Elevated levels of Dickkopf-1 are associated with β-catenin accumulation and poor prognosis in patients with chondrosarcoma

Dickkopf-1 Acts as a Profibrotic Mediator in Progressive Chronic Kidney Disease

Chronic kidney disease (CKD) is a serious public health problem. Due to a high variability in the speed of CKD progression to end-stage renal disease (ESRD) and the critical involvement of Wnt/β-catenin signaling in CKD, we investigated the role of the Wnt antagonist Dickkopf-1 (DKK1) in CKD progression. Our data revealed that patients with CKD stages 4-5 had higher DKK1 levels in their serum and renal tissues than the control subjects. In an 8-year follow-up, the serum DKK1-high group in the enrolled CKD patients showed a faster progression to ESRD than the serum DKK1-low group. Using a rat model of 5/6 nephrectomy (Nx)-induced CKD, we consistently detected elevated serum levels and renal production of DKK1 in 5/6 Nx rats compared to sham-operated rats. Importantly, the knockdown of the DKK1 levels in the 5/6 Nx rats markedly attenuated the CKD-associated phenotypes. Mechanistically, we demonstrated that the treatment of mouse mesangial cells with recombinant DKK1 protein induced not only the production of multiple fibrogenic proteins, but also the expression of endogenous DKK1. Collectively, our findings suggest that DKK1 acts as a profibrotic mediator in CKD, and elevated levels of serum DKK1 may be an independent predictor of faster disease progression to ESRD in patients with advanced CKD.

Association of FBXW11 levels with tumor development and prognosis in chondrosarcoma

INTRODUCTION

The E3 ubiquitin ligase FBXW11 exerts an oncogenic or tumor suppressive function in a cellular context-dependent manner. However, the clinical significance and biological role of FBXW11 in chondrosarcoma have not been clearly characterized. This study focuses on the expression profile, prognostic value and biological function of FBXW11 in chondrosarcoma.

METHODS

FBXW11 expression was analyzed by qRT-PCR and Western blot in six cases of chondrosarcoma specimens and the matched adjacent non-tumor tissues. The expression profile and prognostic value of FBXW11 were investigated in sixty-three cases of chondrosarcoma patients. Cell viability, colony formation, migration, invasion and apoptosis assays were further detected in SW1353 chondrosarcoma cells with restored FBXW11 expression.

RESULTS

Downregulation of FBXW11 was remarkably detected in human chondrosarcoma specimens compared with the corresponding non-tumor tissues and benign cartilage tumors. Downregulated FBXW11 expression significantly correlated with high-grade chondrosarcoma and poor prognosis. Furthermore, FBXW11 was identified as an independent prognostic factor for the overall survival of chondrosarcoma patients. Restored expression of FBXW11 significantly suppressed chondrosarcoma cell growth and induced apoptosis.

CONCLUSIONS

These findings establish that FBXW11 was markedly downregulated and recognized as an independent prognostic factor for patients with chondrosarcoma, and restored FBXW11 expression can suppress chondrosarcoma growth and induce apoptosis, highlighting a novel biological marker and potential therapeutic target against chondrosarcoma.

Culture and multiomic analysis of lung cancer patient-derived pleural effusions revealed distinct druggable molecular types

Malignant pleural effusion (MPE) is an independent determinant of poor prognostic factor of non-small cell lung cancer (NSCLC). The course of anchorage independent growth within the pleural cavity likely reforms the innate molecular characteristics of malignant cells, which largely accounts for resistance to chemotherapy and poor prognosis after the surgical resection. Nevertheless, the genetic and transcriptomic features with respect to various drug responses of MPE-complicated NSCLC remain poorly understood. To obtain a clearer overview of the MPE-complicated NSCLC, we established 28 MPE-derived lung cancer cell lines which were subjected to genomic, transcriptomic and pharmacological analysis. Our results demonstrated MPE-derived NSCLC cell lines recapitulated representative driver mutations generally found in the primary NSCLC. It also exhibited the presence of distinct translational subtypes in accordance with the mutational profiles. The drug responses of several targeted chemotherapies accords with both genomic and transcriptomic characteristics of MPE-derived NSCLC cell lines. Our data also suggest that the impending drawback of mutation-based clinical diagnosis in evaluating MPE-complicated NSCLS patient responses. As a potential solution, our work showed the importance of comprehending transcriptomic characteristics in order to defy potential drug resistance caused by MPE.

Dickkopf Proteins and Their Role in Cancer: A Family of Wnt Antagonists with a Dual Role

The Wnt signaling pathway regulates crucial aspects such as cell fate determination, cell polarity and organogenesis during embryonic development. Wnt pathway deregulation is a hallmark of several cancers such as lung, gastric and liver cancer, and has been reported to be altered in others. Despite the general agreement reached by the scientific community on the oncogenic potential of the central components of the pathway, the role of the antagonist proteins remains less clear. Deregulation of the pathway may be caused by overexpression or downregulation of a wide range of antagonist proteins. Although there is growing information related to function and regulation of Dickkopf (DKK) proteins, their pharmacological potential as cancer therapeutics still has not been fully developed. This review provides an update on the role of DKK proteins in cancer and possible potential as therapeutic targets for the treatment of cancer; available compounds in pre-clinical or clinical trials are also reviewed.

