Reduction In Β-catenin Expression Research Articles

GPR97 deficiency suppresses Wnt/β-catenin signaling in hypertensive nephropathy.

Accumulating evidence shows that renal fibrosis plays a key role in the development of hypertensive nephropathy (HTN). Therefore, a better understanding of the underlying mechanism of renal fibrosis regulation in HTN would be critical for designing rational strategies for therapeutic interventions. In this study, we revealed that GPR97, a novel identified adhesion G coupled receptor, plays an important role in the regulation of Wnt/β-catenin signaling, which is the crucial driver of renal fibrosis in HTN. First, we identified that the expression of GPR97 correlated with the β-catenin expression in renal biopsy from patients with HTN. Moreover, we found that GPR97 deficiency inhibited Wnt/β-catenin signaling in mice with HTN, as evidenced by the reduction of β-catenin expression and downstream target proteins, including MMP7 and Fibronectin. Mechanistically, we found that GPR97 could directly bind with Wnt1 in cultured tubular cells and TGF-β1 treatment enhanced the binding ability of GPR97 and Wnt1. In addition, the gene silencing of GPR97 could decrease the Wnt1-induced fibrotic phenotype of tubular cells and inflammatory responses, suggesting that the binding of GPR97 and Wnt1 promoted Wnt/β-catenin signaling. Collectively, our studies reveal that GPR97 is a regulator of Wnt/β-catenin signaling in HTN, and targeting GPR97 may be a novel therapeutic strategy for HTN treatment.

Notch1 Is Involved in Physiologic Cardiac Hypertrophy of Mice via the p38 Signaling Pathway after Voluntary Running.

Appropriate exercise such as voluntary wheel-running can induce physiological cardiac hypertrophy. Notch1 plays an important role in cardiac hypertrophy; however, the experimental results are inconsistent. In this experiment, we aimed to explore the role of Notch1 in physiological cardiac hypertrophy. Twenty-nine adult male mice were randomly divided into a Notch1 heterozygous deficient control (Notch1+/- CON) group, a Notch1 heterozygous deficient running (Notch1+/- RUN) group, a wild type control (WT CON) group, and a wild type running (WT RUN) group. Mice in the Notch1+/- RUN and WT RUN groups had access to voluntary wheel-running for two weeks. Next, the cardiac function of all of the mice was examined by echocardiography. The H&E staining, Masson trichrome staining, and a Western blot assay were carried out to analyze cardiac hypertrophy, cardiac fibrosis, and the expression of proteins relating to cardiac hypertrophy. After two-weeks of running, the Notch1 receptor expression was decreased in the hearts of the WT RUN group. The degree of cardiac hypertrophy in the Notch1+/- RUN mice was lower than that of their littermate control. Compared to the Notch1+/- CON group, Notch1 heterozygous deficiency could lead to a decrease in Beclin-1 expression and the ratio of LC3II/LC3I in the Notch1+/- RUN group. The results suggest that Notch1 heterozygous deficiency could partly dampen the induction of autophagy. Moreover, Notch1 deficiency may lead to the inactivation of p38 and the reduction of β-catenin expression in the Notch1+/- RUN group. In conclusion, Notch1 plays a critical role in physiologic cardiac hypertrophy through the p38 signaling pathway. Our results will help to understand the underlying mechanism of Notch1 on physiological cardiac hypertrophy.

Ubiquitin specific protease 7 maintains pluripotency of mouse embryonic stem cells through stabilization of β-catenin.

