Expression of the Wnt antagonist Dickkopf-3 is associated with prognostic clinicopathologic characteristics and impairs proliferation and invasion in endometrial cancer

Molecular Investigation of DKK3 in Cerebral Ischemic/Reperfusion Injury

Dickkopf-3 (Dkk3) is an atypical member of the Dkk family of Wnt inhibitors, which has been implicated in the pathophysiology of neurodegenerative disorders. Its role in the mechanisms of cellular degeneration and protection is still unknown. The aim of our work is to investigate the endogenous activation of the DKK3 pathway in a model of transient occlusion of the middle cerebral artery in rats. In particular, the animals were subjected to 1 h of ischemia followed by different reperfusion times (1 h, 6 h, 12 h and 24 h) to evaluate the downstream pathway and the time course of its activation. Western blot analysis showed increased Dkk3 expression in animals with the highest time of reperfusion. The increased levels of Dkk3 were accompanied by reduced Wnt3a, Frz1 and PIWI1a expression in the cytosol while FOXM1 and β-catenin decreased in the nucleus. These molecular changes led to an increase in the apoptotic pathway, as showed by the increased expression of Caspase 3 and Bax and the reduced levels of Bcl-2, and to a decrease in neurogenesis, as shown by the decreased expression of Tbr2, Ngn2 and Pax6. In the second part of the study, we decided to employ curcumin, an activator of the Wnt/β-catenin signaling, to investigate its effect on Dkk3. In particular, curcumin was administered 1 and 6 h after ischemia, and animals were sacrificed 24 h later when the expression of Dkk3 was higher. Our data displayed that curcumin administration decreased Dkk3 expression, and increased Wnt3a, Frz1 and PIWI1a levels. Well in line with these data, curcumin administration increased nuclear β-catenin and FOXM1 expression. The down-regulation of Dkk3 by curcumin led to reduced apoptosis and increased neurogenesis. Summarizing, our results showed that Dkk3 acts as an inhibitor of Wnt/β-catenin signaling during cerebral ischemia. Additionally, its inhibition and the contextual activation of the Wnt/β-catenin pathway are protective against ischemic stroke.

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.

Addressing activation of WNT beta-catenin pathway in diverse landscape of endometrial carcinogenesis

The WNT-beta-catenin pathway (WP) is one of the major oncogenic pathways in solid tumors. Wnt beta-catenin pathway plays a unique role in a wide range of endometrial dysfunctions, from embryo implantation failure to severe pathogenic changes like endometriosis and endometrial cancer. Although abnormal activation of the pathway has long been known to be associated with endometrial tumorigenesis, the pathway's exact mode of involvement remains to be understood. As more evidence has been presented in favor of a crucial role of the WP in solid tumors, including endometrial cancer, anti-WP drugs are currently being tested to manage the disease. Aggressive tumor cells are nurtured by the tumor microenvironment (TME). The genetic alterations within tumor cells are the primary driving force to activate the extra-tumoral micro-environment. TME (a) provides metabolic support for the proliferation of tumor cells, (b) orchestrates immune-evasion, (c) initiates mechanistic signaling for several metastasis-associated phenotypes, and (d) supports cellular events for the development of drug resistance. To get metabolic as well as immune support from the tumor microenvironment, tumor cells cross-talk with components of the TME, most critically to the cancer-associated fibroblasts. Thus it is expected that the tumor-TME cross-talk throughout the process of tumorigenesis and metastasis is one of the characteristic features of an aggressive tumor. Here we review the WP's mechanistic involvement as a common culprit (Un Colpevole Comune) in endometrial tumor cells and endometrial cancer-associated fibroblast (CAF). In this review, we have attempted to discuss the activation of the WP in the genesis and progression of endometrial cancers, including endometrial tumor biology, tumor microenvironment, cancer-associated fibroblasts, and wnt-beta catenin genetic alteration. We interrogated the available literature on the various aspects of endometrial carcinogenesis leading to the pathway's activation. We examined how genetic alterations in WP directly influence tumor cell signaling to bring out different tumor cell phenotypes, and present palpable evidence to envision a role of WP inhibitors in the future management of the disease.

