BACKGROUND & AIMS: The Wnt signaling pathway is required for maintenance of the intestinal epithelia; blocking this pathway reduces the proliferative capacity of the intestinal stem cells. However, aberrant Wnt signaling leads to intestinal cancer. We investigated the roles of the Wnt pathway in homeostasis of the intestinal epithelium and during malignant transformation in human cells and mice. METHODS: We performed chromatin immunoprecipitation (ChIP) with DNA microarray analysis (ChIP-on-chip) to identify genes regulated by Wnt signaling in human colorectal cancer cells Colo320, DLD1, LS174T, and SW480. Formation of intestinal tumor was induced in C57BL/6J mice using azoxymethane and dextran sulfate. Intestinal tissues from these mice, as well as Apc(+/Min) and Apc(CKO/CKO)/Lgr5-EGFP-IRES-CreERT2 mice, were analyzed by immunohistochemistry and in situ hybridization. RESULTS: We identified promoter regions of 960 genes that interacted with the Wnt pathway nuclear effector T-cell factor 4 in 4 different human colorectal cancer-derived cell lines; 18 of these promoters were present in all chromatin precipitates. Wnt signaling up-regulated a member of the tumor necrosis factor receptor superfamily called TROY. Levels of TROY messenger RNA were increased in human cells with deficiencies in the adenomatous polyposis coli (APC) gene and in cells stimulated with the Wnt3a ligand. Expression of Troy was significantly up-regulated in neoplastic tissues from mice during intestinal tumorigenesis. Lineage tracing experiments revealed that Troy is produced specifically by fast-cycling intestinal stem cells. TROY associated with a unique marker of these cells, leucine-rich repeat-containing G-protein coupled receptor (LGR) 5. In organoids established from the intestinal crypts, Troy suppressed signaling mediated by R-spondin, a Wnt agonist. CONCLUSIONS: TROY is up-regulated in human colorectal cancer cell lines and in intestinal tumors in mice. It functions as a negative modulator of the Wnt pathway in LGR5-positive stem cells.

• MeSH
• apoptóza MeSH
• experimentální nádory MeSH
• hybridizace in situ MeSH
• imunohistochemie MeSH
• kolorektální nádory genetika   metabolismus   patologie   MeSH
• lidé MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• nádorová transformace buněk genetika   metabolismus   patologie   MeSH
• nádorové buněčné linie MeSH
• nádorové kmenové buňky metabolismus   patologie   MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• proliferace buněk MeSH
• receptory spřažené s G-proteiny fyziologie   MeSH
• receptory TNF fyziologie   MeSH
• regulace genové exprese u nádorů * MeSH
• RNA nádorová genetika   MeSH
• sekvenční analýza hybridizací s uspořádaným souborem oligonukleotidů MeSH
• signální dráha Wnt fyziologie   MeSH
• střevní sliznice metabolismus   patologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• Lgr5 protein, mouse MeSH Prohlížeč
• receptory spřažené s G-proteiny MeSH
• receptory TNF MeSH
• RNA nádorová MeSH
• Tnfrsf19 protein, mouse MeSH Prohlížeč

BACKGROUND: In this work we studied the relationship between the enhanced expression of DR5 receptor and the effect of combination of TRAIL and ionizing radiation on cell cycle arrest and apoptosis induction in human leukemia cell line HL-60. MATERIAL AND METHODS: DR5, APO2.7 and cell cycle were analyzed by flow cytometry. Proteins Bid and Mcl-1 were analyzed by Western-blotting. For clonogenic survival, colony assay on methylcellulose was used. RESULTS: Ionizing radiation caused significantly enhanced positivity of DR5 receptors 24 h after irradiation with high doses (6 and 8 Gy). An increase of DR5 receptor positivity after a dose of 2 Gy was not statistically significant and application of TRAIL 48 h after irradiation did not increase the apoptosis induction. However, a decrease of radiation-induced G(2) phase arrest and an increase of apoptosis were observed when TRAIL was applied 16 h before irradiation with the dose of 2 Gy. Incubation with 6 microg/l TRAIL for 16 h reduced D(0) value from 2.9 Gy to 1.5 Gy. The induction of apoptosis by TRAIL was accompanied by Bid cleavage and a decrease of antiapoptotic Mcl-1 16 h after incubation with TRAIL. CONCLUSION: TRAIL in concentration of 6 microg/l applied 16 h before irradiation by the dose of 1.5 Gy caused the death of 63% of clonogenic tumor cells, similarly as the dose of 2.9 Gy alone, which is in good correlation with the enhanced apoptosis induction.

• MeSH
• buněčný cyklus účinky léků   účinky záření   MeSH
• G2 fáze účinky léků   fyziologie   účinky záření   MeSH
• HL-60 buňky MeSH
• lidé MeSH
• membránové glykoproteiny farmakologie   MeSH
• protein TRAIL MeSH
• proteiny regulující apoptózu farmakologie   MeSH
• receptory TNF fyziologie   účinky záření   MeSH
• TNF-alfa farmakologie   MeSH
• TRAIL receptory MeSH
• vztah dávky záření a odpovědi MeSH
• záření gama MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• membránové glykoproteiny MeSH
• protein TRAIL MeSH
• proteiny regulující apoptózu MeSH
• receptory TNF MeSH
• TNF-alfa MeSH
• TNFRSF10B protein, human MeSH Prohlížeč
• TNFSF10 protein, human MeSH Prohlížeč
• TRAIL receptory MeSH

This review focuses on apoptosis and its regulation as a tool of principal control mechanism of tissue homeostasis. Defects in regulation of apoptosis contribute to a various pathological processes, including tumor development, chronic inflammatory diseases, immunological disorders and many others. Apoptosis influences sensitivity to radiotherapy and chemotherapy of tumours. Microscopically the apoptosis is characterized by morphological changes, which result in the formation of apoptotic bodies. Apoptosis is an active process, which require synthesis and activation of a set of the specific cellular proteins. Among them, the key role belongs to the family of cystein proteases--caspases activated either through the death receptors or via activation steps starting with the release of a mitochondrial cytochrome c. Activation of caspases promotes the activation of downstream effectors leading to the cleavage of target cellular proteins and genomic DNA. The members of Bcl-2 family and p53 are- the others important proteins influencing the regulation of apoptosis. Enhancing of our knowledge about apoptosis and its mechanisms highly improves the rationale for diagnostics and therapy in oncology.

• MeSH
• apoptóza * MeSH
• kaspasy fyziologie   MeSH
• lidé MeSH
• mitochondrie metabolismus   fyziologie   MeSH
• nádory patofyziologie   terapie   MeSH
• receptory TNF fyziologie   MeSH
• signální transdukce MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• kaspasy MeSH
• receptory TNF MeSH