Embryonic stem cells (ESCs), which are derived from the undifferentiated inner cell mass of the embryo, can differentiate every cell type of the body regarding their pluripotency. Therefore, human or mouse ESCs can be used as an unlimited cell source for numerous researches or therapeutical approaches. However, pluripotency maintenance of ESCs during in vitro culture is challenging because of their endless differentiation capacity. In the current study, the effect of USP7 on pluripotency maintenance of mouse ESCs (mESCs) has been investigated with the help of cell viability assay, morphological analysis, alkaline phosphatase (ALP) staining, qPCR analysis, and Western Blotting. 600 nM P5091 application, which showed no significant toxicity in mESCs, increased the total ubiquitinated protein amount as a proof of the accomplishment of proper USP7 inhibition. Morphological analysis and ALP activity evaluation indicated that dual inhibition of GSK3 and MEK together with leukemia inhibitory factor (LIF) treatment protects the pluripotency in presence of active USP7 enzyme. Yet, inactivation of USP7 reduced the ALP activity and altered the cell morphology in each treatment group. This morphological change and decreased ALP activity refer to differentiated mESCs. These findings were supported by gene expression and protein analysis. Gene expressions and protein amounts of pluripotency related Oct4, Nanog, c-Myc, Sox2 and Klf4 transcription factors decreased significantly after USP7 inhibition. Together with this observation, a remarkable reduction in β-Catenin expression was also noticed. It was also observed that USP7 inactivation shortens the half-live of β-Catenin and GSK3β proteins. This study demonstrates that USP7 activation is crucial for proper pluripotency maintenance, which is provided through β-Catenin stabilization.

Axin-1 binds to Caveolin-1 to regulate the LPS-induced inflammatory response in AT-I cells

Caveolin-1 has been reported to play an important role in the pathogenesis of acute respiratory distress syndrome (ARDS). This study was designed to identify Caveolin-1-interacting proteins to reveal the molecular mechanisms of ARDS. Yeast two-hybrid screening was performed using Caveolin-1 as the bait, and Axin-1 was identified as a binding partner for Caveolin-1. Co-immunoprecipitation demonstrated that the binding domains were located in the N-terminal region (1–100 aa) of Caveolin-1 and the C-terminal region (710–797 aa) of Axin-1. Caveolin-1 gene knockout or Axin-1 knockdown significantly decreased the levels of TNF-α and IL-6 in the supernatants of alveolar type I (AT-I) epithelial cells treated with LPS. Disrupting the interaction between Caveolin-1 and Axin-1 using CRISPR/Cas9 technology led to a significant increase in TNF-α and IL-6 from AT-I cells, along with a significant reduction in β-catenin expression. In conclusion, Axin-1 functions as an adaptor of Caveolin-1 and affects the production of inflammatory cytokines in AT-I cells challenged with LPS via β-catenin-mediated negative regulation.

Wnt/β‑catenin pathway activation and silencing of the APC gene in HPV‑positive human cervical cancer‑derived cells.

Although persistent infections with high-risk human papilloma virus (HPV) constitute the most significant cofactor for the development of cervical cancer, they are insufficient on their own. Mutations or epigenetic inactivation of the tumor suppressor adenomatous polyposis coli (APC), the two acting as prominent oncogenic mechanisms in a number of types of cancer, are frequently associated with aberrant activation of the Wnt/β-catenin pathway. According to these observations, it was hypothesized that APC alteration may lead to β-catenin deregulation and the abnormal expression of direct targets of the Wnt pathway in HPV-infected cervical cancer cells. The present study confirmed that the stabilization of β-catenin correlates with enhanced transcriptional activity of the β-catenin/T-cell factor complex in cervical cancer cell lines. Sequence analysis of the ‘hot-spot’ in the mutation cluster region did not exhibit genetic alterations that may be associated with APC gene inactivation. In addition, it was identified that there was a good correlation with the hypermethylation status of the APC promoter 1A and the abnormal accumulation of endogenous β-catenin in cell lines and biopsies infected with HPV16, although not HPV18. Removal of the epigenetic markers led to an increase in APC levels and a reduction of β-catenin expression in two transcriptional targets of the Wnt pathway: Matrix metalloproteinase-7 and vascular endothelial growth factor. The present study suggested that the increase in Wnt activity in certain cervical cancer-derived cells may be associated with an alteration in the methylation status of the APC gene promoter 1A.

Silencing of FRAT1 by siRNA inhibits the proliferation of SGC7901 human gastric adenocarcinoma cells.

