Activation of NF‐κB in human osteoblasts by stimulators of bone resorption

Abstract
Several bone resorptive stimuli affect osteoclasts indirectly by modulating the production and release of osteoblastic factors. Using electrophoretic mobility shift assays, we found that not only tumour necrosis factor‐α (TNF‐α) but also interleukin‐1β and parathyroid hormone (PTH) caused dose and time‐related increases in nuclear factor κB (NF‐κB)‐DNA binding in Saos‐2 human osteoblastic (hOB) cells. Activation of NF‐κB by TNF‐α was reproduced in primary hOBs. In contrast, consistent with their previously reported lack of response to steroid hormones, Saos‐2 cells did not respond to 1,25‐dihydroxyvitamin D3. We suggest that NF‐κB activation in osteoblastic cells constitutes an important pathway in osteoblast‐mediated resorptive signalling.