Dickkopf-1 (DKK1) blockade mitigates osteogenesis imperfecta (OI) related bone disease.

BACKGROUND: The current treatment of osteogenesis imperfecta (OI) is imperfect. Our study thus delves into the potential of using Dickkopf-1 antisense (DKK1-AS) to treat OI. METHODS: We analysed serum DKK1 levels and their correlation with lumbar spine and hip T-scores in OI patients. Comparative analyses were conducted involving bone marrow stromal cells (BMSCs) and bone tissues from wild-type mice, untreated OI mice, and OI mice treated with DKK1-ASor DKK1-sense (DKK1-S). RESULTS: Significant inverse correlations were noted between serum DKK1 levels and lumbar spine (correlation coefficient = - 0.679, p = 0.043) as well as hip T-scores (correlation coefficient = - 0.689, p = 0.042) in OI patients. DKK1-AS improved bone mineral density (p = 0.002), trabecular bone volume/total volume fraction (p < 0.001), trabecular separation (p = 0.010), trabecular thickness (p = 0.001), trabecular number (p < 0.001), and cortical thickness (p < 0.001) in OI mice. DKK1-AS enhanced the transcription of collagen 1α1, osteocalcin, runx2, and osterix in BMSC from OI mice (all p < 0.001), resulting in a higher von Kossa-stained matrix area (p < 0.001) in ex vivo osteogenesis assays. DKK1-AS also reduced osteoclast numbers (p < 0.001), increased ß-catenin and T-cell factor 4 immunostaining reactivity (both p < 0.001), enhanced mineral apposition rate and bone formation rate per bone surface (both p < 0.001), and decreased osteoclast area (p < 0.001) in OI mice. DKK1-AS upregulated osteoprotegerin and downregulated nuclear factor-kappa B ligand transcription (both p < 0.001). Bone tissues from OI mice treated with DKK1-AS exhibited significantly higher breaking force compared to untreated OI mice (p < 0.001). CONCLUSIONS: Our study elucidates that DKK1-AS has the capability to enhance bone mechanical properties, restore the transcription of osteogenic genes, promote osteogenesis, and inhibit osteoclastogenesis in OI mice.

WNT3a Signaling Inhibits Aromatase Expression in Breast Adipose Fibroblasts-A Possible Mechanism Supporting the Loss of Estrogen Responsiveness of Triple-Negative Breast Cancers.

Estrogen-dependent breast cancers rely on a constant supply of estrogens and expression of estrogen receptors. Local biosynthesis, by aromatase in breast adipose fibroblasts (BAFs), is their most important source for estrogens. Triple-negative breast cancers (TNBC) rely on other growth-promoting signals, including those from the Wnt pathway. In this study, we explored the hypothesis that Wnt signaling alters the proliferation of BAFs, and is involved in regulation of aromatase expression in BAFs. Conditioned medium (CM) from TNBC cells and WNT3a consistently increased BAF growth, and reduced aromatase activity up to 90%, by suppression of the aromatase promoter I.3/II region. Database searches identified three putative Wnt-responsive elements (WREs) in the aromatase promoter I.3/II. In luciferase reporter gene assays, promoter I.3/II activity was inhibited by overexpression of full-length T-cell factor (TCF)-4 in 3T3-L1 preadipocytes, which served as a model for BAFs. Full-length lymphoid enhancer-binding factor (LEF)-1 increased the transcriptional activity. However, TCF-4 binding to WRE1 in the aromatase promoter, was lost after WNT3a stimulation in immunoprecipitation-based in vitro DNA-binding assays, and in chromatin immunoprecipitation (ChIP). In vitro DNA-binding assays, ChIP, and Western blotting revealed a WNT3a-dependent switch of nuclear LEF-1 isoforms towards a truncated variant, whereas ß-catenin levels remained unchanged. This LEF-1 variant revealed dominant negative properties, and most likely recruited enzymes involved in heterochromatin formation. In addition, WNT3a induced the replacement of TCF-4 by the truncated LEF-1 variant, on WRE1 of the aromatase promoter I.3/II. The mechanism described here may be responsible for the loss of aromatase expression predominantly associated with TNBC. Tumors with (strong) expression of Wnt ligands actively suppress aromatase expression in BAFs. Consequently a reduced estrogen supply could favor the growth of estrogen-independent tumor cells, which consequently would make estrogen receptors dispensable. In summary, canonical Wnt signaling within (cancerous) breast tissue may be a major factor controlling local estrogen synthesis and action.

