MicroRNA-145 overexpression attenuates apoptosis and increases matrix synthesis in nucleus pulposus cells

Aims: Lower back pain is often associated with intervertebral disc degeneration (IDD), which results from a decrease in nucleus pulposus (NP) cells and an imbalance between the degradation and synthesis of extracellular matrix (ECM) components. Multiple microRNAs play crucial roles in the modulation of NP cell apoptosis and matrix degradation. miR-145 is an important microRNA related to degenerative diseases such as osteoarthritis. Here, the effect of miR-145 in IDD was elucidated. The aim of this study was to explore the role and mechanism of miR-145 in the apoptosis of NP cells and in matrix metabolism in NP cells.

Materials and methods: Real-time PCR, western blotting and flow cytometry analysis were used to observe the effect of miR-145 on NP cell apoptosis in the absence or presence of oxidative stress. Cell transfection, loss-of-function experiments using an ADAM17 inhibitor or lentiviral shADAM17, immunofluorescence, real-time PCR and western blotting were performed to demonstrate the role and mechanism of miR-145 in NP cell matrix metabolism.

Key findings: miR-145 attenuated NP cell apoptosis in the absence and presence of oxidative stress. Moreover, miR-145 overexpression increased and miR-145 suppression decreased matrix synthesis. ADAM17, which is expressed in degenerative discs, is the target of miR-145. ADAM17 gene suppression with lentiviral shRNA or an inhibitor enhanced matrix synthesis in NP cells. In addition, siADAM17 reversed the matrix degradation induced by miR-145 inhibition.

Significance: miR-145 suppresses apoptosis and promotes ECM synthesis in NP cells. miR-145 is thus a potential therapeutic microRNA for IDD.