Circ-SMARCA5 suppresses progression of multiple myeloma by targeting miR-767-5p

We aimed to investigate the correlation of Circ-SMARCA5 with disease severity and prognosis in multiple myeloma (MM), and its underlying mechanisms in regulating cell proliferation and apoptosis.

Bone marrow samples from 105 MM patients and 36 healthy controls were collected for Circ-SMARCA5 expression measurement. And the correlation of Circ-SMARCA5 expression with patients' characteristics and survival was determined. In vitro, the effect of Circ-SMARCA5 on MM cell proliferation and apoptosis was evaluated by altering Circ-SMARCA5 expression through transfection. Rescue experiments and luciferase assay were further performed to explore the mechanism of Circ-SMARCA5 as well as its potential target miR-767-5p in regulating MM cell activity.

Circ-AMARCA5 was downregulated in MM and presented a good value in distinguishing MM patients from controls and it was also negatively correlated with Beta-2-microglobulin (β2-MG) level and International Staging System (ISS) stage. Additionally, Circ-SMARCA5 high expression was associated with higher CR as well as better PFS and OS. As for in vitro experiments, Circ-SMARCA5 expression was lower in MM cell lines compared with normal cells, and Circ-SMARCA5 overexpression inhibited cell proliferation but promoted cell apoptosis in RPMI8226 cells. Rescue experiments disclosed that the effect of Circ-SMARCA5 on cell activity was attenuated by miR-767-5p, and luciferase reporter assay revealed direct binding between Circ-SMARCA5 and miR-767-5p.

Circ-SMARCA5 is downregulated and correlated with lower β2-MG level and ISS stage as well as better prognosis in MM patients, and it inhibits proliferation but promotes apoptosis of MM cells via directly sponging miR-767-5p.