T-cell factor (TCF/LEF1) binding elements (TBEs) of FasL (Fas ligand or CD95 ligand) bind and cluster Fas (CD95) and form complexes with the TCF-4 and b-catenin transcription factors in vitro and in vivo which result in triggering cell death and/or cell activation.

T-cell factor 4 (TCF4) is an important transcription factor of the Wnt signaling system. ß-catenin, an upstream protein of TCF4, accumulates in the cytoplasm, then translocates to the nucleus to activate the ß-catenin/T-cell factor/lymphoid enhancer factor (TCF/LEF) transcriptional machinery and regulates target genes. Previous studies showed that TCF4 was involved in cell proliferation and apoptosis. However, its expression and function in central nervous system injury are unclear. We performed a traumatic brain injury (TBI) model in adult rats. The expression of TCF4 in the brain cortex detected by Western blot increased after TBI. Double immunofluorescence staining revealed that TCF4 was expressed by neurons and microglia. In addition, co-localization of TCF4 with active caspase-3 or proliferating cell nuclear antigen was observed in neurons and microglia, respectively, suggesting that TCF4 might participate in neuronal apoptosis and microglial proliferation after TBI. To further investigate the functions of TCF4, PC12 and HAPI cells were employed to establish a neuronal apoptosis and microglial proliferation model in vitro, respectively. Knocking down TCF4 with siRNA proved the pro-apoptotic and pro-proliferation effect of TCF4 in PC12 and HAPI cells, respectively. Taken together, TCF4 might promote neuronal apoptosis and microglial proliferation after TBI.

Loss of exon 4 in a human T-cell factor-4 isoform promotes hepatic tumourigenicity.

BACKGROUND: T-cell factor (TCF) proteins represent key transcription factors that activate Wnt/ß-catenin signalling. We have reported that a pair of TCF-4 isoforms (TCF-4C and TCF-4D) exhibit differential TCF transcriptional activity in hepatocellular carcinoma (HCC) cells, although their structure differs by only the presence (TCF-4D) or absence (TCF-4C) of exon 4. AIM: To demonstrate a regulatory role of exon 4 in HCC development. METHODS: TCF-4C and TCF-4D expression profiles were examined in 27 pairs of human HCC and adjacent liver tissues. The functional role of the TCF-4 isoforms was evaluated in OUMS-29 (an immortalized hepatocyte-derived) and HAK-1A (a well-differentiated HCC) cell lines using stable clones overexpressing the TCF-4 isoforms. RESULTS: TCF-4C was significantly upregulated in HCC tissues compared with corresponding peritumour and normal liver tissues; in contrast, there was no difference in TCF-4D expression. TCF-4C clones derived from both cell lines exhibited increased TCF activity, Wnt-responsive target genes, cell proliferation, cell cycle progression and resistance to chemotherapeutic drugs compared with TCF-4D clones. Capability of cell migration and colony formation was significantly higher in TCF-4C than TCF-4D clones. In a nude mice xenograft model, the HAK-1A-derived TCF-4C clone rapidly developed tumours compared with the TCF-4D clone. TCF-4C clone-derived tumours exhibited upregulation of Wnt-responsive target genes compared with the slow developing and small TCF-4D-derived tumours. CONCLUSION: These results demonstrate that the TCF-4C isoform lacking exon 4 is associated with a malignant phenotype compared with the exon 4-harbouring TCF-4D isoform, indicating that exon 4 of TCF-4 plays a prominent role in HCC development.

