Antiproliferative and antibiofilm potentials of endolichenic fungi associated with the lichen Nephroma laevigatum.

AIMS: The objective of this study was to explore the diversity of endolichenic fungi from Nephroma laevigatum and to investigate their antiproliferative and antibiofilm potential. METHODS AND RESULTS: Forty-six isolates were obtained and identified by DNA barcoding. They belonged to genera Nemania, Daldinia, Peziza and Coniochaeta. Six strains belonging to the most represented species were selected and tested for their antiproliferative and antibiofilm activities. Extracts were analysed by reversed-phase HPLC. Activities against fungal and bacterial biofilm were evaluated using tetrazolium salt (XTT) assay and crystal violet assay respectively. Antiproliferative responses of extracts were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis induction by two extracts was observed in two cell lines (HT-29 and PC-3) via morphological changes, pro-apoptotic and anti-apoptotic proteins analysis (Western blotting) and DNA fragmentation. Four extracts displayed activities against Candida albicans biofilm with IC50 values ranging from 25 to 200 µg ml-1 . All extracts were inactive against Staphylococcus aureus and Pseudomonas aeruginosa biofilms. The most active isolates against human colorectal (HT-29 and HCT116) and prostate (PC-3 and DU145) cancer cell lines were Nemania serpens (NL08) and Nemania aenea var. aureolatum (NL38) with IC50 values ranging from 13 to 39 µg ml-1 . These extracts induced an apoptotic process through activation of caspases 8 and 3, poly(ADP-ribose) polymerase cleavage and DNA fragmentation. CONCLUSIONS: Selected crude fungal extracts have antiproliferative and antibiofilm activities. Data suggest that this antipoliferative effect is due to apoptosis process. This is the first report showing the effects of endolichenic fungi from N. laevigatum. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlights the therapeutic potential of endolichenic fungi metabolites as sources for drug discovery programmes.

Impact of new cyclooxygenase 2 inhibitors on human cytomegalovirus replication in vitro.

BACKGROUND: Human cytomegalovirus (HCMV) is involved in complications on immunocompromised patients. Current therapeutics are associated with several drawbacks, such as nephrotoxicity. PURPOSE: As HCMV infection affects inflammation pathways, especially prostaglandin E2 (PGE2) production via cyclooxygenase 2 enzyme (COX-2), we designed 2'-hydroxychalcone compounds to inhibit human cytomegalovirus. STUDY DESIGN: We first selected the most efficient new synthetic chalcones for their effect against COX-2-catalyzed PGE2. STUDY SAMPLE: Among the selected compounds, we assessed the antiviral efficacy against different HCMV strains, such as the laboratory strain AD169 and clinical strains (naïve or multi-resistant to conventional drugs) and toxicity on human cells. RESULTS: The most efficient and less toxic compound (chalcone 7) was tested against HCMV in combination with other antiviral molecules: artesunate (ART), baicalein (BAI), maribavir (MBV), ganciclovir (GCV), and quercetin (QUER) using Compusyn software. Association of chalcone 7 with MBV and BAI is synergistic, antagonistic with QUER, and additive with GCV and ART. CONCLUSION: These results provide a promising search path for potential bitherapies against HCMV.

Roots of Daphne gnidium L. inhibit cell proliferation and induce apoptosis in the human breast cancer cell line MCF-7.

Daphne gnidium L. is a well-known Moroccan plant with cancer-related ethnobotanical use. In order to systematically evaluate its potential activity in breast cancer, four extracts from this plant of different polarity were tested for their antiproliferative effects on MCF-7 cells. The second aspect of this study related to understanding the nature and mechanism of the antiproliferative effect. Results from a viability assay showed the potent antiproliferative capacity of the hexane (IC(50)-48 h: 630 +/- 16 microg/ml), dichloromethane (IC(50)-48 h: 112 +/- 7 microg/ml) and ethyl acetate extracts (IC(50)-48 h: 263 +/- 9 microg/ml). On the other hand the methanol extract was inactive. LDH test revealed the cytotoxicity of the hexane extract as opposed to two others. The characterization of the ethyl acetate extract showed its dose-dependent pro-apoptotic effect. Surprisingly, we observed that activation of the inducible cyclooxygenase-2 followed the kinetics of apoptosis development. On the other hand, the dichloromethane extract showed a distinct effect on COX-2 activity as a function of the used dose. A low dose seemed to inhibit COX-2 activity whereas a high dose seemed to increase it. These findings suggest that Daphne gnidium L. might be of potential chemopreventive interest. Other studies are in hand to isolate the active agents responsible for the antiproliferative effect.

