Dkk3, downregulated in cervical cancer, functions as a negative regulator of β-catenin

A Synopsis of Biomarkers in Glioblastoma: Past and Present

Accounting for 48% of malignant brain tumors in adults, glioblastoma has been of great interest in the last decades, especially in the biomolecular and neurosurgical fields, due to its incurable nature and notable neurological morbidity. The major advancements in neurosurgical technologies have positively influenced the extent of safe tumoral resection, while the latest progress in the biomolecular field of GBM has uncovered new potential therapeutical targets. Although GBM currently has no curative therapy, recent progress has been made in the management of this disease, both from surgical and molecular perspectives. The main current therapeutic approach is multimodal and consists of neurosurgical intervention, radiotherapy, and chemotherapy, mostly with temozolomide. Although most patients will develop treatment resistance and tumor recurrence after surgical removal, biomolecular advancements regarding GBM have contributed to a better understanding of this pathology and its therapeutic management. Over the past few decades, specific biomarkers have been discovered that have helped predict prognosis and treatment responses and contributed to improvements in survival rates.

ICBP90, an epigenetic regulator, induces DKK3 promoter methylation, promotes glioma progression, and reduces sensitivity to cis-platinum

Glioma is the most common brain malignancy, characterized by high morbidity, high mortality, and treatment-resistance. Inverted CCAAT box Binding Protein of 90 kDa (ICBP90) has been reported to be involved in tumor progression and the maintenance of DNA methylation. Herein, we constructed ICBP90 over-expression and knockdown glioma cell lines, and found that ICBP90 knockdown inhibited glioma cell proliferation, migration, and invasion. ICBP90 silencing potentially enhanced cellular sensitivity to cis-platinum (DDP) and exacerbated DDP-induced pyroptosis, manifested by the elevated levels of gasdermin D-N-terminal and cleaved caspase 1; whereas, ICBP90 over-expression exhibited the opposite effects. Consistently, ICBP90 knockdown inhibited tumor growth in an in vivo mouse xenograft study using U251 cells stably expressing sh-ICBP90 and oe-ICBP90. Further experiments found that ICBP90 reduced the expression of Dickkopf 3 homolog (DKK3), a negative regulator of β-catenin, by binding its promoter and inducing DNA methylation. ICBP90 knockdown prevented the nuclear translocation of β-catenin and suppressed the expression of c-Myc and cyclin D1. Besides, DKK3 over-expression restored the effects of ICBP90 over-expression on cell proliferation, migration, invasion, and DDP sensitivity. Our findings suggest that ICBP90 inhibits the expression of DKK3 in glioma by maintaining DKK3 promoter methylation, thereby conducing to ICBP90-mediated carcinogenesis and drug insensitivity.

Mechanisms and markers of malignant transformation of oral submucous fibrosis

Oral submucous fibrosis (OSF) is a chronic premalignant disease associated with betel quid chewing. Epidemiological studies indicate that there are approximately 5 million individuals suffering from OSF worldwide, with a concerning malignancy transformation rate of up to 4.2 %. When OSF progresses to oral squamous cell carcinoma (OSCC), the 5-year survival rate for OSCC drops to below 60 %. Therefore, early screening and diagnosis are essential for both preventing and effectively treating OSF and its potential malignant transformation. Numerous studies have shown that the malignant transformation of OSF is associated with various factors, including epigenetic reprogramming, epithelial-mesenchymal transition, hypoxia, cell cycle changes, immune regulation disturbances, and oxidative damage. This review article focuses on the unraveling the potential mechanisms underlying the malignant transformation of OSF, as well as the abnormal expression of biomarkers throughout this transformative process, with the aim of aiding early screening for carcinogenic changes in OSF. Furthermore, we discuss the significance of utilizing blood and saliva components from patients with OSF, along with optical diagnostic techniques, in the early screening of OSF malignant transformation.

Wnt/β-catenin signaling pathway in the tumor progression of adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is an uncommon, aggressive endocrine malignancy with a high rate of recurrence, a poor prognosis, and a propensity for metastasis. Currently, only mitotane has received certification from both the US Food and Drug Administration (FDA) and the European Medicines Agency for the therapy of advanced ACC. However, treatment in the advanced periods of the disorders is ineffective and has serious adverse consequences. Completely surgical excision is the only cure but has failed to effectively improve the survival of advanced patients. The aberrantly activated Wnt/β-catenin pathway is one of the catalysts for adrenocortical carcinogenesis. Research has concentrated on identifying methods that can prevent the stimulation of the Wnt/β-catenin pathway and are safe and advantageous for patients in view of the absence of effective treatments and the frequent alteration of the Wnt/β-catenin pathway in ACC. Comprehending the complex connection between the development of ACC and Wnt/β-catenin signaling is essential for accurate pharmacological targets. In this review, we summarize the potential targets between adrenocortical carcinoma and the Wnt/β-catenin signaling pathway. We analyze the relevant targets of drugs or inhibitors that act on the Wnt pathway. Finally, we provide new insights into how drugs or inhibitors may improve the treatment of ACC.

The Multifaceted Role of Human Dickkopf-3 (DKK-3) in Development, Immune Modulation and Cancer

The human Dickkopf (DKK) family includes four main secreted proteins, DKK-1, DKK-2, DKK-3, and DKK-4, as well as the DKK-3 related protein soggy (Sgy-1 or DKKL1). These glycoproteins play crucial roles in various biological processes, and especially modulation of the Wnt signaling pathway. DKK-3 is distinct, with its multifaceted roles in development, stem cell differentiation and tissue homeostasis. Intriguingly, DKK-3 appears to have immunomodulatory functions and a complex role in cancer, acting as either a tumor suppressor or an oncogene, depending on the context. DKK-3 is a promising diagnostic and therapeutic target that can be modulated by epigenetic reactivation, gene therapy and DKK-3-blocking agents. However, further research is needed to optimize DKK-3-based therapies. In this review, we comprehensively describe the known functions of DKK-3 and highlight the importance of context in understanding and exploiting its roles in health and disease.

A novel ΔNp63-dependent immune mechanism improves prognosis of HPV-related head and neck cancer

Background

Deconvoluting the heterogenous prognosis of Human Papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OSCC) is crucial for enhancing patient care, given its rapidly increasing incidence in western countries and the adverse side effects of OSCC treatments.

Methods

Transcriptomic data from HPV-positive OSCC samples were analyzed using unsupervised hierarchical clustering, and clinical relevance was evaluated using Kaplan-Meier analysis. HPV-positive OSCC cell line models were used in functional analyses and phenotypic assays to assess cell migration and invasion, response to cisplatin, and phagocytosis by macrophages in vitro.

Results

We found, by transcriptomic analysis of HPV-positive OSCC samples, a ΔNp63 dependent molecular signature that is associated with patient prognosis. ΔNp63 was found to act as a tumor suppressor in HPV-positive OSCC at multiple levels. It inhibits cell migration and invasion, and favors response to chemotherapy. RNA-Seq analysis uncovered an unexpected regulation of genes, such as DKK3, which are involved in immune response-signalling pathways. In agreement with these observations, we found that ΔNp63 expression levels correlate with an enhanced anti-tumor immune environment in OSCC, and ΔNp63 promotes cancer cell phagocytosis by macrophages through a DKK3/NF-κB-dependent pathway.

Conclusion

Our findings are the first comprehensive identification of molecular mechanisms involved in the heterogeneous prognosis of HPV-positive OSCC, paving the way for much-needed biomarkers and targeted treatment.

Research progress on the role of the Wnt signaling pathway in pituitary adenoma

Pituitary adenoma (PA) is the third most common central nervous system tumor originating from the anterior pituitary, but its pathogenesis remains unclear. The Wnt signaling pathway is a conserved pathway involved in cell proliferation, Self-renewal of stem cells, and cell differentiation. It is related to the occurrence of various tumors, including PA. This article reviews the latest developments in Wnt pathway inhibitors and pathway-targeted drugs. It discusses the possibility of combining Wnt pathway inhibitors with immunotherapy to provide a theoretical basis for the combined treatment of PA.

Chidamide: Targeting epigenetic regulation in the treatment of hematological malignancy

Epigenetic alterations frequently participate in the onset of hematological malignancies. Histone deacetylases (HDACs) are essential for regulating gene transcription and various signaling pathways. Targeting HDACs has become a novel treatment option for hematological malignancies. Chidamide is the first oral selective HDAC inhibitor for HDAC1, HDAC2, HDAC3, and HDAC10 and was first approved for the treatment of R/R peripheral T-cell lymphoma by the China Food and Drug Administration in 2014. Chidamide was also approved under the name Hiyasta (HBI-8000) in Japan in 2021. In vitro studies revealed that chidamide could inhibit proliferation and induce apoptosis via cell cycle arrest and the regulation of apoptotic proteins. In clinical studies, chidamide was also efficacious in multiple myeloma, acute leukemia and myelodysplastic syndrome. This review includes reported experimental and clinical data on chidamide monotherapy or chidamide treatment in combination with chemotherapy for various hematological malignancies, offering a rationale for the renewed exploration of this drug.