Methylation Patterns of DKK1, DKK3 and GSK3β Are Accompanied with Different Expression Levels in Human Astrocytoma

In the present study, we investigated genetic and epigenetic changes and protein expression levels of negative regulators of Wnt signaling, DKK1, DKK3, and APC as well as glycogen synthase kinase 3 (GSK3β) and β-catenin in 64 human astrocytomas of grades II-IV. Methylation-specific PCR revealed promoter methylation of DKK1, DKK3, and GSK3β in 38%, 43%, and 18% of samples, respectively. Grade IV comprised the lowest number of methylated GSK3β cases and highest of DKK3. Evaluation of the immunostaining using H-score was performed for β-catenin, both total and unphosphorylated (active) forms. Additionally, active (pY216) and inactive (pS9) forms of GSK3β protein were also analyzed. Spearman's correlation confirmed the prevalence of β-catenin's active form (r_s = 0.634, p < 0.001) in astrocytoma tumor cells. The Wilcoxon test revealed that astrocytoma with higher levels of the active pGSK3β-Y216 form had lower expression levels of its inactive form (p < 0.0001, Z = -5.332). Changes in APC's exon 11 were observed in 44.44% of samples by PCR/RFLP. Astrocytomas with changes of APC had higher H-score values of total β-catenin compared to the group without genetic changes (t = -2.264, p = 0.038). Furthermore, a positive correlation between samples with methylated DKK3 promoter and the expression of active pGSK3β-Y216 (r_s = 0.356, p = 0.011) was established. Our results emphasize the importance of methylation for the regulation of Wnt signaling. Large deletions of the APC gene associated with increased β-catenin levels, together with oncogenic effects of both β-catenin and GSK3β, are clearly involved in astrocytoma evolution. Our findings contribute to a better understanding of the etiology of gliomas. Further studies should elucidate the clinical and therapeutic relevance of the observed molecular alterations.

Dickkopf-1: A Promising Target for Cancer Immunotherapy

Clinical studies in a range of cancers have detected elevated levels of the Wnt antagonist Dickkopf-1 (DKK1) in the serum or tumors of patients, and this was frequently associated with a poor prognosis. Our analysis of DKK1 gene profile using data from TCGA also proves the high expression of DKK1 in 14 types of cancers. Numerous preclinical studies have demonstrated the cancer-promoting effects of DKK1 in both in vitro cell models and in vivo animal models. Furthermore, DKK1 showed the ability to modulate immune cell activities as well as the immunosuppressive cancer microenvironment. Expression level of DKK1 is positively correlated with infiltrating levels of myeloid-derived suppressor cells (MDSCs) in 20 types of cancers, while negatively associated with CD8⁺ T cells in 4 of these 20 cancer types. Emerging experimental evidence indicates that DKK1 has been involved in T cell differentiation and induction of cancer evasion of immune surveillance by accumulating MDSCs. Consequently, DKK1 has become a promising target for cancer immunotherapy, and the mechanisms of DKK1 affecting cancers and immune cells have received great attention. This review introduces the rapidly growing body of literature revealing the cancer-promoting and immune regulatory activities of DKK1. In addition, this review also predicts that by understanding the interaction between different domains of DKK1 through computational modeling and functional studies, the underlying functional mechanism of DKK1 could be further elucidated, thus facilitating the development of anti-DKK1 drugs with more promising efficacy in cancer immunotherapy.

Targeting Wnt Signaling for Gastrointestinal Cancer Therapy: Present and Evolving Views

Wnt signaling governs tissue development, homeostasis, and regeneration. However, aberrant activation of Wnt promotes tumorigenesis. Despite the ongoing efforts to manipulate Wnt signaling, therapeutic targeting of Wnt signaling remains challenging. In this review, we provide an overview of current clinical trials to target Wnt signaling, with a major focus on gastrointestinal cancers. In addition, we discuss the caveats and alternative strategies for therapeutically targeting Wnt signaling for cancer treatment.

Seven immune-related genes prognostic power and correlation with tumor-infiltrating immune cells in hepatocellular carcinoma

Background

Given poor prognosis and the lack of efficient therapy for advanced hepatocellular carcinoma, immunotherapy has emerged as an increasingly important role. However, there were few reports on the correlation between immune‐related genes and HCC. The purpose of this study is to construct a novel immune‐related gene‐based prognostic signature for HCC and to explore the potential mechanisms.

Methods

We organized expression data of 374 HCC samples and 50 nontumor samples from TCGA database. A robust signature was constructed by Cox regression analysis based on the immune‐related genes, which were filtered by differential genes analysis and Cox regression analysis. Then, the correlation analysis between the signature and clinical characteristics was conducted. And the signature was validated in ICGC database. Furthermore, the relationships between immune cell infiltration and the signature were explored by bioinformatics analysis.

