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

Molecular mechanisms of sorafenib action in liver cancer cells

Sorafenib, a multikinase inhibitor, recently received FDA approval for the treatment of advanced hepatocellular carcinoma (HCC). However, as the clinical application of sorafenib evolves, there is increasing interest in defining the mechanisms underlying its anti-tumor activity. Considering that this specific inhibitor could target unexpected molecules depending on the biologic context, a precise understanding of its mechanism of action could be critical to maximize its treatment efficacy, while minimizing adverse effects. Two human HCC cell lines (HepG2 and Huh7), carrying different biological and genetic characteristics, were used in this study to examine the intracellular events leading to sorafenib-induced HCC cell-growth inhibition. Sorafenib inhibited cell growth in both cell lines in a dose- and time-dependent manner and significantly altered expression levels of 826 and 2011 transcripts in HepG2 and Huh7 cells, respectively. Genes functionally involved in angiogenesis, apoptosis, transcription regulation, signal transduction, protein biosynthesis and modification were predominantly upregulated, while genes implicated in cell cycle control, DNA replication recombination and repair, cell adhesion, metabolism and transport were mainly downregulated upon treatment. However, each sorafenib-treated HCC cell line displayed specificity in the expression and activity of crucial factors involved in hepatocarcinogenesis. The altered expression of some of these genes was confirmed by semiquantitative and quantitative RT-PCR and by western blotting. Many novel genes emerged from our transcriptomics analysis that had not previously been reported to be effected by sorafenib. Further functional analyses may determine whether these genes can serve as potential molecular targets for more effective anti-HCC strategies.

Clinical significance of serum and tissue Dickkopf-1 levels in patients with gastric cancer

BACKGROUND

Dickkopf-1 (DKK1), a secreted protein known as a negative regulator of the Wnt signaling pathway, has been implicated in tumorigenesis. However, the clinical significance of DKK1 in gastric cancer has not been clarified.

METHODS

Serum concentrations of DKK1 in 153 patients with gastric cancer and 173 healthy controls were assessed. For tissue DKK1, immunohistochemistry was performed in 144 cancer specimens from 153 patients and in an additional 265 consecutive gastric cancer specimens.

RESULTS

The serum DKK1 concentrations were significantly higher in the gastric cancer patients than in the healthy controls (p<0.001). At a cutoff concentration of 31.9150 pg/ml, the sensitivity and the specificity for gastric cancer diagnosis were 87.6% and 87.9%, respectively. The gastric cancer patients with a serum DKK1 level of ≥ 60.0 pg/ml had significantly diminished survival compared with the patients whose serum DKK1 levels were lower (p=0.033). The DKK1 overexpression in the cancer specimens significantly correlated with the increased serum DKK1 concentrations.

CONCLUSIONS

Serum DKK1 levels have the potential as a diagnostic marker at a low cutoff value and as a prognostic marker at a high cutoff value. Serum and tissue DKK1 levels may aid in diagnosing gastric cancer and predicting patient outcomes.

RUNX3 downregulation in human lung adenocarcinoma is independent of p53, EGFR or KRAS status

RUNX3 aberrations play a pivotal role in the oncogenesis of breast, gastric, colon, skin and lung tissues. The aim of this study was to characterize further the expression of RUNX3 in lung cancers. To achieve this, a lung cancer tissue microarray (TMA), frozen lung cancer tissues and lung cell lines were examined for RUNX3 expression by immunohistochemistry, while the TMA was also examined for EGFR and p53 expression. RUNX3 promoter methylation status, and EGFR and KRAS mutation status were also investigated. Inactivation of RUNX3 was observed in 70% of the adenocarcinoma samples, and this was associated with promoter hypermethylation but not biased to EGFR/KRAS mutations. Our results suggest a central role of RUNX3 downregulation in pulmonary adenocarcinoma, which may not be dependent of other established cancer-causing pathways and may have important diagnostic and screening implications.

