Waldemar Wagner

HIF-1α Is Up-Regulated in Activated Mast Cells by a Process That Involves Calcineurin and NFAT

Mast cells play important roles in many pathological conditions where local hypoxia is observed, including asthma, rheumatic diseases, and certain types of cancer. Here, we investigated how expression of the hypoxia-inducible factor 1, α subunit gene (HIF1A), is regulated in mast cells. The product of HIF1A is hypoxia-inducible factor 1α (HIF-1α), is a major nuclear transcription factor modulating gene expression in response to hypoxic conditions. We observed that under hypoxic conditions, exposure of mast cells to ionomycin and substance P resulted in significant up-regulation of HIF1A expression as compared with resting mast cells incubated under identical conditions. The ionomycin-mediated increase in HIF-1α protein levels was sensitive to the transcription inhibitor actinomycin D and to inhibitors of calcineurin, cyclosporin A (CsA), and FK506. The increased HIF-1α protein level was paralleled by a severalfold increase in HIF-1α mRNA that could be also inhibited with actinomycin D and CsA. The HIF1A promoter activity was significantly increased in ionomycin-activated mast cells, and the promoter activity could be inhibited by CsA and FK506. Furthermore, in situ mutagenesis experiments showed that the ionomycin-mediated HIF1A promoter activity depends on a conservative NFAT-binding site. Thus, accumulation of HIF-1α in activated mast cells requires up-regulation of HIF1A gene transcription and depends on the calcineurin-NFAT signaling pathway.

Orexins Protect Neuronal Cell Cultures Against Hypoxic Stress: an Involvement of Akt Signaling

Orexins A and B are peptides produced mainly by hypothalamic neurons that project to numerous brain structures. We have previously demonstrated that rat cortical neurons express both types of orexin receptors, and their activation by orexins initiates different intracellular signals. The present study aimed to determine the effect of orexins on the Akt kinase activation in the rat neuronal cultures and the significance of that response in neurons subjected to hypoxic stress. We report the first evidence that orexins A and B stimulated Akt in cortical neurons in a concentration- and time-dependent manner. Orexin B more potently than orexin A increased Akt phosphorylation, but the maximal effect of both peptides on the kinase activation was very similar. Next, cultured cortical neurons were challenged with cobalt chloride, an inducer of reactive oxygen species and hypoxia-mediated signaling pathways. Under conditions of chemical hypoxia, orexins potently increased neuronal viability and protected cortical neurons against oxidative stress. Our results also indicate that Akt kinase plays an important role in the pro-survival effects of orexins in neurons, which implies a possible mechanism of the orexin-induced neuroprotection.

L- and D-lactate enhance DNA repair and modulate the resistance of cervical carcinoma cells to anticancer drugs via histone deacetylase inhibition and hydroxycarboxylic acid receptor 1 activation

BackgroundThe consideration of lactate as an active metabolite is a newly emerging and attractive concept. Recently, lactate has been reported to regulate gene transcription via the inhibition of histone deacetylases (HDACs) and survival of cancer cells via hydroxycarboxylic acid receptor 1 (HCAR1). This study examined the role of L- and D-lactate in the DNA damage response in cervical cancer cells.MethodsThree cervical cancer cell lines were examined: HeLa, Ca Ski and C33A. The inhibitory activity of lactate on HDACs was analysed using Western blot and biochemical methods. The lactate-mediated stimulation of DNA repair and cellular resistance to neocarzinostatin, doxorubicin and cisplatin were studied using γ-H2AX, comet and clonogenic assays. HCAR1 and DNA repair gene expression was quantified by real-time PCR. DNA-PKcs activity and HCAR1 protein expression were evaluated via immunocytochemistry and Western blot, respectively. HCAR1 activation was investigated by measuring intracellular cAMP accumulation and Erk phosphorylation. HCAR1 expression was silenced using shRNA.ResultsL- and D-lactate inhibited HDACs, induced histone H3 and H4 hyperacetylation, and decreased chromatin compactness in HeLa cells. Treating cells with lactate increased LIG4, NBS1, and APTX expression by nearly 2-fold and enhanced DNA-PKcs activity. Based on γ-H2AX and comet assays, incubation of cells in lactate-containing medium increased the DNA repair rate. Furthermore, clonogenic assays demonstrated that lactate mediates cellular resistance to clinically used chemotherapeutics. Western blot and immunocytochemistry showed that all studied cell lines express HCAR1 on the cellular surface. Inhibiting HCAR1 function via pertussis toxin pretreatment partially abolished the effects of lactate on DNA repair. Down-regulating HCAR1 decreased the efficiency of DNA repair, abolished the cellular response to L-lactate and decreased the effect of D-lactate. Moreover, HCAR1 shRNA-expressing cells produced significantly lower mRNA levels of monocarboxylate transporter 4. Finally, the enhancement of DNA repair and cell survival by lactate was suppressed by pharmacologically inhibiting monocarboxylate transporters using the inhibitor α-cyano-4-hydroxycinnamic acid (α-CHCA).ConclusionsOur data indicate that L- and D-lactate present in the uterine cervix may participate in the modulation of cellular DNA damage repair processes and in the resistance of cervical carcinoma cells to anticancer therapy.

