Dikkopf-1 as a novel serologic and prognostic biomarker for lung and esophageal carcinomas

The Role of Serum Dickkopf1 and CKAP4 Levels in Diagnosing Colorectal Cancer and Measuring the Disease Severity: A Prospective Study

Background and Objective: Colorectal cancer (CRC) is among the most common types of cancer. Although the disease is treatable in its early stages, five-year survival falls below 20% in the later stages. CEA and CA19-9 are tumor markers used in the diagnosis and follow-up of the disease in clinical practice; however, their diagnostic effectiveness is insufficient. Therefore, the identification of biomarkers that can be easily studied from serum and can diagnose CRC and determine its severity is highly important. In this context, dickkopf1 (DKK1) and cytoskeleton-associated protein 4 (CKAP4) are both promising biomarkers. Materials and Methods: Serum DKK1 and CKAP4 levels were measured in 55 patients with CRC and 40 healthy controls. The patients with CRC were divided into groups based on pathological stages and histological differentiation. The serum levels of both proteins in patients with CRC were measured preoperatively and 10 and 30 days postoperatively. Results: Serum DKK1 and CKAP4 were significantly higher in the CRC group than in the healthy controls (p < 0.05). Serum levels of both proteins rose in line with the disease stage and grade but decreased following surgical resection. A positive correlation was observed between tumor diameter and protein blood levels. The diagnostic efficacy of DKK1 and CKAP4 in CRC (approximately 95%) was higher than that of markers such as CEA and CA19-9. Conclusions: The DKK1 and CKAP4 serum values of patients with CRC are promising biomarkers. They can potentially be used in CRC management, namely, in the diagnosis and treatment of tumor response access and in tumor aggressiveness prediction.

Development of therapeutic monoclonal antibodies against DKK1 peptide-HLA-A2 complex to treat human cancers

BACKGROUND

Targeted immunotherapy with monoclonal antibodies (mAbs) is an effective and safe method for the treatment of malignancies. Development of mAbs with improved cytotoxicity, targeting new and known tumor-associated antigens, therefore continues to be an active research area. We reported that Dickkopf-1 (DKK1) is a good target for immunotherapy of human cancers based on its wide expression in different cancers but not in normal tissues. As DKK1 is a secreted protein, mAbs binding directly to DKK1 have limited effects on cancer cells in vivo.

METHODS

The specificity and antibody-binding capacity of DKK1-A2 mAbs were determined using indirect ELISA, confocal imaging, QIFIKIT antibody-binding capacity and cell surface binding assays. The affinity of mAbs was determined using a surface plasmon resonance biosensor. A flow cytometry-based cell death was performed to detect tumor cell apoptosis. Antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) assays were used to evaluate the ability of DKK1-A2 mAbs to mediate ADCC and CDC activities against tumor cells in vitro. Flow cytometry data were collected with an FACSymphony A3 cell analyzer and analyzed with FlowJo V.10.1 software. Human cancer xenograft mouse models were used to determine the in vivo therapeutic efficacy and the potential safety and toxicity of DKK1-A2 mAbs. In situ TUNEL assay was performed to detect apoptosis in tumors and mouse organs.

RESULTS

We generated novel DKK1-A2 mAbs that recognize the DKK1 P20 peptide presented by human HLA-A*0201 (HLA-A2) molecules (DKK1-A2 complexes) that are naturally expressed by HLA-A2+DKK1+ cancer cells. These mAbs directly induced apoptosis in HLA-A2+DKK1+ hematologic and solid cancer cells by activating the caspase-9 cascade, effectively lysed the cancer cells in vitro by mediating CDC and ADCC and were therapeutic against established cancers in their xenograft mouse models. As DKK1 is not detected in most human tissues, DKK1-A2 mAbs neither bound to or killed HLA-A2+ blood cells in vitro nor caused tissue damage in tumor-free or tumor-bearing HLA-A2-transgenic mice.

CONCLUSION

Our study suggests that DKK1-A2 mAbs may be a promising therapeutic agent to treat human cancers.

Effects of Dickkopf-1 (DKK-1) on Prostate Cancer Growth and Bone Metastasis

Osteoblastic bone metastases are commonly detected in patients with advanced prostate cancer (PCa) and are associated with an increased mortality rate. Dickkopf-1 (DKK-1) antagonizes canonical WNT/β-catenin signaling and plays a complex role in bone metastases. We explored the function of cancer cell-specific DKK-1 in PCa growth, metastasis, and cancer-bone interactions using the osteoblastic canine PCa cell line, Probasco. Probasco or Probasco + DKK-1 (cells transduced with human DKK-1) were injected into the tibia or left cardiac ventricle of athymic nude mice. Bone metastases were detected by bioluminescent imaging in vivo and evaluated by micro-computed tomography and histopathology. Cancer cell proliferation, migration, gene/protein expression, and their impact on primary murine osteoblasts and osteoclasts, were evaluated in vitro. DKK-1 increased cancer growth and stimulated cell migration independent of canonical WNT signaling. Enhanced cancer progression by DKK-1 was associated with increased cell proliferation, up-regulation of NF-kB/p65 signaling, inhibition of caspase-dependent apoptosis by down-regulation of non-canonical WNT/JNK signaling, and increased expression of epithelial-to-mesenchymal transition genes. In addition, DKK-1 attenuated the osteoblastic activity of Probasco cells, and bone metastases had decreased cancer-induced intramedullary woven bone formation. Decreased bone formation might be due to the inhibition of osteoblast differentiation and stimulation of osteoclast activity through a decrease in the OPG/RANKL ratio in the bone microenvironment. The present study indicated that the cancer-promoting role of DKK-1 in PCa bone metastases was associated with increased growth of bone metastases, reduced bone induction, and altered signaling through the canonical WNT-independent pathway. DKK-1 could be a promising therapeutic target for PCa.

Dickkopf-1 and ROCK2 upregulation and associated protein aggregation in pseudoexfoliation syndrome and glaucoma

AIMS

The etiology of pseudoexfoliation (PEX), a stress-induced fibrillopathy and a leading cause of secondary glaucoma worldwide, remains limited. This study aims to understand the role of the Wnt antagonist Dickkopf-related protein 1 (DKK1) in PEX pathophysiology and assess its candidature as a biomarker for PEX.

MAIN METHODS

Expression levels of DKK1 and Wnt signaling genes were assayed in the anterior ocular tissues of study subjects by qRT-PCR, Western blotting, and immunohistochemistry. Protein aggregation was studied through Proteostat staining. Role of DKK1 in protein aggregation and regulation of target Wnt signaling genes was elucidated through overexpression and knockdown studies in Human Lens Epithelial cells (HLEB3). Levels of DKK1 in circulating fluids were assayed through ELISA.

KEY FINDINGS

DKK1 upregulation was observed in lens capsule and conjunctiva tissues of PEX individuals compared to controls correlating with an upregulation of the Wnt signaling target, ROCK2. Proteostat staining showed increased protein aggregates in lens epithelial cells of PEX patients. HLE B-3 cells overexpressed with DKK1 showed increased protein aggregates along with upregulation of ROCK2, and knockdown of DKK1 in HLE B-3 cells demonstrated downregulation of ROCK2. Further, ROCK2 inhibition by Y-27632 in DKK1 overexpressed cells showed that DKK1 regulated protein aggregation via ROCK2. Also, increased levels of DKK1 were observed in patients' plasma and aqueous humor compared to controls.

SIGNIFICANCE

This study shows that DKK1 and ROCK2 might play a role in protein aggregation in PEX. Further, elevated levels of DKK1 in aqueous humor serve as a fair classifier of pseudoexfoliation glaucoma.

Guidelines on lung adenocarcinoma prognosis based on immuno-glycolysis-related genes

OBJECTIVES

This study developed a new model for risk assessment of immuno-glycolysis-related genes for lung adenocarcinoma (LUAD) patients to predict prognosis and immunotherapy efficacy.

METHODS

LUAD samples and data obtained from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases are used as training and test columns, respectively. Twenty-two (22) immuno-glycolysis-related genes were screened, the patients diagnosed with LUAD were divided into two molecular subtypes by consensus clustering of these genes. The initial prognosis model was developed using the multiple regression analysis method and Receiver Operating characteristic (ROC) analysis was used to verify its predictive potential. Gene set enrichment analysis (GSEA) showed the immune activities and pathways in different risk populations, we calculated immune checkpoints, immune escape, immune phenomena (IPS), and tumor mutation burden (TMB) based on TCGA datasets. Finally, the relationship between the model and drug sensitivity was analyzed.

RESULTS

Fifteen (15) key differentially expressed genes (DEGs) with prognostic value were screened and a new prognostic model was constructed. Four hundred and forty-three (443) samples were grouped into two different risk cohorts based on median model risk values. It was observed that survival rates in high-risk groups were significantly low. ROC curves were used to evaluate the model's accuracy in determining the survival time and clinical outcome of LUAD patients. Cox analysis of various clinical factors proved that the risk score has great potential as an independent prognostic factor. The results of immunological analysis can reveal the immune infiltration and the activity of related functions in different pathways in the two risk groups, and immunotherapy was more effective in low-risk patients. Most chemotherapeutic agents are more sensitive to low-risk patients, making them more likely to benefit.