Frequently rearranged in advanced T cell lymphomas-1 (FRAT1) positively regulates the Wnt/β-catenin signaling pathway by inhibiting glycogen synthase kinase-3 mediated phosphorylation of β-catenin. FRAT1 is a proto-oncogene, implicated in tumorigenesis. The present study aimed to investigate the effects of FRAT1 silencing on the proliferation and apoptosis of SGC7901 cells. FRAT1 in SGC7901 cells was silenced by RNA interference. Reverse transcription-quantitative polymerase chain reaction was used for the analysis of FRAT1 mRNA and western blotting was used to evaluate FRAT1 and β-catenin protein levels. Cell proliferation was analyzed by the MTT assay. Cell cycle distribution and apoptosis were analyzed by flow cytometry. The expression of FRAT1 mRNA, FRAT1 and β-catenin protein in FRAT1-silenced SGC7901 cells were reduced significantly compared to untreated cells. The proliferation of FRAT1 silenced SGC7901 cells decreased significantly The FRAT1 silenced SGC7901 cells were arrested at G0/G1 stage to a greater degree, and apoptosis was increased. In summary, silencing of FRAT1 inhibits SGC7901 cell proliferation and induces apoptosis, possible through a reduction in β-catenin expression. FRAT1 may serve as a prognostic biomarker and therapeutic target for gastric cancer.

Brewers' rice modulates oxidative stress in azoxymethane-mediated colon carcinogenesis in rats.

To investigate the mechanistic action of brewers' rice in regulating the Wnt/nuclear factor-kappa B (NF-κB)/Nrf2-signaling pathways during colon carcinogenesis in male Sprague-Dawley rats. Male Sprague-Dawley rats were randomly divided into the following five groups (six rats in each group): (G1) normal, (G2) azoxymethane (AOM) alone, (G3) AOM + 10% (weight (w)/weight (w)) brewers' rice, (G4) AOM + 20% (w/w) brewers' rice, and (G5) AOM + 40% (w/w) brewers' rice. They were intraperitoneally administered 15 mg/kg body weight of AOM in saline once weekly over a two-week period and treated with an American Institute of Nutrition (AIN)-93G diet containing 10%, 20%, and 40% (w/w) brewers' rice. The mRNA levels of glycogen synthase kinase 3β (GSK3β), β-catenin, key inflammation markers, nuclear factor E2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1)-dependent transcriptional activity were assessed by quantitative real-time polymerase chain reaction analyses. The colon superoxide dismutase, malondialdehyde, and nitric oxide levels were also analyzed to assess the antioxidant effect of these treatments. The results were analyzed using one-way analysis of variance (ANOVA), and a P value of < 0.05 was considered significant. The overall analyses demonstrated that the dietary administration of brewers' rice in AOM-induced rat colon carcinogenesis resulted in the transcriptional upregulation of GSK3β, inducible nitric oxide synthase (iNOS), Nrf2, and HO-1. We discovered that the dietary administration of brewers' rice downregulated the β-catenin and NF-κB mRNA levels. A significant reduction in β-catenin expression was found in the groups administered with 20% (0.611 ± 0.034) and 40% (0.436 ± 0.045) (w/w) brewers' rice compared with that of the group treated with AOM alone (1.000 ± 0.064) (P < 0.05). The NF-κB expression was significantly lower between the AOM-alone group (1.000 ± 0.048) and those groups fed with diets containing 10% (w/w) brewers' rice (0.255 ± 0.022), 20% (w/w) brewers' rice (0.450 ± 0.045), or 40% (w/w) brewers' rice (0.541 ± 0.027) (P < 0.05). Brewers' rice improved the antioxidant levels, indicating that brewers' rice can enhance effective recovery from oxidative stress induced by AOM. Our results provide evidence that brewers' rice can suppress colon cancer via the regulation of Nrf2 expression and the inhibition of the Wnt/NF-κB signaling pathways.

