17 results on '"Tou L"'
Search Results
2. Regulation of human cbfa1 gene transcription in osteoblasts by selective estrogen receptor modulators (SERMs)
- Author
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Tou, L., Quibria, N., and Alexander, J. M.
- Published
- 2001
- Full Text
- View/download PDF
3. A novel single-port robotic proximal gastrectomy with right-sided overlap and single-flap valvuloplasty (RPG-ROSF) to treat gastroesophageal cancer: A case report.
- Author
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Tou L, Jiang C, Wu D, Zheng J, Luo D, Que H, Sun Z, Wang C, Wang Y, Tao X, Wang J, Li C, Li S, Zhu X, and Xu H
- Subjects
- Humans, Male, Middle Aged, Esophageal Neoplasms surgery, Esophageal Neoplasms pathology, Surgical Flaps, Robotic Surgical Procedures, Gastrectomy methods, Stomach Neoplasms surgery, Stomach Neoplasms pathology, Adenocarcinoma surgery, Adenocarcinoma pathology
- Abstract
Robotic surgery has been widely used in surgical gastric cancer treatments, including proximal gastrectomy. Single-port robotic system is gaining more popularity in robotic surgery, but there has been no report on its application in robotic proximal gastrectomy with right-sided overlap and single-flap valvuloplasty (RPG-ROSF). Here, we report an RPG-ROSF using a novel single-port robotic system in a 51-year-old male patient with an early-stage gastroesophageal cancer detected by gastroscopy. It took 90 min for robotic setup, 143 min for dissection, and 161 min for digestive tract reconstruction. There was no complication during and after the surgery. The patient was discharged in 8 days postsurgery. The pathological staging of the adenocarcinoma was pT1aN0M0. This preliminary study demonstrated the feasibility and safety of a novel single-port robot in RPG-ROSF., (© 2024 Asia Endosurgery Task Force and Japan Society of Endoscopic Surgery and John Wiley & Sons Australia, Ltd.)
- Published
- 2024
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- View/download PDF
4. The prognostic role of palliative gastrectomy in advanced gastric cancer: a systematic review and meta-analysis.
- Author
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Luo D, Xu H, Jiang C, Zheng J, Wu D, Tou L, Que H, and Sun Z
- Subjects
- Humans, Prognosis, Length of Stay statistics & numerical data, Stomach Neoplasms surgery, Stomach Neoplasms mortality, Stomach Neoplasms pathology, Gastrectomy methods, Palliative Care
- Abstract
Background: The effectiveness of palliative gastrectomy for advanced GC remains a topic of debate. This study sought to establish whether palliative gastrectomy has an impact on prolonging survival., Methods: We carried out systematic searches in PubMed, Cochrane Library, Web of Science, and the EMBASE databases from database inception to July 2023 to gather studies that examined the connection between palliative gastrectomy and the prognosis of advanced GC. The study employed overall survival as the primary outcome, with the hazard ratio serving as the selected parameter to gauge the association. Subgroup analyses were performed to delve into potential differences within the included studies, categorizing them by study region and sample size in order to examine possible sources of heterogeneity. The stability of individual studies was assessed through sensitivity analysis. The analysis included 20 articles, encompassing a total of 23,061 patients., Results: According to the meta-analysis results, patients who underwent palliative gastrectomy exhibited a noteworthy enhancement in overall survival (HR: 1.49; 95% CI: 1.12-1.99; P = 0.006) in comparison to those who did not receive this procedure. There was no association between the type of surgery and the length of hospital stay, as revealed by the analysis (HR = -0.02; 95% CI: -0.84-0.81; P = 0.970)., Conclusions: Based on this meta-analysis, patients with advanced gastric cancer who underwent palliative gastrectomy may experience an extended survival duration without a significant prolongation of their hospitalization., (© 2024. The Author(s).)
- Published
- 2024
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- View/download PDF
5. NEK2 affects the ferroptosis sensitivity of gastric cancer cells by regulating the expression of HMOX1 through Keap1/Nrf2.
