本研究评估了乳腺癌相关成纤维细胞 (CAF) 和乳腺癌 (BCa) 细胞之间的旁分泌信号传导。解决 BCa 肿瘤微环境 (TME) 中的细胞间通讯将有助于新疗法的开发。在这里，我们利用了我们的专利 TAME（组织结构和微环境工程）3D 培养微生理系统，这是一个适合 BCa TME 研究的拟病化身。我们在 3D BCa 细胞和 CAF 中单独培养或一起共培养，发现共培养时，CAF 增强了肿瘤细胞的侵袭特性，如肿瘤细胞增殖和扩散到周围基质的增加所示。 3D 培养物的分泌组分析显示 CAF 分泌相对较高的 IL-6。当癌细胞和 CAF 共培养时，还观察到粒细胞巨噬细胞集落刺激因子 (GM-CSF) 的分泌显着增加。我们推测 CAF 分泌的 IL-6 以旁分泌方式发挥作用，诱导癌细胞表达和分泌 GM-CSF。通过评估暴露于 CAF 条件培养基 (CAF-CM) 的癌细胞中 STAT3 的激活和 GM-CSF 的基因表达，证实了这一点。此外，用 BCa cell-CM 处理 CAF 会导致 GM-CSF 短暂上调，随后显着下降，表明 CAF 中 GM-CSF 受到严格调控。 CAF 分泌的 IL-6 驱动 BCa 细胞中 STAT3 的激活，进而驱动 GM-CSF 的表达和分泌。结果，暴露于 BCa 细胞分泌的 GM-CSF 的 CAF 上调炎症相关基因，如 IL-6、IL-6R 和 IL-8，从而形成正反馈循环。我们认为，CAF 中 GM-CSF 的严格调控可能是一种新的调控途径，旨在破坏 CAF:BCa 细胞共生关系。这些数据提供了管理 BCa TME 的细胞间通信网络的另一部分。

This study evaluated the paracrine signaling between breast carcinoma-associated fibroblasts (CAFs) and breast cancer (BCa) cells. Resolving cell-cell communication in the BCa tumor microenvironment (TME) will aid the development of new therapeutics. Here, we utilized our patented TAME (tissue architecture and microenvironment engineering) 3D culture microphysiological system, which is a suitable pathomimetic avatar for the study of the BCa TME. We cultured in 3D BCa cells and CAFs either alone or together in cocultures and found that when cocultured, CAFs enhanced the invasive characteristics of tumor cells, as shown by increased proliferation and spread of tumor cells into the surrounding matrix. Secretome analysis from 3D cultures revealed a relatively high secretion of IL-6 by CAFs. A marked increase in the secretion of granulocyte macrophage-colony stimulating factor (GM-CSF) when carcinoma cells and CAFs were in coculture was also observed. We theorized that the CAF-secreted IL-6 functions in a paracrine manner to induce GM-CSF expression and secretion from carcinoma cells. This was confirmed by evaluating the activation of STAT3 and gene expression of GM-CSF in carcinoma cells exposed to CAF-conditioned media (CAF-CM). In addition, the treatment of CAFs with BCa cell-CM yielded a brief upregulation of GM-CSF followed by a marked decrease, indicating a tightly regulated control of GM-CSF in CAFs. Secretion of IL-6 from CAFs drives the activation of STAT3 in BCa cells, which in turn drives the expression and secretion of GM-CSF. As a result, CAFs exposed to BCa cell-secreted GM-CSF upregulate inflammation-associated genes such as IL-6, IL-6R and IL-8, thereby forming a positive feedback loop. We propose that the tight regulation of GM-CSF in CAFs may be a novel regulatory pathway to target for disrupting the CAF:BCa cell symbiotic relationship. These data provide yet another piece of the cell-cell communication network governing the BCa TME.