Crow Jennifer, Atay Safinur, Banskota Samagya, Artale Brittany, Schmitt Sarah, Godwin Andrew K
Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, USA.
Department of Biomedical Engineering, Duke University, Durham, North Carolina, NC, USA.
Oncotarget. 2017 Feb 14;8(7):11917-11936. doi: 10.18632/oncotarget.14440.
Exosomes have been implicated in the cell-cell transfer of oncogenic proteins and genetic material. We speculated this may be one mechanism by which an intrinsically platinum-resistant population of epithelial ovarian cancer (EOC) cells imparts its influence on surrounding tumor cells. To explore this possibility we utilized a platinum-sensitive cell line, A2780 and exosomes derived from its resistant subclones, and an unselected, platinum-resistant EOC line, OVCAR10. A2780 cells demonstrate a ~2-fold increase in viability upon treatment with carboplatin when pre-exposed to exosomes from platinum-resistant cells as compared to controls. This coincided with increased epithelial to mesenchymal transition (EMT). DNA sequencing of EOC cell lines revealed previously unreported somatic mutations in the Mothers Against Decapentaplegic Homolog 4 (SMAD4) within platinum-resistant cells. A2780 cells engineered to exogenously express these SMAD4 mutations demonstrate up-regulation of EMT markers following carboplatin treatment, are more resistant to carboplatin, and release exosomes which impart a ~1.7-fold increase in resistance in naive A2780 recipient cells as compared to controls. These studies provide the first evidence that acquired SMAD4 mutations enhance the chemo-resistance profile of EOC and present a novel mechanism in which exchange of tumor-derived exosomes perpetuates an EMT phenotype, leading to the development of subpopulations of platinum-refractory cells.
外泌体已被证明参与致癌蛋白和遗传物质的细胞间转移。我们推测，这可能是上皮性卵巢癌（EOC）中具有内在铂抗性的细胞群体对周围肿瘤细胞产生影响的一种机制。为了探究这种可能性，我们使用了一种铂敏感细胞系A2780及其耐药亚克隆衍生的外泌体，以及一种未经筛选的铂耐药EOC细胞系OVCAR10。与对照组相比，当A2780细胞预先暴露于来自铂耐药细胞的外泌体后，用卡铂处理时其活力增加了约2倍。这与上皮-间质转化（EMT）增加相吻合。EOC细胞系的DNA测序揭示了铂耐药细胞中母系对五体不全同源物4（SMAD4）中以前未报道的体细胞突变。经过基因工程改造以外源表达这些SMAD4突变的A2780细胞在卡铂处理后表现出EMT标志物的上调，对卡铂更具抗性，并释放出外泌体，与对照组相比，这些外泌体使未处理的A2780受体细胞的抗性增加了约1.7倍。这些研究提供了首个证据，即获得性SMAD4突变增强了EOC的化疗抗性，并提出了一种新机制，其中肿瘤来源的外泌体交换使EMT表型持续存在，导致铂难治性细胞亚群的形成。
