FOSL2 promotes VEGF-independent angiogenesis by transcriptionnally activating Wnt5a in breast cancer-associated fibroblasts.
FOSL2 promotes VEGF-independent angiogenesis by transcriptionnally activating Wnt5a in breast cancer-associated fibroblasts.
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FOSL2 通过转录激活乳腺癌相关成纤维细胞中的 Wnt5a 促进不依赖 VEGF 的血管生成
作者：
Wan X;Guan S;Hou Y;Qin Y;Zeng H;Yang L;Qiao Y;Liu S;Li Q;Jin T;Qiu Y;Liu M
癌症相关成纤维细胞（CAF）是肿瘤微环境的主要组成部分，有助于积极的血管生成进展。在临床实践中，传统的抗血管生成治疗，主要是抗VEGF，提供了非常有限的乳腺癌的有益效果。在这里，我们揭示了FOS-like 2（FOSL 2），乳腺CAFs中的转录因子，在基质成纤维细胞中VEGF非依赖性血管生成中起着关键作用。研究方法：通过qRT-PCR、蛋白质印迹和免疫组织化学评估原代和永生化CAF和临床样品中的FOSL 2和Wnt 5a表达。建立FOSL 2或Wnt 5a沉默的CAFs和FOSL 2过表达的NF以探索其促血管生成作用。作为血管生成实验，进行了侵袭、小管形成、三维发芽测定和原位异种移植。用抗VEGF抗体和阿西替尼阻断VEGF/VEGFR后，通过蛋白质印迹法评价FZD 5/NF-κB/ERK信号传导激活。采用双荧光素酶报告基因检测和染色质免疫沉淀法检测FOSL 2对Wnt 5a表达的调节作用，并检测患者血清中Wnt 5a的含量，评价其对乳腺癌患者的临床诊断价值。结果：乳腺CAFs中FOSL 2的增强与患者的血管生成和临床进展显著相关。高表达FOSL 2的CAFs的上清液以VEGF非依赖性方式强烈促进人脐静脉内皮细胞（HUVECs）的管形成和发芽，并促进血管生成以及体内肿瘤生长。从机制上讲，CAFs中增强的FOSL 2受雌激素/cAMP/PKA信号转导的调节。FOSL 2的直接靶点Wnt 5a特异性激活HUVECs中的FZD 5/NF-κB/ERK信号通路，促进VEGF非依赖性血管生成。此外，在乳腺癌患者血清中普遍检测到高水平的Wnt 5a，并且与乳腺肿瘤组织中的微血管密度密切相关，这表明Wnt 5a在乳腺癌诊断中具有很好的临床价值。结论：FOSL 2/Wnt 5a信号转导以VEGF非依赖性方式在乳腺癌血管生成中起重要作用，靶向CAFs中的FOSL 2/Wnt 5a信号转导轴可能为抗血管生成治疗提供潜在选择。
Cancer-associated fibroblasts (CAFs), a predominant component of the tumor microenvironment, contribute to aggressive angiogenesis progression. In clinical practice, traditional anti-angiogenic therapy, mainly anti-VEGF, provides extremely limited beneficial effects to breast cancer. Here, we reveal that FOS-like 2 (FOSL2), a transcription factor in breast CAFs, plays a critical role in VEGF-independent angiogenesis in stromal fibroblasts. Methods: FOSL2 and Wnt5a expression was assessed by qRT-PCR, western blotting and immunohistochemistry in primary and immortalized CAFs and clinical samples. FOSL2- or Wnt5a-silenced CAFs and FOSL2-overexpressing NFs were established to explore their proangiogenic effects. Invasion, tubule formation, three-dimensional sprouting assays, and orthotopic xenografts were conducted as angiogenesis experiments. FZD5/NF-κB/ERK signaling activation was evaluated by western blotting after blocking VEGF/VEGFR with an anti-VEGF antibody and axitinib. Dual luciferase reporter assays and chromatin immunoprecipitation were performed to test the role of FOSL2 in regulating Wnt5a expression, and Wnt5a in the serum of the patients was measured to assess its clinical diagnostic value for breast cancer patients. Results: Enhanced FOSL2 in breast CAFs was significantly associated with angiogenesis and clinical progression in patients. The supernatant from CAFs highly expressing FOSL2 strongly promoted tube formation and sprouting of human umbilical vein endothelial cells (HUVECs) in a VEGF-independent manner and angiogenesis as well as tumor growth in vivo. Mechanistically, the enhanced FOSL2 in CAFs was regulated by estrogen/cAMP/PKA signaling. Wnt5a, a direct target of FOSL2, specifically activated FZD5/NF-κB/ERK signaling in HUVECs to promote VEGF-independent angiogenesis. In addition, a high level of Wnt5a was commonly detected in the serum of breast cancer patients and closely correlated with microvessel density in breast tumor tissues, suggesting a promising clinical value of Wnt5a for breast cancer diagnostics. Conclusion: FOSL2/Wnt5a signaling plays an essential role in breast cancer angiogenesis in a VEGF-independent manner, and targeting the FOSL2/Wnt5a signaling axis in CAFs may offer a potential option for antiangiogenesis therapy.