Critical function for nuclear envelope protein TMEM209 in human pulmonary carcinogenesis

Therapeutic targets for more effective and less toxic treatments of lung cancer remain important. Here we report the identification of the integral nuclear envelope protein TMEM209 as a critical driver of human lung cancer growth and survival. TMEM209 expression was normally limited to testis, but we found that it was widely expressed in lung cancer, in which it localized to the nuclear envelope, Golgi apparatus, and the cytoplasm of lung cancer cells. Ectopic overexpression of TMEM209 promoted cell growth, whereas TMEM209 attenuation was sufficient to block growth. Mass spectrometric analysis identified the nucleoporin protein NUP205 as a TMEM209-interacting protein, stabilizing NUP205 and increasing the level of c-Myc in the nucleus. Taken together, our findings indicate that TMEM209 overexpression and TMEM209-NUP205 interaction are critical drivers of lung cancer proliferation, suggesting a promising new target for lung cancer therapy.

Expression of dickkopf-1 and beta-catenin related to the prognosis of breast cancer patients with triple negative phenotype

Background and Aim

We investigated the prognostic importance of dickkopf-1(DKK1) and beta-catenin expression in triple negative breast cancers.

Methods

The expression of DKK1 and beta-catenin was evaluated in breast cell lines using RT-PCR and western blot. Immunohistochemistry was used to characterize the expression pattern of DKK1 and beta-catenin in 85 triple negative breast cancers and prognostic significance was assessed by Kaplan-Meier analysis and Cox proportional hazards regression modeling.

Results

The expression of DKK1 was confirmed in hormone-resistant breast cell lines MDA-MB-231, MDA-MB-231-HM and MDA-MB-435. Expression of DKK1 in triple negative breast cancers correlated with cytoplasmic/nuclear beta-catenin (p = 0.000). Elevated expression of DKK1 and cytoplasmic/nuclear beta-catenin in triple negative cancers indicate poor outcome of patients. DKK1 was also a prognostic factor for patients with earlier stage or no lymph node metastasis.

Conclusion

DKK1 together with beta-catenin might be important prognostic factors in triple negative breast carcinoma. DKK1 might be a valuable biomarker in predicting the prognosis of patients with earlier stage or no lymph node metastasis. It is possible that through further understanding of the role of Wnt/beta-catenin pathway activation, beta-catenin would be a potential therapeutic target for the triple negative breast cancer.

STAT5 isoforms regulate colorectal cancer cell apoptosis via reduction of mitochondrial membrane potential and generation of reactive oxygen species

Although the two isoforms of signal transducer and activator of transcription 5 (STAT5) protein, STAT5a and STAT5b, have 94% sequence identity, they are encoded by different genes. Previous studies have been unable to define clearly the roles of the STAT5 genes in colorectal cancer (CRC). To investigate the role of STAT5 isoforms in CRC oncogenesis, immunohistochemical staining was performed. Colorectal adenocarcinomas showed higher expression of STAT5a/5b than normal colonic mucosa (P < 0.05), and STAT5b expression was significantly higher than that of STAT5a in colorectal adenocarcinoma tissue (P < 0.05). Furthermore, STAT5b expression was significantly associated with TNM stage. To delineate the roles of STAT5a/5b in CRC carcinogenesis, we studied CRC cells depleted of each isoform by treating the cells with small interfering RNA. Both STAT5a and STAT5b were found to be involved in cell growth, cell cycle progression, and apoptosis of CRC cells, and exerted their effects via the regulation of downstream targets of the STAT genes. However, STAT5b influenced CRC cell apoptosis more than STAT5a (P < 0.05), reducing mitochondrial membrane potential and generating reactive oxygen species. In conclusion, both isoforms of STAT5 are involved in the growth and cell cycle progression of CRC cells, STAT5b could play a more important role than STAT5a in the clinicopathological characteristics of CRC and CRC cell apoptosis.

Serological antibodies against LY6K as a diagnostic biomarker in esophageal squamous cell carcinoma

OBJECTIVES

To evaluate the diagnostic values of autoantibodies against lymphocyte antigen 6 complex locus K (LY6K) in esophageal squamous cell carcinoma (ESCC).

METHODS

After cloning, expressing, and purifying LY6K as fusion proteins, LY6K autoantibodies were measured in 62 patient and 58 control serum samples using enzyme-linked immunosorbent assay (ELISA). Reverse transcription polymerase chain reaction (RT-PCR) was used to measure the LY6K mRNA levels in ESCC and adjacent tissues.