Increased cyclooxygenase-2 and thromboxane synthase expression is implicated in diosgenin-induced megakaryocytic differentiation in human erythroleukemia cells.

Differentiation induction as a therapeutic strategy has, so far, the greatest impact in hematopoietic malignancies, most notably leukemia. Diosgenin is a very interesting natural product because, depending on the specific dose used, its biological effect is very different in HEL (human erythroleukemia) cells. For example, at 10 microM, diosgenin induced megakaryocytic differentiation, in contrast to 40 microM diosgenin, which induced apoptosis in HEL cells previously demonstrated using sedimentation field-flow fractionation (SdFFF). The goal of this work focused on the correlation between cyclooxygenase-2 (COX-2) and thromboxane synthase (TxS) and megakaryocytic differentiation induced by diosgenin in HEL cells. Furthermore, the technique of SdFFF, having been validated in our models, was used in this new study as an analytical tool that provided us with more or less enriched differentiated cell fractions that could then be used for further analyses of enzyme protein expression and activity for the first time. In our study, we showed the implication of COX-2 and TxS in diosgenin-induced megakaryocytic differentiation in HEL cells. Furthermore, we showed that the analytical technique of SdFFF may be used as a tool to confirm our results as a function of the degree of cell differentiation.

Study of diosgenin-induced apoptosis kinetics in K562 cells by Sedimentation Field Flow Fractionation.

Recently, the use of SdFFF in cancer research has been studied in order to better understand major phenomena implicated in cancer development and therapy: apoptosis and differentiation. In this report, we used SdFFF as a monitoring and cell separation tool to study the kinetics of apoptosis. Incubation of K562 cells with diosgenin, used as cellular model, led to a surprising apoptotic process occurring in two phases (after 24 and 48 h incubation), associated with specific p-ERK expression. Based on the capacity to sort apoptotic cells, results showed that SdFFF cell separation was an effective analytical tool to obtain different subpopulations regardless of the kinetics and extent of apoptosis. Results also showed that, after proper biological calibration of elution profiles, SdFFF can be used to monitor either the induction or the kinetics of a biological event.

Sedimentation field flow fractionation to study human erythroleukemia cell megakaryocytic differentiation after short period diosgenin induction.

Anti-cancer differentiation therapy could be one strategy to stop cancer cell proliferation. We propose a new sedimentation field flow fractionation (SdFFF) cell separation application in the field of cancer research. It concerns the study of megakaryocytic differentiation processes after a short exposure to an inducting agent (diosgenin). Washout process and early dual SdFFF separation--removing the influence of diosgenin and decreasing the influence of undifferentiated cells--resulted in the preparation of an enriched population to study the mechanism and kinetics of megakaryocytic differentiation. A short exposure to diosgenin was able to induce complete differentiation leading to maximal maturation which ended naturally after 192h incubation without the influence of a secondary effect of diosgenin. The study of isolated undifferentiated cells also showed that no resistance to diosgenin was observed. This result suggested different sensitivities to differentiation induction, and SdFFF cell separation would be of great interest to explore this phenomena.

Pre-apoptotic sub-population cell sorting from diosgenin apoptosis induced 1547 cells by Sedimentation Field-Flow Fractionation. The effect of channel thickness on sorting performance.

Apoptosis is one of the most important phenomena in cell biology. Pre-apoptotic cells, defined as cells engaged in early stages of apoptosis, could be used as a cellular tool to study apoptosis pathways. The human 1547 osteosarcoma cell line and diosgenin (a plant steroid) association was selected as an in vitro cellular apoptosis model. In a previous study, using this model, we demonstrated that SdFFF monitored apoptosis induction as early as 6h after incubation. In this study, we investigated the capacity of Sedimentation Field-Flow Fractionation (SdFFF) to sort an enriched population of pre-apoptotic cells from 1547 cells incubated for 6 h with 40 microM diosgenin. In that way, two different separation devices which differed especially in channel thickness, 125 and 175 microm, were used and compared. Results showed, for the first time, that SdFFF is an effective method to obtain an enriched pre-apoptotic sub-population. These results suggest, as a new application, that SdFFF could be an included tool in the study of apoptotic mechanisms or the kinetic action of apoptotic drugs.

