Fig. 7

MM cells secrete circHNRNPU into the BM microenvironment through exosomes. A Transmission electron microscopy (TEM) was used to characterize exosomes from the culture supernatant of ARP1 and CAG cells. B WB analysis showed the presence of exosome markers Alix and CD9. C-D RNA levels of circHNRNPU and linear HNRNPU ± RNase R were determined by RT-PCR and qRT-PCR. E Graphic illustration of cocultured WT ARP1, CAG, HEK-293, HS-5 cells with the CAG circHNRNPU-OE cells using transwell. F qPCR analysis of circHNRNPU expression in ARP1, CAG, HEK-293, HS-5 cells cocultured with CAG circHNRNPU-OE cells. G WB analysis of circHNRNPU_603aa expression in ARP1, CAG, HEK-293, HS-5 cells cocultured with CAG circHNRNPU-OE cells using HA tag antibody. H The specific peptides from circHNRNPU_603aa were identified by mass spectrometry analysis. I-J Representative confocal images for HA and DAPI showed that circHNRNPU_603aa expression was in time-dependent manner in (I) ARP1 and (J) CAG cells. K MTT assay indicated higher cell proliferation rate of cocultured circHNRNPU-OE MM cells than WT cells. L Cell cycle assay exhibited higher G2/M proportion of cocultured circHNRNPU-OE MM cells than WT cells. The data are presented as mean ± SD.*p < 0.05, **p < 0.01, ***p < 0.001