Results

Seven genes‐based model (Risk score = BIRC5 * 0.0238 + FOS * 0.0055 + DKK1 * 0.0085 + FGF13 * 0.3432 + IL11 * 0.0135 + IL17D * 0.0878 + SPP1 * 0.0003) was constructed eventually and it was proved to be an independent prognostic factor for HCC patients. The signature‐calculated risk scores were shown to be positively correlated with the infiltration of these five immune cells, including macrophages, neutrophils, CD8+T, dendritic, and B cells. And the results suggested that high amplication of BIRC5, FGF13, IL11, IL17D, and SPP1 were more likely correlated with immune cell infiltration. Finally, PPI network, TFs‐based regulatory network and gene enrichment plots were performed to show potential molecular mechanisms.

Conclusion

We construct a robust immune‐related gene‐based prognostic signature with seven genes and explore potential mechanisms about it, which may contribute to the immunotherapy research for HCC.

Wnt signaling modulator DKK1 as an immunotherapeutic target in ovarian cancer

OBJECTIVES

Wnt pathway mutations are a hallmark of endometrioid and clear cell subtypes of epithelial ovarian carcinoma (EOC). However, no drugs targeting the Wnt pathway in EOC are FDA-approved. Dickkopf-related protein 1 (DKK1), a modulator of the Wnt pathway, has emerged as a promising therapeutic target. We aimed to examine the role of DKK1 and the effects of a monoclonal antibody against DKK1 (DKN-01) in vivo and in a murine model of ovarian cancer.

METHODS

We examined in vitro the role of DKK1 and the effects of DKK1 inhibition in EOC cell lines. We then studied in vivo the role of DKN-01 and DKK1 overexpression on tumor burden and anti-tumor immune cell populations using the ID8 syngeneic mouse model.

RESULTS

DKN-01 did not phenotypically alter ES2 cells in vitro; however, DKK1 inhibition promoted Wnt signaling. Tumor burden and immune populations were unchanged in ID8 challenged mice treated with mDKN01. Mice challenged with ID8 cells overexpressing DKK1 had tumor burden similar to controls (p = 0.175). However, the overexpression of DKK1 decreased CD45⁺ leukocyte infiltration into the peritoneum (p = 0.008) and omentum (p = 0.032), reducing both natural killer (NK) and CD8 T cells, and reducing interferon-gamma (IFNγ) expression on activated CD8 T cells.

CONCLUSIONS

Our results suggest that DKK1 inhibition does not affect tumor growth in the ID8 ovarian cancer model. DKK1 overexpression alters anti-tumor immune populations within the tumor microenvironment. Thus, our findings confirm DKK1 as a new therapeutic target in EOC and suggest that DKK1 inhibition may function best in a combinatorial, immune-modulatory therapy.

Prognostic role of dickkopf-1 in patients with cancer

As an antagonist for the WNT signal passway, dickkopf-1(DKK1) have a great important role in the occurence and development of various type cancer. The present paper performed a meta-analysis to evaluate the predictive significance of DKK1 in cancer.To assess the relationship between the expression of DKK1 and prognostic role in human cancers, a total of 16 articals were screened from the multiple online databases (Pubmed, EMBASE, CNKI, Web of Science and Google Scholar) in our study. By using the STATA soft,pooled hazard ratio and 95% confidence intervals of overall survival (OS), progression-free survival, disease-free survival and time to recurrence were used to evaluate the strength of this relationship.The meta-analysis showed that higher expression of DKK1 was significantly associated with shorter OS in cancer patients. In stratified analyzes, the higher expression of DKK1 could reduced the OS in patients with breast cancer,digestive system cancer and urogenital system cancer, but not patients with the lung cancer. It also showed that higher expression of DKK1 was significantly associated with shorter progression-free survival, disease-free survival and time to recurrence in cancer patients.The present study indicate that higher expression of DKK1 predict an unfavorable clinical outcome in patients with breast cancer, digestive system cancer and urogenital system cancer.

Upregulation of miR-211 Promotes Chondrosarcoma Development via Targeting Tumor Suppressor VHL

Introduction

miR-211 has been demonstrated to be aberrantly expressed and plays a pivotal role in human cancers. However, its expression profiles and potential roles in chondrosarcoma development remain still elusive. This study aims to determine the clinical values and underlying roles of miR-211 in chondrosarcoma.

Methods

miR-211 expression was analyzed by qRT-PCR in chondrosarcoma specimens and the matched adjacent non-tumor tissues. The relationships among miR-211 expression, clinicopathological factors and overall survival were also evaluated. Cell viability, colony formation, migration and invasion were further investigated in chondrosarcoma cells. Potential target of miR-211 was predicted using bioinformatics to delineate the molecular mechanisms.