Expression of arachidonate platelet-type 12-lipoxygenase in human rheumatoid arthritis type B synoviocytes.

In the present study, we have demonstrated platelet-type 12-lipoxygenase (12-LOX) expression in human rheumatoid arthritis (RA) type B synoviocytes by reverse-transcription polymerase chain reaction (RT-PCR). The presence of 12-LOX mRNA in these cells was revealed by classical RT-PCR analysis using platelet-type 12-LOX cDNA primers and the PCR fragment (246 bp) was purified, amplified and sequenced. By sequence analysis, this fragment was determined to be 100% identical to that from platelet-type 12-LOX cDNA. Immunofluorescence data demonstrate that interleukin-1beta (IL-1beta) increases cellular 12-LOX protein. Other results associate specific inflammatory cytokines with the activity of 12-LOX in human RA type B synoviocytes. IL-1beta increased 12S-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) production (4-fold) and we also observed an increase in 12-HETE production (2.5-fold) after incubation of human RA type B synoviocytes with TNF alpha. In contrast to the action of IL-1beta on 12-HETE synthesis, IL-4 and IL-6 did not enhance 12-HETE production. This is the first demonstration of platelet-type 12-LOX cDNA derived from the mRNA of cultured human RA type B synoviocytes.

A plant steroid, diosgenin, induces apoptosis, cell cycle arrest and COX activity in osteosarcoma cells.

Cyclooxygenases (COXs) are key enzymes in the conversion of arachidonic acid into prostanoids which are involved in apoptosis and inflammation. Two distinct COXs have been identified: COX-1 which is constitutively expressed and COX-2 which is induced by different products such as tumor promoters or growth factors. Previously, we demonstrated that a plant steroid, diosgenin, was a new megakaryocytic differentiation inducer of human erythroleukemia cells. In our study, we investigated the effect of diosgenin on the proliferation rate, cell cycle distribution and apoptosis in the human osteosarcoma 1547 cell line. The effects of this compound were also tested on COX expression and COX activities. Diosgenin treatment caused an inhibition of 1547 cell growth with a cycle arrest in G1 phase and apoptosis induction. Moreover, we found a correlation between p53, p21 mRNA expression and nuclear factor-kappaB activation and we observed a time-dependent increase in PGE2 synthesis after diosgenin treatment.

15-Deoxy-delta12,14-PGJ2, but not troglitazone, modulates IL-1beta effects in human chondrocytes by inhibiting NF-kappaB and AP-1 activation pathways.

The activation of peroxisome proliferator-activated receptor gamma (PPARgamma) has been shown to inhibit the production and the effects of proinflammatory cytokines. Since interleukin-1beta (IL-1beta) directly mediates cartilage degradation in osteoarthritis, we investigated the capability of PPARgamma ligands to modulate IL-1beta effects on human chondrocytes. RT-PCR and Western blot analysis revealed that PPARgamma expression was decreased by IL-1beta. 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2), in contrast to troglitazone, was highly potent to counteract IL-1beta-induced cyclooxygenase-2 and inductible nitric oxide synthase expression, NO production and the decrease in proteoglycan synthesis. Western blot and gel-shift analyses demonstrated that 15d-PGJ2 inhibited NF-kappaB activation, while troglitazone was ineffective. Although 15d-PGJ2 attenuated activator protein-1 binding on the DNA, it potentiated c-jun migration in the nucleus. The absence or the low effect of troglitazone suggests that 15d-PGJ2 action in human chondrocytes is mainly PPARgamma-independent.

Changes in lipoxygenase activities in human erythroleukemia (HEL) cells during diosgenin-induced differentiation.

