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  • 1
    Keywords: TRANSGENIC MICE ; WORKING-MEMORY ; AMYOTROPHIC-LATERAL-SCLEROSIS ; KNOCKOUT MICE ; CEREBRAL-CORTEX ; HUNTINGTONS-DISEASE MUTATION ; RAT PREFRONTAL CORTEX ; RISK GENE NEUREGULIN-1 ; YAC128 MOUSE MODEL ; STRIATAL NEURONAL LOSS
    Abstract: D1-dopamine receptors (Drd1a) are highly expressed in the deep layers of the cerebral cortex and the striatum. A number of human diseases such as Huntington disease and schizophrenia are known to have cortical pathology involving dopamine receptor expressing neurons. To illuminate their functional role, we exploited a Cre/Lox molecular paradigm to generate Emx-1(tox) MUT mice, a transgenic line in which cortical Drd1a-expressing pyramidal neurons were selectively ablated. Emx-1(tox) MUT mice displayed prominent forelimb dystonia, hyperkinesia, ataxia on rotarod testing, heightened anxiety-like behavior, and age-dependent abnormalities in a test of social interaction. The latter occurred in the context of normal working memory on testing in the Y-maze and for novel object recognition. Some motor and behavioral abnormalities in Emx-1(tox) MUT mice overlapped with those in CamKIIalpha(tox) MUT transgenic mice, a line in which both striatal and cortical Drd1a-expressing cells were ablated. Although Emx-1(tox) MUT mice had normal striatal anatomy, both Emx-1(tox) MUT and CamKIIalpha(tox) MUT mice displayed selective neuronal loss in cortical layers V and VI. This study shows that loss of cortical Drd1a-expressing cells is sufficient to produce deficits in multiple motor and behavioral domains, independent of striatal mechanisms. Primary cortical changes in the D1 dopamine receptor compartment are therefore likely to model a number of core clinical features in disorders such as Huntington disease and schizophrenia.
    Type of Publication: Journal article published
    PubMed ID: 25684539
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  • 2
    Keywords: brain ; RECEPTOR ; CELLS ; CELL ; SUPPORT ; MICE ; TIME ; MECHANISM ; mechanisms ; BINDING ; DISORDER ; MEMORY ; PHENOTYPES ; AGE ; PHENOTYPE ; STRATEGIES ; DISORDERS ; ADULT ; interaction ; adaptation ; therapeutic ; STRATEGY ; hypothesis ; Young Adult
    Abstract: In this study we characterize the behavioural and cellular phenotype of mutant (MUT) mice with progressive loss of D1 dopamine receptor (Drd1a)-expressing cells. Adult [14-19 weeks] MUT mice showed intact working memory in the spontaneous alternation test but evidenced anxiety-like behaviour in the elevated plus maze and the light-dark test. The ethogram of mature adult MUT [average age 22 weeks] was compared with that of young adult MUT mice [average age 12 weeks]. While MUT mice evidenced hyperactivity over initial exploration at both time points, the topography of hyperactivity shifted. Moreover, initial hyperactivity was sustained over habituation at 12 weeks, but not at 22 weeks. Thus, by 22 weeks MUT mice evidenced shifts in, and mitigation of, these early phenotypic effects. However, orofacial behaviours of chewing and sifting were reduced similarly at 12 and 22 weeks. These data support the hypothesis that aspects of the mutant phenotype change with time. Quantitative autoradiography at 20 weeks revealed loss of D1-like dopamine receptor binding in the entire basal ganglia, with upregulated D2-like binding. There appear to be topographically specific interactions between normal maturational processes and compensatory mechanisms evoked subsequent to targeted ablation of D1 dopamine receptor-expressing cells. Understanding the mechanistic bases of mitigation vs persistence of individual phenotypes in relation to neural adaptation consequent to cell loss may lead to novel therapeutic strategies for basal ganglia disorders.
    Type of Publication: Journal article published
    PubMed ID: 19733597
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  • 3
    Keywords: GROWTH ; proliferation ; MODEL ; NETWORK ; DIFFERENTIATION ; MOUSE ; senescence ; PC3 CELLS
    Abstract: The miR-34 family was originally found to be a direct target of p53 and is a group of putative tumor suppressors. Surprisingly, mice lacking all mir-34 genes show no increase in cancer formation by 18 months of age, hence placing the physiological relevance of previous studies in doubt. Here, we report that mice with prostate epithelium-specific inactivation of mir-34 and p53 show expansion of the prostate stem cell compartment and develop early invasive adenocarcinomas and high-grade prostatic intraepithelial neoplasia, whereas no such lesions are observed after inactivation of either the mir-34 or p53 genes alone by 15 months of age. Consistently, combined deficiency of p53 and miR-34 leads to acceleration of MET-dependent growth, self-renewal, and motility of prostate stem/progenitor cells. Our study provides direct genetic evidence that mir-34 genes are bona fide tumor suppressors and identifies joint control of MET expression by p53 and miR-34 as a key component of prostate stem cell compartment regulation, aberrations in which may lead to cancer.