Results

miR-211 was remarkably increased in chondrosarcoma compared with the matched adjacent non-tumor tissues. High miR-211 level was identified as 66.7% in chondrosarcoma specimens, which were significantly associated with histological grade and MSTS stage. miR-211 had significant influences on the prognosis of chondrosarcoma patients. Multivariate analysis demonstrated that miR-211 was an independent prognostic factor for overall survival of chondrosarcoma patients. We also found that overexpression or inhibitor of miR-211 promotes or suppresses chondrosarcoma cell proliferation, migration and invasion, respectively. Mechanistically, miR-211 binds to the 3ʹ-UTR of Von Hippel-Lindau (VHL) and suppresses its expression, while restoration of VHL suppressed the potentiated function of miR-211 on proliferation and invasion of chondrosarcoma cells.

Conclusion

miR-211 is identified as a potent oncogenic function in chondrosarcoma development, which can serve as a novel biomarker to predict the survival of chondrosarcoma patients. miR-211 potentiates chondrosarcoma growth via targeting VHL, highlighting a novel attractive target for chondrosarcoma treatment.

PRMT1 potentiates chondrosarcoma development through activation of YAP activity

Protein arginine methyltransferase 1 (PRMT1) is identified as an oncogene implicated in various types of human cancers, while Yes-associated protein (YAP) as a key transcriptional coactivator of the Hippo signaling plays a vital role in tissue homeostasis and tumorigenesis. To date, the underlying biological functions, prognostic values, and potential mechanisms of PRMT1 and YAP in chondrosarcoma development have not been clearly elucidated. Here, we show that upregulation of PRMT1 and YAP is significantly detected in human chondrosarcoma specimens. Elevated levels of PRMT1 positively correlated with YAP nuclear accumulation are significantly associated with high-grade chondrosarcoma and poor prognosis. Moreover, YAP is recognized as an independent prognostic factor for chondrosarcoma patients. Ectopic expression of PRMT1 potentiates, but depletion of PRMT1 attenuates, chondrosarcoma cell growth in vitro and in vivo. Mechanistically, we have discovered that PRMT1 functions upstream of LATS1 and suppresses LATS1-mediated phosphorylation of YAP (Ser127), and thus promotes chondrosarcoma cell survival in a YAP-dependent manner. Collectively, our study identifies PRMT1 as a positive regulator of YAP activity in chondrosarcoma, highlighting a novel therapeutic target against chondrosarcoma and other YAP-driven cancers.

Altered DNA methylation is associated with aberrant stemness gene expression in early‑stage HNSCC

Head and neck squamous cell carcinoma (HNSCC) is characterized by morphological and functional cellular heterogeneity, which are properties of progenitor cells, as opposed to cell alterations caused by accidental expression of stem cell‑related molecules. The expression levels of stemness molecules and their distribution in HNSCC are unclear. As regards sporadic cellular heterogeneity, methylation is an important factor for transcriptional regulation in tumors. Integrative screening analysis of mRNA expression and altered methylation status was performed with original microarrays in 12 tumor and non‑tumor pairs of oral squamous cell carcinoma (SCC) cases. From this data set, genes regulated via aberrant DNA methylation and classified proteins were validated by function clustering. Olfactomedin 4 (OLFM4), known as an intestinal stemness molecule and cell‑cell adhesion factor, was found to be highly expressed in tumors, with an mRNA expression ratio [tumor/normal (T/N)] of 40.7686 and low methylation (‑18.02%) in the promoter region. In addition, the OLFM4 expression levels increased following treatment with the demethylating agent 5‑azacytidine in two HNSCC cell lines. Furthermore, the expression levels of OLFM4 in 59 cases of early‑stage tongue SCC were analyzed using immunohistochemistry to examine protein expression corresponding to the histopathological definition of tumors and to evaluate prognosis. The aberrant stemness gene expression caused by altered DNA methylation appeared to regulate early‑stage HNSCC characteristics. The results of the present study indicated a correlation between OLFM4 expression and promoter methylation, and suggest that it plays an important role in tumor cell heterogeneity in HNSCC.

Elevated DKK1 expression is an independent unfavorable prognostic indicator of survival in head and neck squamous cell carcinoma

PURPOSE

DKK1 is an antagonist of the Wnt signaling pathway that has various roles in human physiology. Notably, aberrant DKK1 expression is observed in several cancers. In this retrospective study, we assessed the association between DKK1 expression levels and head and neck squamous cell carcinoma (HNSCC) and its prognostic value.

MATERIALS AND METHODS

Using RNA-seq data from HNSCC tumors (N=520) and adjacent normal tissue (N=44) in The Cancer Genome Atlas, we evaluated DKK1 expression levels. Additionally, we evaluated the association of DKK1 expression levels and pathophysiological features of patients with HNSCC and the value of DKK1 expression for prediction of overall survival (OS). We also explored the correlation between DKK1 expression and methylation of its promoter in HNSCC.

