We previously reported that matrix metalloproteinase-3(MMP-3) accelerates wound healing following dental pulp injury. In this study, we tested the hypothesis that induction of MMP-3 activity by interleukin-1βwould promote proliferation and apoptosis of dental pulp cells.MATERIALS AND METHODS:
Dental pulp cells were isolated from rat incisors and subjected to interleukin-1β. Matrix metalloproteinase-3 mRNA and protein expression were assessed using reverse transcription–polymerase chain reaction and Western blotting, respectively. Matrix metalloproteinase-3 activity was measured using fluorescence. Dental pulp cell proliferation and apoptosis were determined using enzyme-linked immunosorbent assays (ELISA) for BrdU and DNA fragmentation, respectively. siRNA was used to reduce MMP-3 transcripts in these cells.RESULTS:
Treatment with interleukin-1βincreased MMP-3 mRNA and protein levels as well as its activity in dental pulp cells. Cell proliferation was also markedly increased, with no changes in apoptosis observed. Treatment with siRNA against MMP-3 potently suppressed this interleukin-1β-induced increase in MMP-3 expression and activity, and also suppressed cell proliferation but unexpectedly increased apoptosis in these cells (P< 0.05). This siRNA-mediated increase in apoptosis could be reversed with exogenous MMP-3 stimulation (P< 0.05).CONCLUSIONS:
Interleukin-1βinduces MMP-3-regulated cell proliferation and suppresses apoptosis in dental pulp cells.