PDHB-AS suppresses cervical cancer progression and cisplatin resistance via inhibition on Wnt/β-catenin pathway

Cervical cancer (CC) is the most prevalent gynecological malignancy occurring in the cervix. Long non-coding RNAs (lncRNAs) can act as oncogenes or anti-oncogenes in CC development. Here, we investigated the functional role and detailed mechanism of lncRNA pyruvate dehydrogenase E1 subunit beta antisense (PDHB-AS) in CC. At first, we found that PDHB-AS was significantly down-regulated in CC cells. Besides, overexpression of PDHB-AS repressed CC cell malignant behaviors. HKF-derived exosomes carried miR-4536-5p to CC cells and thereby inhibited PDHB-AS expression. Moreover, PDHB-AS inactivated the Wnt/β-catenin pathway via impeding the nuclear translocation of β-catenin in CC cells. In addition, miR-582-5p could bind with both PDHB-AS and Dickkopf-1 (DKK1). PDHB-AS recruited poly(A) binding protein cytoplasmic 1 (PABPC1) to inhibit Wnt7b expression. PDHB-AS interacted with RNA-binding motif protein X-linked (RBMX) to regulate cisplatin resistance in CC. Finally, we conducted in vivo experiments to confirm that HKF promoted CC tumor growth whereas PDHB-AS suppressed CC tumor growth. Collectively, PDHB-AS plays a tumor-suppressive role in the progression of CC, which suggests the therapeutic potential of PDHB-AS for CC.

Patterns of NFkB activation resulting from damage, reactive microglia, cytokines, and growth factors in the mouse retina

Müller glia are a cellular source for neuronal regeneration in vertebrate retinas. However, the capacity for retinal regeneration varies widely across species. Understanding the mechanisms that regulate the reprogramming of Müller glia into progenitor cells is key to reversing the loss of vision that occurs with retinal diseases. In the mammalian retina, NFkB signaling promotes glial reactivity and represses the reprogramming of Müller glia into progenitor cells. Here we investigate different cytokines, growth factors, cell signaling pathways, and damage paradigms that influence NFkB-signaling in the mouse retina. We find that exogenous TNF and IL1β potently activate NFkB-signaling in Müller glia in undamaged retinas, and this activation is independent of microglia. By comparison, TLR1/2 agonist indirectly activates NFkB-signaling in Müller glia, and this activation depends on the presence of microglia as Tlr2 is predominantly expressed by microglia, but not other types of retinal cells. Exogenous FGF2 did not activate NFkB-signaling, whereas CNTF, Osteopontin, WNT4, or inhibition of GSK3β activated NFkB in Müller glia in the absence of neuronal damage. By comparison, dexamethasone, a glucocorticoid agonist, suppressed NFkB-signaling in Müller glia in damaged retinas, in addition to reducing numbers of dying cells and the accumulation of reactive microglia. Although NMDA-induced retinal damage activated NFkB in Müller glia, optic nerve crush had no effect on NFkB activation within the retina, whereas glial cells within the optic nerve were responsive. We conclude that the NFkB pathway is activated in retinal Müller glia in response to many different cell signaling pathways, and activation often depends on signals produced by reactive microglia.

Canine osteosarcoma in comparative oncology: Molecular mechanisms through to treatment discovery

Cancer is a leading cause of non-communicable morbidity and mortality throughout the world, similarly, in dogs, the most frequent cause of mortality is tumors. Some types of cancer, including osteosarcoma (OSA), occur at much higher rates in dogs than people. Dogs therefore not only require treatment themselves but can also act as an effective parallel patient population for the human disease equivalent. It should be noted that although there are many similarities between canine and human OSA, there are also key differences and it is important to research and highlight these features. Despite progress using chorioallantoic membrane models, 2D and 3D in vitro models, and rodent OSA models, many more insights into the molecular and cellular mechanisms, drug development, and treatment are being discovered in a variety of canine OSA patient populations.

Dickkopf-3: An Update on a Potential Regulator of the Tumor Microenvironment

Dickkopf-3 (Dkk-3) is a member of the Dickkopf family protein of secreted Wingless-related integration site (Wnt) antagonists that appears to modulate regulators of the host microenvironment. In contrast to the clear anti-tumorigenic effects of Dkk-3-based gene therapies, the role of endogenous Dkk-3 in cancer is context-dependent, with elevated expression associated with tumor promotion and suppression in different settings. The receptors and effectors that mediate the diverse effects of Dkk-3 have not been characterized in detail, contributing to an ongoing mystery of its mechanism of action. This review compares the various functions of Dkk-3 in the tumor microenvironment, where Dkk-3 has been found to be expressed by subpopulations of fibroblasts, endothelial, and immune cells, in addition to epithelial cells. We also discuss how the activation or inhibition of Dkk-3, depending on tumor type and context, might be used to treat different types of cancers.

Establishment of anti-DKK3 peptide for the cancer control in head and neck squamous cell carcinoma (HNSCC)

Background

Head and neck squamous cell carcinoma (HNSCC) is the most common malignant tumor of the head and neck. We identified cancer-specific genes in HNSCC and focused on DKK3 expression. DKK3 gene codes two isoforms of proteins (secreted and non-secreted) with two distinct cysteine rich domains (CRDs). It is reported that DKK3 functions as a negative regulator of oncogenic Wnt signaling and, is therefore, considered to be a tumor suppressor gene. However, our series of studies have demonstrated that DKK3 expression is specifically high in HNSCC tissues and cells, and that DKK3 might determine the malignant potentials of HNSCC cells via the activation of Akt. Further analyses strongly suggested that both secreted DKK3 and non-secreted DKK3 could activate Akt signaling in discrete ways, and consequently exert tumor promoting effects. We hypothesized that DKK3 might be a specific druggable target, and it is necessary to establish a DKK3 inhibitor that can inhibit both secreted and non-secreted isoforms of DKK3.

Methods

Using inverse polymerase chain reaction, we generated mutant expression plasmids that express DKK3 without CRD1, CRD2, or both CRD1 and CRD2 (DKK3ΔC1, DKK3ΔC2, and DKK3ΔC1ΔC2, respectively). These plasmids were then transfected into HNSCC-derived cells to determine the domain responsible for DKK3-mediated Akt activation. We designed antisense peptides using the MIMETEC program, targeting DKK3-specific amino acid sequences within CRD1 and CRD2. The structural models for peptides and DKK3 were generated using Raptor X, and then a docking simulation was performed using CluPro2. Afterward, the best set of the peptides was applied into HNSCC-derived cells, and the effects on Akt phosphorylation, cellular proliferation, invasion, and migration were assessed. We also investigated the therapeutic effects of the peptides in the xenograft models.

Results

Transfection of mutant expression plasmids and subsequent functional analyses revealed that it is necessary to delete both CRD1 and CRD2 to inhibit Akt activation and inhibition of proliferation, migration, and invasion. The inhibitory peptides for CRD1 and CRD2 of DKK3 significantly reduced the phosphorylation of Akt, and consequently suppressed cellular proliferation, migration, invasion and in vivo tumor growth at very low doses.

Conclusions

This inhibitory peptide represents a promising new therapeutic strategy for HNSCC treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02783-9.

Apogossypolone Inhibits Cell Proliferation and Epithelial-Mesenchymal Transition in Cervical Cancer via Activating DKK3

Apogossypolone (ApoG2), a novel derivative of gossypol lacking of two aldehyde groups, exhibits anti-tumor effects. However, the mechanisms by which ApoG2 regulates cervical cancer (CC) cells remain unclear. In this study, we treated two CC cell lines (CaSki and HeLa) with an increasing concentration of ApoG2 for 24 h. Cell Counting Kit-8 (CCK-8) assay, colony formation assay, flow cytometry and transwell invasion assay were utilized to detect cell proliferation, apoptosis and invasion in vitro. We first observed that ApoG2 inhibited cell proliferation, invasion and epithelial-to-mesenchymal transition (EMT) process in CC cells, along with upregulation of Dickkopf Wnt signaling pathway inhibitor 3 (DKK3) in a dose-dependent manner. The immunohistochemistry confirmed the downregulation of DKK3 in tumor tissues. Moreover, DKK3 was correlated with FIGO stage and lymph node metastasis. Functionally, DKK3 overexpression significantly suppressed cell viability, colony formation and invasion, but promoted apoptosis in CaSki and HeLa cells. Overexpression of DKK3 upregulated the protein levels of cleaved caspase-3 and E-cadherin, but downregulated the protein levels of Bcl-2, N-cadherin and Vimentin. Furthermore, DKK3 knockdown reversed the suppressive effects of ApoG2 on CaSki cell proliferation, invasion and EMT markers, while DKK3 overexpression enhanced these effects. In addition, ApoG2 treatment inhibited CC xenograft tumor growth and upregulated the protein levels of DKK3, cleaved caspase-3 and E-cadherin. In conclusions, these findings suggested that ApoG2 could effectively inhibit the growth and invasion of CC cells at least partly by activating DKK3.