RESULTS

LY6K autoantibodies were found significantly higher in patients than controls. The area under the receiver-operating characteristic (ROC) curve (AUC) was 0.85, and the optimal sensitivity and specificity for ESCC detection were 80.6 and 78.7%, respectively. LY6K mRNA expressions in patients were upregulated.

CONCLUSIONS

Autoantibodies against LY6K may be a good diagnostic biomarker for ESCC.

Dickkopf-1 expression is a novel prognostic marker for gastric cancer

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.

Characterization of an Opa interacting protein 5 involved in lung and esophageal carcinogenesis

To identify potential molecular targets for diagnosis, treatment and/or prevention of lung and esophageal carcinomas, we screened for genes that were overexpressed in tumors through gene expression analyses of 120 lung cancers and 19 esophageal squamous-cell carcinomas using a cDNA microarray consisting of 27,648 cDNA or expressed sequence tags. In this process, we identified a gene, Opa interacting protein 5 (OIP5), to be highly transactivated in the majority of lung and esophageal cancers. Immunohistochemical staining using 336 archived non-small cell lung cancers and 305 esophageal squamous-cell carcinomas specimens demonstrated that OIP5 expression was significantly associated with poor prognosis of lung and esophageal cancer patients (P = 0.0053 and 0.0168, respectively), and multivariate analysis confirmed its independent prognostic value for non-small cell lung cancers (P = 0.0112). Suppression of OIP5 expression with siRNA effectively suppressed the growth of cancer cells, whereas the exogenous expression of OIP5 enhanced the growth of cancer cells. In addition, OIP5 protein is likely to be stabilized through its interaction with Raf1. OIP5 is a promising target for developing new prognostic biomarkers and anti-cancer drugs.

Dickkopf1: a tumor suppressor or metastasis promoter?

Dickkopf1 (DKK1), a secreted inhibitor of the Wnt/β-catenin pathway, is a negative regulator of bone formation. DKK1 acts as a switch that transitions prostate cancer bone metastases from osteolytic to osteoblastic and also is an active indicator of poor outcome for multiple myeloma. However, in other tumor types, DKK1 upregulation or overexpression suppresses tumor growth. Thus, the role of DKK1 in cancer appears to be diverse. This raises a question: Could the increased levels of DKK1 still be tumor protective when observed in high levels in the serum of patients? Here, we summarize the diverse, seemingly contradicting roles of DKK1 and attempt to explain the apparent dichotomy in its activity. We propose that DKK1 is a critical secreted factor that modulates microenvironment. Based on the location and components of the microenvironment DKK1 will support different outcomes.

Clinicopathological and prognostic significance of serum and tissue Dickkopf-1 levels in human hepatocellular carcinoma

BACKGROUND

Although Dickkopf-1 (DKK1) is known to be a negative regulator of the Wnt/β-catenin pathway, it has been recently found to be upregulated in cancers.

AIMS

We investigated the clinical and prognostic significance of both serum and transcript DKK1 and its functional roles in human hepatocellular carcinoma (HCC).

METHODS

We evaluated the expression level of DKK1 in both tissue and serum samples from patients with HCC using GeneChip microarray and real-time-quantitative PCR and sandwich ELISA system respectively. The clinicopathological and prognostic significance of serum and tissue DKK1 levels was examined. Functional characterization of DKK1 with regard to cell migration, invasion and tumour growth was performed.

RESULTS

Both DKK1 transcript and serum protein were upregulated in a stepwise manner in human HCCs. Its transcript levels were associated with more aggressive tumour behaviour, in terms of venous invasion (P = 0.003), advanced tumour stage (P = 0.003). DKK1 transcript correlated with shorter overall (P = 0.006) and disease-free survival (P = 0.012), and higher serum DKK1 levels correlated with shorter disease-free survival (P = 0.046). Knockdown of DKK1 significantly reduced both migratory and invasive abilities of HCC cells, whereas overexpression of DKK1 enhanced the tumour formation efficiency and tumour growth in vivo.

CONCLUSIONS

Serum and tissue DKK1 levels increased in a stepwise manner in multistep hepatocarcinogenesis and had prognostic significance. DKK1 plays a functional role in cell migration, invasion and tumour growth.

