No abstract

The recombinant Chlorobium tepidum ferritin (rCtFtn) is able to oxidize iron using ferroxidase activity but its ferroxidase activity is intermediate between the H-chain human ferritin and the L-chain human ferritin. The rCtFtn has an unusual C-terminal region composed of 12 histidine residues, as well as aspartate and glutamate residues. These residues act as potential metal ion ligands, and the rCtFtn homology model predicts that this region projects inside the protein cage. The rCtFtn also lacks a conserved Tyr residue in position 19. In order to know if those differences are responsible for the altered ferroxidase properties of rCtFtn, we introduced by site-directed mutagenesis a stop codon at position 166 and a Tyr residue replaced Ala19 in the gene of rCtFtn (rCtFtn 166). The rCtFtn166 keeps the canonical sequence considered important for the activity of this family of proteins. Therefore, we expected that rCtFtn 166 would possess similar properties to those described for this protein family. The rCtFtn 166 is able to bind, oxidize and store iron; and its activity is inhibit by Zn(II) as was described for other ferritins. However, the rCtFtn 166 possesses a decrease ferroxidase activity and protein stability compared with the wild type rCtFtn. The analysis of the Ala19Tyr rCtFtn shows that this change does not affect the kinetic of iron oxidation. Therefore, these results indicate that the C-terminal regions have an important role in the activity of the ferroxidase center and the stability of rCtFtn.

Purpose One strategy for treating cancer is to prevent metastatic spread. Matrix metalloproteinase are considered potential targets for cancer therapy because of their role in degrading the extracellular matrix and fostering tumor progression. In some cancer models, the small molecule 1,2,3,4,6-Penta-O-galloyl-β-d-glucose (PGG) exhibited inhibitory properties against matrix metalloproteinase (MMP) related metastatic activity. This study explored whether PPG may limit the potential for metastatic spread in oral squamous cell carcinoma. Materials and methods This study used Cal-27 cells, a cell line derived from a squamous cell carcinoma line of human tongue origin, and antibodies for MMP-1,-2,-3,-9,-13, MT1-MMP signal transducers and activators of transcription 3 (Stat3), and pStat3. Cells were treated with PGG at different concentrations to evaluate MMP and Stat3 activation. Expansion assays were performed using Matrigel matrixes to measure Cal-27 invasiveness in the presence of PGG. Results PGG decreased the expression of MMP-2,-9 and-13 in the Cal-27 cell line, decreased phosphorylation of Stat3 and reduced gene expression of MMP-2,-9 and-13. As observed in Matrigel expansion assays, PGG limited the invasiveness of Cal-27 cells in a dose-dependent manner. Conclusion PPG is a small molecule inhibitor with the potential to reduce the expression of the matrix metalloproteinases and to limit the invasiveness of the squamous cell carcinoma line, Cal-27. By controlling the expression of molecules responsible for metastasis, PPG may offer a new therapeutic option for treating oral squamous cell carcinoma.

No abstract