Exosome-mediated transfer of lncRNA HCG18 promotes M2 macrophage polarization in gastric cancer.

Gastric cancer (GC) derived exosomes (Exos) aggravate GC development by facilitating M2 macrophage polarization and long non-coding RNA (lncRNA) HCG18 was highly expressed in GC. This study aimed to investigate whether the exosomal lncRNA HCG18 regulated the M2 macrophage polarization in GC and the possible mechanism. The isolated GC cells (GCCs)-Exos were identified using transmission electron microscopy, Nanoparticle Tracking Analysis and Western blot. The GCCs-Exos function was verified by enzyme-linked immunosorbent assay and flow cytometry. Meanwhile, the exosomal lncRNA HCG18 function was determined using thein vitro assays. Furthermore, the underlying mechanism of the exosomal lncRNA HCG18 that regulated M2 macrophage polarization in GC was investigated using dual-luciferase reporter gene assay and RNA pull-down. After the validation of GCCs-Exos, the GCCs-Exos facilitated the M2 macrophage polarization. The in vitro assays confirmed that the exosomal lncRNA HCG18 positively regulated the M2 macrophage polarization. Mechanistically, lncRNA HCG18 bound to miR-875-3p, miR-875-3p bound to KLF4. Furthermore, GCCs-exosomal lncRNA HCG18 elevated the KLF4 expression by decreasing miR-875-3p in macrophages to facilitate M2 macrophage polarization, thus alleviating GC. The in vivo assays clarified that the GCCs-exosomal lncRNA HCG18 restrained the tumor growth of GC induced by M2 macrophages. GCCs-exosomal lncRNA HCG18 elevated KLF4 expression by decreasing miR-875-3p in macrophages to facilitate the M2 macrophage polarization.

Xin L ，Wu Y ，Liu C ，Zeng F ，Wang JL ，Wu DZ ，Wu JP ，Yue ZQ ，Gan JH ，Lu H ，Yuan YW ，Zhou LQ ... -  《-》

Long non-coding RNA HCG18 promotes M1 macrophage polarization through regulating the miR-146a/TRAF6 axis, facilitating the progression of diabetic peripheral neuropathy.

Ren W ，Xi G ，Li X ，Zhao L ，Yang K ，Fan X ，Gao L ，Xu H ，Guo J ... -  《-》

Gastric cancer-derived exosomal miR-519a-3p promotes liver metastasis by inducing intrahepatic M2-like macrophage-mediated angiogenesis.

Liver metastasis (LM) is a major obstacle to the prognosis of gastric cancer (GC) patients, but the molecular mechanism underlying gastric cancer liver metastasis (GC-LM) remains unknown. Exosomes have been identified as an important mediator of communication between tumor cells and the microenvironment. Therefore, we sought to investigate the effects of primary GC cells on the liver microenvironment and the role of exosomal microRNAs (exo-miRNA) in GC-LM. Sequential differential centrifugation, transmission electron microscopy and NanoSight analysis were used to extract and characterize exosomes. MicroRNA sequencing in GC-derived exosomes and mRNA sequencing in PMA-treated THP-1 cells were used to identify differentially expressed miRNAs in exosomes and the functional targets of exosomal miR-519a-3p (exo-miR-519a-3p) in macrophages, respectively. Tracing and internalization of exosomes and transfer of exo-miR-519a-3p were observed by immunofluorescence. Tubule formation assays, aortic ring assays, and exosome-educated GC-LM model were used to investigate the roles of GC-derived exosomes and exo-miR-519a-3p in angiogenesis and GC-LM. Luciferase reporter assay, qRT-PCR, Western blot, ELISA, flow cytometry and immunofluorescence were used to investigate the regulatory mechanism of exo-miR-519a-3p at GC-LM. The expression level of miR-519a-3p in serum exosomes was significantly higher in GC-LM patients than in patients without LM, and high expression of exo-miR-519a-3p indicates a worse prognosis. GC-derived exosomes are mainly accumulated in the liver and internalized by intrahepatic macrophages. Mechanistically, exo-miR-519a-3p activates the MAPK/ERK pathway by targeting DUSP2, thereby causing M2-like polarization of macrophages. M2-like polarized macrophages accelerate GC-LM by inducing angiogenesis and promoting intrahepatic premetastatic niche formation. Our results indicate that exo-miR-519a-3p plays a critical role in mediating crosstalk between primary GC cells and intrahepatic macrophages and is a potential therapeutic target for GC-LM.