CONCLUSION

A novel prognostic model for LUAD patients was established based on IGRG, which could more accurately predict the prognosis and an effective immunotherapy approach for patients.

Dickkopf-1 drives tumor immune evasion by inducing PD-L1 expression in hepatocellular carcinoma

Understanding the mechanisms regulating PD-L1 expression in hepatocellular carcinoma (HCC) is important to improve the response rate to PD-1/PD-L1 blockade therapy. Here, we show that DKK1 expression is positively associated with PD-L1 expression and inversely correlated with CD8⁺ T cell infiltration in human HCC tumor specimens. In a subcutaneous xenograft tumor model, overexpression of DKK1 significantly promotes tumor growth, tumoral PD-L1 expression, but reduces tumoral CD8⁺ T cell infiltration; whereas knockdown of DKK1 has opposite effects. Moreover, enforced expression of DKK1 dramatically promotes PD-L1 expression, Akt activation, β-catenin phosphorylation and total protein expression in HCC cells. By contrast, knockdown of DKK1 inhibits all, relative to controls. In addition, CKAP4 depletion, Akt inhibition, or β-catenin depletion remarkably abrogates DKK1 overexpression-induced transcriptional expression of PD-L1 in HCC cells. Reconstituted expression of the active Akt1 largely increased PD-L1 transcriptional expression in HCC cells. Similarly, expression of WT β-catenin, but not the phosphorylation-defective β-catenin S552A mutant, significantly promotes PD-L1 expression. Correlation analysis of human HCC tumor specimens further revealed that DKK1 and PD-L1 expression were positively correlated with p-β-catenin expression. Together, our findings revealed that DKK1 promotes PD-L1 expression through the activation of Akt/β-catenin signaling, providing a potential strategy to enhance the clinical efficacy of PD-1/PD-L1 blockade therapy in HCC patients.

Correlation of NNMT and DKK1 Protein Expression With Clinicopathological Characteristics and Prognosis of Breast Cancer

Background

Nicotinamide N-methyltransferase (NNMT) and Dickkopf-1 (DKK1) play an important role in the development of breast cancer, and the purpose of this study was designed to examine the clinical and prognostic significance of NNMT and DKK1 in breast cancer.

Methods

The GEPIA2 database was used to evaluate the expression and survival of NNMT mRNA and DKK1 mRNA of breast cancer. Then an immunohistochemical study was carried out on 374 cases of breast tissue to identify the protein expression and significance of NNMT and DKK1. Next, the prognostic significance of DKK1 in breast cancer was explored by COX and Kaplan-Meier models.

Results

Protein NNMT expression was correlated with lymph node metastasis and histological grade (P < .05) while protein DKK1 expression was related to tumor size, pT stage, histological grade, and Ki-67 (P < .05). Protein DKK1 was related to disease-specific survival (DSS), and low DKK1 expression indicated a poor prognosis of breast cancer patients (P < .05). Combined expression of protein NNMT and protein DKK1 predicted different prognosis of DSS (P < .05).

Conclusions

Nicotinamide N-methyltransferase and DKK1 were linked to breast cancer malignancy and invasion. Breast cancer patients with low DKK1 expression had a worse prognosis. Oncotypes of NNMT and DKK1 expression predicted patient outcomes.

Signaling pathways and their potential therapeutic utility in esophageal squamous cell carcinoma

Esophageal cancer is a complex gastrointestinal malignancy with an extremely poor outcome. Approximately 80% of cases of this malignancy in Asian countries including India are of squamous cell origin, termed Esophageal Squamous Cell Carcinoma (ESCC).The five-year survival rate in ESCC patients is less than 20%. Neo-adjuvant chemo-radiotherapy (NACRT) followed by surgical resection remains the major therapeutic strategy for patients with operable ESCC. However, resistance to NACRT and local recurrence after initial treatment are the leading cause of dismal outcomes in these patients. Therefore, an alternative strategy to promote response to the therapy and reduce the post-operative disease recurrence is highly needed. At the molecular level, wide variations have been observed in tumor characteristics among different populations, nevertheless, several common molecular features have been identified which orchestrate disease progression and clinical outcome in the malignancy. Therefore, determination of candidate molecular pathways for targeted therapy remains the mainstream idea of focus in ESCC research. In this review, we have discussed the key signaling pathways associated with ESCC, i.e., Notch, Wnt, and Nrf2 pathways, and their crosstalk during disease progression. We further discuss the recent developments of novel agents to target these pathways in the context of targeted cancer therapy. In-depth research of the signaling pathways, gene signatures, and a combinatorial approach may help in discovering targeted therapy for ESCC.

Defective expression of C20orf54 in esophageal dysplasia: a possible biomarker of esophageal carcinoma for early detection

BACKGROUND

C20orf54 has been identified as an esophageal squamous cell carcinoma (ESCC) susceptibility gene in previous genome-wide association studies. Here, we attempted to clarify the expression level of C20orf54 in ESCC, non-tumoral esophageal tissues, and esophageal squamous intraepithelial neoplasia (ESIN).

METHODS

We assessed C20orf54 expression in 146 ESCC, 108 non-tumoral esophageal tissues, and 148 ESIN using immunohistochemistry on tissue microarrays. We also evaluated the possible correlations of C20orf54 expression with clinicopathological characteristics. The survival rates were analyzed using the Kaplan-Meier method and log-rank test.

RESULTS

C20orf54 expression was significantly lower in ESCC, high-grade ESIN, and low-grade ESIN than in the non-tumoral esophageal tissues. The level observed for ESCC was also significantly lower than that in low-grade ESIN and high-grade ESIN, whereas no difference was observed between high-grade ESIN and low-grade ESIN. Furthermore, the C20orf54 defective expression correlated significantly with differentiation, lymph node metastasis, and invasion depth. The overall survival time was inversely associated with lymph node metastasis, an advanced TNM stage (III + IV), and deeper invasion.

CONCLUSIONS

This study provides the first evidence of C20orf54 defective expression in ESCC and precancerous lesions, demonstrating a potential role in tumor progression and metastasis. C20orf54 could be used as a potential biomarker for the early detection of ESCC.

Pan-Cancer Analyses Reveal Oncogenic and Immunological Role of Dickkopf-1 (DKK1)

WNT signaling pathway inhibitor Dickkopf-1 (DKK1) is related to cancer progression; however, its diagnostic and prognostic potential have not been investigated in a pan-cancer perspective. In this study, multiple bioinformatic analyses were conducted to evaluate therapeutic value of DKK1 in human cancers. The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) project served as data resources. The Wilcoxon rank test was performed to evaluate the expression difference of DKK1 between cancer tissues and normal tissues. A Kaplan-Meier curve and Cox regression were used for prognosis evaluation. Single-sample gene set enrichment analysis (ssGSEA) was used to evaluate the association of DKK1 expression with the immune cell infiltration. The potential function of DKK1 was explored by STRING and clusterProfiler. We found that the expression level of DKK1 is significantly different in different cancer types. Importantly, we demonstrated that DKK1 is an independent risk factor in ESCA, LUAD, MESO, and STAD. Further analysis revealed that DKK1 had a large effect on the immune cell infiltration and markers of certain immune cells, such as Th1 and Th2 cells. PPI network analysis and further pathway enrichment analysis indicated that DKK1 was mainly involved in the WNT signaling pathway. Our findings suggested that DKK1 might serve as a marker of prognosis for certain cancers by affecting the WNT signaling pathway and tumor immune microenvironment.

RYR2 mutation in non-small cell lung cancer prolongs survival via down-regulation of DKK1 and up-regulation of GS1-115G20.1: A weighted gene Co-expression network analysis and risk prognostic models

RYR2 mutation is clinically frequent in non-small cell lung cancer (NSCLC) with its function being elusive. We downloaded lung squamous cell carcinoma and lung adenocarcinoma samples from the TCGA database, split the samples into RYR2 mutant group (n = 337) and RYR2 wild group (n = 634), and established Kaplan-Meier curves. The results showed that RYR2 mutant group lived longer than the wild group (p = 0.027). Weighted gene co-expression network analysis (WGCNA) of differentially expressed genes (DEGs) yielded prognosis-related genes. Five mRNAs and 10 lncRNAs were selected to build survival prognostic models with other clinical features. The AUCs of 2 models are 0.622 and 0.565 for predicting survival at 3 years. Among these genes, the AUCs of DKK1 and GS1-115G20.1 expression levels were 0.607 and 0.560, respectively, which predicted the 3-year survival rate of NSCLC sufferers. GSEA identified an association of high DKK1 expression with TP53, MTOR, and VEGF expression. Several target miRNAs interacting with GS1-115G20.1 were observed to show the relationship with the phenotype, treatment, and survival of NSCLC. NSCLC patients with RYR2 mutation may obtain better prognosis by down-regulating DKK1 and up-regulating GS1-115G20.1.