    Type of Publication: Journal article published
    PubMed ID: 24630988
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  • 4
    Keywords: CELL LUNG-CANCER ; COLORECTAL-CANCER ; COLON-CANCER ; STEM-CELLS ; EPITHELIAL-MESENCHYMAL TRANSITION ; MICRORNA EXPRESSION ; TUMOR-INITIATING CELLS ; NONALCOHOLIC FATTY LIVER ; NEGATIVE FEEDBACK LOOP ; INHIBITS PROSTATE-CANCER
    Abstract: The tumor suppressor p53 is one of the most frequently mutated genes in human cancers. MicroRNAs (miRNAs) are small non-protein coding RNAs that regulate gene expression on the post-transcriptional level. Recently, it was shown that p53 regulates the expression of several miRNAs, thereby representing an important mechanism of p53 signaling. Several independent studies identified the members of the miR-34 family as the most prevalent p53-induced miRNAs. miR-34s are frequently silenced in variety of tumor entities, suggesting that they are important tumor suppressors. Indeed, ectopic expression of miR-34s inhibits proliferation, epithelial to mesenchymal transition, migration, invasion, and metastasis of various cancer cell entities. Moreover, delivery or re-expression of miR-34 leads to notable repression of tumor growth and metastasis in cancer mouse models, and may therefore represent an efficient strategy for future cancer therapeutics. Besides their crucial functions in cancer, members of the miR-34 family also play important roles in spermatogenesis, stem cell differentiation, neuronal development, aging, and cardiovascular functions. Consequently, miR-34 has also been implicated in various non-cancerous diseases, such as brain disorders, osteoporosis, and cardiovascular complications.
    Type of Publication: Journal article published
    PubMed ID: 24815299
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  • 5
    Abstract: The p53-inducible miR-34a and miR-34b/c genes are frequently silenced in colorectal cancer. To address the in vivo relevance of miR-34a/b/c function for suppression of intestinal tumor formation, we generated ApcMin/+ mice with deletions of the miR-34a and/or miR-34b/c genes separately or in combination. Combined deletion of miR-34a/b/c increased the number of intestinal stem cells as well as Paneth and Goblet cells, resulting in enlarged intestinal crypts. miR-34a/b/c-deficient ApcMin/+ mice displayed an increased tumor burden and grade and decreased survival. miR-34a/b/c-deficient adenomas showed elevated proliferation and decreased apoptosis and displayed pronounced bacterial infiltration, which may be due to an observed decrease in infiltrating immune cells and downregulation of barrier proteins. mRNA induction in miR-34a/b/c-deficient tumors was enriched for miR-34a/b/c seed-matching sites and for mRNAs encoding proteins related to epithelial-mesenchymal transition, stemness, and Wnt signaling. Accordingly, cells explanted from miR-34a/b/c-deficient adenomas formed tumor organoids at an increased rate. Several upregulated miR-34 targets displayed elevated expression in primary human colorectal cancers that was associated with lymph-node metastases (INHBB, AXL, FGFR1, and PDFGRB) and upregulation of INHBB and AXL in primary colorectal cancer was associated with poor patient survival. In conclusion, our results show that miR-34a/b/c suppress tumor formation caused by loss of Apc and control intestinal stem cell and secretory cell homeostasis by downregulation of multiple target mRNAs. Cancer Res; 77(10); 2746-58. (c)2017 AACR.
