Molecular analysis of differential antiproliferative activity of resveratrol, epsilon viniferin and labruscol on melanoma cells and normal dermal cells.

Very recently, we have produced new resveratrol derived compounds, especially labruscol by culture of elicited grapevine cell suspensions (Vitis labrusca L.). This new polyphenolic oligomer could function as cancer chemopreventive agent in similar manner of resveratrol. In this study, we have determined the efficiency of resveratrol, ε-viniferin and the labruscol on human melanoma cell with or without metastatic phenotype. Our results show a differential activity of the three compounds where the resveratrol remains the polyphenolic compound with the most effective action compared to other oligomers. These three compounds block cell cycle of melanoma cells in S phase by modulating key regulators of cell cycle i.e. cyclins A, E, D1 and their cyclin-dependent kinases 1 and 2. These effects are associated with an increase of cell death while these compounds have no cytotoxic action on normal human dermal fibroblasts.

Cytotoxicity of Labruscol, a New Resveratrol Dimer Produced by Grapevine Cell Suspensions, on Human Skin Melanoma Cancer Cell Line HT-144.

A new resveratrol dimer (1) called labruscol, has been purified by centrifugal partition chromatography of a crude ethyl acetate stilbene extract obtained from elicited grapevine cell suspensions of Vitis labrusca L. cultured in a 14-liter stirred bioreactor. One dimensional (1D) and two dimensional (2D) nuclear magnetic resonance (NMR) analyses including ¹H, 13C, heteronuclear single-quantum correlation (HSQC), heteronuclear multiple bond correlation (HMBC), and correlation spectroscopy (COSY) as well as high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) were used to characterize this compound and to unambiguously identify it as a new stilbene dimer, though its relative stereochemistry remained unsolved. Labruscol was recovered as a pure compound (>93%) in sufficient amounts (41 mg) to allow assessment of its biological activity (cell viability, cell invasion and apoptotic activity) on two different cell lines, including one human skin melanoma cancer cell line HT-144 and a healthy human dermal fibroblast (HDF) line. This compound induced almost 100% of cell viability inhibition in the cancer line at a dose of 100 µM within 72 h of treatment. However, at all tested concentrations and treatment times, resveratrol displayed an inhibition of the cancer line viability higher than that of labruscol in the presence of fetal bovine serum. Both compounds also showed differential activities on healthy and cancer cell lines. Finally, labruscol at a concentration of 1.2 µM was shown to reduce cell invasion by 40%, although no similar activity was observed with resveratrol. The cytotoxic activity of this newly-identified dimer is discussed.

Anti-Cancer Activity of Resveratrol and Derivatives Produced by Grapevine Cell Suspensions in a 14 L Stirred Bioreactor.

In the present study, resveratrol and various oligomeric derivatives were obtained from a 14 L bioreactor culture of elicited grapevine cell suspensions (Vitis labrusca L.). The crude ethyl acetate stilbene extract obtained from the culture medium was fractionated by centrifugal partition chromatography (CPC) using a gradient elution method and the major stilbenes contained in the fractions were subsequently identified by using a 13C-NMR-based dereplication procedure and further 2D NMR analyses including HSQC, HMBC, and COSY. Beside δ-viniferin (2), leachianol F (4) and G (4'), four stilbenes (resveratrol (1), ε-viniferin (5), pallidol (3) and a newly characterized dimer (6)) were recovered as pure compounds in sufficient amounts to allow assessment of their biological activity on the cell growth of three different cell lines, including two human skin malignant melanoma cancer cell lines (HT-144 and SKMEL-28) and a healthy human dermal fibroblast HDF line. Among the dimers obtained in this study, the newly characterized resveratrol dimer (6) has never been described in nature and its biological potential was evaluated here for the first time. ε-viniferin as well as dimer (6) showed IC50 values on the three tested cell lines lower than the ones exerted by resveratrol and pallidol. However, activities of the first two compounds were significantly decreased in the presence of fetal bovine serum although that of resveratrol and pallidol was not. The differential tumor activity exerted by resveratrol on healthy and cancer lines was also discussed.

A role for peroxisome proliferator-activated receptor gamma in resveratrol-induced colon cancer cell apoptosis.

SCOPE: Resveratrol may function as a chemopreventive agent. A recent clinical study demonstrates a reduction in tumor cell proliferation in colorectal patients receiving repeated oral ingestion of resveratrol. However, gaps remain in our knowledge of the molecular mechanisms by which resveratrol exerts its chemopreventive effect. We have previously demonstrated that resveratrol induces apoptosis in colon cancer cells and that resveratrol can sensitize chemoresistant colon cancer cells to various drugs. Based on its ability to activate peroxisome proliferator-activated receptor gamma (PPARγ) in colon cancer cells, we sought to determine the implication of this nuclear transcription factor in resveratrol-induced apoptosis. METHODS AND RESULTS: Transient transfection of cancer cells with a dominant-negative PPARγ mutant or treatment with a PPARγ antagonist (GW9662) reversed the inhibitory effect of resveratrol. Moreover, GW9662 prevented disruption of the cell cycle induced by resveratrol and consequently abrogated resveratrol-induced apoptosis. Tumor cell death was potentiated by combining resveratrol with rosiglitazone, a PPARγ agonist. CONCLUSION: The results show that PPARγ plays a role in resveratrol-induced apoptosis of colon carcinoma cells. The combination of resveratrol with a PPARγ agonist could be a promising pharmacological approach for treatment of colorectal cancer.