Dickkopf signaling, beyond Wnt-mediated biology

Dickkopf1 (DKK1) was originally identified as a secreted protein that antagonizes Wnt signaling. Although DKK1 is essential for the developmental process, its functions in postnatal and adult life are unclear. However, evidence is accumulating that DKK1 is involved in tumorigenesis in a manner unrelated to Wnt signaling. In addition, recent studies have revealed that DKK1 may control immune reactions, although the relationship of this to Wnt signaling is unknown. Other DKK family members, DKK2-4, are likely to have their own functions. Here, we review the possible novel functions of DKKs. We summarize the characteristics of receptors of DKKs and the signaling mechanisms through DKKs and their receptors, provide evidence showing that DKKs are involved in tumor aggressiveness independently of Wnt signaling, and emphasize promising cancer therapies targeting DKKs and receptors. Lastly, we discuss various physiological and pathological processes controlled by DKKs.

High Serum Levels of Wnt Signaling Antagonist Dickkopf-Related Protein 1 Are Associated with Impaired Overall Survival and Recurrence in Esophageal Cancer Patients

Simple Summary

Dickkopf-related protein 1 (DKK1), an antagonist of the canonical Wnt pathway has been the subject of research for many years. Especially in gastrointestinal cancers, research suggests a pivotal role of DKK1. In order to understand the role of DKK1 in esophageal cancer, we analyzed blood samples of esophageal cancer patients for their DKK1 levels and retrospectively analyzed the clinicopathological data. In our study cohort, we observed a negative prognostic role of high DKK1 serum levels with respect to overall survival in esophageal cancer patients. These data may suggest serum DKK1 as a novel biomarker for improved risk stratification and treatment monitoring in esophageal cancer patients.

Abstract

Dickkopf-related protein 1 (DKK1), an antagonist of the canonical Wnt pathway, has received tremendous attention over the past years as its dysregulation is said to be critically involved in a wide variety of gastrointestinal cancers. However, the potential clinical implications of DKK1 remain poorly understood. Although multimodal treatment options have been implemented over the past years, esophageal cancer (EC) patients still suffer from poor five-year overall survival rates ranging from 15% to 25%. Especially prognostic factors and biomarkers for risk stratification are lacking to choose the most beneficial treatment out of the emerging landscape of different treatment options. In this study, we analyzed the serum DKK1 (S-DKK1) levels of 91 EC patients prior to surgery in a single center study at the University Medical Center Hamburg-Eppendorf by enzyme-linked immunosorbent assay. High levels of S-DKK1 could be especially observed in patients suffering from esophageal adenocarcinoma which may promote the hypothesis of a crucial role of DKK1 in inflammation. S-DKK1 levels of ≥5800 pg/mL were shown to be associated with unfavorable five-year survival rates and the presence of CTCs. Interestingly, significantly lower S-DKK1 levels were detected in patients after neoadjuvant treatment, implying that S-DKK1 may serve as a useful biomarker for treatment monitoring. Multivariate analysis identified S-DKK1 as an independent prognostic marker with respect to overall survival in EC patients with a hazard ratio of 2.23. In conclusion, our data implicate a negative prognostic role of DKK1 with respect to the clinical outcome in EC patients. Further prospective studies should be conducted to implement S-DKK1 into the clinical routine for risk stratification and treatment monitoring.

miR-33a-5p inhibits the progression of esophageal cancer through the DKK1-mediated Wnt/β-catenin pathway

Esophageal cancer (EC) is one of the most lethal malignancies in humans, and multiple miRNAs have been identified to modulate EC progression by targeting different targets. However, the effect and related mechanism of microRNA-33a-5p (miR-33a-5p) on EC development remain elusive. In this study, we explored the clinical value, function, and possible mechanism of miR-33a-5p in EC. We uncovered that miR-33a-5p and DKK1 are involved in the progression of EC. Significantly, the expression levels of miR-33a-5p were reduced and DKK1 levels were elevated in serum and tissues of clinical EC samples and in EC cell lines. The downregulation of miR-33a-5p and DKK1 upregulation were related to high TNM staging and poor differentiation of patients. The area under the curves (AUCs) of miR-33a-5p and DKK1 for the occurrence of EC were 0.914 and 0.900, respectively. Down-regulation of miR-33a-5p or overexpression of DKK1 indicated a worse prognosis. The miR-33a-5p overexpression or DKK1 depletion induced apoptosis and repressed proliferation, migration, and invasion of EC cells. The repression of miR-33a-5p by inhibitor or DKK1 overexpression presented the conversed effects on EC cells. Mechanically, miR-33a-5p suppressed DKK1 expression, and miR-33a-5p targeted DKK1 to affect the biological behavior of EC through the Wnt/β-catenin pathway. Meanwhile, miR-33a-5p inhibited the tumor growth of EC in vivo. Thus, we concluded that miR-33a-5p inhibited the progression of EC through the DKK1-mediated Wnt/β-catenin pathway. MiR-33a-5p and DKK1 can be used as potential therapeutic targets of EC.

The Dickkopf1 and FOXM1 positive feedback loop promotes tumor growth in pancreatic and esophageal cancers

Dickkopf1 (DKK1) is overexpressed in various cancers and promotes cancer cell proliferation by binding to cytoskeleton-associated protein 4 (CKAP4). However, the mechanisms underlying DKK1 expression are poorly understood. RNA sequence analysis revealed that expression of the transcription factor forkhead box M1 (FOXM1) and its target genes concordantly fluctuated with expression of DKK1 in pancreatic ductal adenocarcinoma (PDAC) cells. DKK1 knockdown decreased FOXM1 expression and vice versa in PDAC and esophageal squamous cell carcinoma (ESCC) cells. Inhibition of either the DKK1-CKAP4-AKT pathway or the ERK pathway suppressed FOXM1 expression, and simultaneous inhibition of both pathways showed synergistic effects. A FOXM1 binding site was identified in the 5'-untranslated region of the DKK1 gene, and its depletion decreased DKK1 expression and cancer cell proliferation. Clinicopathological and database analysis revealed that PDAC and ESCC patients who simultaneously express DKK1 and FOXM1 have a poorer prognosis. Multivariate analysis demonstrated that expression of both DKK1 and FOXM1 is the independent prognostic factor in ESCC patients. Although it has been reported that FOXM1 enhances Wnt signaling, FOXM1 induced DKK1 expression independently of Wnt signaling in PDAC and ESCC cells. These results suggest that DKK1 and FOXM1 create a positive feedback loop to promote cancer cell proliferation.

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.

Serum Dickkopf-1 in Combined with CA 19-9 as a Biomarker of Intrahepatic Cholangiocarcinoma

Simple Summary

Cholangiocarcinoma (CCC) is a rare cancer, but its incidence and mortality have been increased in the past few decades worldwide, representing a global health problem. CCC is usually asymptomatic in early stages and, therefore, often diagnosed when the disease is already in advanced stages, which highly compromises therapeutic options, resulting in a dismal prognosis. The current diagnosis of CCC by non-invasive approaches such as serum biomarker, carbohydrate antigen 19-9 (CA 19-9), is not accurate enough due to the limitations in its low sensitivity, especially at the early stages of the disease. Therefore, new biomarkers with higher sensitivity and specificity are needed. As the clinical significance of dickkopf-related protein-1 (DKK-1) has been reported in various tumors including intrahepatic CCC (ICC), we aimed to identify the diagnostic and prognostic performance of the DKK-1 and its additive effect combined with CA 19-9 in patients with CCC.

Abstract

Dickkopf-related protein 1 (DKK-1) has a diagnostic and prognostic value in various malignant tumors. We investigated the diagnostic and prognostic performance of DKK-1 in combination with carbohydrate antigen 19-9 (CA 19-9) in cholangiocarcinoma (CCC) patients. Serum DKK-1 levels were measured using enzyme-linked immunosorbent assay. The receiver operating characteristic (ROC) curve, area under ROC (AUROC) analyses, Kaplan–Meier method, and Cox proportional hazard model were used to evaluate the diagnostic and prognostic performance of DKK-1 in combination with CA 19-9. We checked DKK-1 levels in 356 CCC patients and found that DKK-1 was significantly elevated only in 79 intrahepatic CCC (ICC) patients compared to controls (340.5 vs. 249.8 pg/mL, p = 0.002). The optimal cutoff level of DKK-1 used to identify ICC patients was 258.0 pg/mL (AUROC = 0.637, sensitivity = 59.5%, specificity = 56.9%, positive predictive value (PPV) = 40.5%, negative predictive value (NPV) = 74.0%, positive likelihood ratio (LR) = 1.38, and negative LR = 0.71). Using this cutoff, 47 (59.5%) patients were correctly diagnosed with ICC. DKK-1 in combination with CA 19-9 showed a better diagnostic performance (AUROC = 0.793, sensitivity = 74.7%, specificity = 56.3%, PPV = 45.7, NPV = 81.8, positive LR = 1.71, and negative LR = 0.45) than CA 19-9 alone. The low DKK-1 and CA 19-9 expression group had a significantly longer overall survival (OS) than the high expression group (p = 0.006). The higher level of DKK-1 and CA 19-9 was independently associated with shorter OS (hazard ratio = 3.077, 95% confidence interval 1.389–6.819, p = 0.006). The diagnostic and prognostic performance of DKK-1 in combination with CA 19-9 might be better than those of CA 19-9 alone in ICC patients.