Cantharidin inhibits osteosarcoma proliferation and metastasis by directly targeting miR-214-3p/DKK3 axis to inactivate β-catenin nuclear translocation and LEF1 translation

Background: As the leading primary bone cancer in adolescents and children, osteosarcoma patients with metastasis show a five-year-survival-rate of 20-30%, without improvement over the past 30 years. Wnt/β-catenin is important in promoting osteosarcoma development. DKK3 is a Wnt/β-catenin antagonist and predicted to have the specific binding site in 3′-UTR with miR-214-3p.

Methods: miR-214-3p and DKK3 levels were investigated in human osteosarcoma tissues and cells by RT-qPCR; the prognostic importance of DKK3 level in osteosarcoma patients was determined with Log-rank test; direct binding between DKK3 with miR-214-3p was identified with targetscan; anti-osteosarcoma mechanism of cantharidin was investigated by miR-214-3p silence/over-expression with or without cantharidin treatment, and nuclear/cytoplasmic protein assay in osteosarcoma cells.

Results: Down-regulated DKK3 indicated poor prognosis of osteosarcoma patients. Up-regulated miR-214-3p promoted proliferation and migration, while suppressed apoptosis of osteosarcoma cells by increasing β-catenin nuclear translocation and LEF1 translation via degradation of DKK3. Cantharidin suppressed viabilities, migration and invasion, while promoted cell cycle arrest and apoptosis in 143B and U-2 OS cells via down-regulating miR-214-3p to up-regulate DKK3, thus inhibited p-GSK-3β expression, β-catenin nuclear translocation and LEF1 translation. Meanwhile, cantharidin inhibited tumor growth in xenograft-bearing mice with 143B cell injection in tibia.

Conclusion: miR-214-3p mediated Wnt/β-catenin/LEF1 signaling activation by targeting DKK3 to promote oncogenesis of osteosarcoma; cantharidin inhibited proliferation and metastasis of osteosarcoma cells via down-regulating miR-214-3p to up-regulate DKK3 and decrease β-catenin nuclear translocation, indicating that cantharidin may be a prospective candidate for osteosarcoma treatment by targeting miR-214-3p/DKK3/β-catenin signaling.

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.

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.

Wnt/β-Catenin Signaling Pathway-Related Proteins (DKK-3, β-Catenin, and c-MYC) Are Involved in Prognosis of Nasopharyngeal Carcinoma

The Wnt/β-catenin signaling pathway is one of the highly conserved signaling pathway widely reported to play essential roles in the development of various tumors and human cancers, thus serving as a potential target for anticancer therapy. However, the specific effects of the related proteins in the Wnt/β-catenin signaling pathway in nasopharyngeal carcinoma (NPC) still remain elusive. Thus, this study was performed to uncover the correlation between the Wnt/β-catenin signaling pathway-related proteins and the clinical characteristics and prognosis of NPC. NPC tissues were revealed to present high expression of β-catenin and v-myc myelocytomatosis viral oncogene homolog (c-MYC) but low expression of Dickkopf-3 (DKK-3). Immunohistochemical staining revealed that DKK-3 was positively linked to but β-catenin and c-MYC were negatively linked to differentiation, tumor-node-metastasis (TNM) stage and lymph node metastasis of patients with NPC. In addition, c-MYC was identified to be positively correlated to DKK-3 in NPC tissues. The positive expression of β-catenin and c-MYC had negative relations with and that of DKK-3 had positive relations with survival rate of patients with NPC, which was analyzed by Kaplan-Meier method. Moreover, it was shown that later TNM stage and positive expression of β-catenin were risk factors for NPC-related death. These findings provide evidence that the proteins related to the Wnt/β-catenin signaling pathway (DKK-3, β-catenin, and c-MYC) participate in the development of NPC and positive expression of DKK-3 and negative expression of β-catenin, and c-MYC can serve as essential prognostic biomarkers, shedding new light on the prognosis and treatment of NPC.