Antimicrobial agent chloroxylenol targets ß­catenin­mediated Wnt signaling and exerts anticancer activity in colorectal cancer.

Chloroxylenol is the active ingredient of the antibacterial agent Dettol. The anticancer effect and underlying mechanisms of this compound and other common antimicrobial agents have not been clearly elucidated. In the present study, the effects of chloroxylenol, benzalkonium chloride, benzethonium chloride, triclosan and triclocarban on ß­catenin­mediated Wnt signaling in colorectal cancer were evaluated using the SuperTOPFlash reporter assay. It was demonstrated that chloroxylenol, but not the other antimicrobial agents tested, inhibited the Wnt/ß­catenin signaling pathway by decreasing the nuclear translocation of ß­catenin and disrupting ß­catenin/T­cell factor 4 complex, which resulted in the downregulation of the Wnt target genes Axin2, Survivin and Leucine­rich G protein­coupled receptor­5. Chloroxylenol effectively inhibited the viability, proliferation, migration and invasion, and sphere formation, and induced apoptosis in HCT116 and SW480 cells. Notably, chloroxylenol attenuated the growth of colorectal cancer in the MC38 cell xenograft model and inhibited organoid formation by the patient­derived cells. Chloroxylenol also demonstrated inhibitory effects on the stemness of colorectal cancer cells. The results of the present study demonstrated that chloroxylenol could exert anti­tumor activities in colorectal cancer by targeting the Wnt/ß­catenin signaling pathway, which provided an insight into its therapeutic potential as an anticancer agent.

lncRNA EGFEM1P promotes thyroid cancer progression by acting as an miR-369-3p sponge and upregulating TCF4.

Thyroid cancer is the most commonly diagnosed endocrine cancer, with the incidence of 14.42 per 100,000 person-years in 2010-2013. It is important to conduct an in-depth exploration into the molecular mechanisms of thyroid cancer, providing insights into the improvements of therapy. Long non-coding RNAs (lncRNAs) act as oncogenes or tumor suppressors in thyroid cancer by sponging microRNAs (miRNAs), however, the functions of numerous lncRNAs are still unknown. In the present study, via the comprehensive analysis of microarray data derived from papillary thyroid tumors and the RNA sequencing of thyroid tumors from The Cancer Genome Atlas database, EGF like and EMI domain containing 1 (EGFEM1P) expression levels in papillary thyroid tumors and normal adjacent tissues were explored. Reverse transcription-quantitative PCR was used to detect EGFEM1P, microRNA (miR)-369-3p and T cell factor 4 (TCF4) expression levels. Western blotting was used to detect TCF4 protein and cleaved caspase-3/8 expression levels. Cell proliferative ability and apoptosis were assessed using the Cell Counting Kit-8 assay and flow cytometry, respectively. The interactions between EGFEM1P and miR-369-3p, and miR-369-3p and TCF4, were determined using the dual-luciferase reporter assay. The results demonstrated that EGFEM1P was upregulated in papillary thyroid tumors and thyroid cancer cells compared with normal adjacent tissues and human normal thyroid epithelial Nthy-ori 3-1 cell line. In the examined thyroid cancer cells, EGFEM1P was demonstrated to interact with miR-369-3p and decreased miR-369-3p expression levels. Thereafter, TCF4 was determined to be a target gene of miR-369-3p and EGFEM1P promoted TCF4 expression via regulating miR-369-3p expression levels. At last, it was found that EGFEM1P expression promoted rapid cell proliferation and inhibited cell apoptosis in thyroid cancer cells via acting as a miR-369-3p sponge. In conclusion EGFEM1P promoted thyroid cancer progression via acting as a sponge of the miR-369-3p/TCF4 axis.

Protocatechuic aldehyde protects cardiomycoytes against ischemic injury via regulation of nuclear pyruvate kinase M2.

