14 research outputs found

    Control of reactive oxygen species (ROS) machinery to maintain the cellular homeostasis

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    早稲田大学博士(理学)早大学位記番号:新9569doctoral thesi

    Cancer cell reprogramming to identify the genes competent for generating liver cancer stem cells

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    Abstract The cancer stem cell (CSC) hypothesis postulates that cancer originates from the malignant transformation of stem/progenitor cells and is considered to apply to many cancers, including liver cancer. Identification that CSCs are responsible for drug resistance, metastasis, and secondary tumor appearance suggests that these populations are novel obligatory targets for the treatment of cancer. Here, we describe our new method for identifying potential CSC candidates. The reprogramming of cancer cells via induced pluripotent stem cell (iPSC) technology is a novel therapy for the treatment and for the study of CSC-related genes. This technology has advantages for studying the interactions between CSC-related genes and the cancer niche microenvironment. This technology may also provide a useful platform for studying the genes involved in the generation of CSCs before and after reprogramming, and for elucidating the mechanisms underlying cancer initiation and progression. The present review summarizes the current understanding of transcription factors involved in the generation of liver CSCs from liver cancer cell-derived iPSCs and how these contribute to oncogenesis, and discusses the modeling of liver cancer development

    Generation of Human Stomach Cancer iPSC-Derived Organoids Induced by <i>Helicobacter pylori</i> Infection and Their Application to Gastric Cancer Research

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    There is considerable cellular diversity in the human stomach, which has helped to clarify cell plasticity in normal development and tumorigenesis. Thus, the stomach is an interesting model for understanding cellular plasticity and for developing prospective anticancer therapeutic agents. However, many questions remain regarding the development of cancers in vivo and in vitro in two- or three-dimensional (2D/3D) cultures, as well as the role of Helicobacter pylori (H. p.) infection. Here, we focus on the characteristics of cancer stem cells and their derived 3D organoids in culture, including the formation of stem cell niches. We define the conditions required for such organoid culture in vitro and examine the ability of such models for testing the use of anticancer agents. We also summarize the signaling cascades and the specific markers of stomach-cancer-derived organoids induced by H. p. infection, and their stem cell niches

    FOXM1-CD44 Signaling Is Critical for the Acquisition of Regorafenib Resistance in Human Liver Cancer Cells

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    Regorafenib is a multikinase inhibitor that was approved by the US Food and Drug administration in 2017. Cancer stem cells (CSCs) are a small subset of cancer-initiating cells that are thought to contribute to therapeutic resistance. The forkhead box protein M1 (FOXM1) plays an important role in the regulation of the stemness of CSCs and mediates resistance to chemotherapy. However, the relationship between FOXM1 and regorafenib resistance in liver cancer cells remains unknown. We found that regorafenib-resistant HepG2 clones overexpressed FOXM1 and various markers of CSCs. Patients with hepatocellular carcinoma also exhibited an upregulation of FOXM1 and resistance to regorafenib, which were correlated with a poor survival rate. We identified a close relationship between FOXM1 expression and regorafenib resistance, which was correlated with the survival of patients with hepatocellular carcinoma. Thus, a strategy that antagonizes FOXM1&ndash;CD44 signaling would enhance the therapeutic efficacy of regorafenib in these patients

    Stem Cell Biomarkers and Tumorigenesis in Gastric Cancer

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    Stomach cancer has a high mortality, which is partially caused by an absence of suitable biomarkers to allow detection of the initiation stages of cancer progression. Thus, identification of critical biomarkers associated with gastric cancer (GC) is required to advance its clinical diagnoses and treatment. Recent studies using tracing models for lineage analysis of GC stem cells indicate that the cell fate decision of the gastric stem cells might be an important issue for stem cell plasticity. They include leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5+), Cholecystokinin receptor 2 (Cckr2+), and axis inhibition protein 2 (Axin2+) as the stem cell markers in the antrum, Trefoil Factor 2 (TFF2+), Mist1+ stem cells, and Troy+ chief cells in the corpus. By contrast, Estrogen receptor 1 (eR1), Leucine-rich repeats and immunoglobulin-like domains 1 (Lrig1), SRY (sex determining region Y)-box 2 (Sox2), and B lymphoma Mo-MLV insertion region 1 homolog (Bmi1) are rich in both the antrum and corpus regions. These markers might help to identify the cell-lineage identity and analyze the plasticity of each stem cell population. Thus, identification of marker genes for the development of GC and its environment is critical for the clinical application of cancer stem cells in the prevention of stomach cancers

