Partial rescue of geldanamycin-induced TrkA depletion by a proteasome inhibitor in PC12 cells

Influence of TEGDMA monomer on MMP-2, MMP-8, and MMP-9 production and collagenase activity in pulp cells

Objectives

Resin-based composites may leach monomers such as triethylene-glycol dimethacrylate (TEGDMA), which could contribute to intrapulpal inflammation. The aim of this investigation was to examine whether various concentrations of TEGDMA are able to influence dentally relevant Matrix metalloproteinase (MMP)-2, MMP-8, and MMP-9 production, total collagenase/gelatinase activity in pulp cells, and suggest possible signaling mechanisms.

Materials and methods

Pulp cells were cultured, followed by a 1-day exposure to sublethal TEGDMA concentrations (0.1, 0.2, and 0.75 mM). Total MMP activity was measured by an EnzCheck total collagenase/gelatinase assay, while the production of specific MMPs and the relative changes of phosphorylated, i.e., activated signaling protein levels of extracellular signal-regulated kinase (ERK)1/2, p38, c-Jun N-terminal kinase (JNK) were identified by western blot. Immunocytochemistry image data was also plotted and analyzed to see whether TEGDMA could possibly alter MMP production.

Results

An increase in activated MMP-2, MMP-8, and MMP-9 production as well as total collagenase activity was seen after a 24-h exposure to the abovementioned TEGDMA concentrations. Increase was most substantial at 0.1 (P = 0.002) and 0.2 mM (P = 0.0381). Concurrent p-ERK, p-p38, and p-JNK elevations were also detected.

Conclusions

Results suggest that monomers such as TEGDMA, leached from resin-based restorative materials, activate and induce the production of dentally relevant MMPs in pulp cells. Activation of ERK1/2, p38, or JNK and MMP increase may play a role in and/or can be part of a broader stress response.

Clinical relevance

Induction of MMP production and activity may further be components in the mechanisms of intrapulpal monomer toxicity.

Effects of geldanamycin on neurite outgrowth-related proteins and kinases in nerve growth factor-differentiated pheochromocytoma 12 cells

Heat shock protein 90 (HSP90) antagonists are currently being evaluated as potential anticancer drugs. However, adverse effects related to these drugs, such as fatigue and pain, suggest that they affect neurons. Therefore, to understand the influence of HSP90 inhibitors on neurons, we investigated the effects of geldanamycin, an HSP90 antagonist, on nerve growth factor (NGF)-differentiated pheochromocytoma 12 (PC12) cells, particularly, on the expression and phosphorylation of proteins and kinases in the NGF pathway. Geldanamycin significantly inhibited NGF-induced neurite outgrowth and phosphorylation of Akt and extracellular signal-related kinase 1/2 in PC12 cells. Furthermore, geldanamycin inhibited the phosphorylation of collapsin response mediator protein 2 and the expression of cyclin-dependent kinase 5 in the presence of NGF, but did not significantly affect the expression of glycogen synthase kinase 3β. These results suggest that geldanamycin influences microtubule-binding proteins and kinases relating to neurite outgrowth, thereby inducing neuronal impairment.