Identification of a four-gene panel predicting overall survival for lung adenocarcinoma

Background

Lung cancer is the most frequently diagnosed carcinoma and the leading cause of cancer-related mortality. Although molecular targeted therapy and immunotherapy have made great progress, the overall survival (OS) is still poor due to a lack of accurate and available prognostic biomarkers. Therefore, in this study we aimed to establish a multiple-gene panel predicting OS for lung adenocarcinoma.

Methods

We obtained the mRNA expression and clinical data of lung adenocarcinoma (LUAD) from TCGA database for further integrated bioinformatic analysis. Lasso regression and Cox regression were performed to establish a prognosis model based on a multi-gene panel. A nomogram based on this model was constructed. The receiver operating characteristic (ROC) curve and the Kaplan–Meier curve were used to assess the predicted capacity of the model. The prognosis value of the multi-gene panel was further validated in TCGA-LUAD patients with EGFR, KRAS and TP53 mutation and a dataset from GEO. Gene set enrichment analysis (GSEA) was performed to explore potential biological mechanisms of a novel prognostic gene signature.

Results

A four-gene panel (including DKK1, GNG7, LDHA, MELTF) was established for LUAD prognostic indicator. The ROC curve revealed good predicted performance in both test cohort (AUC = 0.740) and validation cohort (AUC = 0.752). Each patient was calculated a risk score according to the model based on the four-gene panel. The results showed that the risk score was an independent prognostic factor, and the high-risk group had a worse OS compared with the low-risk group. The nomogram based on this model showed good prediction performance. The four-gene panel was still good predictors for OS in LUAD patients with TP53 and KRAS mutations. GSEA revealed that the four genes may be significantly related to the metabolism of genetic material, especially the regulation of cell cycle pathway.

Conclusion

Our study proposed a novel four-gene panel to predict the OS of LUAD, which may contribute to predicting prognosis accurately and making the clinical decisions of individual therapy for LUAD patients.

Development of novel monoclonal antibodies and immunoassays for sensitive and specific detection of SULF1 endosulfatase

BACKGROUND

Cell-surface heparan sulfate proteoglycans (HSPGs) function as receptors or co-receptors for ligand binding and mediate the transmission of critical extracellular signals into cells. The complex and dynamic modifications of heparan sulfates on the core proteins are highly regulated to achieve precise signaling transduction. Extracellular endosulfatase Sulf1 catalyzes the removal of 6-O sulfation from HSPGs and thus regulates signaling mediated by 6-O sulfation on HSPGs. The expression of Sulf1 is altered in many cancers. Further studies are needed to clarify Sulf1 role in tumorigenesis, and new tools that can expand our knowledge in this field are required.

METHODS

We have developed and validated novel SULF1 monoclonal antibodies (mAbs). The isotype and subclass for each of these antibodies were determined. These antibodies provide invaluable reagents to assess SULF1- tissue and blood levels by immunohistochemistry and ELISA assays, respectively.

RESULTS

This study reports novel mAbs and immunoassays developed for sensitive and specific human Sulf1 protein detection. Using these SULF1 mAbs, we developed an ELISA assay to investigate whether blood-derived SULF1 may be a useful biomarker for detecting cancer early. Furthermore, we have demonstrated the utility of these antibodies for Sulf1 protein detection, localization, and quantification in biospecimens using various immunoassays.

CONCLUSIONS

This study describes novel Sulf1 mAbs suitable for various immunoassays, including Western blot analysis, ELISA, and immunohistochemistry, which can help understand Sulf1 pathophysiological role.

GENERAL SIGNIFICANCE

New tools to assess and clarify SULF1 role in tumorigenesis are needed. Our novel Sulf1 mAbs and immunoassays assay may have utility for such application.

Diagnosis Accuracy and Prognostic Significance of the Dickkopf-1 Protein in Gastrointestinal Carcinomas: Systematic Review and Network Meta-analysis

Objective: To evaluate the diagnosis accuracy and prognostic significance of bio-marker dickkopf-1(DKK-1) protein in GIC, and also sub-type of hepatocellular carcinoma (HCC), pancreas carcinomas (PC), oesophageal carcinoma (EPC) and Adenocarcinoma of esophago-gastric junction (AEGJ), etc.

Methods: Electronic databases were searched from inception to May 2020. Patients were diagnosed with gastrointestinal carcinomas, and provided data on the correlation between high and low DKK-1 expression and diagnosis or prognosis.

Results: Forty-three publications involving 9318 participants were included in the network meta-analysis, with 31 of them providing data for diagnosis value and 18 records were eligible for providing prognosis value of DKK-1. DKK-1 has a moderate diagnostic value for overall GIC, HCC and PC. In addition, for the combined diagnosis value of DKK-1 +AFP, high diagnostic accuracy value could be determined in HCC and early HCC group, respectively. Whereas, diagnosis efficiency of DKK-1+CA19-9 was also better than that of DKK-1 alone with AUC value is above 0.95. For the prognosis meta-analysis of histopathological stratification, we found that EPC and AEGJ ranked the best for the histopathological stratification of prognosis from network meta-analysis. This systematic review protocol was registered with the PROSPERO registry (No.CRD42020167910).

Conclusion: DKK-1 has good diagnostic accuracy, especially combination of DKK-1+AFP in HCC and DKK-1+CA19-9 in PC, whereas modest prognostic significant in GIC. Future head-to-head researches are warranted for DKK-1 expression in HCC and PC tissue.

Comparison of the diagnostic value of CEA combined with OPN or DKK1 in non-small cell lung cancer

Carcinoma embryonic antigen (CEA), osteopontin (OPN), and Dickkopf-1 (DKK1) expressed in serum are associated with hypoxia in tumor progression. However, the role of these proteins in the plasma of patients with non-small cell lung cancer (NSCLC) is poorly understood. The diagnostic values of CEA combined with OPN or DKK1 were compared in non-small cell lung cancer. This study investigated the diagnostic value of CEA combined with OPN and DKK1, respectively, in NSCLC. Eighty patients with NSCLC (NSCLC group) and 60 patients with benign lung diseases (benign lung disease group) admitted to Shandong Provincial Third Hospital from May 2014 to January 2015 were selected as the study subjects. In addition, 60 healthy subjects undergoing normal physical examination were selected as healthy control group. The OPN and DKK1 in serum of the two groups were detected by enzyme linked immunosorbent assay (ELISA), and the CEA expression was measured by Electrochemical Photometric method. The diagnostic value of CEA combined with OPN and DKK1, respectively, in NSCLC was analyzed. The expression of CEA, OPN, and DKK1 in serum of NSCLC group was significantly higher than that of healthy control group and benign lung disease group (P<0.05). The expression of CEA, OPN and DKK1 in serum of NSCLC patients was correlated with tumor diameter, lymph node metastasis, degree of pathological differentiation and clinical stage (P<0.05). ROC curve for diagnosis of NSCLC was drawn by further combination of serum CEA and OPN. The AUC of combined diagnosis of CEA and OPN for NSCLC was 0.920 (95% CI, 0.875-0.964), and the diagnostic sensitivity and specificity were 87.50 and 86.67%, respectively; the AUC of combined diagnosis of CEA and DKK1 for NSCLC was 0.912 (95% CI, 0.866-0.958), and the diagnostic sensitivity and specificity were 92.50 and 76.67%, respectively. CEA, OPN and DKK1 may be involved in the occurrence and progression of NSCLC and have good sensitivity and specificity in the diagnosis of NSCLC and may be new biomarkers for the diagnosis of NSCLC.

Characterization of KIF20A as a prognostic biomarker and therapeutic target for different subtypes of breast cancer

The aim of the present study was to identify novel prognostic biomarkers and therapeutic targets for breast cancer; thus, genes that are frequently overexpressed in several types of breast cancer were screened. Kinesin family member 20A (KIF20A) was identified as a candidate molecule during this process. Immunohistochemical staining performed using tissue microarrays from 257 samples of different breast cancer subtypes revealed that KIF20A was expressed in 195 (75.9%) of these samples, whereas it was seldom expressed in normal breast tissue. KIF20A protein was expressed in all types of breast cancer observed. However, it was more frequently expressed in human epidermal growth factor receptor 2 (HER2)‑positive and triple‑negative breast cancer than in the luminal type. Moreover, KIF20A expression was significantly associated with the poor prognosis of patients with breast cancer. A multivariate analysis indicated that KIF20A expression was an independent prognostic factor for patients with breast cancer. The suppression of endogenous KIF20A expression using small interfering ribonucleic acids or via treatment with paprotrain, a selective inhibitor of KIF20A, significantly inhibited breast cancer cell growth through cell cycle arrest at the G2/M phase and subsequent mitotic cell death. These results suggest that KIF20A is a candidate prognostic biomarker and therapeutic target for different types of breast cancer.