Tubulin polymerization promoting protein 1 (TPPP1) increases β-catenin expression through inhibition of HDAC6 activity in U2OS osteosarcoma cells

The Rho-associated coiled-coil kinase (ROCK) family of proteins, including ROCK1 and ROCK2, are key regulators of actin and intermediate filament morphology. The newly discovered ROCK substrate Tubulin polymerization promoting protein 1 (TPPP1) promotes microtubule polymerization and inhibits the activity of Histone deacetylase 6 (HDAC6). The effect of TPPP1 on HDAC6 activity is inhibited by ROCK signaling. Moreover, it was recently demonstrated that ROCK activity increases the cellular expression of the oncogene β-catenin, which is a HDAC6 substrate. In this study, we investigated the interplay between ROCK-TPPP1-HDAC6 signaling and β-catenin expression. We demonstrate that β-catenin expression is increased with ROCK signaling activation and is reduced with increased TPPP1 expression in U2OS cells. Further investigation revealed that ROCK-mediated TPPP1 phosphorylation, which prevents its binding to HDAC6, negates TPPP1-mediated reduction in β-catenin expression. We also show that increased HDAC6 activity resulting from ROCK signaling activation reduced β-catenin acetylation at Lys-49, which was also accompanied by its decreased phosphorylation by Caesin kinase 1 (CK1) and Glycogen synthase kinase 3β (GSK3β), thus preventing its proteasomal degradation. Overall, our results suggest that ROCK regulates β-catenin stability in cells via preventing TPPP1-mediated inhibition of HDAC6 activity, to reduce its acetylation and degradation via phosphorylation by CK1 and GSK3β.

Silencing Mutated β-Catenin Inhibits Cell Proliferation and Stimulates Apoptosis in the Adrenocortical Cancer Cell Line H295R

ContextAdrenocortical carcinoma (ACC) is a rare and highly aggressive endocrine neoplasm, with limited therapeutic options. Activating β-catenin somatic mutations are found in ACC and have been associated with a poor clinical outcome. In fact, activation of the Wnt/β-catenin signaling pathway seems to play a major role in ACC aggressiveness, and might, thus, represent a promising therapeutic target.ObjectiveSimilar to patient tumor specimen the H295 cell line derived from an ACC harbors a natural activating β-catenin mutation. We herein assess the in vitro and in vivo effect of β-catenin inactivation using a doxycyclin (dox) inducible shRNA plasmid in H295R adrenocortical cancer cells line (clone named shβ).ResultsFollowing dox treatment a profound reduction in β-catenin expression was detectable in shβ clones in comparison to control clones (Ctr). Accordingly, we observed a decrease in Wnt/βcatenin-dependent luciferase reporter activity as well as a decreased expression of AXIN2 representing an endogenous β-catenin target gene. Concomitantly, β-catenin silencing resulted in a decreased cell proliferation, cell cycle alterations with cell accumulation in the G1 phase and increased apoptosis in vitro. In vivo, on established tumor xenografts in athymic nude mice, 9 days of β-catenin silencing resulted in a significant reduction of CTNNB1 and AXIN2 expression. Moreover, continous β-catenin silencing, starting 3 days after tumor cell inoculation, was associated with a complete absence of tumor growth in the shβ group while tumors were present in all animals of the control group.ConclusionIn summary, these experiments provide evidences that Wnt/β-catenin pathway inhibition in ACC is a promising therapeutic target.

The influence of matriptase-2 on prostate cancer in vitro: A possible role for β-catenin

