Galectin-3 (gal-3) is a β-galactoside binding protein related to many tumoral aspects, e.g. angiogenesis, cell growth and motility and resistance to cell death. Evidence has shown its upregulation ...upon hypoxia, a common feature in solid tumors such as glioblastoma multiformes (GBM). This tumor presents a unique feature described as pseudopalisading cells, which accumulate large amounts of gal-3. Tumor cells far from hypoxic/nutrient deprived areas express little, if any gal-3. Here, we have shown that the hybrid glioma cell line, NG97ht, recapitulates GBM growth forming gal-3 positive pseudopalisades even when cells are grafted subcutaneously in nude mice. In vitro experiments were performed exposing these cells to conditions mimicking tumor areas that display oxygen and nutrient deprivation. Results indicated that gal-3 transcription under hypoxic conditions requires previous protein synthesis and is triggered in a HIF-1α and NF-κB dependent manner. In addition, a significant proportion of cells die only when exposed simultaneously to hypoxia and nutrient deprivation and demonstrate ROS induction. Inhibition of gal-3 expression using siRNA led to protein knockdown followed by a 1.7-2.2 fold increase in cell death. Similar results were also found in a human GBM cell line, T98G. In vivo, U87MG gal-3 knockdown cells inoculated subcutaneously in nude mice demonstrated decreased tumor growth and increased time for tumor engraftment. These results indicate that gal-3 protected cells from cell death under hypoxia and nutrient deprivation in vitro and that gal-3 is a key factor in tumor growth and engraftment in hypoxic and nutrient-deprived microenvironments. Overexpression of gal-3, thus, is part of an adaptive program leading to tumor cell survival under these stressing conditions.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Previously we isolated migracin A from a Streptomyces culture filtrate as an inhibitor of cancer cell migration. In the present research, we found that migracin A inhibited migration and invasion of ...ovarian clear cell carcinoma ES-2 cells. In the course of our mechanistic study, migracin A was shown to enhance vasohibin-1 expression in an angiogenesis array. We also confirmed that it increased the mRNA expression of this protein. Moreover, overexpression of vasohibin-1 lowered the migration but not the invasion of ES-2 cells. Then, we looked for another target protein employing a motility array, and found that migracin A lowered the IGF-1 expression. Knockdown of IGF-1 by siRNA decreased the migration and invasion of ES-2 cells. Migracin A also decreased Akt phosphorylation involved in the downstream signaling. Crosstalk analysis indicated that overexpression of vasohibin-1 decreased the IGF-1 expression. On the other hand, it showed no direct anticancer activity in terms of the ES-2 growth in agar. Migracin A inhibited the migration and IGF-1 expression in not only ES-2 but also another ovarian clear cell carcinoma JHOC-5 cells. In addition, it also inhibited capillary tube formation of human umbilical vein endothelial cells. Since its cytotoxicity is very low, migracin A may be a candidate for an anti-metastasis agent not exhibiting prominent toxicity.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Recent progress in molecular analysis has revealed the possible involvement of multiple inflammatory signaling pathways in pathogenesis of retinal degeneration. However, how aberrant signaling ...pathways cause tissue damage and dysfunction is still being elucidated. Here, we focus on 5'-adenosine monophosphate (AMP)-activated protein kinase (AMPK), originally recognized as a key regulator of energy homeostasis. AMPK is also modulated in response to inflammatory signals, although its functions in inflamed tissue are obscure. We investigated the role of activated AMPK in the retinal neural damage and visual function impairment caused by inflammation. For this purpose, we used a mouse model of lipopolysaccharide-induced inflammation in the retina, and examined the effects of an AMPK activator, 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR). During inflammation, activated AMPK in the neural retina was decreased, but AICAR treatment prevented this change. Moreover, the electroretinogram (ERG) a-wave response, representing photoreceptor function, showed visual dysfunction in this model that was prevented by AICAR. Consistently, the model showed shortened photoreceptor outer segments (OSs) with reduced levels of rhodopsin, a visual pigment concentrated in the OSs, in a post-transcriptional manner, and these effects were also prevented by AICAR. In parallel, the level of activated NF-κB increased in the retina during inflammation, and this increase was suppressed by AICAR. Treatment with an NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ) preserved the rhodopsin level during inflammation, suppressing NF-κB. These findings indicated that AMPK activation by AICAR and subsequent NF-κB inhibition had a protective effect on visual function, and that AMPK activation played a neuroprotective role during retinal inflammation.