RESULTS

DKK1 expression was significantly upregulated in HNSCC compared with normal tissues. Moreover, DKK1 expression was significantly associated with smoking, alcohol abuse, sex, human papillomavirus status, tumor site, tumor invasion, and pathologic stage in HNSCC patients. Kaplan-Meier curves showed that high DKK1 expression was correlated with inferior OS. In addition, univariate and multivariate analyses showed that elevated DKK1 expression was an independent prognostic factor for poor OS (HR: 1.85, 95% CI: 1.31-2.62, P<0.001). Regression analysis identified a strong negative correlation between DKK1 expression and methylation of its promoter.

CONCLUSION

These findings support the hypothesis that elevated DKK1 expression is modulated via methylation of its promoter and indicate that DKK1 expression is a highly informative prognostic biomarker for patients with HNSCC.

Adenoviral delivery of VHL suppresses bone sarcoma cell growth through inhibition of Wnt/β-catenin signaling

The VHL tumor suppressor gene is frequently inactivated in several human tumors, including bone sarcomas. We previously identified that reduced expression of VHL protein is implicated in sarcomagenesis. However, the underlying biological functions of restored VHL protein expression have not been clearly elucidated in bone sarcomas. Here we initially constructed a recombinant adenovirus 5-VHL vector (Ad5-VHL) and evaluated its expression in bone sarcomas, and antitumor activity in vitro and in vivo. We found that the adenovirus-mediated increase of VHL significantly suppresses bone sarcoma cell growth, attributed to induction of apoptosis mediated by increased caspase-3 activity and modulated Bcl-2 protein family. This suppression effect involves inhibition of Wnt/β-catenin signaling and upregulation of GSK-3β. Moreover, Ad5-VHL showed a dramatic antitumor effect on a chondrosarcoma xenograft model. These findings establish that Ad5-VHL suppresses bone sarcoma cell growth by inhibiting Wnt/β-catenin signaling, and may be a novel target for gene-based therapy of bone sarcomas.

BAG3 promotes chondrosarcoma progression by upregulating the expression of β-catenin

To investigate the roles of B-cell lymphoma-2 associated athanogene 3 (BAG3) in human chondrosarcoma and the potential mechanisms, the expression levels of BAG3 were detected in the present study, and the associations between BAG3 and clinical pathological parameters, clinical stage as well as the survival of patients were analyzed. The present study detected BAG3 mRNA and protein expression in the normal cartilage cell line HC-a and in SW1353 chondrosarcoma cells by reverse transcription-quantitative polymerase chain reaction and western blot analysis. The BAG3 protein expression in 59 cases of chondrosarcoma, 30 patients with endogenous chondroma and 8 cases of normal cartilage was semi-quantitatively analyzed using the immunohistochemical method. In addition, the BAG3 protein expression level, the clinical pathological parameters, clinical stage and the survival time of patients with chondrosarcoma were analyzed. The plasmid transfection method was employed to upregulate the expression BAG3 and small RNA interference to downregulate the expression of BAG3 in SW1353 cells. The expression levels of BAG3 protein and mRNA were significantly increased in the chondrosarcoma cell line when compared with the normal cartilage cell line. The immunohistochemistry results indicated that BAG3 protein was overexpressed in the tissue of human chondrosarcoma. Statistical analysis showed that the expression level of BAG3 was significantly increased in the different Enneking staging of patients with chondrosarcoma and Tumor staging, and there were no statistical differences in age, gender, histological classification and tumor size. In the in vitro experiments, the data revealed that BAG3 significantly promoted chondrosarcoma cell proliferation, colony-formation, migration and invasion; however, it inhibited chondrosarcoma cell apoptosis. It was observed that BAG3 upregulated β-catenin expression at the mRNA and protein levels. In addition, BAG3 induced the expression of runt-related transcription factor 2 (RUNX2) in chondrosarcoma cells by upregulating β-catenin. These clinical analyses revealed a positive association between β-catenin and BAG3 in chondrosarcoma tumors. BAG3 was significantly increased in chondrosarcoma cells and tissues compared with the normal cartilage cells, tissue and cartilage benign tumors. Thus, BAG3 may serve as an oncogene in the development of chondrosarcoma via the induction of RUNX2 expression. The results of the present study contribute to further research on the biological development of chondrosarcoma.

A monoclonal antibody against the Wnt signaling inhibitor dickkopf-1 inhibits osteosarcoma metastasis in a preclinical model

The outcome of patients with metastatic osteosarcoma has not improved since the introduction of chemotherapy in the 1970s. Development of therapies targeting the metastatic cascade is a tremendous unmet medical need. The Wnt signaling pathway has been the focus of intense investigation in osteosarcoma because of its role in normal bone development. Although the role of Wnt signaling in the pathogenesis of osteosarcoma is controversial, there are several reports of dickkopf-1 (DKK-1), a Wnt signaling antagonist, possibly playing a pro-tumorigenic role. In this work we investigated the effect of anti-DKK-1 antibodies on the growth and metastasis of patient-derived osteosarcoma xenografts. We were able to detect human DKK-1 in the blood of tumor-bearing mice and found a correlation between DKK-1 level and tumor proliferation. Treatment with the anti-DKK-1 antibody, BHQ880, slowed the growth of orthotopically implanted patient-derived osteosarcoma xenografts and inhibited metastasis. This effect was correlated with increased nuclear beta-catenin staining and increased expression of the bone differentiation marker osteopontin. These findings suggest that Wnt signaling is anti-tumorigenic in osteosarcoma, and support the targeting of DKK-1 as an anti-metastatic strategy for patients with osteosarcoma.