Qiu S ，Xie L ，Lu C ，Gu C ，Xia Y ，Lv J ，Xuan Z ，Fang L ，Yang J ，Zhang L ，Li Z ，Wang W ，Xu H ，Li B ，Xu Z ... -  《JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH》

LncRNA HCG18 promotes M2 macrophage polarization to accelerate cetuximab resistance in colorectal cancer through regulating miR-365a-3p/FOXO1/CSF-1 axis.

Cetuximab (CET) resistance in colorectal cancer (CRC) is responsible to poor prognosis to some extent. M2 macrophage polarization is closely correlated with drug resistance to cancers. Therefore, this study aims to investigate whether the mechanism of HCG18 on CET resistance to CRC involving in M2 macrophage polarization. Clinic samples and SW620 cells with/without M0 macrophage co-culture served as experimental subjects. CET treatment was performed to induce SW620 cell resistant to CET. qRT-PCR and western blot were employed to evaluate the mRNA and protein expression of genes. The capabilities of cell viability, proliferation, migration and invasion were examined using CCK-8, clone formation assay and transwell. ELISA was employed to examine the protein concentrations of IL-10 and TGF-β1. StarBase and luciferase activity assay were conducted to consolidate the interactions among HCG18, miR-365a-3p and FOXO1. In clinical samples and CRC cells, the abundance of HCG18 was enhanced whereas miR-365a-3p was reduced. Besides, HCG18 expression in CET-resistant tumor tissues was higher than that in CET-sensitive tumor tissues and the trend of miR-365a-3p was opposite to that of HCG18. HCG18 knockdown attenuated macrophage-induced CET resistance in SW620 cells and suppressed M2 polarization of THP-1 cells. Mechanistically, HCG18 interacted with miR-365a-3p and miR-365a-3p targeted FOXO1. MiR-365a-3p inhibitor abolished HCG18 knockdown-mediated inhibition of CET resistance, while FOXO1 knockdown compromised the influences of miR-365a-3p inhibitor. FOXO1 could positively regulate CSF-1 expression to promote M2 macrophage polarization and macrophage-induced CET resistance. Our results revealed that HCG18 promoted M2 macrophage polarization to facilitate CET resistance to CRC cells through modulating miR-365a-3p/FOXO1/CSF-1 axis.

Gao C ，Hu W ，Zhao J ，Ni X ，Xu Y ... -  《-》

Long noncoding RNA HCG18 up-regulates the expression of WIPF1 and YAP/TAZ by inhibiting miR-141-3p in gastric cancer.

Accumulating works show that lncRNAs play critical roles in the development of gastric cancer (GC). LncRNA HLA complex group 18 (HCG18) was implicated in the progression of bladder cancer and glioma, but its role in GC is unknown. RT-PCR was used to detect HCG18 and miR-141-3p expression in GC specimen. GC cell lines (AGS and MKN-28) were exploited as cell model. The biological effect of HCG18 on cancer cells was probed by CCK-8, colony formation, flow cytometry, Transwell and wound-healing experiments in vitro, and subcutaneous xenotransplanted tumor model and tail vein injection model in vivo. Interaction between HCG18 and miR-141-3p was determined by bioinformatics analysis, RT-PCR, and luciferase reporter experiments. Downstream gene expression of miR-141-3p, including Wiskott-Aldrich syndrome protein interacting protein family member 1 (WIPF1), Yes associated protein 1 (YAP), and tafazzin (TAZ) were detected using Western blot. HCG18 was markedly up-regulated in GC specimens, while miR-141-3p was markedly down-regulated. Down-regulation of HCG18 inhibited viability, migration, and invasion of GC cells, while miR-141-3p transfection led to opposite effect. HCG18 could down-regulate miR-141-3p through adsorbing it, and a negative association between HCG18 and miR-141-3p was found in GC specimens. HCG18 promoted WIPF1, YAP and TAZ expression, nonetheless, such influence was reversed by co-transfecting with miR-141-3p. HCG18 was aberrantly up-regulated in GC tissues, and it indirectly regulated the activity of Hippo signaling through counteracting miR-141-3p expression.

Liu Y ，Lin W ，Dong Y ，Li X ，Lin Z ，Jia J ，Zou W ，Pan Y ... -  《Cancer Medicine》