- Author
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Wu J, Luo D, Tou L, Xu H, Jiang C, Wu D, Que H, and Zheng J
- Abstract
NEK2 is a serine/threonine protein kinase that is involved in regulating the progression of various tumors. Our previous studies have found that NEK2 is highly expressed in gastric cancer and suggests that patients have a worse prognosis. However, its role and mechanism in gastric cancer are only poorly studied. In this study, we established a model of ferroptosis induced by RSL3 or Erastin in AGS cells in vitro, and konckdown NEK2, HOMX1, Nrf2 by siRNA. The assay kit was used to analyzed cell viability, MDA levels, GSH and GSSG content, and FeRhoNox™-1 fluorescent probe, BODIPY™ 581/591 C11 lipid oxidation probe, CM-H2DCFDA fluorescent probe were used to detected intracellular Fe
2+ , lipid peroxidation, and ROS levels, respectively. Calcein-AM/PI staining was used to detect the ratio of live and dead cells, qRT-PCR and Western blot were used to identify the mRNA and protein levels of genes in cells, immunofluorescence staining was used to analyze the localization of Nrf2 in cells, RNA-seq was used to analyze changes in mRNA expression profile, and combined with the FerrDb database, ferroptosis-related molecules were screened to elucidate the impact of NEK2 on the sensitivity of gastric cancer cells to ferroptosis. We found that inhibition of NEK2 could enhance the sensitivity of gastric cancer cells to RSL3 and Erastin-induced ferroptosis, which was reflected in the combination of inhibition of NEK2 and ferroptosis induction compared with ferroptosis induction alone: cell viability and GSH level were further decreased, while the proportion of dead cells, Fe2+ level, ROS level, lipid oxidation level, MDA level, GSSG level and GSSG/GSH ratio were further increased. Mechanism studies have found that inhibiting NEK2 could promote the expression of HMOX1, a gene related to ferroptosis, and enhance the sensitivity of gastric cancer cells to ferroptosis by increasing HMOX1. Further mechanism studies have found that inhibiting NEK2 could promote the ubiquitination and proteasome degradation of Keap1, increase the level of Nrf2 in the nucleus, and thus promote the expression of HMOX1. This study confirmed that NEK2 can regulate HMOX1 expression through Keap1/Nrf2 signal, and then affect the sensitivity of gastric cancer cells to ferroptosis, enriching the role and mechanism of NEK2 in gastric cancer., (© 2024. The Author(s).)- Published
- 2024
- Full Text
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6. PN3b as an independent risk factor for poor prognosis and peritoneal recurrence in Borrmann type IV gastric cancer: A retrospective cohort study.
- Author
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Chen Y, Chen Y, Wen L, Tou L, Wang H, and Teng L
- Abstract
Background: The clinicopathological features and surgical treatment strategies of Borrmann type IV gastric cancer (GC) remain controversial. Peritoneal metastasis is the most common recurrence pattern in patients with Borrmann type IV GC., Methods: Among 2026 gastric cancer between January 2009 and August 2019, 159 cases of Borrmann type IV GC were included in this study (7.8%). We retrospectively analyzed the clinicopathological characteristics and prognosis of these patients. Univariate and multivariate Cox proportional hazards were applied to identify independent prognostic factors. Predictors related to peritoneal metastasis of type IV GC were analyzed by multivariate Cox regression analysis., Results: Borrmann type IV gastric cancer was associated with more advanced clinicopathological features at diagnosis than the other Borrmann type GC. Of the 159 patients with Borrmann type IV GC, the median OS was 23 months. The number of patients with peritoneal metastasis was 43, accounted for 27.0% of all the patients and 87.8% of the patients with distant metastasis. Multivariate analyses revealed lymph node metastasis to be independent prognostic factor for survival in Borrmann type IV GC patients. pN3b and tumor size > 50 mm showed to be risk factors for peritoneal metastasis., Conclusions: Borrmann type IV GC is an important independent prognostic factor. pN3b is an independent prognostic factor and a predictor of peritoneal metastasis in patients with Borrmann type IV GC., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2022 Chen, Chen, Wen, Tou, Wang and Teng.)