Rescuing cells from stress damage emerges a potential therapeutic strategy to combat myocardial infarction. Protocatechuic aldehyde (PCA) is a major phenolic acid in Chinese herb Danshen (Salvia miltiorrhiza root). This study investigated whether PCA regulated nuclear pyruvate kinase isoform M2 (PKM2) function to protect cardiomyocytes. In rats subjected to isoprenaline, PCA attenuated heart injury and protected cardiomyocytes from apoptosis. Through DARTS and CETSA assays, we identified that PCA bound and promoted PKM2 nuclear translocation in cardiomyocytes exposed to oxygen/glucose deprivation (OGD). In the nucleus, PCA increased the binding of PKM2 to ß-catenin via preserving PKM2 acetylation, and the complex, in cooperation with T-cell factor 4 (TCF4), was required for transcriptional induction of genes encoding anti-apoptotic proteins, contributing to rescuing cardiomyocyte survival. In addition, PCA ameliorated mitochondrial dysfunction and prevented mitochondrial apoptosis dependent on PKM2. Consistently, PCA increased the binding of PKM2 to ß-catenin, improved heart contractive function, normalized heart structure and attenuated oxidative damage in mice subjected to artery ligation, but the protective effects were lost in Pkm2-deficient heart. Together, we showed that PCA regulated nuclear PKM2 function to rescue cardiomyocyte survival via ß-catenin/TCF4 signaling cascade, suggesting the potential of pharmacological intervention of PKM2 shuttle to protect the heart.

Isorhapontigenin protects against doxorubicin-induced cardiotoxicity via increasing YAP1 expression.

As an effective anticancer drug, the clinical limitation of doxorubicin (Dox) is the time- and dose-dependent cardiotoxicity. Yes-associated protein 1 (YAP1) interacts with transcription factor TEA domain 1 (TEAD1) and plays an important role in cell proliferation and survival. However, the role of YAP1 in Dox-induced cardiomyopathy has not been reported. In this study, the expression of YAP1 was reduced in clinical human failing hearts with dilated cardiomyopathy and Dox-induced in vivo and in vitro cardiotoxic model. Ectopic expression of Yap1 significantly blocked Dox-induced cardiomyocytes apoptosis in TEAD1 dependent manner. Isorhapontigenin (Isor) is a new derivative of stilbene and responsible for a wide range of biological processes. Here, we found that Isor effectively relieved Dox-induced cardiomyocytes apoptosis in a dose-dependent manner in vitro. Administration with Isor (30 mg/kg/day, intraperitoneally, 3 weeks) significantly protected against Dox-induced cardiotoxicity in mice. Interestingly, Isor increased Dox-caused repression in YAP1 and the expression of its target genes in vivo and in vitro. Knockout or inhibition of Yap1 blocked the protective effects of Isor on Dox-induced cardiotoxicity. In conclusion, YAP1 may be a novel target for Dox-induced cardiotoxicity and Isor might be a new compound to fight against Dox-induced cardiotoxicity by increasing YAP1 expression.

T Cell Factor 4 Is Involved in Papillary Thyroid Carcinoma via Regulating Long Non-Coding RNA HCP5.

The annual incidence of papillary thyroid carcinoma has increased dramatically. T cell factor 4 (TCF4) is an important component of Wnt signaling pathway.However, the role of TCF4 in PTC remains unknown. In this study, TCF4 was observed to overexpress in PTC patients and cells by qRT-PCR assay. The colony formation assay, Edu staining and transwell assay indicated thatoverexpression of TCF4 promoted cell proliferation and invasion of TCP-1 cells, whereas knockdown of TCF4 inhibited cell proliferation and invasion of IHH-4 cells. To investigate the mechanism of TCF4 in PTC cells, the luciferase assay demonstrated that TCF4 could modulate HCP5 expression. Besides, GLuc-ON promoter reporter assayproved that TCF4 could bind to HCP5 promoter. Further, knockdown of HCP5 could significantly up-regulated miR-15a, miR-216a-5p, miR-22-3p, miR-139-5p, miR-203, miR-27a-3p and miR-320, and down-regulated miR-186-5p in IHH-4 cells, which might be potential downstream of TFC4/HCP5 axis. In conclusion, up-regulation TCF4 can promote HCP5 expression via binding to HCP5 promoter. It may be the first time to prove that TCF4 regulates HCP5 in PTC, which provides a novel sight for treatment of PTC.

