Correction: Activation of Notch Signaling Is Required for Cholangiocarcinoma Progression and Is Enhanced by Inactivation of p53 In Vivo.
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ABSTRACT:
SUBMITTER: El Khatib M
PROVIDER: S-EPMC6211738 | biostudies-literature | 2018
REPOSITORIES: biostudies-literature
Publications
Correction: Activation of Notch Signaling Is Required for Cholangiocarcinoma Progression and Is Enhanced by Inactivation of p53 In Vivo.
El Khatib Mona M Bozko Przemyslaw P Palagani Vindhya V Malek Nisar P NP Wilkens Ludwig L Plentz Ruben R RR
PloS one 20181101 11
[This corrects the article DOI: 10.1371/journal.pone.0077433.]. ...[more]
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Project description:UnlabelledCholangiocacinoma (CC) is a cancer disease with rising incidence. Notch signaling has been shown to be deregulated in many cancers. However, the role of this signaling pathway in the carcinogenesis of CC is still not fully explored. In this study, we investigated the effects of Notch inhibition by ?-secretase inhibitor IX (GSI IX) in cultured human CC cell lines and we established a transgenic mouse model with liver specific expression of the intracellular domain of Notch (Notch-ICD) and inactivation of tumor suppressor p53. GSI IX treatment effectively impaired cell proliferation, migration, invasion, epithelial to mesenchymal transition and growth of softagar colonies. In vivo overexpression of Notch-ICD together with an inactivation of p53 significantly increased tumor burden and showed CC characteristics.ConclusionOur study highlights the importance of Notch signaling in the tumorigenesis of CC and demonstrates that additional inactivation of p53 in vivo.
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Project description:NOTCH signaling suppresses tumor growth and proliferation in several types of stratified epithelia. Here, we show that missense mutations in NOTCH1 and NOTCH2 found in human bladder cancers result in loss of function. In murine models, genetic ablation of the NOTCH pathway accelerated bladder tumorigenesis and promoted the formation of squamous cell carcinomas, with areas of mesenchymal features. Using bladder cancer cells, we determined that the NOTCH pathway stabilizes the epithelial phenotype through its effector HES1 and, consequently, loss of NOTCH activity favors the process of epithelial-mesenchymal transition. Evaluation of human bladder cancer samples revealed that tumors with low levels of HES1 present mesenchymal features and are more aggressive. Together, our results indicate that NOTCH serves as a tumor suppressor in the bladder and that loss of this pathway promotes mesenchymal and invasive features.
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Project description:Epidemiological studies have indicated diabetes mellitus (DM) as a risk of cholangiocarcinoma (CCA), however, the effects and mechanisms of high glucose on progression of CCA remain unclear. This study reports for the first time of the enhancing effects of high glucose on aggressive phenotypes of CCA cells via STAT3 activation. CCA cells cultured in high glucose media exerted significantly higher rates of cell proliferation, adhesion, migration and invasion than those cultured in normal glucose. The phosphokinase array revealed STAT3 as the dominant signal activated in response to high glucose. Increased nuclear STAT3, p-STAT3 and its downstream target proteins, cyclin D1, vimentin and MMP2, were shown to be underling mechanisms of high glucose stimulation. The link of high glucose and STAT3 activation was confirmed in tumor tissues from CCA patients with DM that exhibited higher STAT3 activation than those without DM. Moreover, the levels of STAT3 activation were correlated with the levels of blood glucose. Finally, decreasing the level of glucose or using a STAT3 inhibitor could reduce the effects of high glucose. These findings suggest that controlling blood glucose or using a STAT3 inhibitor as an alternative approach may improve the therapeutic outcome of CCA patients with DM.
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Project description:PDCD2 (programmed cell death domain 2) is a highly conserved, zinc finger MYND domain-containing protein essential for normal development in the fly, zebrafish and mouse. The molecular functions and cellular activities of PDCD2 remain unclear. In order to better understand the functions of PDCD2 in mammalian development, we have examined PDCD2 activity in mouse blastocyst embryos, as well as in mouse embryonic stem cells (ESCs) and embryonic fibroblasts (MEFs). We have studied mice bearing a targeted PDCD2 locus functioning as a null allele through a splicing gene trap, or as a conditional knockout, by deletion of exon2 containing the MYND domain. Tamoxifen-induced knockout of PDCD2 in MEFs, as well as in ESCs, leads to defects in progression from the G1 to the S phase of cell cycle, associated with increased levels of p53 protein and p53 target genes. G1 prolongation in ESCs was not associated with induction of differentiation. Loss of entry into S phase of the cell cycle and marked induction of nuclear p53 were also observed in PDCD2 knockout blastocysts. These results demonstrate a unique role for PDCD2 in regulating the cell cycle and p53 activation during early embryonic development of the mouse.
