Porf-2 Inhibits Tumor Cell Migration Through the MMP-2/9 Signaling Pathway in Neuroblastoma and Glioma

Tumor migration and invasion are key pathological processes that contribute to cell metastasis as well as treatment failure in patients with malignant tumors. However, the mechanisms governing tumor cell migration remain poorly understood. By analyzing the tumor-related database and tumor cell lines, we found that preoptic regulatory factor-2 (Porf-2) is downexpressed in both neuroblastoma and glioma. Using in vitro assays, our data demonstrated that the expression of Porf-2 inhibits tumor cell migration both in neuroblastoma and glioma cell lines. Domain-mutated Porf-2 plasmids were then constructed, and it was found that the GAP domain, which plays a role in the inactivation of Rac1, is the functional domain for inhibiting tumor cell migration. Furthermore, by screening potential downstream effectors, we found that Porf-2 can reduce MMP-2 and MMP-9 expression. Overexpression of MMP-2 blocked the inhibitory effect of Porf-2 in tumor cell migration both in vitro and in vivo. Taken together, we show for the first time that Porf-2 is capable of suppressing tumor cell migration via its GAP domain and the downregulation of MMP-2/9, suggesting that targeting Porf-2 could be a promising therapeutic strategy for nervous system tumors.

[Dentin barrier cytotoxicity test with three-dimensional cell cultures]

OBJECTIVE

To evaluate the cytotoxicity of four dentin filling materials and two dentin adhesives with a dentin barrier test and to compare the results with those in a conventional filter diffusion test in order to investigate the advantages of the dentin barrier test.

METHODS

Eugenol cement, zinc phosphate cement, adhesive glass ionomer cement, composite resin and two self-etching adhesives (REMI BOND and Adper Easy One) were tested. In the dentin barrier test, L929 mouse fibroblasts were three-dimensional cultured in polystyrene meshes. The dentin disks were cut from the human third molars, near the pulp and in parallel with the occlusal surface, and their permeability within the measurement area was evaluated by a hydraulic permeability device. A mesh with the cells was placed in the "pulp cavity" of the chamber and one dentin disk was put on the cell mesh and its "pulp side" was in contact with the mesh. The test materials and controls were in contact with the "occlusal side" of the dentine disks for 24 h. The cell viability was obtained with MTT assay and the results were expressed as a percentage of control tissues. The Mann-Whitney U test was used to make the statistical analyses. In the filter diffusion test, after a 24 h contact between the test materials and the filters with monolayer cells, the filters were dyed and the grades of cytotoxicity were decided.

RESULTS

A mean permeability of the dentin disks near the pulp was 0.293 μL/(min×cm(2)×cmH(2)O)(1 cmH(2)O=0.098 kPa); In the dentin barrier test, Eugenol cement, REMI BOND and Adper Easy One respectively reduced the cell survival rates to 82%, 63% and 54%. Other materials showed no or very low toxic reactions; In the filter diffusion test, the light-curing composite resin was moderately cytotoxic, the dental adhesive glass ionomer cement was mildly cytotoxic and the others were severely cytotoxic; All the six materials in the dentin barrier test had lower cytotoxicity than in the filter diffusion test.

CONCLUSION

The cytotoxicity of the test materials using the dentin barrier test with three-dimensional cell cultures is lower than that in the filter diffusion test, which has good correlation with the clinical situation.