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Conophylline is a Vinca alkaloid from leaves of the tropical plant Ervatamia microphylla and has been shown to mimic the effect of the growth and differentiation factor activin A on pancreatic ...progenitor cells. However, activin A stimulates fibrosis of pancreatic stellate cells, whereas conophylline inhibits it, suggesting that this compound may serve as an antifibrotic drug. Here we investigated the effects of conophylline on human foreskin fibroblasts, especially focusing on extracellular matrix (ECM) proteins. A gene microarray analysis revealed that conophylline remarkably suppressed expression of the gene for hyaluronan synthase 2 (HAS2) and of its antisense RNA, whereas the expression of collagen genes was unaffected. Of note, immunostaining experiments revealed that conophylline substantially inhibits incorporation of versican and collagens into the ECM in cells treated with transforming growth factor β (TGFβ), which promotes collagen synthesis, but not in cells not treated with TGFβ. Moreover, a protein biosynthesis assay disclosed that conophylline decreases collagen biosynthesis, concomitant with a decrease in total protein biosynthesis, indicating that conophylline-mediated inhibition of fibrosis is not specific to collagen synthesis. Conophylline affected neither TGFβ-induced nuclear translocation of SMAD family member 2/3 (SMAD2/3) nor phosphorylation of SMAD2. However, conophylline substantially inhibited phosphorylation of extracellular signal–regulated kinase 1/2 (ERK1/2), suggesting that conophylline inhibits HAS2 expression via TGFβ-mediated activation of the ERK1/2 pathway. Taken together, our results indicate that conophylline may be a useful inhibitor of ECM formation in fibrosis.
Protein glycosylation, one of the post-translational modifications, is important for many protein functions, such as protein stability, folding and secretion. In the protein glycosylation, ...C-mannosylation was first identified in ribonuclease 2, and some proteins have been reported to be C-mannosylated; however, effects of its modifications for target proteins remain unclear. Hyaluronidase 1 (HYAL1), degrading hyaluronic acid (HA), has two predicted C-mannosylation sites at Trp130 and Trp321. In this study, we examined whether HYAL1 is C-mannosylated or not, and the effect of C-mannosylation on HYAL1. Using mass spectrometry, we first demonstrated that intracellular HYAL1 is C-mannosylated at Trp130 but not at Trp321. Surprisingly, although HYAL1 was secreted into conditioned medium and it possessed enzymatic activity, secreted HYAL1 was not C-mannosylated. Computer simulation demonstrated that C-mannosylation of HYAL1 at Trp130 changed conformation of the catalytic active site, and faced Glu131 in the opposite direction toward its substrate, HA, indicating that C-mannosylation will negatively regulate its secretion, and will attenuate its enzymatic activity. Taken together, this is the first report that demonstrates the presence of C-mannosylation among HYAL family proteins, and our results suggest possible roles of C-mannosylation for secretion and enzymatic activity.
After the long history of screening, it is becoming difficult to find novel compounds from microorganisms and plants anywhere in the world. Until now, more than about 30,000 marine natural products ...have been reported. However, with the development of marine natural products research, the hit rate of new compounds is also decreasing. Scientists are now turning their attention to the deep sea, where a high hit rate of novel compounds is expected. Many small compounds and peptides from microorganisms and sponges are with therapeutic activity are shown in this book. This Special Issue Book, “Natural Products from the Deep Sea”, should be useful for the screening of novel and useful compounds from nature.