Chondrosarcoma: A Rare Misfortune in Aging Human Cartilage? The Role of Stem and Progenitor Cells in Proliferation, Malignant Degeneration and Therapeutic Resistance

Unlike other malignant bone tumors including osteosarcomas and Ewing sarcomas with a peak incidence in adolescents and young adults, conventional and dedifferentiated chondrosarcomas mainly affect people in the 4th to 7th decade of life. To date, the cell type of chondrosarcoma origin is not clearly defined. However, it seems that mesenchymal stem and progenitor cells (MSPC) in the bone marrow facing a pro-proliferative as well as predominantly chondrogenic differentiation milieu, as is implicated in early stage osteoarthritis (OA) at that age, are the source of chondrosarcoma genesis. But how can MSPC become malignant? Indeed, only one person in 1,000,000 will develop a chondrosarcoma, whereas the incidence of OA is a thousandfold higher. This means a rare coincidence of factors allowing escape from senescence and apoptosis together with induction of angiogenesis and migration is needed to generate a chondrosarcoma. At early stages, chondrosarcomas are still assumed to be an intermediate type of tumor which rarely metastasizes. Unfortunately, advanced stages show a pronounced resistance both against chemo- and radiation-therapy and frequently metastasize. In this review, we elucidate signaling pathways involved in the genesis and therapeutic resistance of chondrosarcomas with a focus on MSPC compared to signaling in articular cartilage (AC).

Rationale for targeting the Wnt signalling modulator Dickkopf-1 for oncology

Wnt signalling is a fundamental pathway involved in embryonic development and adult tissue homeostasis. Mutations in the pathway frequently lead to developmental defects and cancer. As such, therapeutic intervention of this pathway has generated tremendous interest. Dickkopf-1 (DKK1) is a secreted inhibitor of β-catenin-dependent Wnt signalling and was originally characterized as a tumour suppressor based on the prevailing view that Wnt signalling promotes cancer pathogenesis. However, DKK1 appears to increase tumour growth and metastasis in preclinical models and its elevated expression correlates with a poor prognosis in a range of cancers, indicating that DKK1 has more complex cellular and biological functions than originally appreciated. Here, we review current evidence for the cancer-promoting activity of DKK1 and recent insights into the effects of DKK1 on signalling pathways in both cancer and immune cells. We discuss the rationale and promise of targeting DKK1 for oncology.

LINKED ARTICLES

This article is part of a themed section on WNT Signalling: Mechanisms and Therapeutic Opportunities. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.24/issuetoc.

Transcriptomic analyses reveal the underlying pro-malignant functions of PTHR1 for osteosarcoma via activation of Wnt and angiogenesis pathways

BACKGROUND

Increasing evidence has indicated parathyroid hormone type 1 receptor (PTHR1) plays important roles for the development and progression of osteosarcoma (OS). However, its function mechanisms remain unclear. The goal of this study was to further illuminate the roles of PTHR1 in OS using microarray data.

METHODS

Microarray data were available from the Gene Expression Omnibus database under the accession number GSE46861, including six tumors from mice with PTHR1 knockdown (PTHR1.358) and six tumors from mice with control knockdown (Ren.1309). Differentially expressed genes (DEGs) between PTHR1.358 and Ren.1309 were identified using the LIMMA method, and then, protein-protein interaction (PPI) network was constructed using data from STRING database to screen crucial genes associated with PTHR1. KEGG pathway enrichment analysis was performed to investigate the underlying functions of DEGs using DAVID tool.

RESULTS

A total of 1163 genes were identified as DEGs, including 617 downregulated (Lef1, lymphoid enhancer-binding factor 1) and 546 upregulated genes (Dkk1, Dickkopf-related protein 1). KEGG enrichment analysis indicated upregulated DEGs were involved in Renin-angiotensin system (e.g., Agt, angiotensinogen) and Wnt signaling pathway (e.g., Dkk1), while downregulated DEGs participated in Basal cell carcinoma (e.g., Lef1). A PPI network (534 nodes and 2830 edges) was constructed, in which Agt gene was demonstrated to be the hub gene and its interactive genes (e.g., CCR3, CC chemokine receptor 3; and CCL9, chemokine CC chemokine ligand 9) were inflammation related.

