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Downregulation of exosomal CLEC3B in hepatocellular carcinoma promotes metastasis and angiogenesis via AMPK and VEGF signals.

ABSTRACT: BACKGROUND:C-Type Lectin Domain Family 3 Member B (CLEC3B), is down-regulated in serum and tumor tissues in different cancers including hepatocellular carcinoma (HCC). However, the functions of CLEC3B in HCC remains elucidated. The aim of this study is to analyze the roles of CLEC3B in HCC. METHODS:The expression of genes was evaluated by immunohistochemistry, western blot, real-time PCR, enzyme-linked immunosorbent assays, and analysis on TCGA-LIHC database and gene expression omnibus. Transmission electron microscopy and immunofluorescence were applied to detect CLEC3B in exosomes. The function of exosomal CLEC3B in tumor progression were performed in vivo and in vitro. RESULTS:We determined that down-regulated CLEC3B in HCC indicated a poor prognosis. Exosomes derived from HCC with down-regulated CLEC3B promoted migration, invasion, epithelial-mesenchymal transition of both tumor cells and endothelial cells (ECs). Moreover, the downregulation CLEC3B in exosomes suppressed VEGF secretion in both HCC cells and ECs, and eventually inhibited angiogenesis. Mechanistically, CLEC3B-mediated VEGF expression in tumor cells and ECs depends on the activation of AMPK signal pathway. CONCLUSION:This study demonstrates that CLEC3B acts as a novel independent prognostic factor, and CLEC3B in exosomes might be a potential therapeutic target for hepatocellular carcinoma.

SUBMITTER: Dai W

PROVIDER: S-EPMC6721425 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Downregulation of exosomal CLEC3B in hepatocellular carcinoma promotes metastasis and angiogenesis via AMPK and VEGF signals.

Dai Wenjuan W Wang Yilin Y Yang Tianxiao T Wang Jing J Wu Weicheng W Gu Jianxin J

Cell communication and signaling : CCS 20190902 1

<h4>Background</h4>C-Type Lectin Domain Family 3 Member B (CLEC3B), is down-regulated in serum and tumor tissues in different cancers including hepatocellular carcinoma (HCC). However, the functions of CLEC3B in HCC remains elucidated. The aim of this study is to analyze the roles of CLEC3B in HCC.<h4>Methods</h4>The expression of genes was evaluated by immunohistochemistry, western blot, real-time PCR, enzyme-linked immunosorbent assays, and analysis on TCGA-LIHC database and gene expression om ...[more]

PMID: 31477130

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Project description:Background: By providing oxygen, nutrients and metastatic conduits, tumour angiogenesis is essential for cancer metastasis. Cancer cell-secreted microRNAs can be packaged into exosomes and are implicated in different aspects of tumour angiogenesis. However, the underlying mechanisms are incompletely understood. Methods: The GEPIA database and in situ hybridization assay were used to analyse expression of miR-205 in ovarian tissues. Immunohistochemistry was performed to examine the relationship between miR-205 and microvessel density. Expression of circulating miR-205 was evaluated by RT-PCR and GEO database analysis. Co-culture and exosome labelling experiments were performed to assess exosomal miR-205 transfer from ovarian cancer (OC) cells to endothelial cells ECs. Exosome uptake assays were employed to define the cellular pathways associated with the endocytic uptake of exosomal miR-205. The role of exosomal miR-205 in angiogenesis was further investigated in vivo and in vitro. Western blotting and rescue experiments were applied to detect regulation of the PTEN-AKT pathway by exosomal miR-205 in ECs. Results: miR-205 was up-regulated in OC tissues, and high expression of miR-205 was associated with metastatic progression in OC patients. Moreover, miR-205 was highly enriched in cancer-adjacent ECs, and up-regulation of miR-205 correlated positively with high microvessel density in OC patients. Importantly, miR-205 was markedly enriched in the serum of OC patients, and a high level of miR-205 in circulating exosomes was associated with OC metastasis. In addition, OC-derived miR-205 was secreted into the extracellular space and efficiently transferred to adjacent ECs in an exosome-dependent manner, and the lipid raft-associated pathway plays an important role in regulating uptake of exosomal miR-205. Exosomal miR-205 from OC cells significantly promoted in vitro angiogenesis and accelerated angiogenesis and tumour growth in a mouse model. Furthermore, we found that exosomal miR-205 induces angiogenesis via the PTEN-AKT pathway. Conclusion: These findings demonstrate an exosome-dependent mechanism by which miR-205 derived from cancer cells regulates tumour angiogenesis and implicate exosomal miR-205 as a potential therapeutic target for OC.

Project description:AimArgonaute2 (AGO2) protein is the active part of RNA-induced silencing complex, cleaving the target mRNA strand complementary to their bound siRNA. An increasing number of miRNAs has been identified as essential to angiogenesis of hepatocellular carcinoma (HCC). In this study we investigated how AGO2 affected HCC angiogenesis.MethodsHuman HCC cell lines HepG2, Hep3B, Huh7, SMMC-7721, Bel-7404, MHCC97-H and LM-3, and human umbilical vein endothelial cells (HUVEC) were tested. The expression of AGO2 in HCC cells was knocked down with siRNA and restored using recombinant adenovirus expressing Ago2. The levels of relevant mRNAs and proteins were examined using RT-PCR, Western blot and EILSA. Nude mice were implanted with Huh7 or SMMC-7721 cells, and tumor volumes were measured. After the mice were euthanized, the xenograft tumors were used for immunohistological analysis.ResultsIn 6 HCC cell lines, AGO2 protein expression was significantly correlated with VEGF expression (r=+0.79), and with VEGF secretion (r=+0.852). Knockdown of Ago2 in Huh7 cells and SMMC-7721 cells substantially decreased VEGF expression, whereas the restoration of AGO2 reversed both VEGF expression and secretion. Furthermore, knockdown of Ago2 significantly up-regulated the expression of PTEN (a tumor suppressor involved in the inhibition of HCC angiogenesis), and vice versa. Moreover, the specific PTEN inhibitor bisperoxovanadate (7, 14, 28 nmol/L) dose-dependently restored the expression of VEGF and the capacity of HCC cells to induce HUVECs to form capillary tubule structures. In the xenograft nude mice, knockdown of Ago2 markedly suppressed the tumor growth and decreased PTEN expression and CD31-positive microvascular in the xenograft tumors.ConclusionA direct relationship exists between the miRNA processing machinery AGO2 and HCC angiogenesis that is mediated by the AGO2/PTEN/VEGF signaling pathway. The results suggest the high value of Ago2 knockdown in anti-angiogenesis therapy for HCC.

Dataset Information

Downregulation of exosomal CLEC3B in hepatocellular carcinoma promotes metastasis and angiogenesis via AMPK and VEGF signals.

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Downregulation of exosomal CLEC3B in hepatocellular carcinoma promotes metastasis and angiogenesis via AMPK and VEGF signals.

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