Cytosolic O-GlcNAcylation and PNG1 maintain Drosophila gut homeostasis by regulating proliferation and apoptosis

Tissue homeostasis requires a delicate balance between stem cell self-renewal, proliferation, and differentiation. Essential to this process is glycosylation, with both intra-and extra-cellular glycosylation being required for stem cell homeostasis. However, it remains unknown how intracellular glycosylation, O-GlcNAcylation, interfaces with cellular components of the extracellular glycosylation machinery, like the cytosolic N-glycanase NGLY1. In this study, we utilize the Drosophila gut and uncover a pathway in which O-GlcNAcylation cooperates with the NGLY1 homologue PNG1 to regulate proliferation in intestinal stem cells (ISCs) and apoptosis in differentiated enterocytes. Further, the CncC antioxidant signaling pathway and ENGase, an enzyme involved in the processing of free oligosaccharides in the cytosol, interact with O-GlcNAc and PNG1 through regulation of protein aggregates to contribute to gut maintenance. These findings reveal a complex coordinated regulation between O-GlcNAcylation and the cytosolic glycanase PNG1 critical to balancing proliferation and apoptosis to maintain gut homeostasis.

Understanding glycosylation is of great importance as changes in both intra- and extra-cellular glycosylation have been well documented in diseases. However, it remains relatively unclear how intracellular glycosylation, O-GlcNAcylation, interfaces with the cellular machinery of extracellular glycosylation. In this study, we seek to understand how coordination between a cytosolic N-glycanase, NGLY1, and intracellular glycosylation, is utilized during stem cell proliferation. Using the Drosophila gut as a model system, our data showed O-GlcNAcylation and the Drosophila homologue of NGY1, PNG1, have key roles in both progenitor and differentiated cells that contribute to tissue homeostasis. Further, the CncC antioxidant signaling pathway and ENGase, an enzyme involved in the processing of free oligosaccharides in the cytosol, interact with O-GlcNAc and PNG1 through regulation of protein aggregates to contribute to gut maintenance. Our study suggests that alterations in O-GlcNAc and NGLY1 could be future targets utilized as therapeutics for nutrient-sensitive stem cell-derived diseases such as cancer.

Abstract B169: Hypoxia-inducible factor 1α (HIF-1α) correlates with epithelial-mesenchymal transition (EMT) and tumor growth in thyroid cancer cell lines

Hypoxia is essential for microenvironment to induce tumor metastasis. Intratumoural hypoxia, followed by stabilization and activation of the HIF-1α transcription complex, is one of the most important mechanisms that promotes metastasis and thereby, increases tumor aggressiveness. EMT (epithelial to mesenchymal transition), one of the central mechanisms that induces invasion and metastasis of tumors. The aim of this study was to investigate the possible role of HIF-1α as one of the microenvironmental influences driving metastatic progression by induction of epithelial to mesenchymal transition in thyroid cancer. In vitro studies revealed a functionally active HIF-1a pathway in several types of thyroid cells with transcriptional activation observed after hypoxia or overexpression. Knock-down of HIF-1α or overexpression of HIF-1α in thyroid cancer cells suggested that HIF-1α promotes epithelial-mesenchymal transition (EMT) and metastastic phenotypes in follicular thyroid cancer cell lines, especially. HIF-1α increases the expression of Vimentin, N-cadherin, Snail, Slug, Twist, MMP2, VEGF but not E-cadherin. Also, wound healing assay and in vitro migration assays showed that the cell migration ability was increased in a HIF1α- dependent manner. Furthermore, knock-down of HIF-1α leads to decreased tumor growth and regulates the expression of EMT marker genes in thyroid tumor xenograft mouse model. Taken together, these results suggest that the HIF-1 signaling induces EMT and metastasis through the regulation of various EMT regulators in vitro as well as in vivo study.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B169.

Citation Format: YJ Yang, HJ Na, Ws Kim, Jp Bong, Sj Baek, Jw Kim, Jh Park, Dy Shin, Hj Hong, Jh Kwon, Ej Lee, Yw Koh, Ec Choi. Hypoxia-inducible factor 1α (HIF-1α) correlates with epithelial-mesenchymal transition (EMT) and tumor growth in thyroid cancer cell lines. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B169.

