Matrix metalloproteinases and their inhibitors in canine mammary tumors.

BACKGROUND: Malignant canine mammary tumors represent 50% of all neoplasms in female dogs. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are thought to be involved in tumor progression, and they are also associated with the reactive stroma, which provides structural and vascular support for tumor growth. RESULTS: MMP-2, MMP-9 and MT1-MMP were expressed at both the mRNA and protein levels in tumor samples. MMP-2 and MMP-9 immunohistochemical reactions were evident both in the epithelial tumor cells and in the stromal compartment to varying degrees; in particular, the intensity of the MMP-2 staining was stronger in the stromal fibroblasts close to epithelial tumor cells in simple carcinomas than in adenomas. These data were supported by gelatin-zymography; bands for the active form of MMP-2 were found in 94% of carcinoma samples, compared with 17% of benign tumor samples. The gene expression and immunohistochemical results for MT1-MMP were comparable to those for MMP-2. The immunoreactivity for MMP-13 and TIMP-2 was lower in carcinomas than in adenomas, confirming the mRNA data for MMP-13 and the other MMP inhibitors that were evaluated. The active form of MMP-9, but not the active form of MMP-2, was identified in the plasma of all of the tested dogs. CONCLUSIONS: Our findings suggest that MMP-9, MMP-2 and MT1-MMP, which are synthesized by epithelial cancer cells and cancer-associated fibroblasts, play an important role in malignant canine mammary tumors. The reduction of MMP-13 and TIMP-2 could also be a significant step in malignant transformation. MMP-2 and MT1-MMP could be further evaluated as future biomarkers for predicting the progression and prognosis of canine mammary tumors.

Overexpression of SERPIN B3 promotes epithelial proliferation and lung fibrosis in mice.

SERPIN B3/B4, members of the serpin superfamily, are fundamental for the control of proteolysis through a known inhibitory function of different proteases. Several studies have documented an important role of SERPIN B3 in the modulation of inflammation, programmed cell death and fibrosis. To confirm the role of SERPIN B3 in lung fibrosis and overall investigate its influence on epithelial dysfunction, a stratified controlled trial randomly assigning bleomycin (BLM) treatment was performed on both SERPIN B3 transgenic (TG) and wild-type (WT) mice. TG and WT animals were killed 48 h (group T48 h) and 20 days (group T20d) after BLM treatment. Lung fibrosis was assessed by histology and hydroxyproline measurement. Architectural remodeling, inflammation, epithelial apoptosis and proliferation were quantified. Moreover, the profibrogenetic cytokine transforming growth factor (TGF)-ß, cathepsin K, L and S were also investigated. No significant differences were observed between TG and WT mice of group T48 h in any parameters. In group T20d, less inflammation and a significant increase in epithelial proliferation were detected in treated TG than WT mice despite a similar apoptotic index, thus resulting in a different apoptosis/proliferation imbalance with a significant gain of epithelial proliferation. Moreover, TG mice showed higher TGF-ß expression and more extended fibrosis. General linear model analysis, applied on morphological data, showed that interaction between SERPIN B3 expression and treatment was mainly significant for fibrosis. This study provides in vivo evidence for a role of SERPIN B3 in inhibiting inflammation and favoring epithelial proliferation with increased TGF-ß secretion and thus the likelihood of consequent fibrogenesis.

Antidepressant hyperforin up-regulates VEGF in CNS tumour cells.

Vascular endothelial growth factor (VEGF) is a key player in neo-angiogenesis; it sustains the progression of solid neoplasias, brain tumours included. It has recently been demonstrated that the use of antidepressants correlates with increasing VEGF levels in the central nervous system (CNS). In order to elucidate whether the most used natural antidepressant [St. John's wort (SJW) extract] modulates VEGF expression, possible relationship between≤µM hyperforin (Hyp, the bioactive component in SJW) and VEGF in CNS tumours has been now examined in medulloblastoma and glioblastoma cells. Real-time PCR and ELISA revealed that under Hyp VEGF expression increased more than three fold in DAOY medulloblastoma cells; while, U87 glioblastoma cells - constitutively expressing high VEGF levels - showed no significant differences. Moreover, Hyp induced endothelial pro-angiogenic behaviour in a multi-parametric Matrigel colonisation assay, and down-modulation of pro-MMP-2 and pro-MMP-9 activities as measured by gelatin zymography. Should these results be confirmed in vivo for this and other types of CNS tumour, the antidepressant use of SJW extracts must be carefully re-considered, in particular for brain tumour patients.

Soluble polyphenols: synthesis and bioavailability of 3,4',5-tri(alpha-D-glucose-3-O-succinyl) resveratrol.

We report the development of a chemical modification method of general applicability to polyphenols, which increases solubility to influence absorption. Glucosyl groups were added to the resveratrol kernel via a succinate linker, yielding 3,4',5-tri-(alpha-D-glucose-3-O-succinyl) resveratrol. The construct was only slowly hydrolyzed in acid and at pH 6.8, but it was destroyed by blood esterases in less than 1h. In rats its administration resulted in a blood concentration versus time curve shifted to longer times in comparison to resveratrol, a useful modulation of pharmacokinetics. The area-under-curve parameter and the metabolite mix were similar to those of resveratrol. The method may be advantageously employed to solubilize other polyphenols and to make them more palatable.

Heterogeneity and standardization of phase II metabolism in cultured cells.

Caco-2 cells are widely used for transepithelial transport and metabolism studies. We analysed the metabolites produced from quercetin (Q) during transport of this flavonoid across Caco-2 monolayers and by plastic-adhering cells. We found that the pattern of Phase II metabolic activity varies markedly depending on the particular cell clone, age of the cell culture, and stressful treatment such as freezing/thawing. Prolonged culturing and stress cause a decrease of "detoxifying" conjugating activity. This can be re-established by growing the cells with a low concentration of the transport/metabolism substrate for a few days. We suggest this metabolism-activating procedure be used to make studies with these cells more readily comparable.

Development of mitochondria-targeted derivatives of resveratrol.

To target natural polyphenols to the subcellular site where their redox properties might be exploited at best, that is, mitochondria, we have synthesised new proof-of-principle derivatives by linking resveratrol (3,4',5-trihydroxy-trans-stilbene) to the membrane-permeable lipophilic triphenylphosphonium cation. The new compounds, (4-triphenylphosphoniumbutyl)-4'-O-resveratrol iodide and its bis-acetylated derivative, the latter intended to provide transient protection against metabolic conjugation, accumulate into energized mitochondria as expected and are cytotoxic for fast-growing but not for slower-growing cells. They provide a powerful potential tool to intervene on mitochondrial and cellular redox processes of pathophysiological relevance.