INTRODUCTION: Wnt/β‐catenin (hereafter called Wnt) pathways are key inducers and regulators of joint development, and are involved in the formation of bone and cartilage. We previously reported that the Wnt signaling pathway plays an essential role in the control of cellular proliferation and cell senescence in intervertebral disc cells (Hiyama et al. Arthritis and Rheum, 2010). In the present study, we provide evidence that the expression of c‐myc, a key protein required for cell proliferation, is regulated by the Wnt signaling pathway in intervertebral disc cells.
METHODS: A total of 32 Sprague Dawley (SD) rats (12 weeks old) were used for this study. To ascertain whether the Wnt signaling pathway regulated the expression of cmyc in nucleus pulposus cells, we measured its transcript, gene and protein expression. In addition, to test whether Wnt signaling activation is sufficient to promote or inhibit nucleus pulposus cell proliferation, the viability of cells was evaluated by the MTT assay.
RESULTS: Following treatment with LiCl, a Wnt signaling activator, there was suppression of c‐myc at both the mRNA and protein levels. In addition, when nucleus pulposus cells were treated with c‐myc, a significant increase in viability was observed. On the other hand, treatment with a c‐myc inhibitor resulted in decreased cell viability.
DISCUSSION: These results suggest that c‐myc is an important factor that promotes the proliferation of nucleus pulposus cells. These findings provide new insight into the regulation and maintenance of cell proliferation by the Wnt signaling pathway in nucleus pulposus cells.