙螯合剂BAPTA-AM可消除囊泡诱导。钙库操纵的钙内流（SOCE）在钙库耗竭后维持细胞外囊泡生物发生中起重要作用。这些发现有助于进一步加深我们对细胞外囊泡生物发生的理解。此外，由于细胞外囊泡是有害癌症特征（如癌症多药耐药性（MDR））细胞间转移的关键介质，了解癌症中控制其生物发生的分子机制是寻找规避细胞外囊泡介导的多药耐药性的新治疗靶点的关键第一步。