- Published
- 2022
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7. Induction, Proliferation, Regeneration and Kinsenoside and Flavonoid Content Analysis of the Anoectochilus roxburghii (Wall.) Lindl Protocorm-like Body.
- Author
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Wang H, Chen X, Yan X, Xu Z, Shao Q, Wu X, Tou L, Fang L, Wei M, and Wang H
- Abstract
Anoectochilus roxburghii (Wall.) Lindl has been used in Chinese herbal medicine for treating various ailments. However, its wild resources are endangered, and artificial cultivation of the plant is limited by the low regeneration rate of conventional propagation methods. The lack of A. roxburghii resources is detrimental to the commercial production of the plant and kinsenoside, which is unique to Anoectochilus species. To develop highly efficient methods for A. roxburghii micropropagation and find alternative resources for kinsenoside production, we created an induction, proliferation, and regeneration of PLBs (IPR-PLB) protocol for A. roxburghii . We also analyzed the kinsenoside and flavonoid contents during the induction and proliferation of PLBs. The best media of IPR-PLB for PLB induction and proliferation (secondary PLB induction and proliferation), shoot formation, and rooting medium were Murashige and Skoog (MS) + 3 mg/L 6-benzylaminopurine (6-BA) + 0.5 mg/L naphthaleneacetic acid (NAA) + 0.8 mg/L zeatin (ZT) + 0.2 mg/L 2,4-dichlorophenoxyacetic acid (2, 4-D), MS + 3 mg/L 6-BA + 0.5 mg/L NAA, and MS + 0.5 mg/L NAA, respectively. On these optimized media, the PLB induction rate was 89 ± 2.08%, secondary PLB induction rate was 120 ± 5%, secondary PLB proliferation rate was 400 ± 10% and 350 ± 10 % in terms of the quantity and biomass at approximately 1 month, shoot induction rate was 10.5 shoots/PLB mass, and root induction rate was 98%. All plantlets survived after acclimation. Darkness or weak light were essential for PLB proliferation, and light was crucial for PLB differentiation on these optimized media. The kinsenoside contents of PLBs and secondary PLBs were 10.38 ± 0.08 and 12.30 ± 0.08 mg/g fresh weight (FW), respectively. Moreover, the peak kinsenoside content during the proliferation of secondary PLBs was 34.27 ± 0.79 mg/g FW, which was slightly lower than that of the whole plant (38.68 ± 3.12 mg/g FW). Two flavonoids exhibited tissue- or temporal-specific accumulation patterns, and astragalin accumulated exclusively during the first 2 weeks of cultivation. The IPR-PLB protocol for A. roxburghii may facilitate the efficient micropropagation of A. roxburghii plants. Furthermore, the PLBs are a good alternative resource for kinsenoside production., Competing Interests: The authors declare that there are no conflicts of interest.
- Published
- 2022
- Full Text
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8. The effect of splicing MST1R in gastric cancer was enhanced by lncRNA FENDRR.