Polyphenols from Evening Primrose (Oenothera paradoxa) Defatted Seeds Induce Apoptosis in Human Colon Cancer Caco-2 Cells

Polyphenols extracted from evening primrose seeds (industrial waste product) were studied as apoptosis inducers in human colorectal adenocarcinoma Caco-2 and HT-29 cell lines and in rat normal intestinal IEC-6 cells. The extract dose-dependently inhibited the growth of Caco-2, HT-29, and IEC-6 cells. However, nuclear DNA fragmentation characteristic of apoptosis was observed only in Caco-2. After 72 h of incubation with the extract at 150 μM gallic acid equivalents (44.1 μg extract/mL), Caco-2 cell numbers decreased to 19% of control and 48.8% of the cells were identified by flow cytometry as apoptotic. Under the same conditions only 8% of HT-29 cells and 12.6% of IEC-6 cells exhibited hypodiploid DNA content. The effects of the extract and its fractions on phosphatidylserine exposure and cell membrane integrity were assessed by high content screening image cytometry. The fractions strongly and dose-dependently reduced Caco-2 cell numbers, whereas HT-29 and IEC-6 cells were affected to lesser extents.

Effect of an angiotensin II type 1 receptor blocker on caveolin-1 expression in prostate cancer cells

Introduction Caveolin-1, the major structural protein of caveolae, interacts directly with the AT1 receptor. The biological functions of caveolin-1 in cancer are compound, multifaceted, and depend on cell type, tumour grade and cancer stage. The AT1-R-caveolin complex in caveolae may coordinate angiotensin II (Ang II) induced signalling. The aim of this study was to determine the effect of the angiotensin II receptor type 1 blocker candesartan on caveolin expression in human metastatic prostate adenocarcinoma cells PC-3. Material and methods WST-1 and BrdU assays were used as indicators of cell viability and proliferation after angiotensin II and/or candesartan stimulation. Real-time RT–PCR and western blot were used to study the effect of Ang II and/or candesartan on the expression of Cav-1 and AT1-R in PC-3 cells Results We found that the expression of caveolin-1 mRNA in the PC-3 cells treated with CV was significantly decreased in comparison with the control (2.9 ±0.17, 4.7 ±0.6, p < 0.05), whereas a higher caveolin-1 mRNA expression was observed in those after Ang II treatment (6.0 ±0.43, 4.7 ±0.6, p < 0.05). Protein analysis indicate that the expression of caveolin-1 protein in the PC-3 cells treated with candesartan was significantly decreased when compared with the control (0.69 ±0.05, 1.6 ±0.12, p < 0.05), whereas higher caveolin-1 protein expression was observed after Ang II treatment (2.5 ±0.20, 1.6 ±0.12, p < 0.05). Conclusions These results provide new information on the action of candesartan and may improve the knowledge about AT1 receptor inhibitors, which can be potentially useful in prostate cancer therapy.

Procyanidins From Japanese Quince (Chaenomeles Japonica) Fruit Induce Apoptosis in Human Colon Cancer Caco-2 Cells in a Degree of Polymerization-Dependent Manner

Plant proanthocyanidins, including procyanidins, display various biological activities. Here we report an inhibition of human colon cancer Caco-2 cell growth by the extract from Japanese quince fruit and the procyanidin-rich fractions of the extract. We observed that the amount of apoptotic Caco-2 cells increased by 52.1% vs. control after 72-h incubation with 50 μg extract/mL, as assessed by flow cytometry and image cytometry. Under the same experimental conditions the corresponding values for human colon cancer HT-29 cells and for rat normal intestinal IEC-6 cells were 5.0% and 8.1%, respectively. The extract fractions enriched with higher oligomers exhibited the highest proapoptotic activity. In conclusion, the Japanese quince procyanidins exhibited proapoptotic activity in Caco-2 cells within a submilimolar concentration range.

Application of cellular biosensors for analysis of bioactivity associated with airborne particulate matter.