Dickkopf-3 Causes Neuroprotection by Inducing Vascular Endothelial Growth Factor

Dickkopf-3 (Dkk3) is an atypical member of the Dkk family of Wnt inhibitors, which has been implicated in the pathophysiology of neurodegenerative disorders. However, the role of Dkk3 in mechanisms of cell degeneration and protection is unknown. We used Dkk3 knockout mice to examine how endogenous Dkk3 influences ischemic brain damage. In addition, we used primary cultures of astrocytes or mixed cultures of astrocytes and neurons to investigate the action of Dkk3 on cell damage and dissect the underlying molecular mechanisms. In a model of focal brain ischemia induced by permanent middle cerebral artery (MCA) occlusion (MCAO) Dkk3^−/− mice showed a significantly greater infarct size with respect to their wild-type counterparts at all time points investigated (1, 3 and 7 days after MCAO). Immunohistochemical analysis showed that Dkk3 expression was enhanced at the borders of the ischemic focus, and was predominantly detected in astrocytes. This raised the possibility that Dkk3 produced by astrocytes acted as a protective molecule. We tested this hypothesis using either primary cultures of cortical astrocytes or mixed cortical cultures containing both neurons and astrocytes. Genetic deletion of Dkk3 was permissive to astrocyte damage induced by either oxidative stress or glucose deprivation. In addition, application of human recombinant Dkk3 (hrDkk3) was highly protective against oxidative stress in cultured astrocytes. We tested the hypothesis that the protective activity of Dkk3 was mediated byvascular endothelial growth factor (VEGF). Interestingly, glucose deprivation up-regulated both Dkk3 and VEGF in cultured astrocytes prepared from wild-type mice. VEGF induction was not observed in astrocytes lacking Dkk3 (i.e., in cultures prepared from Dkk3^−/− mice). In mixed cultures of cortical cells, excitotoxic neuronal death induced by a brief pulse with N-methyl-D-aspartate (NMDA) was significantly enhanced when Dkk3 was lacking in astrocytes, whereas post-NMDA addition of hrDkk3 was neuroprotective. Neuroprotection by hrDkk3 was significantly reduced by pharmacological blockade of type-2 VEGF receptors and was mimicked by hrVEGF. These data offer the first evidence that Dkk3 protects both neurons and astrocytes against a variety of toxic insults, and at least in culture, protection involves VEGF induction.

Dickkopf homolog 3 (DKK3): A candidate for detection and treatment of cancers?

Wnt signaling is an evolutionary highly conserved pathway that is modulated by several inhibitors and activators, and plays a key role in numerous physiological processes. One of the extracellular Wnt inhibitors is the DKK (Dickkopf Homolog) family which has four members (Dkk1-4) and a unique Dkk3-related gene, Dkkl1 (soggy). DKK3 is a divergent member of the DKK protein family. Evidence suggests that DKK3 may serve as a potential therapeutic target in several types of human cancers. We review here the biological role of DKK3 as a tumor suppressor gene (TSG) or oncogene, and its correlation with various miRNAs. In addition, we discuss the role of polymorphisms and promoter methylation of the DKK3 gene, and of its expression in regulating cancer cell proliferation. Finally, we propose that DKK3 may be considered as both a biomarker and a therapeutic target in different cancers.

Moving forward with actionable therapeutic targets and opportunities in endometrial cancer: NCI clinical trials planning meeting report on identifying key genes and molecular pathways for targeted endometrial cancer trials

The incidence and mortality rates from endometrial cancer are increasing. There have been no new drugs approved for the treatment of endometrial cancer in decades. The National Cancer Institute, Gynecologic Cancer Steering Committee identified the integration of molecular and/or histologic stratification into endometrial cancer management as a top strategic priority. Based on this, they convened a group of experts to review the molecular data in this disease. Here we report on the actionable opportunities and therapeutic directions identified for incorporation into future clinical trials.