    Type of Publication: Journal article published
    PubMed ID: 28363996
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  • 6
    Abstract: BACKGROUND & AIMS: In colorectal tumors, hypoxia causes resistance to therapy and promotes metastasis. Loss of the tumor suppressor p53 (encoded by TP53) provides cancer cells with a selective advantage under conditions of hypoxia, but little is known about the mediators of this effect. METHODS: Isogenic colorectal cancer (CRC) cell lines with different TP53 genotypes were placed under conditions of hypoxia. We examined the effects on levels and activity of microRNA-34a (MIR34A) in CRC cells. We determined the expression and localization of protein phosphatase 1 regulatory inhibitor subunit 11 (PPP1R11, also called INH3, HCGV, IPP3, HCGV, TCTE5, TCTEX5, or CFAP255) in 82 human colon cancers. We analyzed data on human colorectal carcinomas from the Cancer Genome Atlas collection to determine whether expression of PPP1R11 was affected by altered level or activity of p53, markers of epithelial-to-mesenchymal transition (EMT), or MIR34A or was associated with metastasis. We determined the effects of disruption Mir34a, Mir34b, and Mir34c in ApcMin/+ mice. DLD-1 cells were transfected with small inhibitor RNAs against PPP1R1, injected into the tail veins of immune-compromised mice, and followed by noninvasive bioluminescence imaging. RESULTS: The hypoxia inducible factor 1 alpha subunit (HIF1A) directly repressed the MIR34A gene in p53-defective CRC cells, whereas expression of MIR34A was induced in p53-proficient CRC cells exposed to hypoxia. Down-regulation of MIR34A was required for hypoxia-induced EMT, invasion and migration, and activation of STAT3 in CRC cells. We identified PPP1R11, whose product inhibits PP1, as a target of MIR34A. PPP1R11 mediates phosphorylation (activation) of STAT3, so expression of MIR34A reduced activation of STAT3 in p53-deficient CRC cells. Ectopic expression of PPP1R11 in CRC cells induced EMT, invasion, and migration, which all required STAT3. Increased expression of PPP1R11 in p53-deficient CRC cells was required for hypoxia-induced EMT, invasion, migration, and resistance to 5-fluorouracil, as well as metastasis of xenograft tumors to lungs of mice. Adenomas and derived tumoroids of ApcMin/+ mice with disruption of Mir34a, Mir34b, and Mir34c had increased levels of PPP1R11. Colorectal tumors from patients had increased levels of PPP1R11 at areas of invasion, compared with other areas of the tumor; increased level PPP1R11 associated with TP53 mutations and metastasis to the liver. CONCLUSIONS: HIF1A represses, whereas p53 increases, expression of MIR34A in CRC cells. MIR34A reduces expression of PPP1R11 to prevent activation of STAT3 and inhibit the EMT and metastasis. Strategies to target this pathway might be developed to inhibit CRC metastasis and overcome resistance to therapy associated with hypoxia.
    Type of Publication: Journal article published
    PubMed ID: 28435028
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  • 7
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  83. Jahresversammlung der Deutschen Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie; 20120516-20120520; Mainz; DOC12hnod442 /20120404/
    Publication Date: 2012-04-05
    Keywords: ddc: 610
    Language: English
    Type: conferenceObject
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  • 8
    Keywords: DOWN-REGULATION ; CELL-SURVIVAL ; TUMOR PROGRESSION ; COLON-CANCER ; MOUSE MODEL ; beta-catenin ; C-MYC ; inflammation ; EPITHELIAL-MESENCHYMAL TRANSITION ; COLITIS-ASSOCIATED CANCER
    Abstract: Members of the miR-34 family are induced by the tumor suppressor p53 and are known to inhibit epithelial-to-mesenchymal transition (EMT) and therefore presumably suppress the early phases of metastasis. Here, we determined that exposure of human colorectal cancer (CRC) cells to the cytokine IL-6 activates the oncogenic STAT3 transcription factor, which directly represses the MIR34A gene via a conserved STAT3-binding site in the first intron. Repression of MIR34A was required for IL-6-induced EMT and invasion. Furthermore, we identified the IL-6 receptor (IL-6R), which mediates IL-6-dependent STAT3 activation, as a conserved, direct miR-34a target. The resulting IL-6R/STAT3/miR-34a feedback loop was present in primary colorectal tumors as well as CRC, breast, and prostate cancer cell lines and associated with a mesenchymal phenotype. An active IL-6R/STAT3/miR-34a loop was necessary for EMT, invasion, and metastasis of CRC cell lines and was associated with nodal and distant metastasis in CRC patient samples. p53 activation in CRC cells interfered with IL-6-induced invasion and migration via miR-34a-dependent downregulation of IL6R expression. In Mir34a-deficient mice, colitis-associated intestinal tumors displayed upregulation of p-STAT3, IL-6R, and SNAIL and progressed to invasive carcinomas, which was not observed in WT animals. Collectively, our data indicate that p53-dependent expression of miR-34a suppresses tumor progression by inhibiting a IL-6R/STAT3/miR-34a feedback loop.
    Type of Publication: Journal article published
    PubMed ID: 24642471
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  • 9
    ISSN: 0749-6036
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0921-4526
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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