DKK3, Downregulated in Invasive Epithelial Ovarian Cancer, Is Associated with Chemoresistance and Enhanced Paclitaxel Susceptibility via Inhibition of the β-Catenin-P-Glycoprotein Signaling Pathway

Simple Summary

Dickkopf-3 (DKK3) is considered a tumor suppressor as it possesses anti-tumoral properties and is frequently downregulated in various cancers. However, the role of DKK3 in ovarian cancer is not known. In this study, we showed that DKK3 loss occurred in 56.1% of patients with ovarian cancer and that it was significantly associated with poor survival and chemoresistance. Secreted DKK3 possessed anti-tumoral properties and enhanced paclitaxel susceptibility by inhibiting the β-catenin-P-glycoprotein signaling pathway in ovarian cancer. This study revealed promising therapeutic effects of secreted DKK3, which targets paclitaxel-resistant ovarian cancer.

Abstract

Dickkopf-3 (DKK3), a tumor suppressor, is frequently downregulated in various cancers. However, the role of DKK3 in ovarian cancer has not been evaluated. This study aimed to assess aberrant DKK3 expression and its role in epithelial ovarian carcinoma. DKK3 expression was assessed using immunohistochemistry with tissue blocks from 82 patients with invasive carcinoma, and 15 normal, 19 benign, and 10 borderline tumors as controls. Survival data were analyzed using Kaplan–Meier and Cox regression analysis. Paclitaxel-resistant cells were established using TOV-21G and OV-90 cell lines. Protein expression was assessed using Western blotting and immunofluorescence analysis. Cell viability was assessed using the MT assay and 3D-spheroid assay. Cell migration was determined using a migration assay. DKK3 was significantly downregulated in invasive carcinoma compared to that in normal, benign, and borderline tumors. DKK3 loss occurred in 56.1% invasive carcinomas and was significantly associated with disease-free survival and chemoresistance in serous adenocarcinoma. DKK3 was lost in paclitaxel-resistant cells, while β-catenin and P-glycoprotein were upregulated. Exogenous secreted DKK3, incorporated by cells, enhanced anti-tumoral effect and paclitaxel susceptibility in paclitaxel-resistant cells, and reduced the levels of active β-catenin and its downstream P-glycoprotein, suggesting that DKK3 can be used as a therapeutic for targeting paclitaxel-resistant cancer.

MYC Hyperactivates Wnt Signaling in APC/CTNNB1-Mutated Colorectal Cancer Cells through miR-92a-Dependent Repression of DKK3

Activation of Wnt signaling is among the earliest events in colon cancer development. It is achieved either via activating mutations in the CTNNB1 gene encoding β-catenin, the key transcription factor in the Wnt pathway, or most commonly by inactivating mutations affecting APC, a major β-catenin binding partner and negative regulator. However, our analysis of recent Pan Cancer Atlas data revealed that CTNNB1 mutations significantly co-occur with those affecting Wnt receptor complex components (e.g., Frizzled and LRP6), underscoring the importance of additional regulatory events even in the presence of common APC/CTNNB1 mutations. In our effort to identify non-mutational hyperactivating events, we determined that KRAS-transformed murine colonocytes overexpressing direct β-catenin target MYC show significant upregulation of the Wnt signaling pathway and reduced expression of Dickkopf 3 (DKK3), a reported ligand for Wnt co-receptors. We demonstrate that MYC suppresses DKK3 transcription through one of miR-17-92 cluster miRNAs, miR-92a. We further examined the role of DKK3 by overexpression and knockdown and discovered that DKK3 suppresses Wnt signaling in Apc-null murine colonic organoids and human colon cancer cells despite the presence of downstream activating mutations in the Wnt pathway. Conversely, MYC overexpression in the same cell lines resulted in hyperactive Wnt signaling, acquisition of epithelial-to-mesenchymal transition markers, and enhanced migration/invasion in vitro and metastasis in a syngeneic orthotopic mouse colon cancer model. IMPLICATIONS: Our results suggest that the MYC→miR-92a-|DKK3 axis hyperactivates Wnt signaling, forming a feed-forward oncogenic loop.

The long noncoding RNA TUNAR modulates Wnt signaling and regulates human β-cell proliferation

Many long noncoding RNAs (lncRNAs) are enriched in pancreatic islets and several lncRNAs are linked to type 2 diabetes (T2D). Although they have emerged as potential players in β-cell biology and T2D, little is known about their functions and mechanisms in human β-cells. We identified an islet-enriched lncRNA, TUNAR (TCL1 upstream neural differentiation-associated RNA), which was upregulated in β-cells of patients with T2D and promoted human β-cell proliferation via fine-tuning of the Wnt pathway. TUNAR was upregulated following Wnt agonism by a glycogen synthase kinase-3 (GSK3) inhibitor in human β-cells. Reciprocally, TUNAR repressed a Wnt antagonist Dickkopf-related protein 3 (DKK3) and stimulated Wnt pathway signaling. DKK3 was aberrantly expressed in β-cells of patients with T2D and displayed a synchronized regulatory pattern with TUNAR at the single cell level. Mechanistically, DKK3 expression was suppressed by the repressive histone modifier enhancer of zeste homolog 2 (EZH2). TUNAR interacted with EZH2 in β-cells and facilitated EZH2-mediated suppression of DKK3. These findings reveal a novel cell-specific epigenetic mechanism via islet-enriched lncRNA that fine-tunes the Wnt pathway and subsequently human β-cell proliferation.NEW & NOTEWORTHY The discovery that long noncoding RNA TUNAR regulates β-cell proliferation may be important in designing new treatments for diabetes.

Histone deacetylase inhibitor chidamide regulates the Wnt/β-catenin pathway by MYCN/DKK3 in B-ALL

Our previous studies revealed that MYCN downregulates the expression of DKK3, activates the Wnt/β-catenin signalling pathway at the transcriptional level, and thereby promotes the development of B cell acute lymphocytic leukaemia (B-ALL) but does not affect the methylation of the DKK3 promoter. Some studies have shown that MYCN is associated with histone acetylation. We speculate that histone deacetylase inhibitors (HDACis) can inhibit the Wnt/β-catenin signalling pathway by inhibiting MYCN and increasing the expression of DKK3. Based on previous experiments, we tested this hypothesis by analysing the changes in MYCN, DKK3 and the Wnt/β-catenin signalling pathways in B-ALL cells after treatment with the selective HDACi chidamide. The in vitro and in vivo experiments confirmed that chidamide inhibited the expression of MYCN and increased the expression of DKK3 by inhibiting the activity of histone deacetylase, and these effects resulted in inhibition of the Wnt/β-catenin signalling pathway and the proliferation of B-ALL cells. These findings indicate that chidamide might be used alone or in combination with other chemotherapy regimens for patients with B-ALL and thus provide a new approach to the treatment of B-ALL.

Molecular Biology of Atherosclerotic Ischemic Strokes

Among the causes of global death and disability, ischemic stroke (also known as cerebral ischemia) plays a pivotal role, by determining the highest number of worldwide mortality, behind cardiomyopathies, affecting 30 million people. The etiopathogenetic burden of a cerebrovascular accident could be brain ischemia (~80%) or intracranial hemorrhage (~20%). The most common site when ischemia occurs is the one is perfused by middle cerebral arteries. Worse prognosis and disablement consequent to brain damage occur in elderly patients or affected by neurological impairment, hypertension, dyslipidemia, and diabetes. Since, in the coming years, estimates predict an exponential increase of people who have diabetes, the disease mentioned above constitutes together with stroke a severe social and economic burden. In diabetic patients after an ischemic stroke, an exorbitant activation of inflammatory molecular pathways and ongoing inflammation is responsible for more severe brain injury and impairment, promoting the advancement of ischemic stroke and diabetes. Considering that the ominous prognosis of ischemic brain damage could by partially clarified by way of already known risk factors the auspice would be modifying poor outcome in the post-stroke phase detecting novel biomolecules associated with poor prognosis and targeting them for revolutionary therapeutic strategies.