- Author
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Zhou D, Zhu X, Wu X, Zheng J, Tou L, and Zhou Y
- Abstract
Gastric cancer (GC) poses a serious threat to human health worldwide. Serine/arginine rich splicing factor 1 (SRSF1) has been reported to serve regulatory roles during the tumorigenesis of GC. In addition, the macrophage stimulating 1 receptor (MST1R) signaling pathway was found to participate in the progression of GC. However, the association between MST1R and SRSF1 in the tumorigenesis of GC remains unclear. The expression levels of MST1R and the recepteur d'origine nantais (RON) Δ160 splicing variant were analyzed in cells using western blotting and immunofluorescence staining. Co-immunoprecipitation assays were used to investigate the interaction between SRSF1 and MST1R. A Cell Counting Kit-8 assay was performed to analyze cell viability. Flow cytometry and Transwell assays were used to determine cell apoptosis and invasiveness levels. The potential interaction between SFSR1 and long non-coding RNAs (lncRNAs) was investigated with an online bioinformatics tool. The findings of the present study revealed that the expression levels of MST1R and RON Δ160 were significantly upregulated in GC Kato III cells. SRSF1 was found to be regulated by the lncRNA FOXF1 adjacent non-coding developmental regulatory RNA (FENDRR). The knockdown of SRSF1 or FENDRR downregulated the expression levels of MST1R in Kato III cells. In addition, the expression levels of RON Δ160 were markedly downregulated in Kato III cells following the knockdown of FENDRR. Meanwhile, SRSF1 directly bound to MST1R, while this phenomenon was partially reversed by FENDRR short interfering RNA. FENDRR could interact with SRSF1 in Kato III cells and the knockdown of FENDRR also induced the apoptosis of GC cells. In conclusion, the findings of the present study suggested that the lncRNA FENDRR may function as an oncogene during the progression of GC by regulating alternative splicing of MST1R and SRSF1 expression levels. lncRNA FENDRR may serve as a potential marker for the diagnosis or target for the treatment of GC., Competing Interests: These authors declare that they have no competing interests., (Copyright: © Zhou et al.)
- Published
- 2021
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9. MAGOH/MAGOHB Inhibits the Tumorigenesis of Gastric Cancer via Inactivation of b-RAF/MEK/ERK Signaling.
- Author
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Zhou Y, Li Z, Wu X, Tou L, Zheng J, and Zhou D
- Abstract
Background: Gastric cancer is one of the most malignant tumors all over the world. It has been reported that proteins play key roles during the tumorigenesis of gastric cancer. To identify novel potential targets for gastric cancer, differential expressed proteins between gastric cancer and adjacent normal tissues were analyzed with proteomics and bioinformatics tool., Methods: The differentially expressed proteins between gastric cancer and adjacent normal tissues were analyzed by Omicsbean (multi-omics data analysis tool). Cell viability was tested by CCK-8 assay. Flow cytometry was used to measure cell apoptosis and cycle. Transwell assay was used to test cell migration and invasion. Gene and protein expressions were detected by RT-qPCR, immunohistochemistry and Western blot, respectively., Results: MAGOH and MAGOHB were found to be notably upregulated in gastric cancer tissues compared with that in normal tissues. Knockdown of MAGOH significantly inhibited the proliferation of gastric cancer cells via inducing the cell apoptosis. In addition, MAGOH knockdown induced G2 phase arrest in gastric cancer cells. Moreover, MAGOH knockdown notably inhibited migration and invasion of gastric cancer cells. Importantly, double knockdown of MAGOH and MAGOHB exhibited much better anti-tumor effects on gastric cancer compared with alone treatment. Finally, double knockdown of MAGOH and MAGOHB mediated the tumorigenesis of gastric cancer via regulation of RAF/MEK/ERK signaling., Conclusion: MAGOH knockdown inhibited the tumorigenesis of gastric cancer via mediation of b-RAF/MEK/ERK signaling, and double knockdown of MAGOH and MAGOHB exhibited much better anti-tumor effects. This finding might provide us a new strategy for the treatment of gastric cancer., Competing Interests: The authors declared no competing interests in this study. Yong Zhou and Zhongqi Li are co-first authors for this study., (© 2020 Zhou et al.)
- Published
- 2020
- Full Text
- View/download PDF
10. The Relationship between Green Organization Identity and Corporate Environmental Performance: The Mediating Role of Sustainability Exploration and Exploitation Innovation.
- Author
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Xing X, Wang J, and Tou L
- Subjects
- China, Conservation of Natural Resources, Organizations statistics & numerical data, Social Identification
- Abstract
The link between green organizational identity (GOI) and corporate environmental performance (CEP) has been investigated, but existing studies have no consistent conclusion. A significant research gap remains regarding the mediating role of sustainability exploration innovation (SER), sustainability exploitation innovation (SEI), and the moderating role of government environmental regulation (GER). This study explored the relationship between GOI and CEP in a moderated meditation model which includes SER, SEI, and GER. Using structural equation modelling and bootstrap method based on data sets from of 380 Chinese companies, the results show that: (1) GOI promotes SER, thereby enhancing CEP; (2) GOI promotes SEI, thereby enhancing CEP; (3) GER can positively moderate the indirect effect of GOI on CEP via SER; (4) GER negatively moderate the indirect effect of GOI on CEP via SEI. These findings suggest that firms choose different innovative ways between SER and SEI to improve CEP which depends on different levels of GER in China.
