Journal Article

CAFs secreted exosomes promote metastasis and chemotherapy resistance by enhancing cell stemness and epithelial-mesenchymal transition in colorectal cancer

Hu, J. L., Wang, F. F., Liao, W. T., Zeng, Z. C., Lan, X. L., Yan, Y. R., Liang, L., Liao, W. J., Liang, Y. S., Zhu, X. H., Wang, W., Ding, Y. Q., Song, F. Y.

2019

Overview

Background Cancer associated fibroblasts (CAFs) are key stroma cells that play dominant roles in tumor progression. However, the CAFs-derived molecular determinants that regulate colorectal cancer (CRC) metastasis and chemoresistance have not been fully characterized. Methods CAFs and NFs were obtained from fresh CRC and adjacent normal tissues. Exosomes were isolated from conditioned medium and serum of CRC patients using ultracentrifugation method and ExoQuick Exosome Precipitation Solution kit, and characterized by transmission electronic microscopy, nanosight and western blot. MicroRNA microarray was employed to identify differentially expressed miRNAs in exosomes secreted by CAFs or NFs. The internalization of exosomes, transfer of miR-92a-3p was observed by immunofluorescence. Boyden chamber migration and invasion, cell counting kit-8, flow cytometry, plate colony formation, sphere formation assays, tail vein injection and primary colon cancer liver metastasis assays were employed to explore the effect of NFs, CAFs and exosomes secreted by them on epithelial-mesenchymal transition, stemness, metastasis and chemotherapy resistance of CRC. Luciferase report assay, real-time qPCR, western blot, immunofluorescence, and immunohistochemistry staining were employed to explore the regulation of CRC metastasis and chemotherapy resistance by miR-92a-3p, FBXW7 and MOAP1. Results CAFs promote the stemness, epithelial-mesenchymal transition (EMT), metastasis and chemotherapy resistance of CRC cells. Importantly, CAFs exert their roles by directly transferring exosomes to CRC cells, leading to a significant increase of miR-92a-3p level in CRC cells. Mechanically, increased expression of miR-92a-3p activates Wnt/β-catenin pathway and inhibits mitochondrial apoptosis by directly inhibiting FBXW7 and MOAP1, contributing to cell stemness, EMT, metastasis and 5-FU/L-OHP resistance in CRC. Clinically, miR-92a-3p expression is significantly increased in CRC tissues and negatively correlated with the levels of FBXW7 and MOAP1 in CRC specimens, and high expression of exosomal miR-92a-3p in serum was highly linked with metastasis and chemotherapy resistance in CRC patients. Conclusions CAFs secreted exosomes promote metastasis and chemotherapy resistance of CRC. Inhibiting exosomal miR-92a-3p provides an alternative modality for the prediction and treatment of metastasis and chemotherapy resistance in CRC.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Adaptor Proteins, Signal Transducing - genetics / Adaptor Proteins, Signal Transducing - metabolism / Animals / Apoptosis / Apoptosis Regulatory Proteins - genetics / Apoptosis Regulatory Proteins - metabolism / Bioinformatics / Biomarkers / Biomedical and Life Sciences / Biomedicine / Boyden chamber / Breast cancer / Cancer metastasis / Cancer Research / Cancer treatment / Cancer-Associated Fibroblasts - metabolism / Cdc4 protein / Cell Line, Tumor / Cell migration / Chemoresistance / Chemotherapy / Chemotherapy resistance / Colon cancer / Colorectal cancer / Colorectal carcinoma / Colorectal Neoplasms - genetics / Colorectal Neoplasms - metabolism / Colorectal Neoplasms - pathology / Development and progression / Drug Resistance, Neoplasm / Efficiency / Epithelial-Mesenchymal Transition / Exosomes / Exosomes - genetics / Exosomes - metabolism / F-Box-WD Repeat-Containing Protein 7 - genetics / F-Box-WD Repeat-Containing Protein 7 - metabolism / Fibroblasts / Flow cytometry / Fluorescent antibody technique / Gene Expression Regulation, Neoplastic / Humans / Immunofluorescence / Immunohistochemistry / Internalization / Liver cancer / Liver Neoplasms - genetics / Liver Neoplasms - metabolism / Liver Neoplasms - pathology / Liver Neoplasms - secondary / Luciferase / Lung cancer / Mesenchyme / Metastases / Metastasis / Mice / MicroRNA / MicroRNAs / MicroRNAs - genetics / Microscopy / miR-92a-3p / miRNA / Mitochondria / Neoplasm Transplantation / Oncology / Precipitation (Meteorology) / Proteins / Stem cells / Stemness / Stroma / Tumors / Ultracentrifugation / Up-Regulation / Wnt protein / Wnt Signaling Pathway / β-Catenin