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Project description:TP53 mutations are found in 50% of all cancers and mutated TP53 status is considered poor for treatment. However, some TP53 mutations exhibit only partial loss-of-function (LOF), meaning they retain residual transcriptional and non-transcriptional activities that are potentially beneficial for therapy. Earlier we have characterized a knock-in mouse model for the partial LOF mutant Trp53E177R (p53RR). Reduced DNA binding cooperativity of this mutant led to the loss of p53-dependent apoptosis, while p53 functions in cell cycle control, senescence, metabolism, and antioxidant defense remained intact. Concomitantly, tumor suppression was evident but strongly compromised compared to wild-type mice. Here we used the Trp53E177R mouse as a model to investigate whether residual functions of mutant p53 can be engaged to induce cell death, which is considered the most desirable outcome of tumor therapy. We made use of Mdm2 knock-out in developing embryos as a sensitive tool for detecting remaining p53 activities. Genetic ablation of Mdm2 led to embryonic lethality in Trp53E177R/E177R homozygotes at days 9.5-11.5. This effect was not rescued by concomitant p21-knockout, indicating its independence of p21-mediated cell cycle arrest. Instead, immunohistochemical analysis showed widespread apoptosis in tissues of defective embryos accompanied by persistent accumulation of p53RR protein. This led to partial restoration of the mutant's proficiency in transcriptional induction of the pro-apoptotic genes Bbc3 (Puma) and Bax. These data indicate that increased quantity can compensate for qualitative defects of p53 mutants and suggest that Mdm2-targeting (potentially in combination with other drugs) might be effective against cells bearing p53 partial LOF mutants.
| S-EPMC6927723 | biostudies-literature
Project description:It is well accepted that the Mdm2 ubiquitin ligase acts as a major factor in controlling p53 stability and activity in vivo. Although several E3 ligases have been reported to be involved in Mdm2-independent p53 degradation, the roles of these ligases in p53 regulation in vivo remain largely unknown. To elucidate the physiological role of the ubiquitin ligase ARF-BP1, we generated arf-bp1 mutant mice. We found that inactivation of arf-bp1 during embryonic development in mice resulted in p53 activation and embryonic lethality, but the mice with arf-bp1 deletion specifically in the pancreatic ?-cells (arf-bp1(FL/Y)/RIP-cre) were viable and displayed no obvious abnormality after birth. Interestingly, these mice showed dramatic loss of ?-cells as mice aged, and >50% of these mice died of severe diabetic symptoms before reaching 1 year of age. Notably, the diabetic phenotype of these mice was largely reversed by concomitant deletion of p53, and the life span of the mice was significantly extended (p53(LFL/FL)/arf-bp1(FL/Y)/RIP-cre). These findings underscore an important role of ARF-BP1 in maintaining ?-cell homeostasis in aging mice and reveal that the stability of p53 is critically regulated by ARF-BP1 in vivo.
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Project description:Notch signaling, involved in development and tissue homeostasis, is activated at the cell-cell interface through ligand-receptor interactions. Previous studies have implicated mechanical forces in the activation of Notch receptor upon binding to its ligand. Here we aimed to determine the single molecular force required for Notch activation by developing a novel low tension gauge tether (LTGT). LTGT utilizes the low unbinding force between single-stranded DNA (ssDNA) and Escherichia coli ssDNA binding protein (SSB) (∼4 pN dissociation force at 500 nm/s pulling rate). The ssDNA wraps around SSB and, upon application of force, unspools from SSB, much like the unspooling of a yoyo. One end of this nano yoyo is attached to the surface though SSB, while the other end presents a ligand. A Notch receptor, upon binding to its ligand, is believed to undergo force-induced conformational changes required for activating downstream signaling. If the required force for such activation is larger than 4 pN, ssDNA will unspool from SSB, and downstream signaling will not be activated. Using these LTGTs, in combination with the previously reported TGTs that rupture double-stranded DNA at defined forces, we demonstrate that Notch activation requires forces between 4 and 12 pN, assuming an in vivo loading rate of 60 pN/s. Taken together, our study provides a direct link between single-molecular forces and Notch activation.
