Procalcitonin NH 2 ‐terminal cleavage peptide has no mitogenic effect on normal human osteoblast‐like cells

The NH 2 ‐terminal cleavage peptide of procalcitonin (N‐proCT) recently was reported to be a bone cell mitogen (Burns DM et al., Proc Natl Acad Sci USA 86:9519–9523, 1989). We have investigated the effect of N‐proCT on the proliferation of normal human cells that have the phenotype of mature osteoblasts (hOB cells). N‐proCT treatment for 24, 48, or 96 h in concentrations from 1 nM to 1 μM did not significantly increase [ 3 H]thymidine uptake (means ranged from ‐19% to 38% of control, no significant differences) in hOB cells (6–10 cell strains per experiment) plated at four different densities. However, the hOB cells responded significantly to treatment with transforming growth factor β (3 ng/ml), bovine insulin (300 μg/ml), or 30% fetal calf serum, which were included in all experiments as positive controls. The [ 3 H]thymidine uptake data were confirmed in a direct cell count experiment tested at 96 h. Thus our data do not support the hypothesis that N‐proCT is a potent mitogen for normal human osteoblasts.