An oxalate-bridged oxidovanadium(iv) binuclear complex that improves the in vitro cell uptake of a fluorescent glucose analog

The centrosymmetric oxidovanadium(IV) complex (Et 3NH) 2[{VO(OH 2)(ox)} 2(μ–ox)] (I), where ox 2− = oxalate, was synthesized and characterized by X-ray diffraction (single-crystal and powder, PXRD), thermogravimetric (TGA), magnetic susceptibility (at room temperature) and spectroscopic analyses (infrared, Raman and electron paramagnetic resonance, EPR, spectroscopies). In the solid state, each vanadium center is coordinated by the oxygen atoms of a bis-bidentate oxalate bridging ligand, a terminal oxalate, an oxo group and one water molecule. The electronic structure of the binuclear complex was investigated by density functional theory (DFT) calculations, both in vacuum and in a simulated aqueous environment, employing the ωB97XD functional and the def2TZVP basis set. The cytotoxicity of I was evaluated in vitro in the human hepatocellular carcinoma cell line HepG2, giving an IC 50 value of 15.67 µmol L −1 after incubation for 24 h. The EPR analysis of I in aqueous solution suggested the maintenance of the binuclear structure, while in the hyperglycemic medium DMEM the complex suffers dissociation to give a mononuclear oxidovanadium(IV) species. HepG2 cell treatment with 0.10 and 0.50 µmol L −1 of I in DMEM increased 2-NBDG (2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose) uptake significantly (up to 91% as compared to HepG2 in hyperglycemic condition, 59%). These results indicate a promising activity of I to be investigated further in additional antidiabetic studies

Fibronectin affects transient MMP2 gene expression through DNA demethylation changes in non-invasive breast cancer cell lines.

Metastasis accounts for more than 90% of cancer deaths. Cells from primary solid tumors may invade adjacent tissues and migrate to distant sites where they establish new colonies. The tumor microenvironment is now recognized as an important participant in the signaling that induces cancer cell migration. An essential process for metastasis is extracellular matrix (ECM) degradation by metalloproteases (MMPs), which allows tumor cells to invade local tissues and to reach blood vessels. The members of this protein family include gelatinase A, or MMP-2, which is responsible for the degradation of type IV collagen, the most abundant component of the basal membrane, that separates epithelial cells in the stroma. It is known that fibronectin is capable of promoting the expression of MMP-2 in MCF7 breast cancer cells in culture. In addition, it was already shown that the MMP2 gene expression is regulated by epigenetic mechanisms. In this work, we showed that fibronectin was able to induce MMP2 expression by 30% decrease in its promoter methylation. In addition, a histone marker for an open chromatin conformation was significantly increased. These results indicate a new role for fibronectin in the communication between cancer cells and the ECM, promoting epigenetic modifications

Wound healing assay in MCF7 cells.

<p>A<b>:</b> Representative images from mock and FN-treated cells were shown. The scratched cells in a line had images obtained under un inverted optical microscopy (20X). B<b>:</b> The graphic represents % of wound-closure after 60 h in culture. Statistical comparison was performed using Student’s <i>t</i> Test. *<i>p</i><0.05.</p

<i>MMP2</i> expression after treatment in breast cancer cell lines.

<p>A: The expression of <i>MMP2</i> after treatments in MCF7 cells was shown. Mock (blue); 5-Aza-treated (white), FN-treated (red) and recultured (green). Results were expressed as mean S.E.M. and statistical comparison was performed using <i>t test</i> analysis. *<i>p</i><0.05 when compared to mock; #<i>p</i><0.05 when FN-treated compared to recultured. B: The expression of <i>MMP2</i> in MDA-MB-436 cells, mock and after FN treatment were shown. Mock (blue) and FN-treated (orange) were expressed as mean S.E.M. and statistical comparison was performed using Student’s <i>t</i> Test. **<i>p</i><0.05 when compared to mock.</p

Epigenetic changes in the <i>MMP2</i> gene promoter in MCF7 cells.

<p>A: Sequencing of the <i>MMP2</i> gene promoter. Closed and open circles represent methylated or unmethylated CpGs, respectively. On the left the number represent the sequenced clones. The 49 analyzed CpGs in the <i>MMP2</i> promoter region are shown. Mock cells are at the top, above is 5-Aza-treated, hereafter FN-treated, recultured (MCF7 FN-treated and then cultured for 48 hours without fibronectin). The global methylation percentage is also shown at the right. B: Graphical analysis of CpG methylation pattern in the <i>MMP2</i> promoter gene. The percentages of CpGs that were methylated in MCF7 mock (blue), MCF7 FN-treated (red) and MCF7 recultured (green) were shown. C: ChIP quantitative PCR analysis. Ct values were normalized between target and endogenous control (<i>MMP2</i>/<i>GAPDH</i>) and the results of mock (blue), FN-treated (red) and recultured (green) cells are shown. At the bottom the samples are separated according to the antibody used in the immunoprecipitation. Statistical comparison was performed using Student’s <i>t</i> Test. *<i>p</i><0.05.</p