Endometrial Carcinoma: Specific Targeted Pathways

Endometrial cancer (EC) is the most common gynecologic malignancy in the western world with more than 280,000 cases per year worldwide. Prognosis for EC at early stages, when primary surgical resection is the most common initial treatment, is excellent. Five-year survival rate is around 70 %.Several molecular alterations have been described in the different types of EC. They occur in genes involved in important signaling pathways. In this chapter, we will review the most relevant altered pathways in EC, including PI3K/AKT/mTOR, RAS-RAF-MEK-ERK, Tyrosine kinase, WNT/β-Catenin, cell cycle, and TGF-β signaling pathways. At the end of the chapter, the most significant clinical trials will be briefly discussed.This information is important to identify specific targets for therapy.

Serum biomarker analysis in patients with recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) occurs in 1–5% of parturients. The sustained therapy and research for RSA is expensive, which is a serious issue faced by both patients and doctors. The aim of the present study was to detect protein expression profiles in the serum of RSA patients and healthy controls, and to identify potential biomarkers for this disease. A 1,000-protein microarray consisting of a combination of Human L-507 and L-493 was used. The microarray data revealed that eight serum protein expression levels were significantly upregulated and 143 proteins were downregulated in RSA patients compared with the healthy controls. ELISA individually validated 5 of these 151 proteins in a larger cohort of patients and control samples, demonstrating a significant decrease in insulin-like growth factor-binding protein-related protein 1 (IFGBP-rp1)/IGFBP-7, Dickkopf-related protein 3 (Dkk3), receptor for advanced glycation end products (RAGE) and angiopoietin-2 levels in patients with RSA. Sensitivity and specificity analyses were calculated by a receiver operating characteristics curve, and were revealed to be 0.881, 0.823, 0.79 and 0.814, with diagnostic cut-off points of 95.44 ng/ml for IFGBP-rp1, 32.84 ng/ml for Dkk3, 147.27 ng/ml for RAGE and 441.40 ng/ml for angiopoietin-2. The present study indicated that these four proteins were downregulated in RSA samples and may be useful as biomarkers for the prediction and diagnosis of RSA. Subsequent studies in larger-scale cohorts are required to further validate the diagnostic value of these markers.

Single nucleotide polymorphisms in DKK3 gene are associated with prostate cancer risk and progression

We had investigated whether sequence variants within DKK3 gene are associated with the development of prostate cancer in a Korean study cohort. We evaluated the association between 53 single nucleotide polymorphisms (SNPs) in the DKK3 gene and prostate cancer risk as well as clinical characteristics (PSA, clinical stage, pathological stage and Gleason score) in Korean men (272 prostate cancer subjects and 173 benign prostate hyperplasia subjects) using unconditional logistic regression analysis. Of the 53 SNPs and 25 common haplotypes, 5 SNPs and 4 haplotypes were associated with prostate cancer risk (P=0.02-0.04); 3 SNPs and 2 haplotypes were significantly associated with susceptibility to prostate cancer, however 2 SNPs and 2 haplotypes exhibited a significant protective effect on prostate cancer. Logistic analyses of the DKK3 gene polymorphisms with several prostate cancer related factors showed that several SNPs were significant; three SNPs and two haplotypes to PSA level, three SNPs and two haplotypes to clinical stage, nine SNPs and two haplotype to pathological stage, one SNP and one haplotypes to Gleason score. To the author's knowledge, this is the first report documenting that DKK3 polymorphisms are not only associated with prostate cancer but also related to prostate cancer-related factors.

