Background/Aims: CD4+ T cells are a critical component of the adaptive immune response. While the mechanisms controlling the differentiation of the Th1, Th17, and regulatory T cell subsets from naïve CD4+ T cells are well described, the factors that induce Th2 differentiation are still largely unknown. Methods: The effects of treatment with exogenous H2O2 on STAT-6 phosphorylation and activation in T cells were examined by immunoblotting, immunofluorescence and gel shift assay. Anti-CD3 antibody and methyl-β-cyclodextrin were utilized to induce lipid raft assembly and to investigate the involvement of lipid rafts, respectively. Results: Jurkat and EL-4 T cells that were exposed to H2O2 showed rapid and strong STAT-6 phosphorylation, and the extent of STAT-6 phosphorylation was enhanced by co-treatment with anti-CD3 antibody. The effect of H2O2 on STAT-6 phosphorylation and translocation was inhibited by disruption of lipid rafts. STAT-6 activation in response to H2O2 treatment regulated IL-4 gene expression, and this response was strengthened by treatment with anti-CD3. Conclusion: Our results indicate that reactive oxygen species such as H2O2 can act on upstream and initiating factors for activation of STAT-6 in T cells and contribute to formation of a positive feedback loop between STAT-6 and IL-4 in the Th2 differentiation process.
Glioblastoma multiform (GBM), a grade IV astrocytoma, is most lethal and common adult primary intracranial tumor. GBM is characterized by diffuse infiltration into normal brain parenchyma, rapid growth and the presence of necrosis and microglia/macrophage infiltration. Among these properties of GBM, necrosis has been implicated to be a strong predictor of poor prognosis; however, the effect of necrosis on GBM progression is poorly understood at present. In this study, we examined the effect of necrosis on glioblastoma cells by exploring molecular mechanisms underlying gene expression and chemokine expression. Data obtaining from chemokine array and ELISA showed that CRT-MG human gliomablastoma cells secreted several chemokines including MCP-1 and MIP-3α in response to necrotic cells. Expression levels of mRNA and protein of MCP-1 and MIP-3α were also increased by treatment with necrotic cells in CRT-MG in a dose-dependent manner. Necrotic cells induced NF-κB/AP-1 activation and their binding to the MCP-1 and MIP-3α promoter, leading to enhanced MCP-1 and MIP-3α production in GBM cells. Finally, transwell migration assay showed that incubation with necrotic cells significantly enhanced the migration of microglia. Our data demonstrate that when GBM cells are exposed to and stimulated by necrotic cells, the expression and secretion of MCP-1 and MIP-3α are enhanced in GBM cells and microglia infiltration/migration to the tumor site are facilitated. Citation Format: Yieun Jung, So-Hee Ahn, Hyunju Park, Jiwoo Lim, Jihee Lee Kang, Youn-Hee Choi, Eun Ju Kim. Necrotic cells promote microglia infiltration in glioblastoma through regulating MCP-1 and MIP-3α expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5924. doi:10.1158/1538-7445.AM2017-5924
Aging is a major risk factor for common neurodegenerative diseases. Although multiple molecular, cellular, structural, and functional changes occur in the brain during aging, the involvement of caveolin-2 (Cav-2) in brain ageing remains unknown. We investigated Cav-2 expression in brains of aged mice and its effects on endothelial cells. The human umbilical vein endothelial cells (HUVECs) showed decreased THP-1 adhesion and infiltration when treated with Cav-2 siRNA compared to control siRNA. In contrast, Cav-2 overexpression increased THP-1 adhesion and infiltration in HUVECs. Increased expression of Cav-2 and iba-1 was observed in brains of old mice. Moreover, there were fewer iba-1-positive cells in the brains of aged Cav-2 knockout (KO) mice than of wild-type aged mice. The levels of several chemokines were higher in brains of aged wild-type mice than in young wildtype mice; moreover, chemokine levels were significantly lower in brains of young mice as well as aged Cav-2 KO mice than in their wild-type counterparts. Expression of PECAM1 and VE-cadherin proteins increased in brains of old wildtype mice but was barely detected in brains of young wildtype and Cav-2 KO mice. Collectively, our results suggest that Cav-2 expression increases in the endothelial cells of aged brain, and promotes leukocyte infiltration and age-associated neuroinflammation.
Promyelocytic leukemia (PML) gene, through alternative splicing of its Cterminal region, generates several PML isoforms that interact with specific partners and perform distinct functions. The PML protein is a tumor suppressor that plays an important role by interacting with various proteins. Herein, we investigated the effect of the PML isoforms on oncostatin M (OSM)-induced signal transducer and activator of transcription-3 (STAT-3) transcriptional activity. PML influenced OSMinduced STAT-3 activity in a cell type-specific manner, which was dependent on the p53 status of the cells but regardless of PML isoform. Interestingly, overexpression of PML exerted opposite effects on OSM-induced STAT-3 activity in p53 wild-type and mutant cells. Specifically, overexpression of PML in the cell lines bearing wild-type p53 (NIH3T3 and U87-MG cells) decreased OSM-induced STAT-3 transcriptional activity, whereas overexpression of PML increased OSM-induced STAT-3 transcriptional activity in mutant p53-bearing cell lines (HEK293T and U251-MG cells). When wild-type p53 cells were co-transfected with PML-IV and R273H-p53 mutant, OSM-mediated STAT-3 transcriptional activity was significantly enhanced, compared to that of cells which were transfected with PML-IV alone; however, when cells bearing mutant p53 were co-transfected with PML-IV and wild-type p53, OSM-induced STAT-3 transcriptional activity was significantly decreased, compared to that of transfected cells with PML-IV alone. In conclusion, PML acts together with wild-type or mutant p53 and influences OSM-mediated STAT-3 activity in a negative or positive manner, resulting in the aberrant activation of STAT-3 in cancer cells bearing mutant p53 probably might occur through the interaction of mutant p53 with PML.
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