Huang Xin, He Chaobin, Hua Xin, Kan Anna, Mao Yize, Sun Shuxin, Duan Fangting, Wang Jun, Huang Peng, Li Shengping
State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, People's Republic of China.
Department of Experimental Research, Sun Yat-sen University Cancer Center, Guangzhou, People's Republic of China.
Clin Transl Med. 2020 Jun;10(2):e41. doi: 10.1002/ctm2.41. Epub 2020 Jun 4.
Cancer-associated fibroblasts (CAFs) are among the most prominent cells during the desmoplastic reaction in pancreatic ductal adenocarcinoma (PDAC). However, CAFs are heterogeneous and the precise origins are not fully elucidated. This study aimed to explore whether monocytes can transdifferentiate into fibroblasts in PDAC and evaluate the clinical significance of this event.
CD14 monocytes were freshly isolated from human peripheral blood. Immunofluorescence, reverse transcription-quantitative PCR, western blot, flow cytometry and enzyme-linked immunosorbent assay were used to detect the expression of αSMA, fibronectin, and other relevant molecules. In addition, latex beads with a mean particle size of 2.0 µm were used to assess the phagocytic capacity. Moreover, RNA sequencing (RNA-seq) was performed to identify the differences induced by H O and the underlying mechanisms.
Immunofluorescence identified αSMA and fibroblast-specific protein 1 expression by tumor-associated macrophages in PDAC. The in vitro experiment revealed that oxidative stress (H O or radiation) induced monocyte-to-myofibroblast transdifferentiation (MMT), as identified by upregulated αSMA expression at both the RNA and protein levels. In addition, compared with freshly isolated monocytes, human monocyte-derived macrophages increased fibronectin expression. RNA-seq analysis identified p53 activation and other signatures accompanying this transdifferentiation; however, the p53 stabilizer nutlin-3 induced αSMA expression through reactive oxygen species generation but not through the p53 transcription/mitochondria-dependent pathway, whereas the p38 inhibitor SB203580 could partially inhibit αSMA expression. Finally, MMT produced a unique subset of CAFs with reduced phagocytic capacity that could promote the proliferation of pancreatic cancer cells.
Oxidative stress in the tumor microenvironment could induce MMT in PDAC, thus inducing reactive stroma, modulating immunosuppression, and promoting tumor progression. Reducing oxidative stress may be a promising future therapeutic regimen.
癌症相关成纤维细胞（CAFs）是胰腺导管腺癌（PDAC）促纤维增生反应中最显著的细胞类型之一。然而，CAFs具有异质性，其确切来源尚未完全阐明。本研究旨在探讨单核细胞是否能在PDAC中转分化为成纤维细胞，并评估这一事件的临床意义。
从人外周血中新鲜分离出CD14单核细胞。采用免疫荧光、逆转录定量PCR、蛋白质印迹、流式细胞术和酶联免疫吸附测定法检测α平滑肌肌动蛋白（αSMA）、纤连蛋白及其他相关分子的表达。此外，使用平均粒径为2.0 µm的乳胶珠评估吞噬能力。此外，进行RNA测序（RNA-seq）以鉴定过氧化氢（H₂O₂）诱导的差异及潜在机制。
免疫荧光鉴定出PDAC中肿瘤相关巨噬细胞表达αSMA和成纤维细胞特异性蛋白1。体外实验表明，氧化应激（H₂O₂或辐射）诱导单核细胞向肌成纤维细胞转分化（MMT），这在RNA和蛋白质水平上均表现为αSMA表达上调。此外，与新鲜分离的单核细胞相比，人单核细胞衍生的巨噬细胞纤连蛋白表达增加。RNA-seq分析确定了伴随这种转分化的p53激活及其他特征；然而，p53稳定剂Nutlin-3通过活性氧生成而非p53转录/线粒体依赖性途径诱导αSMA表达，而p38抑制剂SB203580可部分抑制αSMA表达。最后，MMT产生了具有降低吞噬能力的独特CAFs亚群，其可促进胰腺癌细胞的增殖。
肿瘤微环境中的氧化应激可诱导PDAC中的MMT，从而诱导反应性基质、调节免疫抑制并促进肿瘤进展。降低氧化应激可能是未来一种有前景的治疗方案。