Wnt3a-regulated TCF4/ß-catenin complex directly activates the key Hedgehog signalling genes Smo and Gli1.

The Wnt and Hedgehog signalling pathways serve key roles in diverse developmental processes. However, the molecular associations between these two signalling pathways remains unclear. Previous transcriptome studies on human foreskin fibroblasts have indicated that Wnt signalling activation induces the expression of key Hedgehog signalling genes, including smoothened, frizzled class receptor (Smo) and GLI family zinc finger 1 (Gli1). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) results revealed that Wnt3a treatment induced the expression of the key Hedgehog signalling genes, including Smo, patched (PTCH), Gli1, Gli2 and Gli3. In addition, western blot analyses demonstrated that Wnt3a treatment resulted in the accumulation of cellular Smo and Gli proteins. Furthermore, promoter sequence analysis revealed that the putative ß-catenin/T-cell factor (TCF)-4 complex binding motifs (T/AC/GAAAG) were located within 1.5 kb of the Smo and Gli1 promoters. Results of the chromatin immunoprecipitation experiments and yeast-one hybrid assays revealed that TCF4 directly binds to the Smo and Gli1 promoters, with two binding sites for Smo and a single binding site for Gli1. Further analysis showed that the ß-catenin/TCF4 complex binds to the Smo and Gli1 promoters. To investigate the functions of TCF4 and ß-catenin in transcriptional regulation of Smo and Gli1, TCF4 and ß-catenin were transiently expressed in fibroblast cells. RT-qPCR results demonstrated that overexpression of TCF4 and ß-catenin induced the expression of Smo and Gli1. In addition, small interfering RNA-mediated suppression of ß-catenin resulted in the downregulation of Smo and Gli1 expression levels, even under Wnt3a treatment. Suppression of ß-catenin and Gli1 expression inhibited cell proliferation. Taken together, the results of the present study suggested that the ß-catenin/TCF4 complex directly activates Smo and Gli1 by binding to their promoters, which in turn controls cell proliferation in human fibroblasts.

T-cell factor-4 and MHC upregulation in pigs receiving a live attenuated classical swine fever virus (CSFV) vaccine strain with interferon-gamma adjuvant.

The effect of co-administration of interferon (IFN)-γ in pigs undergoing vaccination with an attenuated strain (LPC) of classical swine fever virus (CSFV) was investigated. Unvaccinated pigs demonstrated pyrexia and died 7-9 days after challenge with virulent CSFV. Pigs receiving the attenuated vaccine remained healthy after virus challenge, except for mild, transient pyrexia, whereas pigs receiving IFN-γ simultaneously with the vaccine demonstrated normal body temperatures after virus challenge. Examination by nested RT-PCR revealed greater viral load in the spleens of the pigs vaccinated with the attenuated CSFV, compared with those that had additionally received IFN-γ. Expression of major histocompatibility complex (MHC) class I and MHC class II molecules was upregulated in the spleens of the IFN-γ treated vaccinated pigs, demonstrated by immunohistochemistry. Based on Western blot analysis, anti-CSFV IgG2 antibodies were elevated in vaccinated pigs by co-administration of IFN-γ (IFN-γ(Hi): P < 0.01; IFN-γ(Lo): P <0.05). By employing the suppression subtractive hybridization technique, RT-PCR, in situ hybridization, and immunohistochemistry, T-cell factor-4 (Tcf-4) mRNA and protein expression were found to be upregulated in the spleens of vaccinated pigs that had received IFN-γ. This study suggests involvement of Tcf-4 in IFN-γ-mediated immune regulation following CSFV vaccination.

Targeting the Wnt signaling pathway in colorectal cancer.

