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Canonical Wnt signaling regulates Slug activity and links epithelial-mesenchymal transition with epigenetic Breast Cancer 1, Early Onset (BRCA1) repression.

ABSTRACT: Slug (Snail2) plays critical roles in regulating the epithelial-mesenchymal transition (EMT) programs operative during development and disease. However, the means by which Slug activity is controlled remain unclear. Herein we identify an unrecognized canonical Wnt/GSK3?/?-Trcp1 axis that controls Slug activity. In the absence of Wnt signaling, Slug is phosphorylated by GSK3? and subsequently undergoes ?-Trcp1-dependent ubiquitination and proteosomal degradation. Alternatively, in the presence of canonical Wnt ligands, GSK3? kinase activity is inhibited, nuclear Slug levels increase, and EMT programs are initiated. Consistent with recent studies describing correlative associations in basal-like breast cancers between Wnt signaling, increased Slug levels, and reduced expression of the tumor suppressor Breast Cancer 1, Early Onset (BRCA1), further studies demonstrate that Slug-as well as Snail-directly represses BRCA1 expression by recruiting the chromatin-demethylase, LSD1, and binding to a series of E-boxes located within the BRCA1 promoter. Consonant with these findings, nuclear Slug and Snail expression are increased in association with BRCA1 repression in a cohort of triple-negative breast cancer patients. Together, these findings establish unique functional links between canonical Wnt signaling, Slug expression, EMT, and BRCA1 regulation.

SUBMITTER: Wu ZQ

PROVIDER: S-EPMC3478591 | biostudies-literature | 2012 Oct

REPOSITORIES: biostudies-literature

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Canonical Wnt signaling regulates Slug activity and links epithelial-mesenchymal transition with epigenetic Breast Cancer 1, Early Onset (BRCA1) repression.

Wu Zhao-Qiu ZQ Li Xiao-Yan XY Hu Casey Yuexian CY Ford Michael M Kleer Celina G CG Weiss Stephen J SJ

Proceedings of the National Academy of Sciences of the United States of America 20120924 41

Slug (Snail2) plays critical roles in regulating the epithelial-mesenchymal transition (EMT) programs operative during development and disease. However, the means by which Slug activity is controlled remain unclear. Herein we identify an unrecognized canonical Wnt/GSK3β/β-Trcp1 axis that controls Slug activity. In the absence of Wnt signaling, Slug is phosphorylated by GSK3β and subsequently undergoes β-Trcp1-dependent ubiquitination and proteosomal degradation. Alternatively, in the presence of ...[more]

PMID: 23011797

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Project description:BackgroundProstate cancer (PCa) is considered one of the most prevalent malignancy globally, and metastasis is a major cause of death. Apigenin (API) is a dietary flavonoid which exerts an antimetastatic effect in various cancer types. Sparc/osteonectin, cwcv, and kazal-like domains proteoglycan 1 (SPOCK1) is a crucial modulator of tumor growth and metastasis in cancers. However, the role and underlying regulatory mechanisms of SPOCK1 in the API-mediated antimetastatic effects of PCa remain unclear.MethodsMTS, colony formation, wound-healing, and transwell assays were conducted to evaluate the effects of API on PCa cell proliferative, migratory, and invasive potentials. In vivo orthotopic bioluminescent xenograft model were employed to determine antitumor activity of API. PCa cells were transfected with either Snail-, Slug-, SPOCK1-overexpressing vector, or small hairpin (sh)SPOCK1 to determine the invasive abilities and expression levels of SPOCK1 and epithelial-to-mesenchymal transition (EMT) biomarkers in response to API treatment. Immunohistochemical (IHC) assays were carried out to evaluate the expression level of SPOCK1 in PCa xenografts and a PCa tissue array. Associations of SPOCK1 expression with clinicopathological features and prognoses of patients with PCa were analyzed by GEO or TCGA RNA-sequencing data.ResultsAPI significantly suppressed in vitro PCa cell proliferation, migration, and invasion and inhibited in vivo PCa tumor growth and metastasis. Moreover, survival times of animals were also prolonged after API treatment. Mechanistic studies revealed that API treatment resulted in downregulation of SPOCK1, which was accompanied by reduced expressions of mesenchymal markers and subsequent attenuation of invasive abilities of PCa cells. Overexpression of SPOCK1 in PCa xenografts resulted in significant promotion of tumor progression and relieved the anticancer activities induced by API, whereas knockdown of SPOCK1 had opposite effects. In clinical, SPOCK1 levels were higher in tumor tissues compared to non-tumor tissues, which was also significantly correlated with shorter disease-free survival in PCa patients.ConclusionsLevels of SPOCK1 increase with the progression of human PCa which suggests that SPOCK1 may act as a prognostic marker or therapeutic target for patients with PCa. Suppression of SPOCK1-mediated EMT signaling contributes to the antiproliferative and antimetastatic activities of API in vitro and in vivo.