Dkk3 prevents familial dilated cardiomyopathy development through Wnt pathway

To date, the role of Dickkopf 3 (Dkk3) on the pathogenesis of familial dilated cardiomyopathy (FDCM), and whether and how Dkk3 interferes with Wnt signaling in heart tissues remains unknown. Here, we demonstrate that strong Dkk3 expression was markedly downregulated in adult hearts from WT mice, and Dkk3 expression was upregulated suddenly in hearts from DCM mouse models. Using Dkk3 transgenic and knockout mice, as well as cTnT(R141W) transgenic mice, which manifests progressive chamber dilation and contractile dysfunction and has pathologic phenotypes similar to human DCM patients, we determined that transgenic expression of Dkk3 increased survival rate, improved cardiac morphology breakage and dysfunction, and ameliorated cardiac pathological changes in the cTnT(R141W) mice. In contrast, Dkk3 knockout reduced the survival rate and aggravated the pathological phenotypes of the cTnT(R141W) mice. The protective effects of Dkk3 appeared clearly at 3 months of age, peaked at 6 months of age, and decreased at 10 months of age in the cTnT(R141W) mice. Furthermore, we determined that Dkk3 upregulated Dvl1 (Dishevelled 1) and key proteins of the canonical Wnt pathway (cytoplasmic and nuclear β-catenin, c-Myc, and Axin2) and downregulated key proteins of the noncanonical Wnt pathway (c-Jun N-terminal kinase (JNK), Ca(2+)/calmodulin-dependent protein kinase II (CAMKII), and histone deacetylase 4 (HDAC4)). In contrast, Dkk3 knockout reversed these changes in the cTnT(R141W) mice. In summary, Dkk3 could prevent FDCM development in mice, especially in the compensatory stage, and probably through activation of the canonical and inhibition of the noncanonical Wnt pathway, which suggested that Dkk3 could serve as a therapeutic target for the treatment of cardiomyopathy and heart failure.

Tumor progression, metastasis, and modulators of epithelial-mesenchymal transition in endometrioid endometrial carcinoma: an update

Endometrioid endometrial carcinoma (EEC), also known as type 1 endometrial cancer (EC), accounts for over 70-80% of all cases that are usually associated with estrogen stimulation and often develops in a background of atypical endometrial hyperplasia. The increased incidence of EC is mainly confined to this type of cancer. Most EEC patients present at an early stage and generally have a favorable prognosis; however, up to 30% of EEC present as high risk tumors, which have invaded deep into the myometrium at diagnosis and progressively lead to local or extra pelvic metastasis. The poor survival of advanced EC is related to the lack of effective therapies, which can be attributed to poor understanding of the molecular mechanisms underlying the progression of disease toward invasion and metastasis. Multiple lines of evidence illustrate that epithelial-mesenchymal transition (EMT)-like events are central to tumor progression and malignant transformation, endowing the incipient cancer cell with invasive and metastatic properties. The aim of this review is to summarize the current knowledge on molecular events associated with EMT in progression, invasion, and metastasis of EEC. Further, the role of epigenetic modifications and microRNA regulation, tumor microenvironment, and microcystic elongated and fragmented glands like invasion pattern have been discussed. We believe this article may perhaps stimulate further research in this field that may aid in identifying high risk patients within this clinically challenging patient group and also lead to the recognition of novel targets for the prevention of metastasis - the most fatal consequence of endometrial carcinogenesis.

Cell and matrix response of temporomandibular cartilage to mechanical loading

OBJECTIVES

The generation of transgenic mice expressing green fluorescent proteins (GFPs) has greatly aided our understanding of the development of connective tissues such as bone and cartilage. Perturbation of a biological system such as the temporomandibular joint (TMJ) within its adaptive remodeling capacity is particularly useful in analyzing cellular lineage progression. The objectives of this study were to determine: (i) if GFP reporters expressed in the TMJ indicate the different stages of cell maturation in fibrocartilage and (ii) how mechanical loading affects cellular response in different regions of the cartilage.

DESIGN/METHODS

Four-week-old transgenic mice harboring combinations of fluorescent reporters (Dkk3-eGFP, Col1a1(3.6 kb)-GFPcyan, Col1a1(3.6 kb)-GFPtpz, Col2a1-GFPcyan, and Col10a1-RFPcherry) were used to analyze the expression pattern of transgenes in the mandibular condylar cartilage (MCC). To study the effect of TMJ loading, animals were subjected to forced mouth opening with custom springs exerting 50 g force for 1 h/day for 5 days. Dynamic mineralization and cellular proliferation (EdU-labeling) were assessed in loaded vs control mice.

