PARATHYROID-HORMONE STIMULATES HYALURONAN SYNTHESIS IN AN OSTEOBLAST-LIKE CELL-LINE

An osteoblast-like cell line (UMR 106-01 BSP), cloned from a transplan table osteosarcoma, was cultured in the presence of parathyroid hormon e (PTH1-34) and metabolically labeled with [S-35]sulfate, [H-3]glucosa mine, and [H-3]tyrosine to determine proteoglycan, glycoconjugate, and protein synthesis, respectively. The synthesis of secreted proteins w as substantially increased by PTH treatment. However, the synthesis of bone sialoprotein and proteoglycans was, at best, only moderately sti mulated by PTH. Hyaluronan (HA) synthesis was dramatically stimulated by PTH in this cell line. A 5-6-fold increase in HA production was obs erved using 10(-8) M PTH, and even a 50% increase was detected using 1 0(-10) M PTH. The PTH-induced stimulation of HA synthesis was rapid an d transient, reaching a maximum level (similar to 560 pmol of HA disac charide equivalents/h/10(6) cells at 10(-8) M PTH) by 4-7 h after horm one exposure and returning to control levels by 12-15 h after the init ial treatment. Lastly, the majority of this HA synthesis stimulated by PTH required only a short exposure (<90 min) to the hormone. These da ta suggest (i) that normal osteoblasts (or a sub-population of preoste oblasts) probably synthesize HA in response to PTH treatment, and (ii) that this PTH-induced synthesis of HA most likely involves some signa l transduction mechanism(s).