Elastin-derived peptides are new regulators of insulin resistance development in mice.

Although it has long been established that the extracellular matrix acts as a mechanical support, its degradation products, which mainly accumulate during aging, have also been demonstrated to play an important role in cell physiology and the development of cardiovascular and metabolic diseases. In the current study, we show that elastin-derived peptides (EDPs) may be involved in the development of insulin resistance (IRES) in mice. In chow-fed mice, acute or chronic intravenous injections of EDPs induced hyperglycemic effects associated with glucose uptake reduction and IRES in skeletal muscle, liver, and adipose tissue. Based on in vivo, in vitro, and in silico approaches, we propose that this IRES is due to interaction between the insulin receptor (IR) and the neuraminidase-1 subunit of the elastin receptor complex triggered by EDPs. This interplay was correlated with decreased sialic acid levels on the ß-chain of the IR and reduction of IR signaling. In conclusion, this is the first study to demonstrate that EDPs, which mainly accumulate with aging, may be involved in the insidious development of IRES.

A novel copper(II) mononuclear complex with the non-steroidal anti-inflammatory drug diclofenac: structural characterization and biological activity.

A copper(II) complex with the non-steroidal anti-inflammatory drug (NSAID) diclofenac has been for the first time synthesized and characterized without any co-organic ligand. Its biological activity against four human cell lines underlined a higher activity of the monomeric complex than the parent molecule in the case of tumoral cell lines. A ternary Cu-diclofenac-albumin complex was suspected to be the reactive species in biological medium.

In vitro and in vivo anti-tumoral effect of curcumin against melanoma cells.

Curcumin, the active ingredient from the spice turmeric (Curcuma longa Linn), is known to be an anti-oxidant and an anti-inflammatory agent. It has been demonstrated recently to possess anti-angiogenic effects and pro-apoptotic activities against Ehrlich ascites tumor cells. In the current study, curcumin was found to be cytotoxic in vitro for B16-R melanoma cells resistant to doxorubicin either cultivated as monolayers or grown in three-dimensional (3-D) cultures (spheroids). We have demonstrated that the cytotoxic effect observed in the 2 culture types can be related to the induction of programmed cell death. In our in vivo studies, we examined the effectiveness of a prophylactic immune preparation of soluble proteins from B16-R cells, or a treatment with curcumin as soon as tumoral appearance, alone or in combination, on the murine melanoma B16-R. The combination treatment resulted in substantial inhibition of growth of B16-R melanoma, whereas each treatment by itself showed little effect. Moreover, animals receiving the combination therapy exhibited an enhancement of their humoral anti-soluble B16-R protein immune response and a significant increase in their median survival time (> 82.8% vs. 48.6% and 45.7% respectively for the immunized group and the curcumin-treated group). Our study shows that curcumin may provide a valuable tool for the development of a therapeutic combination against the melanoma.

Three-dimensional culture and multidrug resistance: effects on immune reactivity of MCF-7 cells by monocytes.

BACKGROUND: Multicellular spheroids are known to be the most adapted model to keep the in vitro resistance properties of cells. This in vivo-like tissue-culture representation was applied to investigate the immune reactivity of MCF-7 cells by monocytes. MATERIALS AND METHODS: Human blood monocytes, obtained by elutriation, were co-cultured with multicellular tumor spheroids of drug-sensitive (MCF-7S) and doxorubicin-resistant (MCF-7DXR) MCF-7 breast cancer cells. RESULTS: Tumor cells, according to their phenotype, induced differential recruitment and behavior of the immune cells towards the two types of spheroids. The secretion of various cytokines and the expression of several adhesion molecules were analysed. The MCF-7DXR/monocytes co-culture supernatant showed higher levels of IL-6 and IL-8 than the MCF-7S/monocytes co-culture supernatant. Cells from the MCF-7DXR spheroids expressed some adhesion molecules, CD-44 and CD-54, leading to a strong cellular cohesion in comparison with the sensitive spheroids. CONCLUSION: The two spheroid phenotypes represented an excellent model system for determining the precise tumor microenvironment in which cells move, the crucial molecular requirements and the mechanisms by which immunotherapeutic strategies could be developed to eradicate chemo-resistant tumors.

Conversion of a postocellar into an ocellar region as a transdetermination event occurring in adult ribbonworms.

Transections and grafting experiments performed in Lineus ruber rostral ends allowed us to generate ribbonworms with a duplication of the postocellar region combined with a deletion of the ocellar region. In such homeotically reconstructed animals, the syngeneic postocellar region transdifferentiated into an ocellar region with functional eyes while the allogeneic postocellar region underwent no transformation. In this case, transdifferentiation is a morphogenetic process leading to the restoration of the normal antero-posterior (A-P) axis pattern in adult worms. This regulative conversion of one adult body region into another, which so far has not been described in any bilaterian animal, is comparable with transdetermination of larval imaginal discs in Drosophila. Under certain conditions, Drosophila, wing imaginal disc cells express the eyeless master control gene and give rise to eyes. Here, we show in Lineus that the transposition of postocellar tissue into the ocellar location causes expression of the eyeless ortholog LsPax-6 and results in eye development. Our results in Lineus clearly suggest that transdifferentiation of adult body regions moved to a different position along the A-P axis is similar to transdetermination of the larval imaginal disc cells which are determined, but not yet differentiated.