RESULTS

Dkk3 expression was seen in the superficial zone of the MCC, followed by Col1 in the cartilage zone, Col2 in the prehypertrophic zone, and Col10 in the hypertrophic zone at and below the tidemark. TMJ loading increased expression of the GFP reporters and EdU-labeling of cells in the cartilage, resulting in a thickness increase of all layers of the cartilage. In addition, mineral apposition increased resulting in Col10 expression by unmineralized cells above the tidemark.

CONCLUSION

The TMJ responded to static loading by forming thicker cartilage through adaptive remodeling.

Expression Patterns of the Wnt Pathway Inhibitors Dickkopf3 and Secreted Frizzled-Related Proteins 1 and 4 in Endometrial Endometrioid Adenocarcinoma: An NRG Oncology/Gynecologic Oncology Group Study

OBJECTIVE

The aim of the study was to determine the differential expression patterns of the wingless-type (Wnt) pathway inhibitors Dkk3 (Dickkopf 3), SFRP1 (secreted frizzled-related protein 1), and SFRP4 in normal müllerian tissue and endometrial endometrioid adenocarcinoma specimens.

METHODS

Messenger RNA (mRNA) and protein levels of the Wnt pathway inhibitors Dkk3, SFRP1, and SFRP4 were evaluated by real-time reverse transcription-polymerase chain reaction and Western blot analysis. A total of 87 human tissue specimens were obtained from 60 women who participated in Gynecologic Oncology Group protocol 210. Twenty-seven normal müllerian tissues, 32 early-stage, and 28 advanced-stage endometrial endometrioid cancer specimens were analyzed.

RESULTS

Median age for this cohort was 60 years, with median body mass index of 32 kg/m. There was a difference in Dkk3 protein expression between normal müllerian tissues and primary endometrial endometrioid adenocarcinoma samples (P = 0.05). There was down-regulation of Dkk3, SFRP1, and SFRP4 mRNA expression in patients with high-grade disease (P = 0.08, 0.06, and 0.05, respectfully). Furthermore, a decrease in SFRP1 and SFPR4 mRNA expression was noted in patients with a diagnosis of locoregional and distant disease recurrence. Lastly, a trend toward decreased progression-free survival in patients with low Dkk3, SFRP1, and SFRP4 mRNA expression levels was noted.

CONCLUSIONS

Wnt pathway inhibitor (Dkk3, sFRP1, and/or sFRP4) expression was down-regulated in patients with high-grade disease and was associated with locoregional and distant disease recurrence. Despite sample size (power) limitations, these results support previous preclinical studies and may suggest a therapeutic role for Wnt signaling in endometrial cancer.

Endometrial Carcinoma: Role of Current and Emerging Biomarkers in Resolving Persistent Clinical Dilemmas

OBJECTIVES

Type II and other high-grade endometrial carcinomas may challenge conventional treatment due to recurrence and metastatic spread and therefore are a persistent clinical dilemma. Effective targeted therapy for these is a goal for clinicians and researchers alike.

METHODS

An extensive review of the literature has been performed for obtaining an in-depth understanding of the clinicopathological characteristics, etiologic factors, and molecular profile of these subsets of endometrial carcinoma. Progress made with current and emerging biomarkers for prognosis assessment and therapeutic targeting has been summarized.

RESULTS

There has been a significant increase in research on potential biomarkers of endometrial cancer, and beneficial targeted therapies have been identified.

CONCLUSIONS

Clinical trials are leading the charge for substantial gains toward personalized treatment of aggressive endometrial carcinoma subtypes.