- Published
- 2019
- Full Text
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11. Research on the Influence Mechanism of Rational Consumers' Food Safety Supervision Satisfaction.
- Author
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Wang J, Diao H, and Tou L
- Subjects
- Attitude, Humans, Research, Safety Management, Consumer Behavior, Food Safety
- Abstract
As emerging food safety incidents have gained widespread concerns, research on consumers' attitudes towards this issue is crucial to create effective solutions. To this end, in accordance with relevant data of consumers in 13 cities with subordinate districts, Jiangsu province, this paper divided different consumer groups by their experience so as to study their degree of satisfaction towards food safety and corresponding influencing factors. According to the descriptive statistics and the building of the cumulative logistic regression model, the results therefrom showed that consumers with direct or indirect experience have separate attitudes towards food safety which cannot be changed by changing consumers' personal characteristics. Moreover, the two groups are divided in their demands in food production and consumption along with exceptions on policy implementation, etc. Finally, suggestions to improve consumers' satisfaction are given in at the end of the paper.
- Published
- 2019
- Full Text
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12. Backbone dynamics of human parathyroid hormone (1-34): flexibility of the central region under different environmental conditions.
- Author
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Scian M, Marin M, Bellanda M, Tou L, Alexander JM, Rosenblatt M, Chorev M, Peggion E, and Mammi S
- Subjects
- Amino Acid Sequence, Buffers, Escherichia coli genetics, Glutathione Transferase metabolism, Humans, Hydrophobic and Hydrophilic Interactions, Micelles, Molecular Sequence Data, Nitrogen Isotopes, Nuclear Magnetic Resonance, Biomolecular, Parathyroid Hormone chemistry, Parathyroid Hormone isolation & purification, Peptide Fragments chemistry, Phosphorylcholine chemistry, Protein Conformation, Protein Structure, Secondary, Protein Structure, Tertiary, Recombinant Fusion Proteins chemistry, Solutions, Parathyroid Hormone analogs & derivatives, Phosphorylcholine analogs & derivatives, Sodium Chloride chemistry
- Abstract
The presence of a stable tertiary structure in the bioactive N-terminal portion of parathyroid hormone (PTH), a major hormone in the maintenance of extracellular calcium homeostasis, is still debated. In this work, 15N relaxation parameters of the 33 backbone amides of human PTH(1-34) were determined in phosphate-buffered saline solution (PBS) and in the presence of dodecylphosphocholine (DPC) micelles. The relaxation parameters were analyzed using both the model-free formalism (G. Lipari and A. Szabo, Journal of the American Chemical Society, 1982, Vol. 104, pp. 4546-4549) and the reduced spectral density functions approach (J.-F. Lefevre, K. T. Dayie, J. W. Peng, and G. Wagner, Biochemistry, 1996, Vol. 35, pp. 2674-2686). In PBS, the region around Gly12 possesses a high degree of flexibility and the C-terminal helix is less flexible than the N-terminal one. In the presence of DPC micelles, the mobility of the entire molecule is reduced, but the stability of the N-terminal helix increases relative to the C-terminal one. A point of relatively higher mobility at residue Gly12 is still present and a new site of local mobility at residues 16-17 is generated. These results justify the lack of experimental nuclear Overhauser effect (NOE) restraints with lack of tertiary structure and support the hypothesis that, in the absence of the receptor, the relative spatial orientation of the two N- and C-terminal helices is undefined. The flexibility in the midregion of PTH(1-34), maintained in the presence of the membrane-mimetic environment, may enable the correct relative disposition of the two helices, favoring a productive interaction with the receptor., (Copyright 2005 Wiley Periodicals, Inc.)