    Independent Signaling of Hepatoma Derived Growth Factor and Tumor Necrosis Factor-Alpha in Human Gastric Cancer Organoids Infected by <i>Helicobacter pylori</i>

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    We prepared three-dimensional (3-D) organoids of human stomach cancers and examined the correlation between the tumorigenicity and cytotoxicity of Helicobacter pylori (H. pylori). In addition, the effects of hepatoma-derived growth factor (HDGF) and tumor necrosis factor (TNFα) on the growth and invasion activity of H. pylori-infected gastric cancer organoids were examined. Cytotoxin-associated gene A (CagA)-green fluorescence protein (GFP)-labeled H. pylori was used to trace the infection in gastric organoids. The cytotoxicity of Cag encoded toxins from different species of H. pylori did not affect the proliferation of each H. pylori-infected cancer organoid. To clarify the role of HDGF and TNFα secreted from H. pylori-infected cancer organoids, we prepared recombinant HDGF and TNFα and measured the cytotoxicity and invasion of gastric cancer organoids. HDGF controlled the growth of each organoid in a species-specific manner of H. pylori, but TNFα decreased the cell viability in H. pylori-infected cancer organoids. Furthermore, HDGF controlled the invasion activity of H. pylori-infected cancer organoid in a species-dependent manner. However, TNFα decreased the invasion activities of most organoids. We found different signaling of cytotoxicity and invasion of human gastric organoids in response to HDGF and TNFα during infection by H. pylori. Recombinant HDGF and TNFα inhibited the development and invasion of H. pylori-infected gastric cancer differently. Thus, we propose that HDGF and TNFα are independent signals for development of H. pylori-infected gastric cancer. The signaling of growth factors in 3-D organoid culture systems is different from those in two-dimensional cancer cells

    Jdp2 is a spatiotemporal transcriptional activator of the AhR via the Nrf2 gene battery

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    Abstract Background Crosstalk between the aryl hydrocarbon receptor (AhR) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling is called the “AhR–Nrf2 gene battery”, which works synergistically in detoxification to support cell survival. Nrf2-dependent phase II gene promoters are controlled by coordinated recruitment of the AhR to adjacent dioxin responsive element (DRE) and Nrf2 recruitment to the antioxidative response element (ARE). The molecular interaction between AhR and Nrf2 members, and the regulation of each target, including phase I and II gene complexes, and their mediators are poorly understood. Methods Knockdown and forced expression of AhR–Nrf2 battery members were used to examine the molecular interactions between the AhR–Nrf2 axis and AhR promoter activation. Sequential immunoprecipitation, chromatin immunoprecipitation, and histology were used to identify each protein complex recruited to their respective cis-elements in the AhR promoter. Actin fiber distribution, cell spreading, and invasion were examined to identify functional differences in the AhR–Jdp2 axis between wild-type and Jdp2 knockout cells. The possible tumorigenic role of Jdp2 in the AhR–Nrf2 axis was examined in mutant Kras-Trp53-driven pancreatic tumors. Results Crosstalk between AhR and Nrf2 was evident at the transcriptional level. The AhR promoter was activated by phase I ligands such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) through the AhR–Jdp2–Nrf2 axis in a time- and spatial transcription-dependent manner. Jdp2 was a bifunctional activator of DRE- and ARE-mediated transcription in response to TCDD. After TCDD exposure, Jdp2 activated the AhR promoter at the DRE and then moved to the ARE where it activated the promoter to increase reactive oxygen species (ROS)-mediated functions such as cell spreading and invasion in normal cells, and cancer regression in mutant Kras-Trp53-driven pancreatic tumor cells. Conclusions Jdp2 plays a critical role in AhR promoter activation through the AhR–Jdp2–Nrf2 axis in a spatiotemporal manner. The AhR functions to maintain ROS balance and cell spreading, invasion, and cancer regression in a mouse model of mutant Kras–Trp53 pancreatic cancer. These findings provide new insights into the roles of Jdp2 in the homeostatic regulation of oxidative stress and in the antioxidation response in detoxification, inflammation, and cancer progression