Analyzing the prognostic value of DKK1 expression in human cancers based on bioinformatics

Background

The Dickkopf1 (DKK1) gene encodes a protein that belongs to the Dickkopf family. The protein can inhibit the Wnt signaling pathway which plays a key role in the carcinogenesis and progression of various types of cancers. Based on this, we hypothesized that the differential expression of DKK1 may figure significantly in cancers by regulating Wnt signaling pathway transduction. In this study, we conducted bioinformatics analysis to evaluate the prognostic and therapeutic value of DKK1 expression level in human cancers.

Methods

The expression level was analyzed by using the Oncomine database and Gene Expression Profiling Interactive Analysis tool. The analysis of prognosis was conducted by using the UALCAN, Gene Expression Profiling Interactive Analysis (GEPIA), and DriverDBv3 databases. We also investigated using DKK1 promoter methylation to define cancer types through the UALCAN database. Meanwhile, the related functional networks of DKK1 were analyzed by using the GeneMANIA interactive tool and Cytoscape software. Furthermore, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis was conducted using the Metascape online website, and we used the cBioPotartal database to explored DKK1 expression, aberrant information, and the co-expression genes in the subgroups of lung cancer. Finally, we performed the overall survival (OS) meta-analysis of the DKK1 expression in lung squamous cell carcinoma (LUSC) via the Lung Cancer Explorer (LCE).

Results

DKK1 was differentially expressed in different types of human cancers. DKK1 was overexpressed in human cancers including head and neck squamous cell carcinoma (HNSC), LUSC, and pancreatic adenocarcinoma (PAAD). Overexpression of DKK1 indicated adverse OS in bladder urothelial carcinoma (BLCA), HNSC, and PADD, but no difference in OS was found between the LUSC and healthy groups. The high expression of DKK1 was also associated with shorter disease-free survival (DFS) in HNSC, LUSC, and PAAD. Gene regulation network analysis indicated that DKK1 was mainly involved in Wnt signaling pathways and several other signaling pathways.

Conclusions

Our findings showed that DKK1 is significantly expressed in various cancers and could be a biomarker for targeted therapy and a predictor for prognosis of these specific cancers. The bioinformatics analysis revealed a significant overexpression of DKK1 in HNSC, LUSC, and PAAD, with DKK1 overexpression being associated with adverse outcome in these patients, but how DKK1 expression levels relate to hematological malignancies and prognosis is still unclear. These new insights into the function of DKK1 may provide a basis for new targeted drug therapy and an avenue for further investigation into the mechanisms underlying carcinogenesis of DKK1 in different cancer types.

Dickkopf-1 contributes to hepatocellular carcinoma tumorigenesis by activating the Wnt/β-catenin signaling pathway

Dysregulation of dickkopf-related protein 1 (DKK1) expression has been reported in a variety of human cancers. We previously reported that DKK1 was upregulated in hepatocellular carcinoma (HCC). However, the role of DKK1 in HCC remains unclear. This study aimed to investigate the clinical significance and biological functions of DKK1 in HCC. The expression of DKK1 was examined in cirrhotic and HCC tissues by immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR). DKK1 was silenced or overexpressed in HCC cell lines, and in vitro and in vivo studies were performed. Immunohistochemistry revealed that DKK1 was weakly expressed in cirrhotic tissues (8/22, 36.4%) but upregulated in HCC tissues (48/53, 90.6%, cohort 1). Significant upregulation of DKK1 was observed in 57.6% (19/33, cohort 2) of HCC tissues by qRT-PCR, and the expression of DKK1 was associated with tumor size (P = 0.024) and tumor number (P = 0.019). Genetic depletion of DKK1 impaired the proliferation, colony-forming ability, invasion, and tumor formation of HCC cells (HepG2 and HUH-7). Conversely, forced expression of DKK1 increased the proliferation, colony-forming ability, and invasion of HepG2 and HUH-7 cells in vitro and enhanced tumor formation in vivo. Subsequent investigation revealed that the DKK1-mediated proliferation and tumorigenicity of HepG2 and HUH-7 cells is dependent on the Wnt/β-catenin signaling pathway. These findings indicate that DKK1 plays an oncogenic role in HCC by activating the Wnt/β-catenin signaling pathway.

Targeting signalling pathways and the immune microenvironment of cancer stem cells - a clinical update

Cancer stem cells (CSCs) have important roles in tumour development, relapse and metastasis; the intrinsic self-renewal characteristics and tumorigenic properties of these cells provide them with unique capabilities to resist diverse forms of anticancer therapy, seed recurrent tumours, and disseminate to and colonize distant tissues. The findings of several studies indicate that CSCs originate from non-malignant stem or progenitor cells. Accordingly, inhibition of developmental signalling pathways that are crucial for stem and progenitor cell homeostasis and function, such as the Notch, WNT, Hedgehog and Hippo signalling cascades, continues to be pursued across multiple cancer types as a strategy for targeting the CSCs hypothesized to drive cancer progression - with some success in certain malignancies. In addition, with the renaissance of anticancer immunotherapy, a better understanding of the interplay between CSCs and the tumour immune microenvironment might be the key to unlocking a new era of oncological treatments associated with a reduced propensity for the development of resistance and with enhanced antimetastatic activity, thus ultimately resulting in improved patient outcomes. Herein, we provide an update on the progress to date in the clinical development of therapeutics targeting the Notch, WNT, Hedgehog and Hippo pathways. We also discuss the interactions between CSCs and the immune system, including the potential immunological effects of agents targeting CSC-associated developmental signalling pathways, and provide an overview of the emerging approaches to CSC-targeted immunotherapy.

Negative regulators of Wnt signaling in non-small cell lung cancer: Theoretical basis and therapeutic potency

Significant advances in the treatment of non-small cell lung cancer (NSCLC) have been made over the past decade, and they predominantly involve molecular targets such as epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements. However, despite the initial good response, drug resistance eventually develops. The Wnt signaling pathway has recently been considered important in embryonic development and tumorigenesis in many cancers, particularly NSCLC. Moreover, the aberrant Wnt pathway plays a significant role in NSCLC and is associated with cancer cell proliferation, metastasis, invasion and drug resistance, and the suppression of canonical or noncanonical Wnt signaling through various biological or pharmacological negative regulators has been proven to produce specific anticancer effects. Thus, blocking the Wnt pathway via its negative regulators may overcome the resistance of current treatment methods and lead to new treatment strategies for NSCLC. Therefore, in this review, we summarize recent studies on the role of negative regulators in Wnt signaling in NSCLC and the therapeutic potency of these molecules as agents and targets for NSCLC treatments.

Correlations of DKK1 with pathogenesis and prognosis of human multiple myeloma

OBJECTIVE

Human multiple myeloma (MM) is a kind of common tumor in middle-aged and elderly people, in which the osteolytic lesion is formed mainly through inhibiting osteoblast (OB) differentiation and promoting osteoclast (OC) differentiation. Dickkopf-1 (DKK1) is a soluble Wnt inhibitor, which has an important correlation with the pathogenesis of human MM. Therefore, the correlations of DKK1 with pathogenesis and prognosis of human MM were investigated in this study.

METHODS

The DKK1 expression in tissues and serum of myeloma patients was detected via immunohistochemistry and enzyme-linked immunosorbent assay (ELISA). Correlation between DKK1 expression and survival time of patients was analyzed via Kaplan-Meier analysis. To further study the mechanism of DKK1 expression in pathogenesis and prognosis of human MM, MM cells were treated with DKK1 neutralizing antibody (BHQ880) or transfected with DKK1-small-interfering ribonucleic acid (siRNA) to study its effects on OB differentiation, osteocalcin level, β-catenin and interleukin-6 (IL-6) secretion. Moreover, the effect of DKK1-siRNA transfection on the activity of U266 cells was detected via methyl thiazolyl tetrazolium (MTT) assay.

RESULTS

The DKK1 expression in tissues and serum of myeloma patients was significantly higher than that in control group (p< 0.01). In terms of survival time, the median survival time (45 months) in patients with low DKK1 expression was significantly longer than that in patients with high DKK1 expression (only 22 months). The DKK1 neutralizing antibody (BHQ880) and DKK1-siRNA significantly reduced the DKK1 level in MM cells, promoted the OB differentiation, increased the osteocalcin deposition, promoted the β-catenin expression and decreased the IL-6 expression and β-catenin phosphorylation. DKK1-siRNA could also reduce the proliferative activity of MM cells.

CONCLUSION

DKK1 is closely related to the pathogenesis and prognosis of human MM, which might be a potential biomarker for the diagnosis of MM.

