Potential of circular RNA itchy E3 ubiquitin protein ligase as a biomarker and treatment target for multiple myeloma

Background: This study aimed to investigate the association of circular RNA itchy E3 ubiquitin protein ligase (circ-ITCH) expression with disease risk, clinical characteristics, progression-free survival (PFS) and overall survival (OS) of multiple myeloma (MM), and to explore the influence of circ-ITCH overexpression on MM cell activities n vitro . Methods: Bone marrow samples from 92 MM patients and 30 healthy controls were collected, and circ- ITCH expression was detected by quantitative polymerase chain reaction. PFS and OS in MM patients were calculated. Circ-ITCH in human MM cell lines and normal bone marrow mononuclear cells (BMMCs) were detected. Circ-ITCH overexpression and control overexpression plasmids were transfected to U226 cell line, and cell proliferation as well as apoptosis were assessed. Results: Circ-ITCH expression was under-expressed in MM patients compared to healthy controls. And receiver operating characteristic curve displayed that circ-ITCH could distinguish MM patients from healthy controls [area under curve: 0.809 (95% CI: 0.722–0.895)]. Additionally, circ-ITCH high expression was associated with decreased International Staging System (ISS) stage in MM patients. Kaplan-Meier curves and Cox’s regression analysis displayed that circ-ITCH expression was positively correlated with PFS and OS. In vitro , circ-ITCH expression was lower in MM cell lines (including RPMI8226, U226 and NCI-H929) compared to normal BMMCs. In U226 cells, cell proliferation was decreased but apoptosis was elevated by circ-ITCH overexpression. Conclusions: Circ-ITCH might serve as a potential biomarker and treatment target for MM.