A human erythroleukemia (HEL) cell line was used as a model to study dynamic changes in human 12-, 15-, 5-lipoxygenases, five lipoxygenase activating protein (FLAP), and leukotriene A4 (LTA4) hydrolase gene expression during megakaryocytic differentiation induced by diosgenin (Beneytout, J.L., Nappez, C., Leboutet, M.J. and Malinvaud, G., Biochem. Biophys. Res. Commun., 207 (1995) 398-404). The study was performed at the transcriptional level: 12- and 5-lipoxygenase mRNAs, FLAP mRNA and LTA4 hydrolase mRNA were detected before and after diosgenin treatment in HEL cells while 15-lipoxygenase mRNA was undetected. When HEL cells were incubated with arachidonic acid, 5-, 12-, 15-hydroxyeicosatetraenoic acids (HETE) and LTC4 were synthesized. In contrast, the diosgenin treatment induced the suppression of 12-lipoxygenase activity and only 5-, 15-HETEs and LTC4 were synthesized.

Dose-dependent modulation of apoptosis and cyclooxygenase-2 expression in human 1547 osteosarcoma cells by NS-398, a selective cyclooxygenase-2 inhibitor.

A selective cyclooxygenase-2 (COX-2) inhibitor, NS-398, was shown to produce an anti-proliferative and pro-apoptotic effect on different types of cell lines. We describe the presence of COX-1 and COX-2 pathways in the human osteosarcoma 1547 cell line, as well as the conflicting effects of NS-398 (10, 50 and 100 microM) on programmed cell death, PGE2 release and COX-2 expression in 1547 cells cultured under apoptotic conditions. We demonstrate a link between the effects of 10 and 100 microM NS-398 on cell apoptosis, PGE2 release, and expression of COX-2 in 1547 cells undergoing apoptosis. At 10 microM, NS-398 acted as a selective COX-2 inhibitor moderately increasing apoptosis without any effect on COX-2 expression. In contrast, at 100 microM, NS-398 induced a cell cycle slowing or arrest, strongly enhanced COX-2 expression which was associated with a high PGE2 release and a marked decrease in apoptosis. This latter property of NS-398 at 100 microM in 1547 human osteosarcoma cells is novel compared to the described NS-398 pro-apoptotic effect on other cell lines.

Enhanced apoptosis in retrovirally transfected osteosarcoma cells after exposure to sodium butyrate.

We investigated the effects of sodium butyrate (NaBu) on two retrovirally transfected osteosarcoma cell lines (1547-TK and 1547-LacZ cells) compared to the corresponding untransfected cell line. The first finding was an inhibitory effect only on the proliferation of both transfected cell lines. This antiproliferative effect was associated with apoptosis induction, which was detected using techniques that monitor either characteristic biochemical or morphological processes. Our findings show that 1547-TK and 1547-LacZ cells were much more sensitive to NaBu treatment than untransfected 1547 cells as concerns both proliferation and apoptosis induction.

Aromatase in synovial cells from postmenopausal women.

Peripheral aromatization of androgens exerts estrogenic actions in many tissues. In this study, osteoarthritis synoviocytes were examined to clarify the possible action of adrenal androgen on synovial cell. Synoviocytes from postmenopausal women are able to express aromatase mRNA. By sequence analysis, the PCR fragment (485 bp) was determined to be 100% identical to that of human placental aromatase cDNA. Moreover, this study demonstrates that adrenal androgen, androstenedione, is converted to estrone (E(1)) and estradiol (E(2)) in synoviocytes by aromatase which is positively regulated by glucocorticoids such as dexamethasone. E(2) production reduced significantly IL-6 secretion. These data provide preliminary evidence that in situ estrogen production by synoviocytes may have a role in OA susceptibility. However the role of E(2) in OA is not clear and remains to be determined.

SdFFF monitoring of cellular apoptosis induction by diosgenin and different inducers in the human 1547 osteosarcoma cell line.

Apoptosis is one of the most important phenomena of cellular biology. Sedimentation field flow fractionation (SdFFF) has been described as an effective tool for cell separation, respecting integrity and viability. Because SdFFF takes advantage of intrinsic properties of eluted cells (size, density, shape or rigidity), we investigated the capacity of SdFFF in monitoring the early and specific biophysical modifications which occurred during cellular apoptosis induction. Then, we used, as an in vitro cellular apoptosis model, the association between human 1547 osteosarcoma cells and diosgenin, a plant steroid known to induce apoptosis. Four other molecules were studied: hecogenin, tigogenin, staurosporine and MG132. Our results demonstrated a correlation between SdFFF elution profile changes (peak shape modification and retention ratio evolution) and effective apoptosis induction. For the first time, we demonstrated that SdFFF could be used to monitor apoptosis induction as early as 6 h incubation, suggesting different applications such as screening series of molecules to evaluate their ability to induce apoptosis, or sorting apoptotic cells to study apoptosis pathway.