Exposure to airborne particulate matter (PM) is a known risk factor for adverse health effects observed in many environmental and occupational settings. The pathological mechanisms involved in PM-mediated toxicity depend on the size and contents of particles that vary depending on the source of emission. Chemical compositions of PM show multiple components with different bioavailabilities that are capable of acting on multiple molecular and cellular targets, making it difficult to predict PM-associated toxicity based solely on chemical analysis. The aim of the study was to develop robust, sensitive and economical assays for environmental pollutants based on genetically modified mammalian cells. We tested the suitability of two biosensor assays, Fluorescent Cell Chip and Oxibios, developed in part in our laboratories, for assessment of the potential toxicity of airborne PM. Reference PM and PM obtained by sampling of diesel exhaust and indoor air in aluminum and copper facilities in Poland were tested with the two bioassays using unified experimental protocols. Resultant data showed complex patterns of stimulatory and inhibitory activities that were consistent with the origin of PM and might be correlated with their chemical composition. The analysis was informative with regard to type and extent of possible toxicity associated with specific PM and allowed for detection of significant differences between PM from different industrial sites and particular locations within the same industrial sites as well as overall ranking of toxicity risk based on chemical analysis.

Interleukin-4 Enhances PARP-Dependent DNA Repair Activity In Vitro

Eukaryotic cells possess several DNA repair mechanisms, including homologous recombination and the non-homologous end-joining (NHEJ) system. There are two known NHEJ systems. The major mechanism depends on the catalytic unit of DNA-dependent protein kinase (DNA-PKcs) and DNA ligase IV, and an alternative mechanism (B-NHEJ) depends on poly(ADP-ribose) polymerase (PARP). These systems are upregulated by genotoxic agents. Interleukin 4 (IL-4) is an immunoregulatory cytokine that is secreted by immune cells upon contact with certain genotoxic compounds and is known to regulate several genes encoding components of DNA repair systems in human monocytes. We have investigated the possible effects of IL-4 on the DNA repair process within murine and human cells exposed to selected genotoxic compounds. In a series of experiments, including the comet assay, cell surface annexin V staining, analysis of histone H2AX phosphorylation, and a DNA end-joining assay, we observed that IL-4 decreased DNA damage in murine fibroblasts and human glioblastoma cells exposed to genotoxic agents and increased DNA ligation activity in the nuclei of these cells in a process that depended on PARP. These observations suggest that IL-4 is capable of upregulating the alternative NHEJ DNA repair mechanism in murine and human cells.

Stimulation of lactate receptor (HCAR1) affects cellular DNA repair capacity

Numerous G-protein coupled receptors have been reported to enhance cancer cell survival and resistance to clinically used chemotherapeutics. Recently, hydroxycarboxylic acid receptor 1 (HCAR1) was shown to drive lactate-dependent enhancement of cell survival and metastasis in pancreatic and breast cancers. Furthermore, our previous study confirmed the involvement of HCAR1 in lactate-related enhancement of DNA repair in cervical cancer cells. In the present study, we examined the possible mechanisms of HCAR1-mediated enhancement of DNA repair capacity. We observed that the HCAR1 agonist dihydroxybenzoic acid (DHBA) up-regulated BRCA1 (breast cancer type 1 susceptibility protein) and NBS1 (Nijmegen breakage syndrome 1) expression in HeLa cells. Moreover, HCAR1 silencing decreased mRNA and protein levels of BRCA1 by 30% and 20%, respectively. Immunocytochemical analyses of BRCA1, nibrin and DNA-PKcs indicated an increased accumulation of these proteins in cell nuclei after DHBA stimulation. Subsequently, these changes in the DNA repair protein levels translated into an enhanced DNA repair rate after doxorubicin treatment, as shown by γ-H2AX and comet assay experiments. In contrast, the down-regulation of HCAR1 decreased the efficiency of DNA repair. Finally, we observed the abrogation of DHBA-driven BRCA1 protein up-regulation and enhanced DNA repair following the preincubation of cells with the PKC inhibitor Gö6983. Taken together, our data indicate that lactate receptor/HCAR1 expression in cervical carcinoma cells may contribute to the modulation of cellular DNA repair mechanisms.

Hepatocyte transplantation reverses the effect of portocaval shunt on rat brain histamine.

Rats with portocaval anastomosis (PCA) serve as experimental models of hepatic encephalopathy associated with chronic liver dysfunction in man. Portocaval shunt is connected with an exaggerated amine production in the central nervous system. The excess histamine produced is largely deposited in neurons, in contrast to serotonin which undergoes catabolism [1, 2]. Experiments with the suicidal histidine decarboxylase inhibitor, a-fluoro-methylhistidine administered few months after the shunt operation have suggested that the accumulated histamine can be mobilised from its neuronal deposits/stores [3]. In the present study, we strengthened these data by using PCA rats in which the substantially reduced hepatic function was improved by hepatocyte transplantation. The therapeutic use of hepatocyte transplantation in chronic liver failure has recently been proposed [4].