Etiology, cancer stem cells and potential diagnostic biomarkers for esophageal cancer

Esophageal cancer (EC) has been a leading cause of cancer death worldwide in part due to late detection and lack of precision treatment. EC includes two major malignancies, esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC). Recent studies reveal that ESCC and EAC have distinct cell of origin and contain cancer stem cells (also known as tumor initiating cells) expressing different cell surface markers. These biomarkers have potentially important values for both early detection and finding effective therapy. In this review we summarize the updated findings for cell of origin and provide an overview of cancer cell biomarkers that have been tested for ESCC and EAC. In addition, we also discuss recent progress in the study of molecular mechanisms leading to these malignancies.

Elevated blood levels of Dickkopf-1 are associated with acute infections

INTRODUCTION

Dickkopf-1 (DKK1) is a soluble protein and antagonist of the Wnt/β-catenin signaling pathway. DKK1 is found elevated in serum from patients affected with various types of cancers and in some instances, it is considered a diagnostic and prognostic biomarker. Elevated serum levels of DKK1 have also been detected in animal models of chronic inflammatory diseases. Previous work from our laboratory has demonstrated upregulation of DKK1 in cells and mouse models of the bone marrow failure (BMF) and cancer-prone disease Fanconi anemia (FA). The present study aimed to investigate whether DKK1 blood levels in patients are associated with FA or inflammatory responses to acute infections.

METHODS

Plasma samples were collected from 58 children admitted to the Centre Mère-Enfant Soleil du Centre Hospitalier de Québec-Université Laval with signs of acute infections. Blood plasma specimens were also collected from healthy blood donors at the Héma-Québec blood donor clinic. Plasmas from patients diagnosed with FA were also included in the study. DKK1 levels in blood plasmas were assessed by standard ELISA.

RESULTS

Patients with acute infections showed dramatically high levels of DKK1 (6072 ± 518 pg/ml) in their blood compared to healthy blood donors (1726 ± 95 pg/ml). No correlations were found between DKK1 levels and C reactive protein (CRP) concentration, platelet numbers, or white blood cell counts. Patients with FA showed higher DKK1 plasma levels (3419 ± 147.5 pg/ml) than healthy blood donors (1726 ± 95 pg/ml) but significantly lower than patients with acute infections.

CONCLUSION

These findings suggest that blood DKK1 is elevated in response to infections and perhaps to inflammatory responses.

Prediction and identification of transcriptional regulatory elements at the lung cancer-specific DKK1 locus

The glycoprotein dickkopf 1 (DKK1) is highly expressed in lung cancer cell lines and tissues. Our previous study demonstrated that DKK1 promoter activity is low in lung cancer cell lines. This may be because it lacks the necessary transcriptional regulatory elements (TREs) required for higher activity levels. However, it is difficult to computationally predict functionally significant TREs, as TREs from different locations can affect large segments of distant DNA. The Encyclopedia of DNA Elements project features multiple integrated technologies and approaches for the discovery and definition of functional elements, including enhancer elements and enhancer-blocking insulators. In the present study, DNase I hypersensitive sites and histone modifications of DKK1 were investigated in the A549 lung cancer cell line using the UCSC Genome Browser. A set of cis-acting enhancer elements were identified by a dual-luciferase reporter gene assay system to increase activity of the DKK1 promoter with lung cancer specificity. To the best of our knowledge, these data provide the first insight into the role of the DKK1 locus in lung cancer, and confirm the contribution of intronic cis-acting elements to the regulation of DKK1 expression, providing a new insight into gene regulation in lung cancer, which could inform the development of targeted therapy.

Bone turnover markers and novel biomarkers in lung cancer bone metastases

CONTEXT

Lung cancer still remains the leading cause of cancer-related mortality worldwide. Bone is one of preferred metastatic sites for lung cancer cells. So far, both accurate diagnosis and effective treatment of lung cancer bone metastases are difficult.

OBJECTIVE

This review aimed to evaluate roles of bone turnover markers (BTMs), microRNAs (miRNAs), dickkopf1 (DKK1) and insulin like growth factor binding protein 3 (IGFBP-3) in lung cancer bone metastases.

METHODS

We searched articles about these four biomarkers in lung cancer bone metastases mainly in PubMed.

RESULT

The levels of bone specific alkaline phosphatase (BALP), cross-linked carboxy-terminal telopeptide of type-I collagen (ICTP) and N-terminal telopeptides of type-I collagen (NTX) were reported to be significantly increased in lung cancer patients with bone metastases. ALP, NTX and bone sialoprotein were thought to be associated with prognosis of lung cancer patients with bone metastases. MiRNA-335, miRNA-33a, miRNA-21, DKK1 and IGFBP-3 were revealed to be novel biomarkers in lung cancer bone metastases.

DISCUSSION AND CONCLUSION

Current researches have revealed that BTMs, miRNAs, DKK1 and IGFBP-3 may be useful in diagnosis, prognosis evaluation or treatment of lung cancer bone metastases. More studies about these biomarkers in lung cancer bone metastases are needed.

Activation of the Dickkopf1-CKAP4 pathway is associated with poor prognosis of esophageal cancer and anti-CKAP4 antibody may be a new therapeutic drug

Aberrant expression of the secretory protein Dickkopf1 (DKK1) is associated with poor prognosis of esophageal squamous cell carcinoma (ESCC), but the underlying mechanism of how DKK1 is involved in aggressiveness of ESCC is not clear. In this study, we show that cytoskeleton-associated protein 4 (CKAP4) functions as a DKK1 receptor in ESCC cells. Immunohistochemical analyses of ESCC revealed that both DKK1 and CKAP4 are minimally expressed in associated normal esophageal squamous mucosa of non-tumor regions, but strongly expressed in tumor lesions. Forty-six of 119 cases (38.7%) were positive for both DKK1 and CKAP4. Those expressing both proteins showed poor prognosis and relapse-free survival. Multivariate analysis demonstrated that expression of both proteins was the poor prognostic factor. The Cancer Genome Atlas data set indicated that the mRNA levels of DKK1 and CKAP4 are significantly elevated in the tumor lesions compared to non-tumor regions. DKK1 bound to CKAP4 at endogenous levels. DKK1 induced the internalization of CKAP4 from and its recycling to the plasma membrane. AKT was activated in ESCC cells in which DKK1 was highly expressed and CKAP4 was localized to the plasma membrane. Knockdown of either DKK1 or CKAP4 inhibited AKT activity and cell proliferation in vitro and xenograft tumor formation. Wild-type CKAP4 or DKK1, but not a DKK1 mutant that was unable to bind to CKAP4, rescued phenotypes induced by CKAP4 or DKK1 knockdown, respectively. The anti-CKAP4 antibody also inhibited AKT activity and suppressed xenograft tumor formation. In contrast, in ESCC cells in which DKK1 was marginally expressed, knockdown of CKAP4 or anti-CKAP4 antibody affected neither AKT activity nor cell proliferation. These findings suggest that the DKK1-CKAP4 pathway promotes ESCC cell proliferation and that CKAP4 might represent a novel therapeutic target for ESCCs expressing both DKK1 and CKAP4.

Bone, muscle, and metabolic parameters predict survival in patients with synchronous bone metastases from lung cancers

BACKGROUND

Lung adenocarcinoma regularly induces bone metastases that are responsible for impaired quality of life as well as significant morbidity, including bone pain and fractures. We aimed at identifying whether bone and metabolic biomarkers were associated with the prognosis of lung adenocarcinoma patients with synchronous bone metastases.

PATIENTS AND METHODS

POUMOS is a prospective cohort of patients diagnosed with lung adenocarcinoma and synchronous bone metastases. All patients underwent biopsy of bone metastases to confirm diagnosis, including genotyping of oncogenic drivers such as EGFR and KRAS. Whole-body composition was assessed using DEXA scan. Serum levels of C-reactive protein, HbA1C, calcaemia, sCTX, and DKK1 were also measured.

RESULTS

Sixty four patients, aged (mean ± SD) 65 ± 11 years, were included. Thirty-nine (61%) patients had a good performance status (PS 0-1); 56% had >5 bone lesions, and 41% a weight-bearing bone (femour or tibia) involvement. Median overall survival was 7 months. In multivariate analysis, HbA1c (HR = 1.69 [1.10-2.63] per 0.5% decrease; p = .02), DKK1 (HR = 1.28 [1.01-1.61] per 10 ng/mL increase; p = .04), and hypercalcaemia (HR = 2.83 [1.10-7.30]; p = .03) were independently associated with poorer survival. In the subgroup of patients with DEXA, sarcopenia was also associated with poorer survival (HR = 2.96, 95%CI [1.40-6.27]; p = .005).

CONCLUSIONS

In patients with lung adenocarcinoma and synchronous bone metastases, bone, sarcopenia, and metabolic parameters were predictors of poor overall survival independently of common prognostic factors. We suggest that, in addition to oncological therapy, supportive treatment dedicated to bone metastases, muscle wasting, and energy metabolism are essential to improve prognosis.