Abstract A90: Feedback activation of EGFR drives resistance to BRAF(V600E) inhibition in breast cancer

Purpose: The BRAFV600E mutation has shown significant activity in the several tumor types, including breast, melanoma, and colorectal cancer. The selective inhibitor of BRAFV600, PLX4032 (vemurafenib), has shown clinical response in patients with BRAFV600Emelanoma, especially but not in 20-40% of patients despite the presence of a BRAFV600E. Thus, it is important to understand the molecular mechanisms of resistance to improve outcomes in patient with BRAF mutation. We aimed to investigate the cause of the limited therapeutic effect of PLX4032 in cancers harboring the mutant BRAFV600E gene.

Experiment Design: We investigated the correlation between RTK pathway activation and sensitivity to PLX4032 in several types of cancer cell lines harboring the BRAFV600E. Cell lines were exposed to PLX4032 and pharmacologic inhibitors and in combination with each other to inhibit RTK signaling. Cell survival and apoptosis were measured using MTT assay, Annexin V/PI staining, and colony forming assay. Real-time PCR, Western blots were performed to determine possible mechanisms of resistance and predictors of synergy.Results: In a comparison with BRAFV600E cancer cells, we show that PLX4032-resistant MDA-MB breast cancer cells have the enhanced level of p-EGFR in the presence of PLX4032. PLX4032 treatment causes a rapid feedback activation of EGFR and up-regulation of AKT in MDA-MB cells, which supports continued proliferation in the presence of BRAFV600E inhibition. We show that EGFR activation acquired resistance to BRAF inhibition using EGFR inhibitor. Gefitinib, EGFR inhibitor, shows strong synergy with a BRAFV600E inhibitor in short-time and long-time treatment. In addition, we investigated that rapid feedback activation of EGFR regulates the expression of epithelial to mesenchymal transition (EMT) regulators by

Real-time PCR, which resulted in high migratory potentials in invasion assay and wound healing assay. These results provide rational therapeutic strategies for clinical studies in this poor prognosis subtype of BRAFV600E inhibitor.

Conclusions: Our data suggest that BRAFV600E mutant breast cancers, for which there are currently no targeted treatment options available, might benefit from combination therapy consisting of BRAF and EGFR inhibitors.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A90.

Citation Format: Yj Yang, HJ Na, Ws Kim, JP Bong, SJ Beak, Jw Kim, Jk Park, Hj Hong, Dy Shin, Jh Kwon, Ej Lee, Yw Koh, Ec Choi. Feedback activation of EGFR drives resistance to BRAF(V600E) inhibition in breast cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A90.

Daeganghwal-tang inhibits the stem cell factor-induced migration and inflammatory cytokines secretion in mast cells

Traditional Oriental medicinal prescription, Daeganghwal-tang (DGHT) has been used for the treatment of rheumatoid arthritis (RA) in Korea. However, its effect in experimental models remains unknown. Recent reports suggest that in patients with RA, synovial mast cells increase in number and show signs of activation and inflammatory cytokines secretion. Our results show that stem cell factor (SCF) is a potent chemotactic factor for the mast cells in vitro. The chemotactic response to SCF was blocked by DGHT. When DGHT (1mg/ml) was added, the secretion of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6 was inhibited by 60.1, 81.8, 72.5%, respectively in phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore A23187-stimulated HMC-1 cells. In addition, the expression of TNF-alpha mRNA in HMC-1 cells was inhibited by DGHT (1mg/ml). These findings indicate that DGHT inhibits SCF-induced migration and PMA plus calcium ionophore-stimulated inflammatory cytokines secretion in mast cells.

Juniper oil inhibits the heat shock-induced apoptosis via preventing the caspase-3 activation in human astrocytes CCF-STTG1 cells

BACKGROUND

Brain astrocytes play a pivotal role in neuronal activities.

METHODS

An investigation was undertaken to determine whether juniper oil inhibits heat shock-induced apoptosis of astrocytes.

RESULTS

Juniper oil inhibited the heat shock-induced apoptosis in human astrocyte CCF-STTG1 cells. Pretreatment of the cells with juniper oil inhibited the heat shock-induced DNA fragmentation and condensation of nuclear chromatin. Juniper oil alone did not affect the apoptosis. Juniper oil inhibited the heat shock-induced caspase-3 activation and poly-ADP-ribose polymerase (PARP) fragmentation in the human astrocytes.

CONCLUSIONS

Juniper oil may inhibit the apoptosis of astrocytes by preventing the caspase-3 activation.