CONCLUSIONS

Our present study preliminarily reveals the pro-malignant effects of PTHR1 in OS cells may be mediated by activating Wnt, angiogenesis, and inflammation pathways via changing the expressions of the crucial enriched genes (Dkk1, Lef1, Agt-CCR3, and Agt-CCL9).

The role of Dickkopf family in cancers: from Bench to Bedside

Numerous epidemiological studies indicate that cancer will be responsible for millions of deaths in one year. Although multiple therapeutic strategies exist, and vast research efforts are being focused on developing newer and better regimens, cancer-related morbidity and mortality remain high. Metastasis and recurrence are prominent causes of treatment failure in cancers. Moreover, early diagnosis and treatment initiation are difficult to achieve in clinical practice. Fortunately, targeted therapy, which exerts its function at the molecular level, has proved to be greatly beneficial in several human diseases including cancers. The Wnt signaling pathway is a crucial regulator of embryogenesis and development in humans, and its dysfunction has been implicated in the incidence and development of cancers and other diseases. The Dickkopf family (Dkks) is a widely studied Wnt signaling pathway antagonist and plays multiple roles in human physiological and pathological process through both Wnt pathway-dependent and -independent manners. However, the precise roles of Dkks in tumorigenesis and the causal mechanisms have not been clearly elucidated. We discuss the pleiotropic roles of Dkks, with a specific focus on the underlying mechanisms, in cancer biology. We review recent literature to explore the potential use of Dkks as a tumor diagnosis biomarker and therapeutic target.

Wnt inhibitory factor 1 (WIF1) methylation and its association with clinical prognosis in patients with chondrosarcoma

Chondrosarcoma (CS) is a rare cancer, but it is the second most common primary malignant bone tumor and highly resistant to conventional chemotherapy and radiotherapy. Aberrant DNA methylation in the promoter CpG island of Wnt inhibitory factor 1 (WIF1) has been observed in different cancers. However, no studies have shown the relationship between WIF1 methylation and CS. In this study, we found promoter methylated WIF1 in both CS cell lines (CS-1 and SW1353) and tumor tissues. Western blot analysis confirmed loss WIF1 expression and activation of Wnt pathway proteins (Wnt5a/b, LRP6, and Dvl2). We subsequently examined the correlation between levels of WIF1 methylation and overall survival (OS) and progression-free survival (PFS) in CS patient samples with a follow-up spanning 234 months (mean: 57.6 months). Kaplan-Meier survival curves and log-rank tests revealed that high levels of WIF1 methylation were associated with lower OS and PFS rates (p < 0.05). Multivariate Cox hazard analysis suggested that detection of high level methylation of WIF1 could be an independent prognostic factor in OS and PFS. In conclusion, we found that WIF1 is epigenetically silenced via promoter DNA methylation in CS and propose that WIF1 methylation may serve as a potential prognostic marker for patients with CS.

Sclerostin expression in skeletal sarcomas

Sclerostin (SOST) is an extracellular Wnt signaling antagonist which negatively regulates bone mass. Despite this, the expression and function of SOST in skeletal tumors remain poorly described. Here, we first describe the immunohistochemical staining pattern of SOST across benign and malignant skeletal tumors with bone or cartilage matrix (n=68 primary tumors). Next, relative SOST expression was compared to markers of Wnt signaling activity and osteogenic differentiation across human osteosarcoma (OS) cell lines (n=7 cell lines examined). Results showed immunohistochemical detection of SOST in most bone-forming tumors (90.2%; 46/51) and all cartilage-forming tumors (100%; 17/17). Among OSs, variable intensity and distribution of SOST expression were observed, which highly correlated with the presence and degree of neoplastic bone. Patchy SOST expression was observed in cartilage-forming tumors, which did not distinguish between benign and malignant tumors or correlate with regional morphologic characteristics. Finally, SOST expression varied widely between OS cell lines, with more than 97-fold variation. Among OS cell lines, SOST expression positively correlated with the marker of osteogenic differentiation alkaline phosphatase and did not correlate well with markers of Wnt/β-catenin signaling activity. In summary, SOST is frequently expressed in skeletal bone- and cartilage-forming tumors. The strong spatial correlation with bone formation and the in vitro expression patterns are in line with the known functions of SOST in nonneoplastic bone, as a feedback inhibitor on osteogenic differentiation. With anti-SOST as a potential therapy for osteoporosis in the near future, its basic biologic and phenotypic consequences in skeletal tumors should not be overlooked.

Genetic variations of DICKKOPF family genes might not be associated with gastric cancer susceptibility

BACKGROUND

Recent studies have implicated that members of the DICKKOPF (DKK) were causally involved in large number of human cancers. This study was designed to investigate the relationship between the genetic variations of DKK family genes and the risk of gastric cancer (GC).

METHODS

Six SNPs (single nucleotide polymorphisms) of DKK family genes, including rs2241529 in DKK1, rs3733635, rs17037102 and rs419764 in DKK2, rs3206824 in DKK3 and rs2073664 in DKK4, were selected and genotyped by restriction fragment length polymorphism (RFLP) and TaqMan SNP genotyping methods in 409 GC cases and 554 cancer-free controls in the Han population in eastern China.

