Hypoxia plays a critical role during the evolution of malignant cells and tumour microenvironment (TME).Tumour-derived exosomes contain informative microRNAs involved in the interaction of cancer and stromal cells, thus contributing to tissue remodelling of tumour microenvironment. This study aims to clarify how hypoxia affects tumour angiogenesis through exosomes shed from lung cancer cells. Lung cancer cells produce more exosomes under hypoxic conditions than do parental cells under normoxic conditions. miR-23a was significantly upregulated in exosomes from lung cancer under hypoxic conditions. Exosomal miR-23a directly suppressed its target prolyl hydroxylase 1 and 2 (PHD1 and 2), leading to the accumulation of hypoxia-inducible factor-1 α (HIF-1 α) in endothelial cells. Consequently, hypoxic lung cancer cells enhanced angiogenesis by exosomes derived from hypoxic cancer under both normoxic and hypoxic conditions. In addition, exosomal miR-23a also inhibits tight junction protein ZO-1, thereby increasing vascular permeability and cancer transendothelial migration. Inhibition of miR-23a by inhibitor administration decreased angiogenesis and tumour growth in a mouse model. Furthermore, elevated levels of circulating miR-23a are found in the sera of lung cancer patients, and miR-23a levels are positively correlated with proangiogenic activities. Taken together, our study reveals the clinical relevance and prognostic value of cancer-derived exosomal miR-23a under hypoxic conditions, and investigates a unique intercellular communication, mediated by cancer-derived exosomes, which modulates tumour vasculature.

The skeleton is the most common metastatic site for breast cancer, with bone metastasis causing pain as well as risk of pathological fractures. Interaction between tumors and the bone microenvironment creates a vicious cycle that accelerates both bone destruction and cancer progression. This study is the first to analyze the soluble factors secreted by breast tumor-associated osteoblasts (TAOBs), which are responsible for promoting cancer progression. The addition of CXCL5 (chemokine (C-X-C motif) ligand 5), present in large amounts in TAOB-condition medium (TAOB-CM), mimicked the inductive effect of TAOB-CM on breast cancer epithelial-mesenchymal transition, migration and invasion. In contrast, inhibition of CXCL5 in OBs decreased TAOB-mediated cancer progression. Inducement of MCF-7 and MDA-MB-231 cancer progression by TAOB-derived CXCL5 is associated with increased Raf/MEK/ERK activation, and mitogen- and stress-activated protein kinase 1 (MSK1) and Elk-1 phosphorylation, as well as Snail upregulation. Activation of Elk-1 facilitates recruitment of phosphorylated MSK1, which in turn enhances histone H3 acetylation and phosphorylation (serine 10) of Snail promoter, resulting in Snail enhancement and E-cadherin downregulation. Moreover, mice treated with anti-CXCL5 antibodies showed decreased metastasis of 4T1 breast cancer cells. Our study suggests that inhibition of CXCL5-mediated ERK/Snail signaling is an attractive therapeutic target for treating metastases in breast cancer patients.

Lung cancer is the leading cause of cancer death worldwide, with metastasis underlying majority of related deaths. Angiomotin (AMOT), a scaffold protein, has been shown to interact with oncogenic Yes-associated protein/transcriptional co-activator with a PDZ-binding motif (YAP/TAZ) proteins, suggesting a potential role in tumor progression. However, the functional role of AMOT in lung cancer remains unknown. This study aimed to identify the patho-physiological characteristics of AMOT in lung cancer progression. Results revealed that AMOT expression was significantly decreased in clinical lung cancer specimens. Knockdown of AMOT in a low metastatic CL1-0 lung cancer cell line initiated cancer proliferation, migration, invasion and epithelial-mesenchymal transition. The trigger of cancer progression caused by AMOT loss was transduced by decreased cytoplasmic sequestration and increased nuclear translocation of oncogenic co-activators YAP/TAZ, leading to increased expression of the growth factor, Cyr61. Tumor promotion by AMOT knockdown was reversed when YAP/TAZ or Cyr61 was absent. Further, AMOT knockdown increased the growth and spread of Lewis lung carcinoma in vivo. These findings suggest that AMOT is a crucial suppressor of lung cancer metastasis and highlight its critical role as a tumor suppressor and its potential as a prognostic biomarker and therapeutic target for lung cancer.