The type II transmembrane serine proteases (TTSPs) are a family of cell surface proteolytic enzymes contributing to a number of processes, such as tumour invasion and metastasis. Within the TTSPs, matriptase-2 is a relatively newly identified member and this protease has been shown to play a key role in cancer progression. β-catenin has long been regarded as an oncogene. The deregulation of the β-catenin signalling pathway plays a significant role in the progression and possibly the development of cancer. However, little is known about the role of matriptase-2 in prostate cancer. This study aimed to examine the correlation between matriptase-2 and β-catenin. Matriptase-2 was knocked down in the normal prostate cells, PZHPV7 and PNT2C2, using a ribozyme transgene targeting matriptase-2. The altered cells were used in a number of invitro experiments designed to investigate the involvement of matriptase-2 with β-catenin and to further characterise its function. The knockdown of matriptase-2 had no effect on cell growth or adhesion but significantly reduced cell motility (PZHPV7 cells, p<0.001; PNT2C2 cells, p=0.001 vs. respective control cells) and invasive capability (PZHPV7 cells, p=0.001; PNT2C2 cells, p=0.007). The knockdown also caused a large increase in β-catenin protein expression at the cell membrane in PZHPV7 and PNT2C2 cells and a decrease in PC3 cells overexpressing matriptase-2, but did not affect the mRNA levels. Matriptase-2 may have an important impact on prostate cancer progression. The data gained from this study suggest that matriptase-2 protects against the development and progression of prostate cancer by regulating the motility and invasive capabilities of prostate cancer cells. Matriptase-2 also reduces the levels of β-catenin at the cell membrane. As β-catenin is highly involved in the regulation of cellular processes, including motility and invasion, the reduction of β-catenin expression by matriptase-2 may be a possible mechanism by which matriptase-2 functions.

Selecting peptides for breast cancer treatment.

e13016 Background: HER2 is a member of epidermal growth factor family of receptors that is an essential mediator of cell proliferation and differentiation. In breast cancer patients, HER2 overexpression is associated with aggressive disease, chemo and hormone therapy resistance and poor prognosis. Currently, a HER2 specific monoclonal antibody, trastuzumab, is in use as a treatment for these breast cancer cases; however, there are many reports of resistance to this treatment. As an alternative we have selected specific peptides to HER2 using a phage display technology. Methods: A cyclic 7 aminoacids random peptide library had been panned using an external domain of recombinant HER2. After each round of binding assays, peptides were sequenced and two were selected. Cellular viability, migration and apoptosis/necrosis induced by these peptides were evaluated using SKBR3 cells. Confocal microscopy was used to determine the peptides co-localization with acidic vesicles and heparan sulfate. Western blotting was performed to evaluated some cell signalling pathways induced by these peptides. Results: The peptides were able to reduce the cell viability and migration around 50% alone and 85% in association. Tavelorb was able to induce apoptosis/ necrosis in 70% of SKBR3 cells and when associated with Hercid, the effect has increased to 90%. These peptides co-localize with acidic vesicles around 40-50%. The peptides and trastuzumab co-localized with heparan sulfate around 70%. The association between Hercid and Tavelorb inhibits Akt (pSer473) and the proteins enrolled in this pathway, as GSK3 and the transcription factor c-myc, however Akt inhibition is not dependent of PTEN. In addition, this peptides decreases BCL-XL, and MCL-1, while enhance Bax. The most important effect of this peptides is the reduction in β-catenin expression. Interestingly, p53 is downregulated in the presence of trastuzumab showing a mechanism by some tumors could be resistant to this therapy. Conclusions: The association of peptides has a very effective antitumoral effect in vitro, and their action seems to be HS dependent. The data propose a potential use of these peptides as a future alternative for breast cancer treatment. Supported by FAPESP, CNPq, CAPES.

Reduction of β-catenin expression in hepatocellular carcinoma inhibited the enhanced metastatic potential of hypoxia

Objective To explore the role of β-catenin in the proinvasive consequences of hypoxia in hepatocellular carcinoma (HCC).Methods We established in vitro and in vivo hypoxic models using the highly metastatic MHCC97 and the stable red fluorescent protein-expressing MHCC97-R cells.The role of β-catenin in hypoxia-mediated aggressiveness was investigated by β-catenin knockdown.Results Hypoxia caused a pronounced arrest of proliferation in MHCC97 cells,suppressed tumor growth in MHCC97-R xenografts,but promoted in vitro invasiveness and in vivo metastasis.β-Catenin-silencing by short hairpin significantly inhibited the enhanced invasiveness of MHCC97 cells due to hypoxia,reduced the increase in distant metastasis by hepatic arterial ligation,but failed to further restrain cell proliferation.Conclusion β-Catenin in HCC cells plays an essential role in the hypoxia-induced metastatic potential.A reduction of βcatenin expression inhibited the proinvasive consequences of hypoxia in HCC. Key words: β-catenin; Hepatocellular carcinoma; Hypoxia; Malignant potential