Dkk-3 induces apoptosis through mitochondrial and Fas death receptor pathways in human mucinous ovarian cancer cells

OBJECTIVE

Dkk-3 is a Wnt signaling inhibitor that is frequently inactivated in human cancers. Dkk-3 possesses an antiproliferative activity and induces apoptosis in tumor cells, suggesting that it functions as a tumor suppressor. In this study, we investigated the molecular function of Dkk-3 in human ovarian cancer cells.

METHODS

We assessed the levels of Dkk-3 protein expression in human mucinous and clear cell ovarian cancer cells, and compared cell viabilities between cell lines that expressed Dkk-3 and those that did not, as well as between cells that expressed Dkk-3 and those whose expression of Dkk-3 was reduced by small interfering RNA. We also evaluated the characteristic fragmentation of DNA to detect apoptosis in Dkk-3-deficient cells. To further investigate the molecular mechanisms of apoptosis, we assessed the expression of molecules involved in apoptosis signaling pathways in Dkk-3-deficient cells.

RESULTS

The expression of the Dkk-3 protein was observed in most of the ovarian cancer cell lines tested. Dkk-3-deficient cells showed faster growth than Dkk-3-replete cells. The characteristic fragmentation of DNA was not observed in Dkk-3-deficient cells, which showed decreased levels of expression in caspase-3, activated caspase-9, Bax, p53, activated caspase-8, and Fas/CD95, as well as an increase in Bcl-2 expression.

CONCLUSIONS

Although Dkk-3 expression was observed in most of human ovarian cancer cell lines, Dkk-3 has a tumor-suppressive function and a proapoptotic effect, inducing apoptosis through mitochondrial and Fas death receptor pathways in human mucinous ovarian cancer MCAS cells.

Wnt signalling in gynaecological cancers: A future target for personalised medicine?

The three major gynaecological cancers, ovarian, uterine and cervical, contribute a significant burden to global cancer mortality, and affect women in both developed and developing countries. However, unlike other cancer types that have seen rapid advances and incorporation of targeted treatments in recent years, personalised medicine is not yet a reality in the treatment of gynaecological cancers. Advances in sequencing technology and international collaborations and initiatives such as The Cancer Genome Atlas are now revealing the molecular basis of these cancers, and highlighting key signalling pathways involved. One pathway which plays a role in all three cancer types, is the Wnt signalling pathway. This complex developmental pathway is altered in most human malignancies, and members of this pathway, particularly the recently linked ROR receptor tyrosine kinases may be attractive future therapeutic targets. This review provides an up-to-date summary of research into Wnt signalling and ovarian, uterine and cervical cancers, and discusses the potential of the Wnt pathway as a future target for personalised medicine in gynaecological cancers.

Dickkopf-3 (DKK-3) obstructs VEGFR-2/Akt/mTOR signaling cascade by interacting of β2-microglobulin (β2M) in ovarian tumorigenesis

In this study, we investigated a possible mechanism of β2-microglobulin (β2M) function in cancer metastases in vitro, using a human ovarian carcinoma cell line. β2M, a modulator acts as a cell growth-promoting and cellular signaling factors, was identified as a dickkopf-3 (DKK-3) interacting protein. We also observed that DKK-3 suppresses endothelial cell angiogenesis of β2M through vascular endothelial growth factor receptor-2 (VEGFR-2) in tumorigenesis. Luciferase activity was remarkably reduced by the transfection of DKK-3 in a dose-dependent manner. In addition, over-expression of β2M activates cell growth by suppressing DKK-3-induced apoptosis. The effect of β2M on cell cycle and apoptosis-regulatory components was also confirmed through the silencing of β2M expression. Furthermore, induction of β2M-mediated VEGFR-2/Akt/mTOR phosphorylation and tumor angiogenesis was significantly suppressed by over-expression of DKK-3. Taken together, our results suggest an underlying mechanism for an increase of β2M-related activity in ovarian tumor cells.