Effects of alumina and zirconium dioxide particles on arachidonic acid metabolism and proinflammatory interleukin production in osteoarthritis and rheumatoid synovial cells.

We describe a model which can be used for in vitro biocompatibility assays of biomaterials. We studied the in vitro response of human osteoarthritis or rheumatoid arthritis fibroblast-like synoviocytes to Al2O3 or ZrO2 particles by analysing the production of interleukin-1 (IL-1) and interleukin-6 (IL-6) and the metabolism of arachidonic acid via lipoxygenase and cyclo-oxygenase pathways. Our results show that, in these cells and under our experimental conditions, Al2O3 and ZrO2 did not significantly modify the synthesis of IL-1 and IL-6 or the metabolism of arachidonic acid.

Honey-induced macrophage stimulation: AP-1 and NF-κB activation and cytokine production are unrelated to LPS content of honey.

Honey is well known for its wound healing properties although the cellular and molecular mechanisms underlying honey-stimulated healing process are still poorly understood. The present study was intended to characterize the stimulation of Raw 264.7 murine macrophages in response to thyme honey. Honey induces significant increase in PGE2 production, and overexpression of both COX-2 and TNF-α (p<0.001). This increase was concomitant with overexpression and activation of the AP-1 and NF-κB transcription factor subunits. The small LPS content of honey could not, by itself, account for the reported observations. These results suggest that other thyme honey components participate in the stimulation of cytokine production required for effective wound healing process.

Diosgenin induces death receptor-5 through activation of p38 pathway and promotes TRAIL-induced apoptosis in colon cancer cells.

Previously, we demonstrated that diosgenin induced apoptosis in colorectal cancer cell lines HCT-116 and HT-29. HT-29 cells have been reported to be one of the most resistant colorectal cancer cell lines to TRAIL-induced apoptosis. In this study, we investigated the effect of diosgenin on TRAIL-induced apoptosis in HT-29 cells. We showed that diosgenin sensitizes HT-29 cells to TRAIL-induced apoptosis. Mechanisms underlying this sensitization mainly involved diosgenin-induced p38 MAPK pathway activation and subsequent DR5 overexpression. Furthermore, we showed that diosgenin alone, TRAIL alone or combination treatment increased COX-2 expression and that the use of a COX-2 inhibitor further increased apoptosis induction.

Analysis of relationship between cell cycle stage and apoptosis induction in K562 cells by sedimentation field-flow fractionation.

Recently, sedimentation field-flow fractionation (SdFFF) was used to study the specific kinetics of diosgenin-induced apoptosis in K562 cells. Here, we propose a new SdFFF cell separation application in the field of cancer research concerning the correlation between induction of a biological event (i.e. apoptosis) and cell status (i.e. cell cycle position). SdFFF isolated subpopulations depending on the cell cycle position allowing the study of apoptosis kinetics and extent. Results showed that cells in G0/G1 phases (F3 cells) underwent significant and earlier apoptosis than cells in the active part of the cell cycle (S/G2/M phases). Results shed light on the correlation between differences in apoptosis kinetics and cell cycle stage when exposure to the inducer began. SdFFF monitoring and size measurement also led to the description of different subpopulations demonstrating complex variations in density between fractions associated with differences in biological processes.

Development of a downscale sedimentation field flow fractionation device for biological event monitoring.

Classically described as a macroscale size-density based method, Sedimentation field flow fractionation (SdFFF) has been successfully used for cell sorting. The goal of this study was to develop a new SdFFF device for downscale applications, in particular for oncology research to rapidly monitor chemical biological event induction in a cell line. The development of a downscale SdFFF device required reduction of the separation channel volume. Taking advantage of a newly laboratory designed apparatus, channel volume was successfully decreased by reducing both length and breadth. To validate the apparatus and method, we used the well-known model of diosgenin dose-dependent induction of apoptosis or megakaryocytic differentiation in HEL cells. After a minute scale acquisition of a reference profile, the downscale device was able to perform fast, early, significant and reproducible monitoring of apoptosis and differentiation, two important biological mechanisms in the field of cancer research.