Chondrolectin is a novel diagnostic biomarker and a therapeutic target for lung cancer

PURPOSE

This study aims to identify molecules that might be useful as diagnostic/prognostic biomarkers and as targets for the development of new molecular therapies for lung cancer.

EXPERIMENTAL DESIGN

We screened for genes that were highly transactivated in a large proportion of 120 lung cancers by means of a cDNA microarray representing 27,648 genes and found chondrolectin (CHODL) as a candidate. Tumor tissue microarray was applied to examine the expression of CHODL protein and its clinicopathologic significance in archival non-small cell lung cancer (NSCLC) tissues from 295 patients. A role of CHODL in cancer cell growth and/or survival was examined by siRNA experiments. Cellular invasive effect of CHODL on mammalian cells was examined by Matrigel assays.

RESULTS

Immunohistochemical staining revealed that strong positivity of CHODL protein was associated with shorter survival of patients with NSCLC (P = 0.0006), and multivariate analysis confirmed it to be an independent prognostic factor. Treatment of lung cancer cells with siRNAs against CHODL suppressed growth of the cancer cells. Furthermore, induction of exogenous expression of CHODL conferred growth and invasive activity of mammalian cells.

CONCLUSIONS

CHODL is likely to be a prognostic biomarker in the clinic and targeting CHODL might be a strategy for the development of anticancer drugs.

Dickkopf-1 is involved in invasive growth of esophageal cancer cells

Dickkopf-1 (DKK1) is an inhibitor of Wnt/β-catenin signaling pathway. High levels of DKK1 protein were found in a series of cancers. However, the role of DKK1 in the progression of esophageal carcinoma is not fully understood. In the present study, RT-PCR and Western blot were used to detect the expression of DKK1 in esophageal carcinoma tissues, matched adjacent normal esophageal tissues, and esophageal carcinoma cell lines. Our results showed that the expression of DKK1 was upregulated on both mRNA and protein levels in esophageal carcinoma tissues compared with the adjacent normal esophageal tissues, meanwhile, in four esophageal carcinoma cell lines analyzed, expression of DKK1 was detected with different levels. Immunohistochemistry and immunofluoresence revealed that the distribution of DKK1 was mainly in the cytoplasm in both carcinoma tissues and cell lines. To further explore the biological effects of DKK1 on proliferation, cell cycle and invasion capability, we constructed the eukaryotic expression vector pCMV-Tab-2b-DKK1 which can effectively overexpress DKK1. Subsequently, we observed that exogenous expression of DKK1 in EC9706 cell line resulted in an increased rate of proliferation, and S stage and G2/M stage ratio whereas G0/G1 ratio was decreased. In order to evaluate the invasion capability Boyden chamber was analyzed which implied that overexpression of DKK1 resulted in an increase in the invasion ability in EC9706 cell line. Taken together, the study indicates that DKK1 might be a key regulator in the progression of esophageal carcinoma and a potential therapeutic target in esophageal carcinoma.

Dickkopfs and Wnt/β-catenin signalling in liver cancer

Liver cancer is the fifth and seventh most common cause of cancer in men and women, respectively. Wnt/β-catenin signalling has emerged as a critical player in both the development of normal liver as well as an oncogenic driver in hepatocellular carcinoma (HCC). Based on the current understanding, this article summarizes the possible mechanisms for the aberrant activation of this pathway with specific focus on HCC. Furthermore, we will discuss the role of dickkopfs (DKKs) in regulating Wnt/β-catenin signalling, which is poorly understood and understudied. DKKs are a family of secreted proteins that comprise at least four members, namely DKK1-DKK4, which act as inhibitors of Wnt/β-catenin signalling. Nevertheless, not all members antagonize Wnt/β-catenin signalling. Their functional significance in hepatocarcinogenesis remains to be further characterized for which these studies should provide new insights into the regulatory role of DKKs in Wnt/β-catenin signalling in hepatic carcinogenesis. Because of the important oncogenic roles, there are an increasing number of therapeutic molecules targeting β-catenin and the Wnt/β-catenin pathway for potential therapy of HCC.

Characterization of a cleavage stimulation factor, 3' pre-RNA, subunit 2, 64 kDa (CSTF2) as a therapeutic target for lung cancer

PURPOSE

This study aims to discover novel biomarkers and therapeutic targets for lung cancers.