The Suppressing Effects of Dkk3 Expression on Aggressiveness and Tumorigenesis of Colorectal Cancer

Dkk3 has been discovered during comparison of immortalized and parental cells. Its expression has been shown to reduce colony formation and induce apoptosis of cancer cells, acting as a tumor suppressor. Herein, we demonstrate that Dkk3 overexpression or protein treatment may inhibit colorectal cancer cell proliferation, migration, and invasion and that they may promote apoptosis and G₂ phase arrest with hypoexpression of Bcl-2, cdc25B, cdc25c, N-cadherin, slug, and twist and hyperexpression of Bax and E-cadherin. This effect is consistent with that of recombinant Dkk3 exposure and blocked with anti-Dkk3 antibody. Dkk3 deletion in intestinal cells was not associated with the emergence of epithelial lesions; however, adenoma emerged after sodium desoxycholate treatment. At both mRNA and protein levels, Dkk3 expression was higher in normal than in cancer tissues (p<0.05). Dkk3 mRNA expression was negatively associated with its promoter methylation, growth pattern, differentiation, and favorable prognosis in the patients with colorectal cancer (p<0.05). Dkk3-related signal pathways in colorectal cancer included those of cellular adhesion and migration, melanogenesis, chemokine, Hedgehog, JAK-STAT, TOLL-like receptor, TGF-β, MAPK, and calcium signaling (p<0.05). These findings indicate that Dkk3 expression levels can help assess cancer aggressiveness and patient prognosis. It might also suppress aggressive phenotypes and tumorigenesis as a molecular target in gene therapy.

Circular RNA Hsa_circ_0004018 Inhibits Wnt/β-Catenin Signaling Pathway by Targeting microRNA-626/DKK3 in Hepatocellular Carcinoma

Background and Aim

Dysexpression of circular RNAs has been identified in multiple types of cancer. Hsa_circ_0004018 was reported to be significantly downregulated in hepatocellular carcinoma (HCC) and to display HCC-stage-specific expression features. However, the role of hsa_circ_0004018 in HCC progression remains unclear.

Methods

The expression of hsa_circ_0004018 or microRNA-626 (miR-626) was detected in tumor tissues and paired non-tumor tissues from HCC patients, as well as in one normal human liver cell line and 5 HCC cell lines by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, dye exclusion assay, clonogenic assay, scratch migration assay and transwell assay were used to measure cell proliferation and migration capacity, respectively. Luciferase report assay and RNA pull down assay were performed to explore the regulatory effect of certain molecules on the expression of target genes.

Results

We found that the expression of hsa_circ_0004018 was lower in tumor tissues than in their paired non-tumor tissues from 28 out of 41 HCC patients. The difference in the expression between tumor tissues and non-tumor tissues was statistically significant (p<0.001). Further analysis revealed that such lower expression in tumor tissues was much more common in bigger tumor size group (≥5cm) compared with the smaller tumor size group (<5cm) (85% vs 42%, p=0.0007). Similarly, hsa_circ_0004018 was downregulated in HCC cell lines. Additionally, a negative correlation between hsa_circ_0004018 and miR-626 expression was noticed in HCC tissues. Moreover, we observed that hsa_circ_0004018 interacted with miR-626/DKK3 and contributed to HCC cell proliferation and migration through inhibiting Wnt/β-catenin signaling pathway in vitro. Furthermore, hsa_circ_0004018 blocked xenograft tumor growth in vivo through inhibiting Wnt/β-catenin signaling pathway by targeting miR-626/DKK3.

Conclusion

We revealed that hsa_circ_0004018/miR-626/DKK3 regulatory axis may be a possible novel therapeutic target for HCC.

Molecular Characterisation of Canine Osteosarcoma in High Risk Breeds

Dogs develop osteosarcoma (OSA) and the disease process closely resembles that of human OSA. OSA has a poor prognosis in both species and disease-free intervals and cure rates have not improved in recent years. Gene expression in canine OSAs was compared with non-tumor tissue utilising RNA sequencing, validated by qRT-PCR and immunohistochemistry (n = 16). Polymorphic polyglutamine (polyQ) tracts in the androgen receptor (AR/NR3C4) and nuclear receptor coactivator 3 (NCOA3) genes were investigated in control and OSA patients using polymerase chain reaction (PCR), Sanger sequencing and fragment analysis (n = 1019 Rottweilers, 379 Irish Wolfhounds). Our analysis identified 1281 significantly differentially expressed genes (>2 fold change, p < 0.05), specifically 839 lower and 442 elevated gene expression in osteosarcoma (n = 3) samples relative to non-malignant (n = 4) bone. Enriched pathways and gene ontologies were identified, which provide insight into the molecular pathways implicated in canine OSA. Expression of a subset of these genes (SLC2A1, DKK3, MMP3, POSTN, RBP4, ASPN) was validated by qRTPCR and immunohistochemistry (MMP3, DKK3, SLC2A1) respectively. While little variation was found in the NCOA3 polyQ tract, greater variation was present in both polyQ tracts in the AR, but no significant associations in length were made with OSA. The data provides novel insights into the molecular mechanisms of OSA in high risk breeds. This knowledge may inform development of new prevention strategies and treatments for OSA in dogs and supports utilising spontaneous OSA in dogs to improve understanding of the disease in people.

β-Catenin: oncogenic role and therapeutic target in cervical cancer

Cervical cancer is a common and fatal malignancy of the female reproductive system. Human papillomavirus (HPV) is the primary causal agent for cervical cancer, but HPV infection alone is insufficient to cause the disease. Actually, most HPV infections are sub-clinical and cleared spontaneously by the host immune system; very few persist and eventually develop into cervical cancer. Therefore, other host or environmental alterations could also contribute to the malignant phenotype. One of the candidate co-factors is the β-catenin protein, a pivotal component of the Wnt/β-catenin signaling pathway. β-Catenin mainly implicates two major cellular activities: cell–cell adhesion and signal transduction. Recent studies have indicated that an imbalance in the structural and signaling properties of β-catenin leads to various cancers, such as cervical cancer. In this review, we will systematically summarize the role of β-catenin in cervical cancer and provide new insights into therapeutic strategies.

Transcriptome analysis of genes related to gonad differentiation and development in Muscovy ducks

BACKGROUND

Sex-related genes play a crucial role in gonadal differentiation into testes or ovaries. However, the genetic control of gonadal differentiation in Muscovy ducks remains unknown. Therefore, the objective of our study was to screen new candidate genes associated with ovarian and testicular development.

RESULTS

In this study, 24 males before gonadal differentiation (MB), 24 females before gonadal differentiation (FB), 24 males after gonadal differentiation (MA) and 24 females after gonadal differentiation (FA) were selected from Putian Muscovy ducks, forming 4 groups. RNA-Seq revealed 101.76 Gb of clean reads and 2800 differentially expressed genes (DEGs), including 46 in MB vs FB, 609 in MA vs FA, 1027 in FA vs FB, and 1118 in MA vs MB. A total of 146 signalling pathways were enriched by KEGG analysis, among which 20, 108, 108 and 116 signalling pathways were obtained in MB vs FB, MA vs MB, MA vs FA and FA vs FB, respectively. In further GO and KEGG analyses, a total of 21 candidate genes related to gonad differentiation and development in Muscovy ducks were screened. Among these, 9 genes were involved in the differentiation and development of the testes, and 12 genes were involved in the differentiation and development of the ovaries. In addition, RNA-Seq data revealed 2744 novel genes.

CONCLUSIONS

RNA-Seq data revealed 21 genes related to gonadal differentiation and development in Muscovy ducks. We further identified 12 genes, namely, WNT5B, HTRA3, RSPO3, BMP3, HNRNPK, NIPBL, CREB3L4, DKK3, UBE2R2, UBPL3KCMF1, ANXA2, and OSR1, involved in the differentiation and development of ovaries. Moreover, 9 genes, namely, TTN, ATP5A1, DMRT1, DMRT3, AMH, MAP3K1, PIK3R1, AGT and ADAMTSL1, were related to the differentiation and development of testes. Moreover, after gonadal differentiation, DMRT3, AMH, PIK3R1, ADAMTSL1, AGT and TTN were specifically highly expressed in males. WNT5B, ANXA2 and OSR1 were specifically highly expressed in females. These results provide valuable information for studies on the sex control of Muscovy ducks and reveal novel candidate genes for the differentiation and development of testes and ovaries.

