Tumor-derived exosomal microRNA-106b-5p activates EMT-cancer cell and M2-subtype TAM interaction to facilitate CRC metastasis.

Epithelial-mesenchymal transition (EMT) is reported to involve in the crosstalk between tumor cells and tumor-associated macrophages (TAMs). Exosomes are considered as important mediators of orchestrating intercellular communication. However, the underlying mechanisms by which EMT-colorectal cancer (CRC) cells promote the M2 polarization of TAMs remain less understood. In this study, we found that EMT-CRC cells promoted the M2-like polarization of macrophages by directly transferring exosomes to macrophages, leading to a significant increase of the microRNA-106b-5p (miR-106b) level in macrophages. Mechanically, an increased level of miR-106b activated the phosphatidylinositol 3-kinase (PI3K)γ/AKT/mammalian target of rapamycin (mTOR) signaling cascade by directly suppressing programmed cell death 4 (PDCD4) in a post-transcription level, contributing to the M2 polarization of macrophages. Activated M2 macrophages, in a positive-feedback manner, promote EMT-mediated migration, invasion, and metastasis of CRC cells. Clinically, miR-106b was significantly elevated in CRC tissues and negatively correlated with the levels of PDCD4 in CRC specimens, and high expression of exosomal miR-106b in plasma was significantly associated with the malignant progression of CRC. Taken together, our results indicate that exosomal miR-106b derived from EMT-CRC cells has an important role in intercellular communication for inducing M2 macrophage polarization, illuminating a novel mechanism underlying CRC progression and offering potential targets for prevention of CRC metastasis.

Yang C ，Dou R ，Wei C ，Liu K ，Shi D ，Zhang C ，Liu Q ，Wang S ，Xiong B ... -  《-》

Exosome-encapsulated miRNAs contribute to CXCL12/CXCR4-induced liver metastasis of colorectal cancer by enhancing M2 polarization of macrophages.

Tumor-associated macrophages (TAMs) are important immunocytes associated with cancer metastasis. However, whether TAMs play a dominant role in mediating CXCL12/CXCR4-induced liver metastasis of colorectal cancer (CRC) remains unexplored. Herein, we found that CD206+ TAMs, which infiltrated at the invasive front, were correlated with CXCR4 expression and liver metastasis of CRC in clinical specimens. Several miRNAs (miR-25-3p, miR-130b-3p, miR-425-5p), upregulated in CRC cells by activation of the CXCL12/CXCR4 axis, could be transferred to macrophages via exosomes. These exosomal miRNAs induced M2 polarization of macrophages by regulating PTEN through activation of PI3K/Akt signaling pathway. In turn, M2 polarized macrophages promoted cancer metastasis by enhancing epithelial-mesenchymal transition (EMT) and secreting vascular endothelial growth factor (VEGF). Co-culture of CRC cells with macrophages transfected with these miRNAs or treated with exosomes enhanced their metastatic capacity both in vitro and in vivo. Clinically, the serum levels of exosomal miR-25-3p, miR-130b-3p and miR-425-5p were correlated with progression and metastasis of CRC. In conclusion, these results reveal a crucial role of exosomal miRNAs in mediating the crosstalk between CXCR4 overexpressing cancer cells and TAMs, providing potential therapeutic targets for circumventing liver metastasis of CRC.

Wang D ，Wang X ，Si M ，Yang J ，Sun S ，Wu H ，Cui S ，Qu X ，Yu X ... -  《-》

miR-195-5p/NOTCH2-mediated EMT modulates IL-4 secretion in colorectal cancer to affect M2-like TAM polarization.

Lin X ，Wang S ，Sun M ，Zhang C ，Wei C ，Yang C ，Dou R ，Liu Q ，Xiong B ... -  《Journal of Hematology & Oncology》

Exosomal miR-106a-5p from highly metastatic colorectal cancer cells drives liver metastasis by inducing macrophage M2 polarization in the tumor microenvironment.

The tumor microenvironment (TME) is a dynamic system orchestrated by intricate cell-to-cell crosstalk. Specifically, macrophages within the TME play a crucial role in driving tumor progression. Exosomes are key mediators of communication between tumor cells and the TME. However, the mechanisms underlying exosome-driven crosstalk between tumor cells and macrophages during colorectal cancer (CRC) progression remain incompletely elucidated. Single-cell RNA sequencing were analyzed using the Seurat package. Exosomes were isolated using ultracentrifugation and characterized by transmission electron microscopy, nanoparticle tracking analysis, and western blot. miRNAs differentially expressed in exosomes were analyzed using the limma package. CD206 expression in CRC tissues, exosomes tracing, and exosomal miR-106a-5p transport were observed through immunofluorescence. Macrophage polarization was assessed via qRT-PCR, ELISA, and flow cytometry. The interactions between miR-106a-5p, hnRNPA1, and SOCS6 were evaluated using miRNA pull-down, RIP, and dual-luciferase reporter assays. Transwell assays and liver metastasis model explored the role of exosomal miR-106a-5p-induced M2 macrophages in promoting CRC liver metastasis. The proportion of M2 macrophages is increased in CRC with liver metastasis compared to those without. Highly metastatic CRC cells release exosomes enriched with miR-106a-5p, which promote macrophages M2 polarization by suppressing SOCS6 and activating JAK2/STAT3 pathway. These M2 macrophages reciprocally enhance CRC liver metastasis. hnRNPA1 regulate the transport of miR-106a-5p into exosomes. Clinically, elevated miR-106a-5p in plasma exosomes correlated with liver metastasis and poor prognosis. CRC-derived exosomal miR-106a-5p plays a critical role in promoting liver metastasis and is a potential biomarker for the prevention and treatment of CRC liver metastasis.

Liang Y ，Li J ，Yuan Y ，Ju H ，Liao H ，Li M ，Liu Y ，Yao Y ，Yang L ，Li T ，Lei X ... -  《JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH》

Colorectal cancer-derived exosomal miR-106b-3p promotes metastasis by down-regulating DLC-1 expression.

Cancer-derived exosomal miRNAs play an important role in the development of metastasis, but the effects and underlying mechanisms remain unclear. In the present study, we investigated the miRNA expression profiles of 5 paired serum exosomal samples from metastatic colorectal cancer (mCRC) and non-mCRC patients via RNA sequencing. After we evaluated the differentially expressed miRNAs in 80 CRC patients, miR-106b-3p was selected as a metastasis-associated miRNA of CRC. We showed that the expression level of serum exosomal miR-106b-3p was significantly higher in CRC patients with metastasis than those without metastasis. Additionally, high serum exosomal miR-106b-3p expression in patients was correlated with a poor prognosis. Coculture of low-metastatic CRC cells with high-metastatic CRC cell-derived exosomes promoted cell migration, invasion, and epithelial-to-mesenchymal transition (EMT), which was caused by the transport and transduction of miR-106b-3p in vitro. Moreover, exosomal miR-106b-3p promoted lung metastasis of CRC cells in vivo. In addition, we demonstrated that miR-106b-3p regulated metastasis by targeting deleted in liver cancer-1 (DLC-1). A negative correlation was also identified between miR-106b-3p and DLC-1 expression in human CRC tumour tissues and in mouse lung metastatic lesions. Collectively, our study indicated that metastasis-associated miR-106b-3p from serum exosomes could be used as a potential prognostic biomarker and therapeutic target for CRC patients.

Liu H ，Liu Y ，Sun P ，Leng K ，Xu Y ，Mei L ，Han P ，Zhang B ，Yao K ，Li C ，Bai J ，Cui B ... -  《-》