- Published
- 2006
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13. Hic-5 regulates an epithelial program mediated by PPARgamma.
- Author
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Drori S, Girnun GD, Tou L, Szwaya JD, Mueller E, Xia K, Shivdasani RA, and Spiegelman BM
- Subjects
- Adipocytes cytology, Adipocytes metabolism, Animals, Cell Differentiation physiology, Colonic Neoplasms metabolism, Cytoskeletal Proteins genetics, DNA-Binding Proteins genetics, Epithelium metabolism, Gastrointestinal Tract embryology, Gene Expression Regulation, Developmental physiology, Kruppel-Like Factor 4, LIM Domain Proteins, Mice, PPAR gamma genetics, RNA, Small Interfering metabolism, Cytoskeletal Proteins metabolism, DNA-Binding Proteins metabolism, Gastrointestinal Tract metabolism, PPAR gamma metabolism
- Abstract
PPARgamma is a dominant regulator of fat cell differentiation. However, this nuclear receptor also plays an important role in the differentiation of intestinal and other epithelial cell types. The mechanism by which PPARgamma can influence the differentiation of such diverse cell lineages is unknown. We show here that PPARgamma interacts with Hic-5, a coactivator protein expressed in gut epithelial cells. Hic-5 and PPARgamma colocalize to the villus epithelium of the small intestine, and their expression during embryonic gut development correlates with the transition from endoderm to a specialized epithelium; expression of both these factors is reduced in tumors. Forced expression of Hic-5 in colon cancer cells enhances the PPARgamma-mediated induction of several gut epithelial differentiation/maturation markers such as L-FABP, kruppel-like factor 4 (KLF4), and keratin 20. siRNA directed against Hic-5 specifically reduces PPARgamma-mediated induction of gut epithelial genes in colon cells and in an ex vivo model of embryonic gut differentiation. Finally, forced expression of Hic-5 during 3T3-L1 preadipocyte differentiation inhibits adipogenesis while inducing inappropriate expression of several mRNAs characteristic of gut epithelium in these mesenchymal cells. These results indicate that Hic5 is an important component in determining an epithelial differentiation program induced by PPARgamma.
- Published
- 2005
- Full Text
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14. Insights into developmental mechanisms and cancers in the mammalian intestine derived from serial analysis of gene expression and study of the hepatoma-derived growth factor (HDGF).
- Author
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Lepourcelet M, Tou L, Cai L, Sawada J, Lazar AJ, Glickman JN, Williamson JA, Everett AD, Redston M, Fox EA, Nakatani Y, and Shivdasani RA
- Subjects
- Animals, Base Pair Mismatch, Cell Differentiation, DNA Repair, DNA, Complementary metabolism, Databases, Genetic, Gene Expression Profiling, Heterogeneous-Nuclear Ribonucleoproteins metabolism, Humans, In Situ Hybridization, Intercellular Signaling Peptides and Proteins genetics, Intestinal Mucosa, Mice, RNA, Messenger metabolism, RNA, Neoplasm, Reverse Transcriptase Polymerase Chain Reaction, Signal Transduction, Time Factors, Gene Expression Regulation, Developmental, Gene Expression Regulation, Neoplastic, Intercellular Signaling Peptides and Proteins physiology, Intestinal Neoplasms genetics, Intestinal Neoplasms metabolism, Neoplasms metabolism
- Abstract
The vertebrate intestine is a model for investigating inductive cellular interactions and the roles of epithelial stem cells in tissue regeneration, and for understanding parallels between development and cancer. We have used serial analysis of gene expression to measure transcript levels across stages in mouse intestine development. The data (http://genome.dfci.harvard.edu/GutSAGE) identify novel differentiation products, potential effectors of epithelial-mesenchymal interactions, and candidate markers and regulators of intestinal epithelium. Transcripts that decline significantly during intestine development frequently are absent from the adult gut. We show that a significant proportion of such genes may be reactivated in human colon cancers. As an example, hepatoma-derived growth factor (HDGF) mRNA is expressed prominently in early gut tissue, with substantially reduced levels after villous epithelial differentiation. HDGF expression is dramatically increased in human colorectal cancers, especially in tumors proficient in DNA mismatch repair, and thus represents a novel marker for a distinctive tumor subtype. HDGF overexpression in fetal intestine explants inhibits maturation, suggesting a role in epithelial differentiation. To investigate the molecular basis for HDGF functions, we isolated components of a nuclear HDGF complex, including heterogeneous nuclear ribonucleoproteins implicated in processing RNA. These genes are regulated in tandem with HDGF during intestine development and one factor, TLS/Fus, is commonly overexpressed in colon cancers. Tumor expression of fetal genes may underlie similarities between developing and malignant tissues, such as self-renewal, invasion and angiogenesis. Our findings also advance understanding of HDGF functions and implicate this developmentally regulated gene in RNA metabolic pathways that may influence malignant behaviors in colorectal cancer.