DKK3 expression and function in head and neck squamous cell carcinoma and other cancers

BACKGROUND

Cancer arises from cumulative genetic or epigenetic aberrations, or the destabilization of central signaling pathways that regulate cell proliferation, differentiation, cell cycle, gene transcription, migration, angiogenesis and apoptosis. Investigating the cancer-specific genetic background is important to get deeper apprehension of cancer biology. In this review, we aimed to identify head and neck squamous cell carcinoma (HNSCC)-specific genes and identified DKK3 gene as a candidate.

HIGHLIGHT

DKK3 belongs to the DKK family (DKK1, DKK2, DKK3 and DKK4), which codes for an evolutionally conserved secreted glycoprotein that is characterized by two distinct cysteine rich domains and functions as an antagonist of the oncogenic Wnt signaling pathway. It has been reported that DKK3 expression is decreased in many kinds of cancers, and it is thus thought to be a tumor suppressor gene. However, our investigations have demonstrated unique expression and function of DKK3 in HNSCC. DKK3 protein expression is predominantly positive in HNSCC, and DKK3-positive patients show significantly shorter disease-free survival rates, whereas DKK3-negative cases do not show metastasis. Molecular biological analyses demonstrated that DKK3 over expression significantly increased HNSCC cell proliferation, migration, and invasion via increased phosphorylation of AKT. Moreover, DKK3 knockdown in HNSCC cells significantly decreased these malignant potentials through decreased AKT phosphorylation.

CONCLUSION

Our previously published data, alongside those from other reports, indicate that DKK3 may have an additional oncogenic function other than tumor suppression.

Serum dickkopf-3 is associated with death and vascular events after ischemic stroke: an observational study from CATIS

BACKGROUND

Dickkopf-3 (Dkk-3) is implicated in the progression of atherosclerosis. This study aimed to investigate the association between serum Dkk-3 and the prognosis of ischemic stroke.

METHODS

We measured serum Dkk-3 levels in 3344 ischemic stroke patients from CATIS (China Antihypertensive Trial in Acute Ischemic Stroke). The primary outcome was a combination of death and vascular events within 3 months after ischemic stroke.

RESULTS

During 3 months of follow-up, the cumulative incidence rates of primary outcome among ischemic stroke patients in five quintiles of serum Dkk-3 (from low to high) were 4.49%, 3.74%, 2.54%, 5.23%, and 6.73%, respectively (log-rank p = 0.004). Multivariable Cox proportional hazards regression analyses showed that compared with the third quintile of serum Dkk-3, the adjusted hazard ratios (95% confidence intervals) associated with the first and fifth quintile were 3.49 (1.46-8.34) and 4.23 (1.86-9.64) for primary outcome, 3.47 (1.06-11.36) and 5.30 (1.81-15.51) for death, and 2.66 (1.01-7.01) and 3.35 (1.33-8.40) for vascular events, respectively. Multivariable-adjusted Cox proportional hazards regression model with restricted cubic splines showed a U-shaped association between serum Dkk-3 and the risk of primary outcome (p for nonlinearity = 0.030). Moreover, adding serum Dkk-3 to conventional risk factors could improve the predictive power for primary outcome (net reclassification improvement 28.44%, p < 0.001; integrated discrimination improvement 0.48%, p = 0.001).

CONCLUSIONS

Both low and high serum Dkk-3 levels are associated with increased risks of death and vascular events within 3 months after ischemic stroke, indicating that serum Dkk-3 may have a special effect on the prognosis of ischemic stroke. We also found that serum Dkk-3 might be a prognostic biomarker for ischemic stroke. Further studies are needed to replicate our findings and to determine the optimal levels of serum Dkk-3.

ALDHHIGH Population Is Regulated by the AKT/β-Catenin Pathway in a Cervical Cancer Model

ALDH is an enzyme involved in different cellular processes, including cancer. It has been shown that a cellular subpopulation with high ALDH activity (ALDH^HIGH) within a tumor is related to functional capabilities such as stemness, chemoresistance, and tumorigenicity. However, few studies have focused on determining the mechanisms behind ALDH activity within the cells. Previously, our group reported that ALDH^HIGH cells have higher tumorigenicity in Cervical Cancer (CC) cell lines. Based on this, we were interested to know the molecular mediators of the ALDH^HIGH cells, specifically β-catenin, inasmuch as β-catenin is regulated through different pathways, such as Wnt signaling, and that it acts as a transcriptional co-activator involved in cancer progression. In this work, we show that the increase in ALDH^HIGH cell percentage is reverted by β-catenin knockdown. Consistently, upon GSK3-β inactivation, a negative regulator of β-catenin, we observed an increase in ALDH^HIGH cells. Additionally, we observed a low percentage of cells positive for Fzd receptor, suggesting that in our model there is a low capacity to respond to Wnt ligands. The analysis of ALDH^HIGH cells in a sphere formation model demonstrated the active state of AKT. In accordance with this, impairment of AKT activity not only reduced β-catenin active state, but also the percentage of ALDH^HIGH cells. This corroborates that AKT acts upstream of β-catenin, thus affecting the percentage of ALDH^HIGH cells. In conclusion, our results show that ALDH^HIGH cells are dependent on β-catenin, in spite of the Wnt pathway seems to be dispensable, while AKT emerges as central player supporting a mechanism in this important axis that is not yet well known but its analysis improves our understanding of ALDH activity on CC.

Dickkopf Homolog 3 (DKK3) Acts as a Potential Tumor Suppressor in Gallbladder Cancer

Gallbladder cancer (GBC) is a common malignancy of biliary tract cancers and its incidence has been rising rapidly worldwide. The prognosis for this disease is dismal as most of the symptoms are non-specific leading to a definitive diagnosis only at a late stage. Loss of DKK3 gene is associated with a possible tumor suppressor role in human cancers. The role and regulation of DKK3 in GBC have not been studied. We found that DKK3 expression levels were low in GBC patients and cell lines. Treatment of GBC cell lines with demethylating agent 5-Aza- 2'-deoxycytidine enhances its expression, establishing impact of methylation on DKK3 expression. We observed low expression of DKK3 in gallbladder adenocarcinoma tumors and highly invasive GBC cell lines. We showed that overexpression of DKK3 can decrease cell invasion, proliferation, and colony forming ability of GBC cells. Our data thus demonstrated the DKK3 gene is a potential tumor suppressor gene in GBC and aberrant promoter methylation could be involved in its downregulation, which may play a role in the tumorigenesis and aggressiveness of GBC.

miR-25-3p promotes glioma cell proliferation and migration by targeting FBXW7 and DKK3

MicroRNAs (miRs) serve important roles in glioma. However, the underlying molecular mechanism of miR-25 in glioma progression remains largely unknown; therefore, it was investigated in the present study. RT-qPCR analysis revealed that miR-25 expression levels were markedly increased in human glioma tissue and glioma cell lines compared with normal brain tissues and normal human astrocytes, respectively. miR-25 upregulation exhibited an association with glioma progression, and the knockdown of miR-25 significantly inhibited glioma cell proliferation and migration. F-box and WD repeat domain containing 7 (FBXW7) and dickkopf WNT signaling pathway inhibitor 3 (DKK3) were identified as target genes of miR-25. FBXW7 and DKK3 expression levels were significantly downregulated in glioma tissue samples compared with normal brain tissue, and their expression levels were negatively regulated by miR-25 expression in glioma cells. Furthermore, inhibition of FBXW7 and DKK3 expression suppressed the miR-25-induced effects on glioma cell proliferation and migration. The findings of the present study suggest that miR-25 may promote glioma cell proliferation and migration by inhibiting the expression of FBXW7 and DKK3. Therefore, miR-25 may serve as a promising molecular target for the treatment of glioma.

Dihydrotestosterone inhibits arylsulfatase B and Dickkopf Wnt signaling pathway inhibitor (DKK)-3 leading to enhanced Wnt signaling in prostate epithelium in response to stromal Wnt3A

BACKGROUND

In tissue microarrays, immunostaining of the enzyme arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase) was less in recurrent prostate cancers and in cancers with higher Gleason scores. In cultured prostate stem cells, decline in ARSB increased Wnt signaling through effects on Dickkopf Wnt Signaling Pathway Inhibitor (DKK)3. The effects of androgen exposure on ARSB and the impact of decline in ARSB on Wnt signaling in prostate tissue were unknown.

