Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia.
Baker Heart and Diabetes Institute, Melbourne, Victoria, 3004, Australia.
Proteomics. 2020 Jul;20(14):e2000016. doi: 10.1002/pmic.202000016.
In localized tumors, basement membrane (BM) prevents invasive outgrowth of tumor cells into surrounding tissues. When carcinomas become invasive, cancer cells either degrade BM or reprogram stromal fibroblasts to breach BM barrier and lead invasion of cancer cells into surrounding tissues in a process called fibroblast-led invasion. However, tumor-derived factors orchestrating fibroblast-led invasion remain poorly understood. Here it is shown that although early-stage primary colorectal adenocarcinoma (SW480) cells are themselves unable to invade Matrigel matrix, they secrete exosomes that reprogram normal fibroblasts to acquire de novo capacity to invade matrix and lead invasion of SW480 cells. Strikingly, cancer cells follow leading fibroblasts as collective epithelial-clusters, thereby circumventing need for epithelial to mesenchymal transition, a key event associated with invasion. Moreover, acquisition of pro-invasive phenotype by fibroblasts treated with SW480-derived exosomes relied on exosome-mediated MAPK pathway activation. Mass spectrometry-based protein profiling reveals that cancer exosomes upregulate fibroblasts proteins implicated in focal adhesion (ITGA2/A6/AV, ITGB1/B4/B5, EGFR, CRK), regulators of actin cytoskeleton (RAC1, ARF1, ARPC3, CYFIP1, NCKAP1, ICAM1, ERM complex), and signalling pathways (MAPK, Rap1, RAC1, Ras) important in pro-invasive remodeling of extracellular matrix. Blocking tumor exosome-mediated signaling to fibroblasts therefore represents an attractive therapeutic strategy in restraining tumors by perturbing stroma-driven invasive outgrowth.
在局部肿瘤中，基底膜（BM）可防止肿瘤细胞侵入周围组织。当癌变为侵袭性时，癌细胞要么降解 BM，要么重新编程基质成纤维细胞以突破 BM 屏障，从而使癌细胞侵入周围组织，这一过程称为成纤维细胞主导的浸润。然而，肿瘤来源的因子协调成纤维细胞主导的浸润仍知之甚少。本研究表明，尽管早期原发性结直肠腺癌（SW480）细胞本身不能侵入 Matrigel 基质，但它们会分泌外泌体，将正常成纤维细胞重新编程为具有新的侵袭基质的能力，并导致 SW480 细胞的浸润。引人注目的是，癌细胞作为集体上皮簇跟随领先的成纤维细胞，从而避免了上皮细胞向间质转化的需要，上皮细胞向间质转化是与浸润相关的关键事件。此外，用 SW480 衍生的外泌体处理的成纤维细胞获得的促侵袭表型依赖于外泌体介导的 MAPK 途径激活。基于质谱的蛋白质谱分析显示，癌细胞外泌体上调了与细胞黏附（ITGA2/A6/AV、ITGB1/B4/B5、EGFR、CRK）、肌动蛋白细胞骨架调节剂（RAC1、ARF1、ARPC3、CYFIP1、NCKAP1、ICAM1、ERM 复合物）和信号通路（MAPK、Rap1、RAC1、Ras）有关的成纤维细胞蛋白，这些蛋白在细胞外基质的促侵袭重塑中起着重要作用。因此，阻断肿瘤外泌体向成纤维细胞的信号传递，通过扰乱基质驱动的侵袭性生长，代表了一种抑制肿瘤的有吸引力的治疗策略。
