Fig. 6

MM cells secrete circCHEK1_246aa circular RNA to induce MM CIN and promote osteoclast differentiation in the bone marrow microenvironment. A The number of exons and exact circCHEK1 sequences produced from CHEK1 were validated by Sanger sequencing. The blue arrow represents the “head-to-tail” splicing sites of circCHEK1. B mRNA levels of circCHEK1 and linear CHEK1 ± RNase R were determined by RT-PCR and qRT-PCR. C After pull-down using a CHEK1 antibody, protein samples at the expected size were excised and subjected to mass spectrometry (MS) analysis, and specific peptides from circCHEK1_246aa were identified. D A Co-IP assay revealed that circCHEK1_246aa more robustly interacted with native CEP170 than mutated CEP170. E–F circCHEK1 OE increased chromosomal plate width and decreased mitotic bipolar spindle length in ARP1 and H929 cells. G TRAP staining revealed that circCHEK1-OE human primary PBMCs developed into significantly more osteoclasts relative to vehicle-transfected control cells. H Graphic illustrating that CHEK1 and circCHEK1_246aa promote multiple myeloma malignancy by evoking CIN and bone lesion formation