Molecular authentication of Panax ginseng species by RAPD analysis and PCR-RFLP

In order to develop convenient and reproducible methods for the identification of ginseng drugs at a DNA level, randomly amplified polymorphic DNA (RAPD) and PCR-restriction fragment length polymorphism (PCR-RFLP) analyses were applied within Panax species. To authenticate Panax ginseng among ginseng populations, RAPD analysis was carried out using a 20 mer-random primer. The similarity coefficients among the DNA of ginseng plants analyzed were low, ranging from 0.197 to 0.491. In addition, by using PCR-RFLP analysis, very different fingerprints were obtained within Korean ginseng plants. These results suggest that these methods are able to authenticate the concerned Panax species. Broader application of this approach to authenticate other morphologically similar medicinal materials is rationalized.

Inhibition of immunologic and nonimmunologic stimulation-mediated anaphylactic reactions by water extract of white eggplant (solanum melongena)

We investigated the effect of water extract of Solanum melongena(SMWE) on immunologic and nonimmunologic stimulation-mediated anaphylactic reactions. Nonimmunologic anaphylactic reaction was induced by compound 48/80 injection. Oral administration of SMWE (1 g kg(-1)) completely inhibited compound 48/80-induced anaphylactic reaction. Immunologic anaphylactic reaction was generated by sensitizing the skin with anti-dinitrophenyl (DNP) IgE followed 48 h later with an injection of antigen. Oral administration of SMWE (0.01--1 g kg(-1)) significantly inhibited passive cutaneous anaphylactic reaction activated by anti-DNP IgE to between 83.10 +/- 1.67% and 70.17 +/- 2.17%. SMWE (0.01--1 mg ml(-1)) also inhibited histamine release activated by compound 48/80 to between 93 +/- 2.65 and 70 +/- 1.50%. Moreover, SMWE (0.01--1 mg ml(-1)) had a significant inhibitory effect on IgE-induced tumor necrosis factor (TNF)-alpha secretion from rat peritoneal mast cells. These results indicate that SMWE inhibits immunologic and nonimmunologic stimulation-mediated anaphylactic reactions and TNF-alpha secretion from mast cells.

Effect of Polygala tenuifolia root extract on the tumor necrosis factor-alpha secretion from mouse astrocytes

We investigated whether an aqueous extract of Polygala tenuifolia root (PTAE) inhibits secretion of tumor necrosis factor-alpha (TNF-alpha) from primary cultures of mouse astrocytes. PTAE dose-dependently inhibited the TNF-alpha secretion by astrocytes stimulated with substance P (SP) and lipopolysaccharide (LPS). Interleukin-1 (IL-1) has been shown to elevate TNF-alpha secretion from LPS-stimulated astrocytes while having no effect on astrocytes in the absence of LPS. We therefore also investigated whether IL-1 mediated inhibition of TNF-alpha secretion from primary astrocytes by PTAE. Treatment of PTAE to astrocytes stimulated with both LPS and SP decreased IL-1 secretion to the level observed with LPS alone. Moreover, incubation of astrocytes with IL-1 antibody abolished the synergistic co-operative effect of LPS and SP. These results suggest that PTAE may inhibit TNF-alpha secretion by inhibiting IL-1 secretion and that PTAE has an anti-inflammatory activity on the central nervous system curing some pathological disease states.

Combining ADA, protein and IFN-gamma best allows discrimination between tuberculous and malignant pleural effusion

BACKGROUND

The purpose of this study is to assess the usefulness of various enzymes, cytokines and biochemical studies of pleural fluid for the differential diagnosis of tuberculosis from malignant pleural effusions, and to clarify the role of combining diagnostic tests.

METHODS

The study group included 39 cases with tuberculous effusions and 31 cases with malignant effusions, whose diagnoses were confirmed by pleural biopsy, cytology or microbiological methods. We compared pleural fluid levels of ADA, TNF-alpha, IFN-gamma, IL-2, IL-6, IL-8, pH, protein, glucose, cholesterol, triglyceride, amylase and lactic dehydrogenase between tuberculous and malignant effusions. Using stepwise logistic regression analysis, we evaluated the benefit of combining various parameters. Receiver operating characteristic(ROC) curves of ADA, cytokines and equations generated from regression analyses were plotted and compared with the area under curve(AUC). Cut-off values showing the best diagnostic accuracy were selected and compared.

RESULTS

Compared to malignant effusion, tuberculous effusion showed significantly higher levels of ADA, IFN-gamma, TNF-alpha and IL-2. There was a good correlation between IFN-gamma and TNF-alpha. By stepwise logistic regression analysis, IFN-gamma, protein and ADA were independent variables predicting tuberculous from malignant effusions. The diagnostic accuracy and AUC of regression equation was greater than any other single parameters.

CONCLUSION

For the differential diagnosis of tuberculosis and malignant pleural effusions, combining ADA, protein and IFN-gamma best allows discrimination.