METHODS

Epithelial and stromal tissues from malignant and normal human prostate were obtained by laser capture microdissection. mRNA expression of ARSB, galactose-6-sulfate-sulfatase (GALNS) and Wnt-signaling targets was determined by QPCR. Non-malignant human epithelial and stromal prostate cells were grown in tissue culture, including two-cell layer cultures. ARSB was silenced by specific siRNA, and epithelial cells were treated with stromal spent media following treatment with IWP-2, an inhibitor of Wnt secretion, and by exogenous recombinant human Wnt3A. Promoter methylation was detected using specific DKK3 and ARSB promoter primers. The effects of DHT and of ARSB overexpression on DKK expression were determined. Cell proliferation was assessed by BrdU incorporation.

RESULTS

Normal stroma showed higher expression of vimentin, ARSB, and Wnt3A than epithelium. Normal epithelium had higher expression of E-cadherin, galactose 6-sulfate-sulfatase (GALNS), and DKK3 than stroma. In malignant epithelium, expression of ARSB and DKK3 declined, and expression of GALNS and Wnt signaling targets increased. In cultured prostate epithelial cells, Wnt-mediated signaling was greatest when ARSB was silenced and cells were exposed to exogenous Wnt3A. Exposure to 5α-dihydrotestosterone (DHT) increased ARSB and DKK3 promoter rmethylation, and effects of DHT on DKK3 expression were reversed when ARSB was overexpressed.

CONCLUSIONS

Androgen-induced declines in ARSB and DKK3 may contribute to prostate carcinogenesis by sustained activation of Wnt signaling in prostate epithelium in response to stromal Wnt3A.

MiR-92a modulates proliferation, apoptosis, migration, and invasion of osteosarcoma cell lines by targeting Dickkopf-related protein 3

Osteosarcoma (OS) is recognized as a common malignant tumor with a high trend of metastasis and diffusion. Despite the progresses that have been made in surgery, chemotherapy, and radiotherapy in the recent decades, the prognosis of patients with OS still remains poor. MiRNAs are being increasingly considered as new therapeutic targets for OS treatment. Our research aims to investigate the regulatory impact of miR-92a in the development of OS. Quantitative real-time PCR (qRT-PCR) results revealed that the expression of miR-92a was aberrantly overexpressed in human OS cell lines. By using cell counting kit-8 (CCK-8) assays, colony formation assays, flow cytometric analyses and Transwell assays, our data suggested that up-regulation of miR-92a promoted the proliferation, migration, and invasion of MNNG and U2OS cells, while inhibiting their apoptosis. In contrast, the knockdown of miR-92a effectively reversed these cellular biological behaviors. Furthermore, bioinformatics analysis indicated that Dickkopf-related protein 3 (DKK3) was a possible target of miR-92a. Subsequently, negative regulation of miR-92a on DKK3 was observed, which further supported the direct binding between them. In addition, silencing DKK3 rescued the inhibitory effect of miR-92a inhibitor on the development of OS. To sum up, our study revealed that miR-92a played a carcinogenic role in the growth of OS by promoting the tumorigenesis of OS cells via targeting of DKK3, thus revealing a new therapeutic target for OS.

Mining Featured Biomarkers Linked with Epithelial Ovarian CancerBased on Bioinformatics

Epithelial ovarian cancer (EOC) is the18th most common cancer worldwide and the 8th most common in women. The aim of this study was to diagnose the potential importance of, as well as novel genes linked with, EOC and to provide valid biological information for further research. The gene expression profiles of E-MTAB-3706 which contained four high-grade ovarian epithelial cancer samples, four normal fallopian tube samples and four normal ovarian epithelium samples were downloaded from the ArrayExpress database. Pathway enrichment and Gene Ontology (GO) enrichment analysis of differentially expressed genes (DEGs) were performed, and protein-protein interaction (PPI) network, microRNA-target gene regulatory network and TFs (transcription factors) -target gene regulatory network for up- and down-regulated were analyzed using Cytoscape. In total, 552 DEGs were found, including 276 up-regulated and 276 down-regulated DEGs. Pathway enrichment analysis demonstrated that most DEGs were significantly enriched in chemical carcinogenesis, urea cycle, cell adhesion molecules and creatine biosynthesis. GO enrichment analysis showed that most DEGs were significantly enriched in translation, nucleosome, extracellular matrix organization and extracellular matrix. From protein-protein interaction network (PPI) analysis, modules, microRNA-target gene regulatory network and TFs-target gene regulatory network for up- and down-regulated, and the top hub genes such as E2F4, SRPK2, A2M, CDH1, MAP1LC3A, UCHL1, HLA-C (major histocompatibility complex, class I, C), VAT1, ECM1 and SNRPN (small nuclear ribonucleoprotein polypeptide N) were associated in pathogenesis of EOC. The high expression levels of the hub genes such as CEBPD (CCAAT enhancer binding protein delta) and MID2 in stages 3 and 4 were validated in the TCGA (The Cancer Genome Atlas) database. CEBPD andMID2 were associated with the worst overall survival rates in EOC. In conclusion, the current study diagnosed DEGs between normal and EOC samples, which could improve our understanding of the molecular mechanisms in the progression of EOC. These new key biomarkers might be used as therapeutic targets for EOC.

The clinicopathological and prognostic significances of Dkk3 expression in cancers: A bioinformatics analysis

BACKGROUND

Dkk3 protein attenuates the expression of Wnt3a, Wnt5a and LRP6, and their interaction, and interacts with βTrCP to suppress wnt/β-catenin pathway.

METHODS

We performed a bioinformatics analysis of Dkk3 mRNA expression through Oncomine, TCGA and Kaplan-Meier plotter databases up to July 10, 2017.

RESULTS

Up-regulated Dkk3 expression was higher in gastric, breast, and ovarian cancers than normal tissues (p< 0.05). Bitter's database showed a higher Dkk3 expression in ovarian cytoadenocarcinoma than clear cell adenocarcinoma (p< 0.05). Dkk3 was more expressed in ductal breast cancer in situ than invasive ductal breast cancer (p< 0.05), in mixed lobular and ductal cancer, and lobular cancer than ductal breast cancer (p< 0.05). In TCGA data, Dkk3 expression was lower in gastric cancers with than without Barret's esophagus (p< 0.05), in intestinal-type than diffuse-type cancers (p< 0.05), and in the cancers of elder than younger patients (p< 0.05). Dkk3 expression was higher in squamous cell carcinoma than adenocarcinoma (p< 0.05). Dkk3 expression was higher in ductal than lobular breast cancer, or in younger than elder patients with breast cancer (p< 0.05). According to Kaplan-Meier plotter, Dkk3 expression was negatively correlated with overall, progression-free, relapse-free or distant-metastasis-free survival rate of gastric, breast or ovarian cancer patients, but versa for lung cancer patients (p< 0.05).

CONCLUSION

Dkk3 expression might be employed as a potential marker to indicate carcinogenesis and histogenesis, even prognosis.

Recent Advances on the Molecular Mechanism of Cervical Carcinogenesis Based on Systems Biology Technologies

Cervical cancer is one of the common malignancies in women worldwide. Exploration of pathogenesis and molecular mechanism of cervical cancer is pivotal for development of effective treatment for this disease. Recently, systems biology approaches based on high-throughput technologies have been carried out to investigate the expression of some genes and proteins in genomics, transcriptomics, proteomics, and metabonomics of cervical cancer. Compared with traditional methods，systems biology technology has been shown to provide large of information regarding prognostic biomarkers and therapeutic targets for cervical cancer. These molecular signatures from system biology technology could be useful to understand the molecular mechanisms of cervical cancer development and progression, and help physicians to design targeted therapeutic strategies for patients with cervical cancer.

TLR-4/Wnt modulation as new therapeutic strategy in the treatment of glioblastomas

Purpose

Glioblastomas are highly aggressive brain tumors. Various pathways are involved in gliomagenesis, among which the Wingless (Wnt) signaling. Dickkopf protein-related protein 3 (Dkk-3) interacts with proteins of Wnt pathwayas inhibitor. The Wnt signaling contributes to activity of the claudins, that are critical components of tight junctions, whose expression was altered selectively in cerebral microvessels of glioblastoma. The aim of this study was to determine the role of Wnt pathways in the regulation of tumor growth, apoptosis process by targeting Dkk-3, tight junctions alteration involving claudin-5, suggesting possible therapeutic interactions involving Wnt/Toll-like receptors (TLRs) pathways.

Results

We showed a significant decreasing of Dkk-3 and claudin-5 in human glioblastoma cell lines, as well as in U-87 MG xenograft tumors and in glioblastoma human patient’s tissues, with an involvement of the apoptosis process. Also, an interesting TLR-4/Wnt modulation highlighted that the absence of TLR-4 determined resistance to the tumor onset.