Activation of interleukin-6-induced glycoprotein 130/signal transducer and activator of transcription 3 pathway in mesenchymal stem cells enhances hepatic differentiation, proliferation, and liver regeneration

Adult bone marrow-derived mesenchymal stem cells (MSCs) exist in all living species and are capable of differentiating into different types of specific cells. In this study, we demonstrate the therapeutic effectiveness of rat MSC transplantation in D-galactosamine (GalN)-induced acute liver injury and identified the novel pathways which are involved in hepatic differentiation of MSCs. In vivo, intraportal transplantation with 5 × 10(6) MSCs at 24 hours after GalN administration resulted in significant reduction in serum levels of alanine aminotransferase, aspartate aminotransferase, and total bilirubin compared to the control group. Engrafted MSCs actively proliferated, differentiated, and further enhanced hepatocyte proliferation activity. In vitro, coculture of MSCs with GalN-induced injured hepatocytes showed efficient differentiation and was evidenced by progressive increase in messenger RNA levels of hepatic markers, including albumin, α-fetoprotein, CCAAT-enhancer binding protein α, α-1-antitryspin, and hepatocyte nuclear factor-3β. Immunofluorescent staining revealed that these cells were positive for albumin, α-fetoprotein, and cytokeratin 18, but not clusters of differentiation 34, cytokeratin 19, or OV6. During hepatic differentiation, signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling were constantly activated, and a gradual down-regulation of β-catenin expression in messenger RNA and protein levels was detected. Hyper-interleukin-6 fusion protein but not interleukin-6 (IL-6) alone caused reduction in β-catenin expression associated with the up-regulation of Wnt-5a in MSCs via activating the glycoprotein 130 (gp130)-mediated STAT3 signaling pathway, which indicates the operation of the trans-signaling mechanism. Activation of IL-6/gp130-mediated STAT3 signaling pathway in MSCs triggered wound healing, cell migration, and proliferation. In conclusion, transplantation of MSCs promotes cell proliferation and organ repair, and activation of IL-6/gp130-mediated STAT3 signaling pathway via soluble IL-6 receptor is crucial in hepatic differentiation of MSCs.

Regulation of leukemic cell adhesion, proliferation, and survival by β-catenin

AbstractIn epithelial cells β-catenin plays a critical role as a component of the cell-cell adhesion apparatus and as a coactivator of the TCF/LEF (T-cell transcription factor/lymphoid enhancer binding factor) family of transcription factors. Deregulation of β-catenin has been implicated in the malignant transformation of cells of epithelial origin. However, a function for β-catenin in hematologic malignancies has not been reported. β-Catenin is not detectable in normal peripheral blood T cells but is expressed in T–acute lymphoblastic leukemia cells and other tumor lines of hematopoietic origin and in primary lymphoid and myeloid leukemia cells. β-Catenin function was examined in Jurkat T–acute lymphoblastic leukemia cells. Overexpression of dominant-negative β-catenin or dominant-negative TCF reduced β-catenin nuclear signaling and inhibited Jurkat proliferation and clonogenicity. Similarly, these constructs inhibited proliferation of K562 and HUT-102 cells. Reduction of β-catenin expression with β-catenin antisense down-regulated adhesion of Jurkat cells in response to phytohemagglutinin. Incubation of Jurkat cells with anti-Fas induced caspase-dependent limited proteolysis of β-catenin N- and C-terminal regions and rapid redistribution of β-catenin to the detergent-insoluble cytoskeleton, concomitant with a marked decline in nuclear β-catenin signaling. Fas-mediated apoptosis was potentiated by inhibition of β-catenin nuclear signaling. The data suggest that β-catenin can play a significant role in promoting leukemic cell proliferation, adhesion, and survival.