Neuromedin B stimulates proliferation of mouse chondrogenic cell line ATDC5

Neuromedin B (NMB), which was originally isolated from porcine spinal cord, is a mammalian bombesin-related peptide that exerts various physiological effects. Previously, we observed expression of NMB in rib cartilage from chicken. Here, we report the initial attempt to elucidate the role of NMB in cartilage. We used RT-PCR to measure the expression of NMB and its receptor (NMB-R) in mouse chondrogenic cell line ATDC5. During chondrogenic differentiation of ATDC5 cells, NMB mRNA transiently increased on day 4 and then decreased on day 14, whereas NMB-R mRNA decreased on days 7 and 14. We also characterized immunoreactive NMB in ATDC5 culture medium using a combination of specific radioimmunoassay (RIA) and reverse phase-high performance liquid chromatography (RP-HPLC). Furthermore, using the WST-8 assay, we demonstrated that NMB significantly induced ATDC5 proliferation; this was inhibited by NMB-R antagonist, BIM 23127. These results implicate that NMB is involved in cartilage development, either in an autocrine or paracrine manner.