EXPERIMENTAL DESIGN

We screened for genes showing elevated expression in the majority of lung cancers by genome-wide gene expression profile analysis of 120 lung cancers obtained by cDNA microarray representing 27,648 genes or expressed sequence tags. In this process, we detected a gene encoding cleavage stimulation factor, 3' pre-RNA, subunit 2, 64 kDa (CSTF2) as a candidate. Immunohistochemical staining using tissue microarray consisting of 327 lung cancers was applied to examine the expression of CSTF2 protein and its prognostic value. A role of CSTF2 in cancer cell growth was examined by siRNA experiments.

RESULTS

Northern blot and immunohistochemical analyses detected the expression of CSTF2 only in testis among 16 normal tissues. Immunohistochemical analysis using tissue microarray showed an association of strong CSTF2 expression with poor prognosis of patients with non-small cell lung cancer (P = 0.0079), and multivariate analysis showed that CSTF2 positivity is an independent prognostic factor. In addition, suppression of CSTF2 expression by siRNAs suppressed lung cancer cell growth, whereas exogenous expression of CSTF2 promoted growth and invasion of mammalian cells.

CONCLUSIONS

CSTF2 is likely to play an important role in lung carcinogenesis and be a prognostic biomarker in the clinic.

Polyfunctionality of a DKK1 self-antigen-specific CD8(+) T lymphocyte clone in lung cancer

Polyfunctionality is the capacity of a T-cell to execute a variety of effector functions mainly mediated by production of cytokines, chemokines, and cytolytic enzymes. Studies in anti-viral immunity have acknowledged the importance of polyfunctionality in the clearance of infections and maintenance of protection. Although accepted in the field, this concept has not been as well characterized in cancer immunology. Here, we report the polyfunctionality profile analysis of a CD8(+) T-cell clone isolated from a lung cancer patient and directed against Dickkopf-1, a potentially new tumor-associated antigen (TAA). The clone showed Tc1/Th1 effector tendencies confirmed by secretion of cytokines such as IFN-γ, IP-10, MIP-1β, MIP-1α, IL-2, GM-CSF, and expression of cytolytic enzyme granzyme B. This secretion profile is of particular interest in the context of an anti-tumor response. Although secretion of IL-5 and IL-13 was also detected, absence of IL-4 and IL-10 opposes the idea of cytokine-dependent Th1 inhibition. Establishing a comprehensive cytokine secretion profile may help predict T cells' specific response against a novel TAA in a peptide vaccination context. It may further help in selecting clones with an optimal functional profile from the peripheral blood of cancer patients for expansion and adoptive cell transfer therapy.

Expression and biological role of DKK1 in human esophageal cancer

AIM: To investigate the expression of dikkopf-1 (DKK1) in esophageal carcinoma tissue and four esophageal carcinoma cell lines and to explore the impact of DKK1 overexpression on cell cycle and invasion in EC9706 cell line.

METHODS: The expression of DKK1 in esophageal carcinoma tissues was detected by immunohistochemistry, and the distribution of DKK1 in esophageal carcinoma cell line TE13 was observed by immunofluorescence. Western blot was used to investigate the expression of DKK1 in esophageal carcinoma tissues and matched normal esophageal tissues, as well as in four esophageal carcinoma cell lines. A eukaryotic expression vector of DKK1 was constructed and transfected into EC9706 cells to evaluate the impact of DKK1 overexpression on cell cycle by flow cytometry and on cell invasion by Boyden chamber assay.

RESULTS: DKK1 was highly expressed in esophageal carcinoma tissues and mainly distributed in the cytoplasm of TE13 cells. The expression of DKK1 protein in carcinoma was obviously higher than that in matched normal esophageal tissue. Differential expression of DKK1 was observed in four esophageal carcinoma cell lines. Overexpression of DKK1 in EC9706 cells decreased the percentage of cells in G0/G1 phase and increased the percentage of cells in sphase and the number of cells penetrating through the membrane of Boyden chamber (252 ± 6.71 vs 99.18 ± 3.02; 252 ± 6.71 vs 112.33 ± 3.21, all P < 0.01).