Project description:Aims/hypothesisDiabetes is associated with epigenetic modifications including DNA methylation and miRNA changes. Diabetic complications in the cornea can cause persistent epithelial defects and impaired wound healing due to limbal epithelial stem cell (LESC) dysfunction. In this study, we aimed to uncover epigenetic alterations in diabetic vs non-diabetic human limbal epithelial cells (LEC) enriched in LESC and identify new diabetic markers that can be targeted for therapy to normalise corneal epithelial wound healing and stem cell expression.MethodsHuman LEC were isolated, or organ-cultured corneas were obtained, from autopsy eyes from non-diabetic (59.87±20.89 years) and diabetic (71.93±9.29 years) donors. The groups were not statistically different in age. DNA was extracted from LEC for methylation analysis using Illumina Infinium 850K MethylationEPIC BeadChip and protein was extracted for Wnt phospho array analysis. Wound healing was studied using a scratch assay in LEC or 1-heptanol wounds in organ-cultured corneas. Organ-cultured corneas and LEC were transfected with WNT5A siRNA, miR-203a mimic or miR-203a inhibitor or were treated with recombinant Wnt-5a (200 ng/ml), DNA methylation inhibitor zebularine (1-20 µmol/l) or biodegradable nanobioconjugates (NBCs) based on polymalic acid scaffold containing antisense oligonucleotide (AON) to miR-203a or a control scrambled AON (15-20 µmol/l).ResultsThere was significant differential DNA methylation between diabetic and non-diabetic LEC. WNT5A promoter was hypermethylated in diabetic LEC accompanied with markedly decreased Wnt-5a protein. Treatment of diabetic LEC and organ-cultured corneas with exogenous Wnt-5a accelerated wound healing by 1.4-fold (p<0.05) and 37% (p<0.05), respectively, and increased LESC and diabetic marker expression. Wnt-5a treatment in diabetic LEC increased the phosphorylation of members of the Ca2+-dependent non-canonical pathway (phospholipase Cγ1 and protein kinase Cβ; by 1.15-fold [p<0.05] and 1.36-fold [p<0.05], respectively). In diabetic LEC, zebularine treatment increased the levels of Wnt-5a by 1.37-fold (p<0.01)and stimulated wound healing in a dose-dependent manner with a 1.6-fold (p<0.01) increase by 24 h. Moreover, zebularine also improved wound healing by 30% (p<0.01) in diabetic organ-cultured corneas and increased LESC and diabetic marker expression. Transfection of these cells with WNT5A siRNA abrogated wound healing stimulation by zebularine, suggesting that its effect was primarily due to inhibition of WNT5A hypermethylation. Treatment of diabetic LEC and organ-cultured corneas with NBC enhanced wound healing by 1.4-fold (p<0.01) and 23.3% (p<0.05), respectively, with increased expression of LESC and diabetic markers.Conclusions/interpretationWe provide the first account of epigenetic changes in diabetic corneas including dual inhibition of WNT5A by DNA methylation and miRNA action. Overall, Wnt-5a is a new corneal epithelial wound healing stimulator that can be targeted to improve wound healing and stem cells in the diabetic cornea.Data availabilityThe DNA methylation dataset is available from the public GEO repository under accession no. GSE229328 ( https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE229328 ).

Project description:Rationale: The role of SLUG in epithelial-mesenchymal transition during tumor progression has been thoroughly studied, but its precise regulation remains poorly explored. Methods: The affinity purification, mass spectrometry and CO-IP were performed to identify the interaction between SLUG and ubiquitin-specific protease 5 (USP5). Cycloheximide chase assays and deubiquitination assays confirmed that the effect of USP5 on the deubiquitin of SLUG. The dual-luciferase reporter and chromatin immunoprecipitation assays were employed to observe the direct transcriptional regulation of E-cadherin by SLUG effected by USP5. EMT related markers was detected by western blotting and immunofluorescence. Molecular docking, SPR sensor (biacore) and co-location were detected to prove Formononetin targets USP5. Bioinformatics analysis was used to study the relation of USP5 and SLUG to malignancy degree of HCC. Cell migration, invasion in HCC cells and xenografts model in nude mouse were conducted to detect the promotion of USP5 and the inhibition of Formononetin on EMT. Results: USP5 interacts with and stabilizes SLUG to regulate its abundance through USP5 deubiquitination activities in epithelial-mesenchymal transition (EMT) of hepatocellular carcinoma (HCC). USP5 is highly expressed and positively correlated with SLUG expression in HCC with high malignancy. Knockdown of USP5 inhibits SLUG deubiquitination and inhibits HCC cells proliferation, metastasis, and invasion, while overexpression of USP5 promotes SLUG stability and EMT in vitro and in vivo. Through virtual screening, we found that Formononetin exhibits excellent binding to USP5. Moreover, Formononetin inhibits deubiquitinating activities of USP5 to SLUG and consequently impedes the EMT and malignant progression of HCC. Conclusion: Our findings reveal that USP5 serve as a potential target for tumor intervention and provide a preliminary antitumor therapy for inhibit EMT by targeting USP5 or its interaction with SLUG in HCC.

Dataset Information

Canonical Wnt signaling regulates Slug activity and links epithelial-mesenchymal transition with epigenetic Breast Cancer 1, Early Onset (BRCA1) repression.

Publications

Canonical Wnt signaling regulates Slug activity and links epithelial-mesenchymal transition with epigenetic Breast Cancer 1, Early Onset (BRCA1) repression.

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