- Published
- 2005
- Full Text
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15. Regulation of mammalian epithelial differentiation and intestine development by class I histone deacetylases.
- Author
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Tou L, Liu Q, and Shivdasani RA
- Subjects
- Acetylation, Animals, Culture Techniques, Embryo, Mammalian anatomy & histology, Embryo, Mammalian physiology, Gene Expression Profiling, Gene Expression Regulation, Histone Deacetylases genetics, Intestinal Mucosa cytology, Intestinal Mucosa physiology, Mice, Promoter Regions, Genetic, Cell Differentiation physiology, Histone Deacetylases metabolism, Intestinal Mucosa growth & development, Morphogenesis
- Abstract
The biochemical mechanisms underlying epigenetic control of gene expression are increasingly well known. In contrast, the contributions of individual modifications toward activation of lineage-specific genes during vertebrate development are poorly understood. Class II histone deacetylases (HDACs), which show restricted tissue distribution, regulate muscle-specific gene expression, in part through interactions with myogenic transcription factors. We have combined gene expression profiling with manipulation of fetal mouse intestinal tissue to define roles for other regulatory factors. We found that in the developing mouse intestine class I HDACs are confined to the prospective epithelium and that their levels decline coincidently with activation of differentiation genes, suggesting a functional relationship between these events. Overexpression of wild-type but not of mutant HDACs 1 and 2 in fetal intestine explants reverses expression of certain maturation markers. HDAC inhibitors, including the selective class I antagonist valproic acid, activate the same genes prematurely and accelerate cytodifferentiation. Chromatin immunoprecipitation of freshly isolated organs reveals early HDAC2 occupancy at differentiation gene promoters and corresponding histone hypoacetylation that reverses as HDAC levels fall. Thus, modulation of endogenous class I HDAC levels represents a previously unappreciated mechanism to enable onset of tissue-restricted gene expression in a developing mammalian organ.
- Published
- 2004
- Full Text
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16. Transcriptional regulation of the human Runx2/Cbfa1 gene promoter by bone morphogenetic protein-7.