INTRODUCTION: The treatment of patients with advanced colorectal cancer still remains challenging, and identification of new target molecules and therapeutic avenues remains a priority. The great majority of colorectal cancers have mutations in one of two genes involved in the Wnt signaling pathway: the adenomatous polyposis coli (APC) and ß-catenin (CTNNB1) genes. Up to now, however, no therapeutics for targeting this pathway have been established. AREAS COVERED: This review article begins with a brief summary of Wnt signaling from the viewpoints of genetics, cancer stem cell biology, and drug development. We then overview current attempts to develop drugs directed at various components of the Wnt signaling pathway. EXPERT OPINION: APC is a tumor suppressor, and therefore only downstream signal transducers of the APC protein can be considered as targets for pharmaceutical intervention. TRAF2 and NCK-interacting protein kinase (TNIK) was identified as the most downstream regulator of Wnt signaling by two independent research groups, and several classes of small-molecule inhibitors targeting this protein kinase have been developed. TNIK is a multifunctional protein with actions that extend beyond Wnt signaling regulation. Such TNIK inhibitors are expected to have a large variety of clinical applications.

Expression of Nemo-like kinase was increased and negatively correlated with the expression of TCF4 in lung cancers.

Nemo-like kinase (NLK), as a mitogen activated protein kinase (MAPK)-like kinase, is involved in the development of several human cancers. In this study, we explored the expression of NLK in lung squamous cell carcinoma (SCC) and adenocarcinoma tissues, and investigated the associations among NLK, ß-catenin, T-cell factor 4 (TCF4), and the clinicopathological factors of lung cancers. The expressions of NLK, ß-catenin, TCF4 were examined in 109 cases of lung cancers using immunohistochemistry method. The expression of NLK was observed in the nuclei of lung cancer tissues, and was significantly higher in lung cancer tissues than that in corresponding normal lung tissues (t = 21.636, n = 109, P < 0.001). The high expression of NLK was found in 45 cases of lung SCCs (45/49, 91.84%), which was much more than that in adenocarcinomas (38/60, 63.33%) (P = 0.001). Furthermore, the high expression of NLK was negatively correlated with TCF4 expression and positively correlated with the membranous expression of ß-catenin. In conclusion, the present study demonstrated that the expression of NLK was localized in nucleus and significantly increased in lung cancers. The expression of NLK was negatively correlated with TCF4 expression and positively correlated with ß-catenin membranous expression in lung cancers.

The prognostic role of TCF4 expression in locally advanced rectal cancer patients treated with neoadjuvant chemoradiotherapy.

BACKGROUND: At present no useful factors to predict the sensitivity to neoadjuvant chemoradiotherapy (nCRT) have been established in patients with locally advanced rectal cancer (LARC). OBJECTIVE: The objective of this study was to explore the prognostic role of T cell factor 4 (TCF4) expression in predicting tumor response to nCRT and tumor outcomes for patients with LARC. METHODS: The study enrolled 96 patients who underwent nCRT followed by total mesorectal excision (TME). The TCF4 expression of all patients' biopsies before nCRT was evaluated by Immunohistochemical staining method. RESULTS: After completion of nCRT, 5 cases (5.2%) achieved clinical complete response (cCR) thus the remaining 91 patients underwent a standardized total mesorectal excision (TME) procedure. There were 44 patients (45.8%) achieved good tumor response (including TRG 3-4 and 5 cCR patients) while poor response (TRG 0-2) was achieved in 52 patients (54.2%). Our results demonstrated that patients with low expression of TCF4 were more sensitive to nCRT than those with high TCF4 expression (P=0.031). Low TCF4 expression before nCRT and good response were significantly associated with improved 5-year disease-free survival and 5-year overall survival (P<0.05). Multivariate analysis confirmed that the pretreatment TCF4 expression was an independent prognostic factor. CONCLUSIONS: Our data revealed that low TCF4 protein expression was a useful predictive factor of good tumor response to nCRT and good outcomes in patients with LARC.