RESULTS

None of the six SNPs achieved significant association with the overall GC risk and stratified analysis by age, gender, smoking status, drinking status, tumor location and pathological classification confirmed these non-significant associations.

CONCLUSIONS

Our study indicated that the studied six SNPs of DKKs would not be the risk factors for GC in this Han Chinese population. Studies of larger population for different ethnicities will be needed to warrant our findings.

Diagnostic investigations of DKK-1 and PDCD5 expression levels as independent prognostic markers of human chondrosarcoma

In this study, we investigated the expression levels of Dickkopf-1 (DKK-1) and programmed cell death 5 (PDCD5) by using quantitative real-time PCR and immunohistochemistry in patients with chondrosarcoma. The DKK-1 mRNA levels were significantly higher in chondrosarcoma when compared with the corresponding nontumor tissues (mean ± SD: 4.23 ± 1.54; 1.54 ± 0.87; P = 0.001). PDCD5 mRNA levels were remarkably deceased in tumor tissues when compared with corresponding nontumor tissues (mean ± SD: 1.94 ± 0.73; 5.42 ± 1.73; P = 0.001). The high and moderate DKK-1 expressions were observed for 60% of chondrosarcoma samples in comparison with 27.5% of corresponding nontumor tissues (P  =  0.001). Moreover, low expression of PDCD5 was found in 67.5% of the tumor tissues when compared with the nontumor tissues (32.5%; P = 0.002). The results of this study showed that high DKK-1 expression levels were strongly related to MSTS stage (P = 0.011) and the advancement of histological grade (P < 0.001). Furthermore, the PDCD5 expression levels were correlated with histological grade (P < 0.001), MSTS stage (P = 0.016), and distant metastasis (P = 0.001). Kaplan-Meier survival and log-rank survival showed that patients with high DKK-1 levels and low PDCD5 levels were correlated with shorter overall survival (log-rank test P < 0.001). PDCD5 levels, histological grade, and tumor stage were independent predictors of overall survival. In conclusion, DKK-1 and PDCD5 can be independent predictors of overall survival in patients suffering from chondrosarcoma. © 2016 IUBMB Life, 68(7):597-601, 2016.

Aberrant activation of Wnt/β-catenin signaling drives proliferation of bone sarcoma cells

Bone sarcomas such as osteosarcoma and chondrosarcoma are frequently refractory to conventional chemotherapy and radiotherapy that exhibit poor prognosis. The Wnt signaling are evolutionarily conserved and implicated in cell proliferation and sarcomagenesis. However, the potential role of the Wnt signaling in bone sarcomas is still unclear. Here we demonstrate aberrant activation of Wnt/β-catenin signaling in bone sarcoma cells, involving an autocrine Wnt signaling loop with upregulation of specific Wnt ligands and receptors. Activation of Wnt/β-catenin signaling with Wnt3a or GSK-3β inhibitor drives the proliferation of bone sarcoma cells, whereas downregulation of activated Wnt signaling with dnTCF4 or siLEF1 suppresses bone sarcoma proliferation and induces cell cycle arrest. Taken together, our findings establish the evidence that aberrant activation of Wnt/β-catenin pathway involving an autocrine Wnt singaling drives the proliferation of bone sarcoma cells, and identify the autocrine activation of the Wnt/β-catenin signaling as a potential novel therapeutic target for bone sarcomas.

Nuclear DICKKOPF-1 as a biomarker of chemoresistance and poor clinical outcome in colorectal cancer

Sporadic colorectal cancer (CRC) insurgence and progression depend on the activation of Wnt/β-catenin signaling. Dickkopf (DKK)-1 is an extracellular inhibitor of Wnt/β-catenin signaling that also has undefined β-catenin-independent actions. Here we report for the first time that a proportion of DKK-1 locates within the nucleus of healthy small intestine and colon mucosa, and of CRC cells at specific chromatin sites of active transcription. Moreover, we show that DKK-1 regulates several cancer-related genes including the cancer stem cell marker aldehyde dehydrogenase 1A1 (ALDH1A1) and Ral-binding protein 1-associated Eps domain-containing 2 (REPS2), which are involved in detoxification of chemotherapeutic agents. Nuclear DKK-1 expression is lost along CRC progression; however, it remains high in a subset (15%) of CRC patients (n = 699) and associates with decreased progression-free survival (PFS) after chemotherapy administration and overall survival (OS) [adjusted HR, 1.65; 95% confidence interval (CI), 1.23-2.21; P = 0.002)]. Overexpression of ALDH1A1 and REPS2 associates with nuclear DKK-1 expression in tumors and correlates with decreased OS (P = 0.001 and 0.014) and PFS. In summary, our findings demonstrate a novel location of DKK-1 within the cell nucleus and support a role of nuclear DKK-1 as a predictive biomarker of chemoresistance in colorectal cancer.