Conclusions

We concluded that combined modulation of Wnt/Dkk-3/claudin-5 and TLR-4 pathways, simultaneously targeting apoptosis and survival signaling defects, might shift the balance from tumor growth stasis to cytotoxic therapeutic responses, flowing in greater therapeutic benefits.

Methods

In the present study we investigated the expression of Dkk-3, claudin-5, apoptosis markers and TLR-4 receptor protein levels in in vitro studies on U-138MG, A-172, LN-18 and LN-229 human glioblastoma cell lines, and in vivo study using TLR-4 KO mice and in glioblastoma human patient’s tissues.

Cenani-Lenz syndrome and other related syndactyly disorders due to variants in LRP4, GREM1/FMN1, and APC: Insight into the pathogenesis and the relationship to polyposis through the WNT and BMP antagonistic pathways

Cenani-Lenz (C-L) syndrome is characterized by oligosyndactyly, metacarpal synostosis, phalangeal disorganization, and other variable facial and systemic features. Most cases are caused by homozygous and compound heterozygous missense and splice mutations of the LRP4 gene. Currently, the syndrome carries one OMIM number (212780). However, C-L syndrome-like phenotypes as well as other syndactyly disorders with or without metacarpal synostosis/phalangeal disorganization are also known to be associated with specific LRP4 mutations, adenomatous polyposis coli (APC) truncating mutations, genomic rearrangements of the GREM1-FMN1 locus, as well as FMN1 mutations. Surprisingly, patients with C-L syndrome-like phenotype caused by APC truncating mutations have no polyposis despite the increased levels of β catenin. The LRP4 and APC proteins act on the WNT (wingless-type integration site family) canonical pathway, whereas the GREM-1 and FMN1 proteins act on the bone morphogenetic protein (BMP) pathway. In this review, we discuss the different mutations associated with C-L syndrome, classify its clinical features, review familial adenomatous polyposis caused by truncating APC mutations and compare these mutations to the splicing APC mutation associated with syndactyly, and finally, explore the pathophysiology through a review of the cross talks between the WNT canonical and the BMP antagonistic pathways.

DKK3 knockdown confers negative effects on the malignant potency of head and neck squamous cell carcinoma cells via the PI3K/Akt and MAPK signaling pathways

Dickkopf‑related protein 3 (DKK3), which is a member of the Dickkopf WNT signaling pathway inhibitor family, is considered to be a tumor suppressor, due to its reduced expression in cancer cells and its ability to induce apoptosis when overexpressed by adenovirus. However, our previous study demonstrated alternative functions for DKK3 in head and neck squamous cell carcinoma (HNSCC). Our study reported that DKK3 expression was predominantly upregulated in HNSCC cell lines and tissue samples, and its expression was significantly correlated with poor prognosis. Furthermore, DKK3 overexpression in HNSCC cells significantly increased cancer cell proliferation, migration, invasion and in vivo tumor growth. These data have led to the hypothesis that DKK3 may exert oncogenic functions and may increase the malignant properties of HNSCC. The present study established a stable DKK3 knockdown cell line (HSC‑3 shDKK3) using lentivirus‑mediated short hairpin RNA, and assessed its effects on cancer cell behavior using MTT, migration and invasion assays. In addition, its effects on in vivo tumor growth were assessed using a xenograft model. Furthermore, the molecular mechanisms underlying the effects of DKK3 knockdown were investigated by microarray analysis, pathway analysis and western blotting. Compared with control cells, HSC‑3 shDKK3 cells exhibited significantly reduced proliferation, migration and invasion, and formed significantly smaller tumor masses when subcutaneously transplanted into nude mice. In addition, in HSC‑3 shDKK3 cells, the expression levels of phosphorylated (p)‑protein kinase B (Akt) (Ser473), p‑phosphoinositide 3‑kinase (PI3K) p85 (Tyr467), p‑PI3K p55 (Try199), p‑3‑phosphoinositide‑dependent protein kinase‑1 (PDK1) (Ser241) and total p38 mitogen‑activated protein kinase (MAPK) were reduced. Furthermore, phosphorylation of mechanistic target of rapamycin (mTOR) (Ser2448) was slightly decreased in HSC‑3 shDKK3 cells, which may be due to the increased expression of DEP domain‑containing mTOR‑interacting protein. Conversely, DKK3 overexpression in HSC‑3 shDKK3 cells rescued cellular proliferation, migration and invasion. With regards to expression levels, p‑PI3K and p‑PDK1 expression was not altered, whereas mTOR and p‑p38 MAPK expression was elevated. These data supported the hypothesis and indicated that DKK3 may contribute to the malignant phenotype of HNSCC cells via the PI3K/Akt/mTOR and MAPK signaling pathways.

Regulatory effect of miR-346/DKK3 axis on tumor cell proliferation in colon cancer

AIM

To investigate the regulatory effect of the miR-346/DKK3 axis on tumor cell proliferation in colon cancer.

METHODS

The expression of miR-346 in normal colon epithelial cells and colon cancer cells as well as in colon tissues and noncancerous tissues was examined by RT-PCR. The effect of miR-346 on the proliferation of colon cancer cells was examined by MTT assay. Flow cytometry was used to detect the effect of miR-346 on the colon cancer cell cycle. The dual luciferase reporter gene assay was used to validate the binding relationship between miR-346 and DKK3. The effect of DKK3 on the function of colon cancer cells was studied by transfecting colon cancer cells with siRNA and pcDNA-DKK3.

RESULTS

The expression of miR-346 in colon cancer cells was significantly upregulated. Overexpression of miR-346 promoted the proliferation of colon cancer cells. The proportion of cells in G1 phase decreased, and the proportion of cells in S phase and G2/M phase increased. The dual luciferase reporter assay showed that miR-346 bound directly to the 3'-UTR of DKK3. Inhibition of DKK3 using siRNA promoted the proliferation of colon cancer cells, reduced the proportion of cells in G1 phase and increased the proportion of cells in S phase and G2/M phase. Further, overexpression of DKK3 partially abrogated the proliferative effect of miR-346 on colon cancer cells.

CONCLUSION

MiR-346 promotes the proliferation of colon cancer cells by inhibiting DKK3.

MicroRNA-92b promotes cell proliferation and invasion in osteosarcoma by directly targeting Dickkopf-related protein 3

Deregulation of microRNA-92b (miR-92b) has been implicated in osteosarcoma. However, the underlying regulatory mechanism of miR-92b in osteosarcoma growth and metastasis remains largely unclear. In the present study, reverse transcription-quantitative polymerase chain reaction and western blotting were used to measure mRNA and protein expression. MTT and Transwell assays were conducted to determine cell proliferation and invasion, and a luciferase reporter assay was performed to confirm the association between miR-92b and Dickkopf3-related protein (DKK3). The results demonstrated that miR-92b was significantly upregulated in osteosarcoma tissues compared with matched adjacent non-tumor tissues. Additionally, high miR-92b levels were significantly associated with lung metastasis and advanced tumor, node, metastasis stage (P<0.05) but not with age, sex, tumor size, location, serum lactate dehydrogenase or serum alkaline phosphatase. miR-92b expression was also significantly upregulated in osteosarcoma cell lines compared with normal osteoblast cells. Knockdown of miR-92b significantly inhibited the proliferation and invasion of osteosarcoma U2OS cells (P<0.01). By contrast, overexpression of miR-92b significantly increased U2OS cell proliferation and invasion (P<0.01). DKK3 was identified as a target gene of miR-92b and it was demonstrated that DKK3 expression was negatively regulated by miR-92b in U2OS cells. Restoration of DKK3 expression abrogated the increased proliferation and invasion of U2OS cells induced by miR-92b overexpression. Notably, DKK3 was significantly downregulated in osteosarcoma tissues compared with adjacent non-tumor tissues and its expression was inversely correlated to miR-92b levels in osteosarcoma tissues. Taken together, these data indicate that miR-92b promotes cell proliferation and invasion in osteosarcoma by targeting DKK3. Therefore, miR-92b may become a potential therapeutic target for osteosarcoma.