Dickkopf-1 expression is associated with tumorigenity and lymphatic metastasis in human hilar cholangiocarcinoma

Dickkopf-1 (DKK1) is involved in tumorigenesis and the invasion of several tumors. However, its biological function in human hilar cholangiocarcinoma (HCCA) has not yet been documented. This study was designed to investigate the clinical significance and biological function of DKK1 in HCCA. The expression of DKK1 was investigated in thirty-seven human HCCA biopsy samples by immunohistochemistry. To further explore the biological effects of DKK1 in HCCA, transient and stable knockdown of DKK1 in two human HCCA cells (QBC939 and FRH0201) were established using small interfering or short hairpin RNA expression vector. In the present study, immunohistochemistry revealed that DKK1 was up-regulated in human HCCA tissues (24/37, 64.9%). High levels of DKK1 in human HCCA correlated with metastasis to the hilar lymph nodes (P=0.038). Genetic depletion of DKK1 in HCCA cells resulted in significantly inhibited proliferation, colony formation and migration compared with controls. Most importantly, DKK1 down-regulation impaired tumor formation capacity of HCCA cells in vivo. Subsequent investigations revealed that β-catenin is an important target of DKK1 and DKK1 exerts its pro-invasion function at least in part through the β-catenin/ matrix metalloproteinase-7 (MMP-7) signaling pathway. Consistently, in human HCCA tissues, DKK1 level was positively correlated with β-catenin and MMP-7 expression, as well as tumor hilar lymphatic metastasis. Taken together, our findings indicate that DKK1 may be a crucial regulator in the tumorigenicity and invasion of human HCCA, DKK1 exerts its pro-invasion function at least in part through the β-catenin/ MMP-7 signaling pathway, suggesting DKK1 as a potential therapeutic target for HCCA.

Dickkopf-1: As a Diagnostic and Prognostic Serum Marker for Early Hepatocellular Carcinoma

Background and aims

The aim of the present study was to evaluate serum Dickkopf-1 (Dkk-1) as a marker for early detection of hepatocellular carcinoma (HCC), as well as for prognostic prediction of early HCC after hepatic resection.

Methods

One-hundred and four cases of matched fresh tissue specimens of early HCC and adjacent non-tumorous liver tissue (ANLT) were obtained for RT-PCR, qRT-PCR, western blot and immunohistochemistry assays. Sera were collected from patients with early HCC (n=184), benign liver tumors (n=29), cirrhosis (n=174), non-cirrhotic hepatitis B (n=193), and from healthy individuals (n=202). The levels of Dkk-1 and alpha fetoprotein (AFP) were measured.

Results

The Dkk-1 mRNA and protein levels were both upregulated in early HCC. Serum levels of Dkk-1 in patients with early HCC were significantly higher than in the other 4 groups (p<0.001). Dkk-1 had a better sensitivity and accuracy than AFP (p<0.05). More importantly, 73.1% of the patients negative for AFP could be diagnosed with early HCC using Dkk-1. A combination of Dkk-1 and AFP further improved the diagnostic efficacy. Patients with a high serum Dkk-1 level had poorer overall and relapse-free survivals than those with a low Dkk-1 level (p=0.028 and p=0.045, respectively). These results were shown in a testing cohort and confirmed in a validation cohort of patients. Univariable and multivariable Cox regression analyses showed serum Dkk-1 level to be an independent prognostic factor for overall survival.

Conclusions

Our data show that Dkk-1 is a diagnostic and prognostic serologic marker for early HCC.

The Expression and Significance of Dickkopf-1 in Epithelial Ovarian Carcinoma

The aim of this study was to investigate the presence and prognostic value of Dickkopf-1 (DKK1) in epithelial ovarian carcinoma. The expression of DKK1 was determined in 56 epithelial ovarian carcinoma tissues, 35 benign ovarian cystadenoma tissues, and 12 normal ovarian tissues by quantitative real-time PCR and immunohistochemistry. The DKK1 mRNA level in the carcinoma tissues was upregulated (5.5±2.7-fold increase) compared with that in the normal tissues (p<0.0001). The mRNA level of DKK1 in the cystadenoma tissues (1.1±0.4-fold increase) was not statistically different from that in the normal tissues (p=0.486). DKK1 protein expression in the carcinoma tissues was also higher (89.29%) than in cystadenoma (65.71%) and normal tissues (58.33%) (p=0.006 and p=0.009, respectively). In epithelial ovarian carcinoma, DKK1 gene and protein overexpression was associated with advanced FIGO stage (p=0.007, p=0.004) and poor differentiation grade (p=0.027, p=0.010). Elevated DKK1 protein levels in ovarian carcinoma samples were associated with a poor outcome in univariate and multivariate analysis (p<0.0001 and p<0.0001, respectively). The study indicated that DKK1 may be a useful prognostic and diagnostic indicator for epithelial ovarian carcinoma.

A novel messenger RNA signature as a prognostic biomarker for predicting relapse in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) death rate and recurrence rate have remained obstinately high. Current methods can not satisfy the need of predicting cancer relapse accurately. Utilizing expression profiles of 10 GEO datasets (N = 774), we identified 154 differentially expressed genes (DEGs) between PDAC and normal pancreas tissue or paracancerous tissue. Next we built a 16-mRNA-based signature by means of the LASSO COX regression model. We also validated the prognostic value of the signature. Patients were classified into high-risk and low-risk group according to the signature risk score; 1 year RFS was 45% (95% CI: 31.6%–63.9%) for high-risk group in contrast to 92.5% (95% CI: 86.3%–99.1%) for low-risk group. Moreover, it could predict RFS well in cases with the receipt of different treatment modalities. The 16-mRNA-based signature was an independent and powerful prognostic biomarker for RFS for PDAC patients (HR = 7.74, 95% CI: 3.25–18.45, p < 0.0001).

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.

Characterization of KIF11 as a novel prognostic biomarker and therapeutic target for oral cancer

Oral cancer has a high mortality rate, and its incidence is increasing gradually worldwide. As the effectiveness of standard treatments is still limited, the development of new therapeutic strategies is eagerly awaited. Kinesin family member 11 (KIF11) is a motor protein required for establishing a bipolar spindle in cell division. The role of KIF11 in oral cancer is unclear. Therefore, the present study aimed to assess the role of KIF11 in oral cancer and evaluate its role as a prognostic biomarker and therapeutic target for treating oral cancer. Immunohistochemical analysis demonstrated that KIF11 was expressed in 64 of 99 (64.6%) oral cancer tissues but not in healthy oral epithelia. Strong KIF11 expression was significantly associated with poor prognosis among oral cancer patients (P=0.034), and multivariate analysis confirmed its independent prognostic value. In addition, inhibition of KIF11 expression by transfection of siRNAs into oral cancer cells or treatment of cells with a KIF11 inhibitor significantly suppressed cell proliferation, probably through G2/M arrest and subsequent induction of apoptosis. These results suggest that KIF11 could be a potential prognostic biomarker and therapeutic target for oral cancer.

Role of Dickkopf-1 in gastrointestinal tumors

As an endogenous inhibitor of the Wnt signaling pathway, Dickkopf-1 (DKK1) plays an important role in the occurrence and development of tumors. However, the role of DKK1 in different tumor types is different, as it is lowly expressed in some tumor types, but over-expressed in others. In recent years, there have been many studies on the role of DKK1 in gastrointestinal tumors. In this paper, we review the latest progress in the understanding of the role of DKK1 in gastrointestinal tumors.

The role of Dickkopf-1 as a potential prognostic marker in pancreatic ductal adenocarcinoma

Dickkopf-1(DKK-1), the downstream target of β-catenin/T-cell factor, participates in a negative feedback loop in the Wnt signaling and reported as an important biomarker in many tumors. In this study, we analyzed the expression of DKK-1 in pancreatic ductal adenocarcinoma (PDAC) patients at both mRNA and protein levels. We used real-time PCR to detect the expression of DKK-1 in 32 PDAC and paired adjacent non-tumor tissues, results suggested that the expression of DKK-1 was increased in PDAC tissues. We found the similar results in the analysis of 3 independent microarray data sets. Immunohistochemical staining of 311 pairs of PDAC tissues suggested that DKK-1 expression was significantly associated with T classification (P = 0.039) and lymph node metastasis (P = 0.035). Furthermore, Kaplan-Meier analysis for DKK-1 expression demonstrated that patients with higher DKK-1 level had shorter overall survival (OS) and relapse-free survival (RFS) time in Ren Ji cohort and online PDAC database at both mRNA and protein levels. Univariable and multivariable Cox regression analysis confirmed that DKK-1 as well as lymph node metastasis and histology were independent predictors of OS in patients with PDAC. This study demonstrated that DKK-1 may be a predictor for prognosis in PDAC patients.