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Project description:Soft tissue sarcomas (STS) are a heterogeneous group of tumors associated with poor clinical outcome. While a subset of STS are characterized by simple karyotypes and recurrent chromosomal translocations, the mechanisms driving cytogenetically complex sarcomas are largely unknown. Clinical evidence led us to partially inactivate Pten and p53 in the smooth muscle lineage of mice, which developed high-grade undifferentiated pleomorphic sarcomas (HGUPS), leiomyosarcomas (LMS) and carcinosarcomas (CS) that widely recapitulate the human disease, including the aberrant karyotype and metastatic behavior. Pten was found haploinsufficient whereas the wild-type allele of p53 invariably gained point mutations. Gene expression profile showed upregulated Notch signaling in PtenM-bM-^HM-^F/+p53M-bM-^HM-^F/+ tumors compared to Pten+/+p53M-bM-^HM-^F/+. Consistently, Pten silencing exacerbated the clonogenic and invasive potential of p53-deficient bone marrow-derived mouse mesenchymal stem cells and tumor cells, while activating the Notch pathway. Moreover, the increased oncogenic behavior of PtenM-bM-^HM-^F/+p53M-bM-^HM-^F/+ and shPten-transduced Pten+/+p53M-bM-^HM-^F/+ tumor cells was counteracted by treatment with a gamma secretase inhibitor (GSI), suggesting that the aggressiveness of those tumors can be attributed, at least in part, to enhanced Notch signaling. This study demonstrates a cooperative role for Pten and p53 suppression in complex karyotype sarcomas while establishing Notch as an important functional player in the crosstalk of these pathways during tumor progression. Our results highlight the importance of molecularly subclassifying high-grade sarcoma patients for targeted treatments. Compare PtenM-bM-^HM-^F/+p53M-bM-^HM-^F/+ to Pten+/+p53M-bM-^HM-^F/+ high-grade undifferentiated pleomorphic sarcomas (HGUPS) 4 PtenM-bM-^HM-^F/+p53M-bM-^HM-^F/+ were compared to 5 Pten+/+p53M-bM-^HM-^F/+ Keywords: Differential gene expression.
2013-01-01 | E-GEOD-42103 | biostudies-arrayexpress
Project description:BackgroundHuman hydroxysteroid dehydrogenase-like 2 (HSDL2), which regulates cancer progression, is involved in lipid metabolism. However, the role of HSDL2 in cholangiocarcinoma (CCA) and the mechanism by which it regulates CCA progression by modulating ferroptosis are unclear.MethodsHSDL2 expression levels in CCA cells and tissues were determined by quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, and immunohistochemistry. The overall survival and disease-free survival of patients with high vs. low HSDL2 expression were evaluated using Kaplan-Meier curves. The proliferation, migration, and invasion of CCA cells were assessed using Cell Counting Kit-8, colony formation, 5-ethynyl-2'-deoxyuridine DNA synthesis, and transwell assays. The effect of p53 on tumor growth was explored using a xenograft mouse model. The expression of SLC7A11 in patients with CCA was analyzed using immunofluorescence. Ferroptosis levels were measured by flow cytometry, malondialdehyde assay, and glutathione assay. HSDL2-regulated signaling pathways were analyzed by transcriptome sequencing. The correlation between p53 and SLC7A11 was assessed using bioinformatics and luciferase reporter assays.ResultsHSDL2 expression was lower in primary human CCA tissues than in matched adjacent non-tumorous bile duct tissues. HSDL2 downregulation was a significant risk factor for shorter overall survival and disease-free survival in patients with CCA. In addition, HSDL2 knockdown enhanced the proliferation, migration, and invasion of CCA cells. The transcriptome analysis of HSDL2 knockdown cells showed that differentially expressed genes were significantly enriched in the p53 signaling pathway, and HSDL2 downregulation increased SLC7A11 levels. These findings were consistent with the qRT-PCR and western blotting results. Other experiments showed that p53 expression modulated the effect of HSDL2 on CCA proliferation in vivo and in vitro and that p53 bound to the SLC7A11 promoter to inhibit ferroptosis.ConclusionsHSDL2 knockdown promotes CCA progression by inhibiting ferroptosis through the p53/SLC7A11 axis. Thus, HSDL2 is a potential prognostic marker and therapeutic target for CCA.
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