- Author
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Tou L, Quibria N, and Alexander JM
- Subjects
- Alkaline Phosphatase biosynthesis, Alkaline Phosphatase metabolism, Animals, Base Sequence, Binding Sites, Bone Morphogenetic Protein 7, Cell Line, Core Binding Factor Alpha 1 Subunit, Core Binding Factors, Down-Regulation, Enhancer Elements, Genetic, Genes, Regulator, Humans, Luciferases genetics, Luciferases metabolism, Mice, Molecular Sequence Data, MyoD Protein metabolism, Neoplasm Proteins isolation & purification, Neoplasm Proteins metabolism, RNA, Messenger metabolism, Transcription Factors isolation & purification, Transcription Factors metabolism, Up-Regulation, Bone Morphogenetic Proteins pharmacology, Myoblasts, Skeletal metabolism, Neoplasm Proteins genetics, Promoter Regions, Genetic, Transcription Factors genetics, Transcriptional Activation, Transforming Growth Factor beta
- Abstract
It is well established that core binding factor Runx2/Cbfa1 is required for osteoblast recruitment and differentiation from mesenchymal stem cells. Transcriptional regulation of the Runx2/Cbfa1 gene by osteogenic factors such as bone morphogenetic proteins (BMPs) plays an important role in the stimulation of bone formation by these cytokines. BMP7 (also termed OP-1) is a member of the transforming growth factor beta (TGF-beta) superfamily and induces osteoblast differentiation from mesenchymal precursor stem cells in vitro as well as bone formation in vivo. This study examines the effects of BMP7 on markers of osteoblast differentiation and specifically on human Runx2/Cbfa1 gene transcription in a mouse C2C12 myoblast cell line where it induces expression of both alkaline phosphatase (ALP) and endogenous Runx2/Cbfa1. To further understand the mechanisms of human Runx2/Cbfa1 transcriptional regulation by BMP7, we cloned 3.0 kb of the human Runx2/Cbfa1 gene 5'-upstream flanking region and created a series of promoter deletions cloned into luciferase-based reporter vectors (Runx2/Cbfa1/Luc). Sequence data revealed six copies of the osteoblastic cis-acting element (OSE2) in the proximal promoter region. In C2C12 cells transiently transfected with Runx2/Cbfa1/Luc deletion constructs, transcriptional activity of Runx2/Cbfa1 was upregulated up to 2-fold after 24 h of BMP7 treatment. Mutational analysis demonstrated that the minimal responsive promoter region for BMP7-regulated transcription maps to a proximal -74 OSE2 site. Electromobility shift assays with C2C12 cellular extracts indicate that BMP7 increases binding of OSE2 promoter sequences, and supershift assays with anti-Runx2/Cbfa1 antibodies demonstrate that Runx2/Cbfa1 is part of the nucleoprotein complex binding OSE2. Together, these data indicate BMP7 can upregulate Runx2/Cbfa1 gene expression in C2C12 myoblast cells, and suggest that Runx2/Cbfa1 may bind to OSE2 elements within its own promoter to autoregulate gene transcription in differentiating osteoblasts.
- Published
- 2003
- Full Text
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17. Calcium-selective ion channel, CaT1, is apically localized in gastrointestinal tract epithelia and is aberrantly expressed in human malignancies.
- Author
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Zhuang L, Peng JB, Tou L, Takanaga H, Adam RM, Hediger MA, and Freeman MR
- Subjects
- Amino Acid Sequence, Animals, Calcium Channels genetics, Calcium Channels immunology, Cells, Cultured, Exocrine Glands metabolism, Female, Fluorescent Antibody Technique, Indirect, Humans, Immunoenzyme Techniques, Male, Mice, Mice, Inbred BALB C, Molecular Sequence Data, RNA, Messenger genetics, Sequence Analysis, Protein, TRPV Cation Channels, Transfection, Calcium Channels metabolism, Intestinal Mucosa metabolism, Neoplasms metabolism
- Abstract
CaT1 is a highly selective calcium entry channel that has been proposed to be responsible for apical calcium entry in the vitamin D-regulated transcellular pathway of Ca(2+) absorption; however, the lack of a CaT1 antibody suitable for immunohistochemistry has prevented the direct testing of this hypothesis by the localization of CaT1 protein in the gastrointestinal tract and other tissues. In this study, we developed two CaT1 antibodies and have used them to establish for the first time that CaT1 localizes to the apical membrane of intestinal absorptive cells, thereby providing the first direct evidence that this protein is in fact an apical entry channel in the gastrointestinal tract. In addition, we found that CaT1 protein is highly expressed in a number of exocrine organs including pancreas, prostate, and mammary gland, suggesting an, as yet, unrecognized role in secretory epithelia. Finally, we found CaT1 protein to be present at elevated levels in comparison with normal tissues in a series of prostate, breast, thyroid, colon, and ovarian carcinomas, consistent with previous reports of up-regulation of CaT1 mRNA in prostate cancer tissues. Our findings indicate that CaT1 is likely to serve as a component of transcellular calcium transport mechanisms in many tissues and epithelial cancers.
- Published
- 2002
- Full Text
- View/download PDF
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