DKK1 promotes migration and invasion of non-small cell lung cancer via β-catenin signaling pathway

Disregulation of dickkopf-related protein 1 (DKK1) has been reported in a variety of human cancers. However, how DKK1 functions in Non-small cell lung cancer has not been revealed. In the current study, DKK1 was knocked out by the lentivirus-mediated short hairpin RNA interference approach in H1299 and 95C non-small cell lung cancer cell lines. Subsequently, the migration and invasion ability were assessed by wound-healing and transwell assays. In addition, epithelial-mesenchymal transition markers and β-catenin were examined by Western blot analysis. The signaling pathway downstream of DKK1 was characterized using the Wnt signaling pathway inhibitor, IWP2, and glycogen synthase kinase 3 beta inhibitor, LiCl. Immunofluorescence analysis investigated the subcellular localization of β-catenin. The results suggested that knockdown of DKK1 caused reduced migration and invasion ability of H1299 and 95C cells. DKK1 silencing resulted in the downregulation of epithelial-mesenchymal transition-related proteins, such as Snail and zinc finger E-box binding homeobox 1. Besides, DKK1 silencing inhibited β-catenin and promoted the phosphorylation of β-catenin. Mechanism results indicated that the expression of β-catenin was reduced in H1299 or 95C cells after being treated with Wnt signaling inhibitor, IWP2. In addition, the inhibition of β-catenin phosphorylation by glycogen synthase kinase 3 beta inhibitor, LiCl, significantly enhanced the migration and invasion capacities in DKK1-knockdown cell lines. Furthermore, cell immunofluorescence revealed that nuclear β-catenin was reduced when DKK1 was knocked down. Taken together, these findings suggest that DKK1 induces the occurrence of epithelial-mesenchymal transition and promotes migration and invasion in non-small cell lung cancer cells. Mechanically, β-catenin plays a vital role in DKK1-induced non-small cell lung cancer cell migration and invasion, and DKK1 inhibits the phosphorylation of β-catenin, resulting in the increased nuclear localization of β-catenin.

Development and Validation of a Serum Biomarker Panel for the Detection of Esophageal Squamous Cell Carcinoma through RNA Transcriptome Sequencing

Serum tumor markers for the diagnosis of esophageal squamous cell carcinoma (ESCC) have low sensitivity. This study aims to identify new serum markers for ESCC diagnosis from RNA sequencing (RNA-seq) data.

RNA-seq was performed using six pairs of ESCC and matched normal tissues. The candidates for ESCC were screened from the differentially expressed genes. The candidates were analyzed by ELISA from the serum of a test group and a validation group. Real-time PCR, Western blotting and immunohistochemistry were used to detect the expression of the candidates in tumor cell lines and tumor tissues.

Ten genes were selected from the RNA-seq data. Serum levels of ADAM12, CHI3L1, MMP13 and SPP1 were significantly higher in the ESCC patients than in the healthy controls. A diagnostic model combining CHI3L1, MMP13, and SPP1 was established. The area under the curve (AUC) values for serum CHI3L1, MMP13, and SPP1 and the diagnostic model for discriminating ESCC patients from controls were 0.732, 0.881, 0.661 and 0.928, respectively. In the validation cohort, the AUC values were 0.753, 0.789, 0.696 and 0.843, respectively. Moreover, the AUC of the model for classifying patients with early ESCC was 0.918 in the test group and 0.857 in the validation group. Overexpression of CHI3L1, MMP13 and SPP1 was observed in the tumor cell lines and tissues.

The diagnostic model composed of CHI3L1, MMP13 and SPP1 discriminates ESCC patients with high sensitivity. Our data highlight the potential of this diagnostic model for the noninvasive diagnosis of ESCC.

The Dickkopf1-cytoskeleton-associated protein 4 axis creates a novel signalling pathway and may represent a molecular target for cancer therapy

Dickkopf 1 (DKK1) is a secreted protein and antagonizes oncogenic Wnt signalling by binding to the Wnt co-receptor, low-density lipoprotein receptor-related protein 6. DKK1 has also been suggested to regulate its own signalling, associated with tumour aggressiveness. However, the underlying mechanism by which DKK1 promotes cancer cell proliferation has remained to be clarified for a long time. The cytoskeleton-associated protein 4 (CKAP4), originally identified as an endoplasmic reticulum membrane protein, was recently found to act as a novel DKK1 receptor. DKK1 stimulates cancer cell proliferation when CKAP4 is expressed on the cell surface membrane. Although there are no tyrosine residues in the intracellular region of CKAP4, CKAP4 forms a complex with PI3K upon the binding of DKK1, leading to the activation of Akt. Both DKK1 and CKAP4 are frequently expressed in pancreatic and lung tumours, and their simultaneous expression is negatively correlated with prognosis. Knockdown of CKAP4 in cancer cells and treatment of mice with the anti-CKAP4 antibody inhibit Akt activity in cancer cells and suppress xenograft tumour formation, suggesting that CKAP4 may represent a therapeutic target for cancers expressing both DKK1 and CKAP4. This review will provide details of the novel DKK1-CKAP4 signalling axis that promotes cancer proliferation and discuss the possibility of targeting this pathway in future cancer drug development.

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.

Serum dickkopf-1 as a clinical and prognostic factor in non-small cell lung cancer patients with bone metastases

Background

The study was designed to evaluate the association between serum dickkopf-1 (DKK1) and non-small cell lung cancer (NSCLC) bone metastases.

Materials and Methods

Serum DKK1 levels were quantified in 470 NSCLC patients, 140 with osseous metastases, 178 with extraosseous metastases, and 152 with early stage in complete remission. The Receiver Operating Characteristic (ROC) curve enabled us to identify a threshold value to distinguish patients with bone metastases.

Results

Serum DKK1 levels in patients with osseous metastases were significantly higher than in the other 2 groups (P < 0.001). ROC curves showed that the optimum cutoff was 311.8 pg/ml (area under curve 0.791, 95% confidence interval 0.739–0.843, sensitivity 77.1% and specificity 71.4%). Of interest, serum DKK1 correlated with the number of bone lesions (P = 0.042) and associated with the poor survival in NSCLC patients with osseous metastases (P = 0.029).

Conclusions

Our data shows that serum DKK1 can be used for the detection of NSCLC bone metastases. More importantly this is the first report to show that serum DKK1 is a good predictor of poor prognosis in NSCLC patients with bone metastases.

Decreased Circulating Levels of Dickkopf-1 in Patients with Exudative Age-related Macular Degeneration

Aberrant activation of the Wnt/β-catenin signaling pathway plays a pathogenic role in retinal inflammation and neovascularization. Here, we investigated whether circulating levels of Dickkopf-1 (DKK-1), a specific inhibitor of this pathway, are altered in patients with exudative age-related macular degeneration (AMD). Plasma was obtained from 128 patients with exudative AMD, 46 patients with atrophic AMD and 111 healthy controls. DKK-1 levels in plasma were measured using ELISA, and data analyzed with one-way ANOVA, logistic regression analysis and receiver-operating characteristic analysis (ROC). We found that DKK-1 levels were decreased in exudative AMD patients, compared with healthy controls (P < 0.001) and atrophic AMD patients (P < 0.001). The decrease was more prominent in patients with classic choroidal neovascularization (CNV) than those with occult CNV (P < 0.001). The odds ratio (OR) of exudative AMD was 11.71 (95% CI; 5.24–6.13) for lowest versus upper quartile of DKK-1 levels. For discriminating exudative AMD patients, the optimum diagnostic cutoff of DKK-1 was 583.1 pg/mL with the area under curve (AUC) 0.76 (95% CI, 0.70–0.82; P < 0.001), sensitivity 78.1% and specificity 63.1%. These findings suggested that decreased circulating DKK-1 levels are associated with the development and severity of exudative AMD, and have potential to become a biomarker for exudative AMD.

The Biological Effects of Dickkopf1 on Small Cell Lung Cancer Cells and Bone Metastasis

The bone is among the most common sites of metastasis in patients with lung cancer. Over 30%–40% of lung cancers can develop bone metastasis, and no effective therapeutic methods exist in clinic cases. Wnt/β-catenin signaling and Dickkopf1 (DKK1) play important roles in the progression of lung cancer, which preferentially metastasizes to the skeleton. However, the role of DKK1 in osteotropism of small cell lung cancer (SCLC) remains to be elucidated. This study aimed to define the role of DKK1 in SCLC bone metastasis and investigate the underlying mechanisms. Our results demonstrated that the expression level of DKK1 was dramatically higher in bone metastatic SCLC cells (SBC-5 cell line) compared with that in cells without bone metastatic ability (SBC-3 cell line). Therefore, we hypothesized that DKK1 was involved in the bone metastasis of SCLC. We then suppressed the DKK1 expression in SBC-5 cells by RNAi and found that downregulation of DKK1 can inhibit cell proliferation, colony formation, cell migration, and invasion, but increase the apoptosis rate. Downregulation of DKK1 did not affect the cell cycle progression of SBC-5 cells in vitro. In vivo, downregulated DKK1 in SBC-5 cells resulted in attenuated bone metastasis. These results indicated that DKK1 may be an important regulator in bone metastases of SCLC, and targeting DKK1 may be an effective method to prevent and treat skeleton metastases in SCLC cases.