ABSTRACT
Tumor microenvironment contributes to tumor angiogenesis. However, the role of the activated cancer associated-fibroblasts (CAFs) in angiogenesis is still unclear. Here we report that miR-205/YAP1 signaling in the activated stromal fibroblasts plays a critical role in VEGF-independent angiogenesis in breast tumor. Methods: miR-205 expression was assessed by quantitative real-time polymerase chain reaction (qRT-PCR); YAP1 expression by qRT-PCR, western blotting and immunohistochemistry; IL11 and IL15 expression by qRT-PCR, western blotting and ELISA. Tube formation and three-dimensioned sprouting assays in vitro, and orthotopic Xenografts in vivo were conducted as angiogenesis experiments. The mechanism of miR-205/YAP1-mediated tumor angiogenesis was analyzed via overexpression and shRNA, siRNA, or antibody neutralization experiments in combination with anti-VEGF antibody or Axitinib. Results: miR-205/YAP1 signaling axis activates breast normal fibroblasts (NFs) into CAFs, promotes tubule formation and sprouting of Human Umbilical Vein Endothelial Cells (HUVECs). Rescue of miR-205 in CAFs blunts angiogenesis processes. YAP1, a target of miR-205, does not regulate VEGF expression but specifically enhances IL11 and IL15 expressions, maintaining tumor angiogenesis even in the presence of Axitinib or after exhaustion of VEGF by neutralizing VEGF antibody. IL11 and IL15 released from CAFs activate STAT3 signaling in HUVECs. Blockage of IL11 and IL15 expression in CAFs results in the inactivation of STAT3-signaling in HUVECs and repression of the CAF-induced angiogenesis. The blunt angiogenesis halts the invasion and metastasis of breast cancer cells in vivo. Conclusions: These results provide a novel insight into breast CAF-induced tumor angiogenesis in a VEGF-independent manner.
Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Breast Neoplasms/metabolism , MicroRNAs/metabolism , Phosphoproteins/metabolism , STAT3 Transcription Factor/metabolism , Adaptor Proteins, Signal Transducing/genetics , Breast Neoplasms/genetics , Female , Fibroblasts/metabolism , Humans , MicroRNAs/genetics , Neovascularization, Pathologic/metabolism , Phosphoproteins/genetics , Signal Transduction/genetics , Signal Transduction/physiology , Transcription Factors , Vascular Endothelial Growth Factor A/metabolism , YAP-Signaling ProteinsABSTRACT
Ardisia violacea is one of the rare and endangered species, and distributes only in Zhejiang and Taiwan Provinces in China. In order to understand the light requirement and adaptability of A. violacea, the effects of different light intensities (shading rate of 90%, 60%, 25%, and the full light) on leaf photosynthetic characteristics and chlorophyll fluorescence of A. violacea were studied. The photosynthetic rate (Pn) and stomatal conductance (g(s)) of A. violacea varied as a bimodal curve with a 'midday depression' phenomenon in full bright light, and as a unimodal curve in the shading treatments. With the increasing shading rate, the Pn and apparent quantum efficiency (AQY) first increased, and then decreased, the light compensation point (LCP) and light saturation point (LSP) decreased, and the g(s), transpiration rate (Tr), original light energy conversion (Fv/Fm) and potential activity of PS II (Fv/Fo) increased. The total quantity of chlorophyll and the carotenoid (Car) content increased, and Chl a/b decreased under shading conditions. When the shading rate was 25%, the specific leaf mass (LMA) and root to shoot (R/T) ratio of A. violacea reached the maximum. A. violacea possessed a strong flexibility to different light environments, suggesting that light could not be the main limiting factor for natural regeneration of A. violacea populations.
