VO-OHpic attenuates intervertebral disc degeneration via PTEN/Akt pathway

Intervertebral disc degeneration (IVDD) is mainly associated with a chronic process of the nucleus pulposus (NP) cells disabled. Also, it is accepted to be the basic result of low back pain. The role of phosphatase and tensin homolog (PTEN) in negatively regulating the Akt/PKB signaling, which is the major cell survival pathway, has been documented in previous studies. The present work aimed to investigate the role of PTEN inhibitor VO-OHpic (VO) in the protection of IVDD and to explore its potential mechanisms.

NP cells isolated from patients' lumbar discs were subjected to different concentrations of IL-1β or H2O2 to establish NP cells degenerated model. Cell proliferation was analyzed by the Cell Counting Kit-8 (CCK-8) assay. The expression levels of collagen II, aggrecan, PTEN, PI3K, Akt, SOD1, SOD2, p16, and β-galactosidase (β-gal) were detected by Western blotting, immunofluorescence staining or RT-PCR. Flow cytometry was used to measure the ROS level and cell cycle distribution.

Our research showed that collagen II, aggrecan, PI3K, and Akt markedly decreased in IL-1β- or H2O2-induced degenerated NP cells. VO could reverse the effects of IL-1β and H2O2 by the PTEN inhibition. Also, we found that VO increased the antioxidant enzymes SOD1, SOD2, CAT, GSH, POD production, and suppressed the ROS in the disc. Besides, data showed VO promoted NP cells proliferation by cell cycle mediation.

These results suggest that VO treatment prevents NP degradation via restraining oxidative stress and increasing cell proliferation through the PTEN/Akt pathway in vitro. VO may become a novel cytokine for the therapy of IVDD in the future.