22943

DKK1

dickkopf WNT signaling pathway inhibitor 1;DKK1;dickkopf WNT signaling pathway inhibitor 1

dickkopf 1 homolog|dickkopf related protein-1|dickkopf-1 like|dickkopf-like protein 1|dickkopf-related protein 1|hDkk-1

10q11.2

protein-coding

The critical role of the Wnt pathway inhibition in sustaining the onset of bone lesions has been demonstrated in a variety of bone diseases and tumors, and it has been associated with cancer aggressiveness. We have previously demonstrated that neuroblastoma cells express Dickkopf 1 (Dkk1), an inhibitor of the canonical Wnt pathway which prevents the differentiation of bone-forming cells. Since Dkk1 is a secreted factor, it could have potential clinical application as tumor marker for detecting bone metastasis and monitoring of disease. In this study, we investigated the diagnostic and prognostic value of Dkk1 plasma levels in 92 children affected by neuroblastoma, including 32 with bone metastases. Fifty-seven children hospitalized for minor surgical problems served as control group. Circulating levels of Dkk1 were higher in healthy children than in normal adults and were comparable to those found in adult patients with aggressive tumors. No significant differences were found between neuroblastoma patients and controls and between patients with and without bone metastases. However, when only patients with metastatic neuroblastoma were considered, the highest Dkk1 levels were detected in patients that poorly responded to induction chemotherapy and in subjects with unamplified MYCN and three or more different metastatic sites. The 'Receiver Operating Characteristic' curve enabled us to identify a threshold value to distinguish patients who were unresponsive to induction treatment. The relationship between Dkk1 and drug resistance was supported by in vitro experiments, since an increased sensitivity to doxorubicin was found in neuroblastoma cells releasing low Dkk1 levels, either constitutively or experimentally following the treatment with specific siRNA. In conclusion, Dkk1 is released by neuroblastoma cells and is able to affect the balance between osteoblastogenesis and osteoclastogenesis, thus favoring the onset of osteolytic metastases. Nevertheless, Dkk1 plasma levels do not allow the detection of bone lesions in neuroblastoma but seem to have a predictive value with regard to the severity and the prognosis of the disease in a subset of patients with metastatic tumor. New knowledge on the biological role of Dkk1 in driving the natural history of neuroblastoma has to be further investigated and could help to establish specific therapeutic strategies able to target key factors of tumor progression.

AIM: To investigate the involvement of Dickkopf-1 expression in gastric cancer. METHODS: Dickkopf-1 mRNA and protein expression were determined by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and immunohistochemistry in specimens of primary cancer and their adjacent noncancerous tissues in gastric cancer patients. RESULTS: Dickkopf-1 mRNA and protein expression levels were both significantly upregulated in gastric cancer lesions compared with adjacent noncancerous tissues. Its positive expression was correlated with depth of invasion, vessel invasion, lymph node and distant metastasis, and TNM stage of tumors. Additionally, in stages I, II, and III gastric cancers, the 5- year survival rate of patients with a high expression of Dickkopf-1 was significantly lower than that in patients with low expression. In stage IV, Dickkopf-1 expression did not correlate with the 5-year survival rate. Further multivariate analysis suggested that the up-regulation of Dickkopf-1 was an independent prognostic indicator for gastric cancer. CONCLUSION: A subset of cases with gastric cancer revealed the up-regulation of Dickkopf-1, which was associated with a progressive pathological feature and an aggressive clinical course. Therefore, Dickkopf-1 expression may be predictor for poor prognosis in patients with gastric cancer. This is the first report describing the involvement of Dickkopf-1 in gastric cancer.

Head and neck squamous cell carcinoma (HNSCC) is a frequently occurring cancer worldwide. Dickkopf (Dkk)-1 gene is suggested to function as tumor suppressor gene (TSG) in several kinds of malignancies. In this study, we performed loss of heterozygosity (LOH) analysis of Dkk-1 and examined the correlation between LOH status and clinicopathological parameters for the first time. A pretty high LOH ratio (50%) was detected. Interestingly, in the cases with Dkk-1 retention group showed less distant metastasis and a tendency of longer disease free survival. These results indicate that Dkk-1 can play a role in HNSCC carcinogenesis and it may also be related to distant metastasis.

CONCLUSIONS: Dickkopf-1 (DKK1) is a novel prognostic biomarker for laryngeal squamous cell carcinoma (LSCC). DKK1 may be a promising strategy for the future treatment of LSCC metastasis and recurrence. OBJECTIVES: DKK1 is reportedly involved in the metastasis and invasion of several tumor types. This study aimed to investigate the prognostic value of DKK1 in LSCC. METHODS: DKK1 expression was measured in Hep-2 cell lines, as well as in tumor and peritumoral tissues, using quantitative real-time PCR and western blot analyses. The role of DKK1 in LSCC was investigated by depleting DKK1 using small interfering RNAs. Tissue microarrays of 102 LSCC patient samples were employed to immunohistochemically detect expression of DKK1, vascular endothelial growth factor C (VEGF-C), and beta-catenin. Prognostic significance was assessed using Kaplan-Meier survival estimates. RESULTS: DKK1 expression was elevated in the Hep-2 cell line and tumor samples. DKK1 depletion decreased cell proliferation, migration, and invasiveness. High DKK1 expression was significantly associated with T and clinical stage, lymph node metastasis, and tumor size (p < 0.05). Increased DKK1 levels in LSCC tissues correlated with elevated VEGF-C and beta-catenin. Multivariate analyses revealed that DKK1 was an unfavorable predictor of overall survival.

BACKGROUND: Dickkopf-1 (DKK1) recently has been reported to be involved in the progress of hepatocellular carcinoma, but its concrete role is not clear. The objective of this study is to investigate the clinical significance, biological function and molecular mechanism of DKK1 in the invasion and metastasis of hepatocellular carcinoma. METHODS: The mRNA and protein expression levels of DKK1 in hepatocellular carcinoma were detected and its prognostic significance was assessed. The biological function of DKK1 in hepatocellular carcinoma was investigated by using wound healing, transwell invasion assay and hepatocellular carcinoma metastatic mouse model. RESULTS: DKK1 was predominantly elevated in hepatocellular carcinoma tissues, especially in tissue with vascular invasion. The increased DKK1 expression was correlated with multiple tumour nodes, high Edmondson-Steiner grade and vein invasion, as well as poor overall and disease-free survival of hepatocellular carcinoma. DKK1 could promote hepatocellular carcinoma cell invasion and metastasis in vitro and in vivo. Finally, a positive relationship of DKK1 expression with RhoA and JNK levels was found in both hepatocellular carcinoma cell lines and tissues, suggesting that DKK1 promotes invasion and metastasis of hepatocellular carcinoma possibly through the non-canonical Wnt pathway. CONCLUSIONS: Collectively, our findings suggest that DKK1 could serve as a novel prognostic marker and therapeutic target for hepatocellular carcinoma.