    Additional file 1 of Jdp2 is a spatiotemporal transcriptional activator of the AhR via the Nrf2 gene battery

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    Additional file 1: Supplementary Figure S1. Luciferase activity driven by the Cyp1b1 promoter in response to TCDD. Supplementary Figure S2. Characteristics of AhR protein expression and effects of Jdp2 on AhR expression. Supplementary Figure S3. Characterization of AhR promoter activity. Supplementary Figure S4. Interaction of the AhR–Jdp2–Nrf2 axis in nuclei and cytoplasm in WT and Jdp2–/–MEFs in response to TCDD or DMSO exposure for the times indicated. Supplementary Figure S5. Characterization of the DRE2 mutation in the AhR promoter region and expression of the Jdp2 target genes. Supplementary Figure S6. EMSA assay of GST–AhR–basic helix-loop-helix (aHLH) binding to DRE2, DRE3 and ARE1 in vitro. Supplementary Figure S7. Relative mRNA expression of the AhR target genes Aldh3a1 (A), Cyp1b1 (B), and Tiparp (C) after exposure to DMSO and TCDD in WT and Jdp2−/− MEFs. Supplementary Figure S8. Uncropped raw data of western blots which were used in this article. Supplementary Table S1. Antibodies used in this study. Supplementary Table S2. Oligonucleotides. Supplementary Table S3. Mutation of ARE1, ARE2, DRE1, DRE2, and DRE3 in AhR promoter. Supplementary Table S4. siRNAs used in this study. Supplementary Table S5. Experimental models: organisms/strains. Supplementary Table S6. Experimental models: cell line. Supplementary Table S7. Critical commercial assay. Supplementary Table S8. Chemicals, peptides, and recombinant proteins. Supplementary Table S9. Recombinant DNA Supplementary Table S10. Software and algorithms

    Bovine Induced Pluripotent Stem Cells Are More Resistant to Apoptosis than Testicular Cells in Response to Mono-(2-ethylhexyl) Phthalate

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    Although the androgen receptor (AR) has been implicated in the promotion of apoptosis in testicular cells (TSCs), the molecular pathway underlying AR-mediated apoptosis and its sensitivity to environmental hormones in TSCs and induced pluripotent stem cells (iPSCs) remain unclear. We generated the iPSCs from bovine TSCs via the electroporation of OCT4. The established iPSCs were supplemented with leukemia inhibitory factor and bone morphogenetic protein 4 to maintain and stabilize the expression of stemness genes and their pluripotency. Apoptosis signaling was assessed after exposure to mono-(2-ethylhexyl) phthalate (MEHP), the active metabolite of di-(2-ethylhexyl) phthalate. Here, we report that iPSCs were more resistant to MEHP-induced apoptosis than were original TSCs. MEHP also repressed the expression of AR and inactivated WNT signaling, and then led to the commitment of cells to apoptosis via the cyclin dependent kinase inhibitor p21CIP1. The loss of the frizzed receptor 7 and the gain of p21CIP were responsible for the stimulatory effect of MEHP on AR-mediated apoptosis. Our results suggest that testicular iPSCs can be used to study the signaling pathways involved in the response to environmental disruptors, and to assess the toxicity of environmental endocrine disruptors in terms of the maintenance of stemness and pluripotency
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