Epigenetic silencing of the WNT antagonist Dickkopf 3 disrupts normal Wnt/β-catenin signalling and apoptosis regulation in breast cancer cells

Dickkopf-related protein 3 (DKK3) is an antagonist of Wnt ligand activity. Reduced DKK3 expression has been reported in various types of cancers, but its functions and related molecular mechanisms in breast tumorigenesis remain unclear. We examined the expression and promoter methylation of DKK3 in 10 breast cancer cell lines, 96 primary breast tumours, 43 paired surgical margin tissues and 16 normal breast tissues. DKK3 was frequently silenced in breast cell lines (5/10) by promoter methylation, compared with human normal mammary epithelial cells and tissues. DKK3 methylation was detected in 78% of breast tumour samples, whereas only rarely methylated in normal breast and surgical margin tissues, suggesting tumour-specific methylation of DKK3 in breast cancer. Ectopic expression of DKK3 suppressed cell colony formation through inducing G0/G1 cell cycle arrest and apoptosis of breast tumour cells. DKK3 also induced changes of cell morphology, and inhibited breast tumour cell migration through reversing epithelial-mesenchymal transition (EMT) and down-regulating stem cell markers. DKK3 inhibited canonical Wnt/β-catenin signalling through mediating β-catenin translocation from nucleus to cytoplasm and membrane, along with reduced active-β-catenin, further activating non-canonical JNK signalling. Thus, our findings demonstrate that DKK3 could function as a tumour suppressor through inducing apoptosis and regulating Wnt signalling during breast tumorigenesis.

BD-Func: a streamlined algorithm for predicting activation and inhibition of pathways

BD-Func (BiDirectional FUNCtional enrichment) is an algorithm that calculates functional enrichment by comparing lists of pre-defined genes that are known to be activated versus inhibited in a pathway or by a regulatory molecule. This paper shows that BD-Func can correctly predict cell line alternations and patient characteristics with accuracy comparable to popular algorithms, with a significantly faster run-time. BD-Func can compare scores for individual samples across multiple groups as well as provide predictive statistics and receiver operating characteristic (ROC) plots to quantify the accuracy of the signature associated with a binary phenotypic variable. BD-Func facilitates collaboration and reproducibility by encouraging users to share novel molecular signatures in the BD-Func discussion group, which is where the novel progesterone receptor and LBH589 signatures from this paper can be found. The novel LBH589 signature presented in this paper also serves as a case study showing how a custom signature using cell line data can accurately predict activity in vivo. This software is available to download at https://sourceforge.net/projects/bdfunc/.

SOX2 promotes tumor metastasis by stimulating epithelial-to-mesenchymal transition via regulation of WNT/β-catenin signal network

SOX2 was reported to promote metastasis in various tumor tissues; however the underlying mechanisms remain elusive. Here, we disclosed that SOX2 improves metastasis of breast and prostate cancer cells by promoting epithelial-to-mesenchymal transition (EMT) through WNT/β-catenin, but not TGF-β or Snail1 signaling. Dual luciferase assay and chromatin immunoprecipitation revealed activation and binding of SOX2 on promoter region of β-catenin. In addition, SOX2 affects the protein expression levels of DKK3, DVL1 and DVL3, which are regulators or downstream molecules of WNT signaling. Taken together, our findings demonstrated β-catenin as one of vital downstream molecules that mediate the EMT induced by SOX2.

p53, SKP2, and DKK3 as MYCN Target Genes and Their Potential Therapeutic Significance

Neuroblastoma is the most common extra-cranial solid tumor of childhood. Despite significant advances, it currently still remains one of the most difficult childhood cancers to cure, with less than 40% of patients with high-risk disease being long-term survivors. MYCN is a proto-oncogene implicated to be directly involved in neuroblastoma development. Amplification of MYCN is associated with rapid tumor progression and poor prognosis. Novel therapeutic strategies which can improve the survival rates whilst reducing the toxicity in these patients are therefore required. Here we discuss genes regulated by MYCN in neuroblastoma, with particular reference to p53, SKP2, and DKK3 and strategies that may be employed to target them.