The Dkk3 gene encodes a vital intracellular regulator of cell proliferation

Members of the Dickkopf (Dkk) family of Wnt antagonists interrupt Wnt-induced receptor assembly and participate in axial patterning and cell fate determination. One family member, DKK3, does not block Wnt receptor activation. Loss of Dkk3 expression in cancer is associated with hyperproliferation and dysregulated ß-catenin signaling, and ectopic expression of Dkk3 halts cancer growth. The molecular events mediating the DKK3-dependent arrest of ß-catenin-driven cell proliferation in cancer cells are unknown. Here we report the identification of a new intracellular gene product originating from the Dkk3 locus. This Dkk3b transcript originates from a second transcriptional start site located in intron 2 of the Dkk3 gene. It is essential for early mouse development and is a newly recognized regulator of ß-catenin signaling and cell proliferation. Dkk3b interrupts nuclear translocation ß-catenin by capturing cytoplasmic, unphosphorylated ß-catenin in an extra-nuclear complex with ß-TrCP. These data reveal a new regulator of one of the most studied signal transduction pathways in metazoans and provides a novel, completely untapped therapeutic target for silencing the aberrant ß-catenin signaling that drives hyperproliferation in many cancers.

A Cytokine-Like Protein Dickkopf-Related Protein 3 Is Atheroprotective

Supplemental Digital Content is available in the text.

Background:

Dickkopf-related protein 3 (DKK3) is a secreted protein that is involved in the regulation of cardiac remodeling and vascular smooth muscle cell differentiation, but little is known about its role in atherosclerosis.

Methods:

We tested the hypothesis that DKK3 is atheroprotective using both epidemiological and experimental approaches. Blood DKK3 levels were measured in the Bruneck Study in 2000 (n=684) and then in 2005 (n=574). DKK3-deficient mice were crossed with apolipoprotein E^-/- mice to evaluate atherosclerosis development and vessel injury-induced neointimal formation. Endothelial cell migration and the underlying mechanisms were studied using in vitro cell culture models.

Results:

In the prospective population-based Bruneck Study, the level of plasma DKK3 was inversely related to carotid artery intima-media thickness and 5-year progression of carotid atherosclerosis independently from standard risk factors for atherosclerosis. Experimentally, we analyzed the area of atherosclerotic lesions, femoral artery injury-induced reendothelialization, and neointima formation in both DKK3^-/-/apolipoprotein E^-/- and DKK3^+/+/apolipoprotein E^-/- mice. It was demonstrated that DKK3 deficiency accelerated atherosclerosis and delayed reendothelialization with consequently exacerbated neointima formation. To explore the underlying mechanisms, we performed transwell and scratch migration assays using cultured human endothelial cells, which exhibited a significant induction in cell migration in response to DKK3 stimulation. This DKK3-induced migration activated ROR2 and DVL1, activated Rac1 GTPases, and upregulated JNK and c-jun phosphorylation in endothelial cells. Knockdown of the ROR2 receptor using specific siRNA or transfection of a dominant-negative form of Rac1 in endothelial cells markedly inhibited cell migration and downstream JNK and c-jun phosphorylation.

Conclusions:

This study provides the evidence for a role of DKK3 in the protection against atherosclerosis involving endothelial migration and repair, with great therapeutic potential implications against atherosclerosis.

MicroRNA-92a promotes cell viability and invasion in cervical cancer via directly targeting Dickkopf-related protein 3

MicroRNA-92a (miR-92a) was recently reported to have an oncogenic role in cervical cancer; however, the underlying mechanism remains largely unclear. The present study aimed to investigate the expression, clinical significance and regulatory mechanism of miR-92a in cervical cancer. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) data indicated that miR-92a was significantly upregulated in cervical cancer tissues compared with matched adjacent non-tumor tissues (P<0.01). High expression of miR-92a was significantly associated with poor differentiation (P=0.031), advanced clinical stage (P=0.011) and lymph node metastasis (P=0.014), but not associated with age, tumor size and distant metastasis. Knockdown of miR-92a significantly inhibited the viability and invasion of cervical cancer HeLa cells, while overexpression of miR-92a significantly enhanced HeLa cell viability and invasion (P<0.01). Luciferase reporter assay identified Dickkopf-related protein 3 (DKK3) as a target gene of miR-92a, and the protein expression of DKK3 was negatively regulated by miR-92a in HeLa cells. Furthermore, overexpression of DKK3 significantly eliminated the stimulative effects of miR-92a on HeLa cell viability and invasion (P<0.01). Additionally, DKK3 was significantly downregulated in cervical cancer tissues compared with adjacent non-tumor tissues (P<0.01), inversely correlated to the miR-92a levels in cervical cancer tissues (P<0.01). In summary, the present study indicated that miR-92a promotes cell viability and invasion in cervical cancer, partly at least, via inhibiting the protein expression of DKK3. Therefore, the present study highlights the clinical significance of the miR-92a/DKK3 axis in cervical cancer.

DKK3 Overexpression Increases the Malignant Properties of Head and Neck Squamous Cell Carcinoma Cells

DKK3, a member of the dickkopf Wnt signaling pathway inhibitor family, is believed to be a tumor suppressor because of its reduced expression in cancer cells. However, our previous studies have revealed that DKK3 expression is predominantly observed in head and neck/oral squamous cell carcinoma (HNSCC/OSCC). Interestingly, HNSCC/OSCC patients with DKK3 expression showed a high rate of metastasis and poorer survival, and siRNA-mediated knockdown of DKK3 in HNSCC-derived cancer cell lines resulted in reduced cellular migration and invasion. From these data, it was hypothesized that DKK3 might exert an oncogenic function specific to HNSCC. In the present research, the DKK3 overexpression model was established, and its influences were investigated, together with molecular mechanism studies. The DKK3 expression profile in cancer cell lines was investigated, including HNSCC/OSCC, esophageal, gastric, colorectal, pancreatic, prostatic, and lung cancers. DKK3 overexpression was performed in HNSCC-derived cells by transfection of expression plasmid. The effects of DKK3 overexpression were assessed on cellular proliferation, migration, invasion, and in vivo tumor growth. The molecular mechanism of DKK3 overexpression was investigated by Western blotting and microarray analysis. DKK3 overexpression significantly elevated cellular proliferation, migration, and invasion, as well as increased mRNA expression of cyclin D1 and c-myc. However, reporter assays did not show TCF/LEF activation, suggesting that the increased malignant property of cancer cells was not driven by the Wnt/β-catenin pathway. For the investigation of the pathways/molecules in DKK3-mediated signals, the Western blot analyses revealed that phosphorylation of Akt (S473) and c-Jun (Ser63) was elevated. The application of a PI3K kinase inhibitor, LY294002, on HSC-3 DKK3 cells significantly decreased tumor cell proliferation, migration, and invasion. From these results, we demonstrated that DKK3 might contribute to cellular proliferation, invasion, migration, and tumor cell survival in HNSCC cells through a mechanism other than the canonical Wnt signaling pathway, which might be attributed to PI3K–Akt signaling.

A novel FOXO1-mediated dedifferentiation blocking role for DKK3 in adrenocortical carcinogenesis

Background

Dysregulated WNT signaling dominates adrenocortical malignancies. This study investigates whether silencing of the WNT negative regulator DKK3 (Dickkopf-related protein 3), an implicated adrenocortical differentiation marker and an established tumor suppressor in multiple cancers, allows dedifferentiation of the adrenal cortex.

Methods

We analyzed the expression and regulation of DKK3 in human adrenocortical carcinoma (ACC) by qRT-PCR, immunofluorescence, promoter methylation assay, and copy number analysis. We also conducted functional studies on ACC cell lines, NCI-H295R and SW-13, using siRNAs and enforced DKK3 expression to test DKK3’s role in blocking dedifferentiation of adrenal cortex.

Results

While robust expression was observed in normal adrenal cortex, DKK3 was down-regulated in the majority (>75%) of adrenocortical carcinomas (ACC) tested. Both genetic (gene copy loss) and epigenetic (promoter methylation) events were found to play significant roles in DKK3 down-regulation in ACCs. While NCI-H295R cells harboring β-catenin activating mutations failed to respond to DKK3 silencing, SW-13 cells showed increased motility and reduced clonal growth. Conversely, exogenously added DKK3 also increased motility of SW-13 cells without influencing their growth. Enforced over-expression of DKK3 in SW-13 cells resulted in slower cell growth by an extension of G1 phase, promoted survival of microcolonies, and resulted in significant impairment of migratory and invasive behaviors, largely attributable to modified cell adhesions and adhesion kinetics. DKK3-over-expressing cells also showed increased expression of Forkhead Box Protein O1 (FOXO1) transcription factor, RNAi silencing of which partially restored the migratory proficiency of cells without interfering with their viability.

Conclusions

DKK3 suppression observed in ACCs and the effects of manipulation of DKK3 expression in ACC cell lines suggest a FOXO1-mediated differentiation-promoting role for DKK3 in the adrenal cortex, silencing of which may allow adrenocortical dedifferentiation and malignancy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3152-5) contains supplementary material, which is available to authorized users.