•We have prepared RelB mutants that are resistant to caspase 3-induced scission.•Vinblastine induced caspase 3-dependent site-specific RelB cleavage in cancer cells.•Cancer cells expressing ...cleavage-resistant RelB showed less sensitivity to vinblastine.•Caspase 3-induced RelB cleavage may provide positive feedback mechanism in apoptosis.
DTCM-glutarimide (DTCM-G) is a newly found anti-inflammatory agent. In the course of experiments with lymphoma cells, we found that DTCM-G induced specific RelB cleavage. Anticancer agent vinblastine also induced the specific RelB cleavage in human fibrosarcoma HT1080 cells. The site-directed mutagenesis analysis revealed that the Asp205 site in RelB was specifically cleaved possibly by caspase-3 in vinblastine-treated HT1080 cells. Moreover, the cells stably overexpressing RelB Asp205Ala were resistant to vinblastine-induced apoptosis. Thus, the specific Asp205 cleavage of RelB by caspase-3 would be involved in the apoptosis induction by anticancer agents, which would provide the positive feedback mechanism.
Increasing metabolic syndromes including type-2 diabetes mellitus, obesity, and steatohepatitis are serious problems in most countries in the world. Neurodegenerative diseases such as Alzheimer, ...Parkinson’s, and Huntington’s diseases are increasing in many countries. However, therapy for these diseases is not sufficient yet. Thus, effective chemotherapy for these diseases is being expected. Conophylline is an alkaloid isolated from the leaves of
Ervatamia microphylla
and related plants. It was found to induce beta-cell differentiation in the precursor pancreatic cells. Oral administration of this compound ameliorated type-2 diabetes mellitus model in mice and rats. Later, fibrosis of the pancreatic islets was found to be greatly reduced by conophylline in the pancreatic islets. It also inhibited chemically induced liver cirrhosis. Further study indicated that conophylline inhibited non-alcoholic steatohepatitis in the model mice. On the one hand, loss of autophagy often causes protein aggregation to give neural cell death. Conophylline was found to activate autophagy in cultured neural cells. Activation of autophagy ameliorated cellular models of Parkinson’s and Huntington’s diseases. Thus, conophylline is likely to be useful for the development of chemotherapy for metabolic and neurodegenerative diseases.
No previous study has addressed the efficacy of NF-κB blockade when bladder tumors develop acquired resistance toward CDDP-treatments. We investigated the changes in NF-κB activation and therapeutic ...impact of NF-κB blockade by the novel NF-κB inhibitor dehydroxymethyl derivative of epoxyquinomicin (DHMEQ) in CDDP-resistant bladder cancer cells.
Two human invasive bladder cancer cell lines, T24 and T24PR, were used. The T24PR cell line was newly established as an acquired platinum-resistant subline by culturing in CDDP-containing medium for 6 months. Expression of intranuclear p65 protein in the fractionated two cell lines was determined by Western blotting analysis. DNA-binding activity of NF-κB was detected by electrophoretic mobility shift assay. The cytotoxic effects and induction of apoptosis were analyzed in vivo and in vitro.
Intranuclear expression and DNA-binding activity of p65 were strongly enhanced in T24PR cells compared with those of T24 cells, and both were significantly suppressed by DHMEQ. Lowered cell viability and strong induction of apoptosis were observed by treatment with DHMEQ alone in these chemo-resistant cells compared with parent cells. As T24PR cells did not show dramatic cross-resistance to paclitaxel in the in vitro study, we next examined whether the combination of DHMEQ with paclitaxel could enhance the therapeutic effect of the paclitaxel treatment in T24PR tumors. Using mouse xenograft models, the mean volume of tumors treated with the combination of DHMEQ (2 mg/kg) and paclitaxel (10 mg/kg) was significantly smaller than those treated with paclitaxel alone (p < 0.05), and the reduction of tumor volume in mice treated with DHMEQ in combination with paclitaxel and paclitaxel alone as compared to vehicle control was 66.9% and 17.0%, respectively.
There was a distinct change in the activation level of NF-κB between T24 and T24PR cells, suggesting strong nuclear localization of NF-κB could be a promising target after developing acquired platinum-resistance in bladder cancer.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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