CONCLUSION: DKK1 is overexpressed in esophageal carcinoma. Overexpression of DKK1 in EC9706 cells remarkably promoted cell invasion and progression from G1 phase to S phase.

Dickkopf-1 is frequently overexpressed in ovarian serous carcinoma and involved in tumor invasion

Dickkopf-1 (DKK1) was known as a negative regulator of the Wnt signaling pathway, which played a crucial role in carcinogenesis. However, its function in human cancers remained elusive. In this study, we aimed to investigate the role of DKK1 in ovarian serous papillary adenocarcinoma (OSC) tumor progression and invasion. Quantitative real-time RT-PCR and Western blot analysis showed that the expression of DKK1 mRNA and protein in 32 OSC tissues were elevated as compared with those in 10 normal ovarian tissues (P = 0.005, P = 0.003, respectively). Immunohistochemical analysis in 178 clinical OSC samples showed that the expression of DKK1 was positively associated with FIGO stage (P = 0.016). Furthermore, the expression of DKK1 protein was positively associated with P-JNK1 protein expression in 178 OSC tissues. DKK1, P-JNK1 and the co-expression of DKK1 and P-JNK1 were all unfavorable prognosis factors for OSC patients (P < 0.0001). DKK1, alone or combined with P-JNK1, was an independent predictor for the 5 year survival (P = 0.015, P < 0.0001, respectively). DKK1 could promote OSC cells invasion and the growth of OSC nude mice xenograft. DKK1 in OSC cells could activate P-JNK1 expression and significantly promote formations of actin filaments and filopodia. Thus, DKK1, alone or combined with P-JNK1, was a novel prognostic predictor for OSC patients and contributed to the invasion of OSC.

Autoantibodies against MMP-7 as a novel diagnostic biomarker in esophageal squamous cell carcinoma

AIM: To evaluate the diagnostic values of serum autoantibodies against matrix metalloproteinase-7 (MMP-7) in patients with esophageal squamous cell carcinoma (ESCC).

METHODS: The MMP-7 cDNA was cloned from ESCC tissues, and MMP-7 was expressed and purified from a prokaryotic system. MMP-7 autoantibodies were then measured in sera from 50 patients with primary ESCC and 58 risk-matched controls, using a reverse capture enzyme-linked immunosorbent assay (ELISA) in which autoantibodies to MMP-7 bound to the purified MMP-7 proteins. In addition, MMP-7 autoantibody levels in sera from 38 gastric cancer patients and from control serum samples were also tested.

RESULTS: The optimum conditions for recombinant MMP-7 protein expression were determined as 0.04 mmol/L Isopropyl-β-D-Thiogalactopyranoside (IPTG) induction at 37°C for four hours. The levels of serum autoantibodies against MMP-7 were significantly higher in patients with ESCC than in the matched-control samples (OD450 = 1.69 ± 0.08 vs OD450 = 1.55 ± 0.10, P < 0.001). The area under the receiver operating characteristic (ROC) curve was 0.87. The sensitivity and specificity for detection of ESCC were 78.0% and 81.0%, respectively, when the OD450 value was greater than 1.65. Although the levels of autoantibodies against MMP-7 were also significantly higher in patients with gastric cancer compared to control samples (OD450 = 1.62 ± 0.06 vs OD450 = 1.55 ± 0.10, P < 0.001), the diagnostic accuracy was less significant than in ESCC patients. The area of ROC curve was 0.75, whereas the sensitivity and specificity were 60.5% and 71.7%, respectively, when the cut-off value of OD450 was set at 1.60.

CONCLUSION: Serum autoantibody levels of MMP-7 may be a good diagnostic biomarker for esophageal squamous cell carcinoma.

Neuroblastoma and bone metastases: clinical significance and prognostic value of Dickkopf 1 plasma levels

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.

Prospective evaluation of operating characteristics of prostate cancer detection biomarkers

PURPOSE

We assessed the independent predictive values of the serum markers free prostate specific antigen, proenzyme prostate specific antigen, neuroendocrine marker and Dickkopf-1 compared to serum prostate specific antigen and other standard risk factors for early prostate cancer detection.

MATERIALS AND METHODS

From the prospectively collected SABOR cohort 250 prostate cancer cases, and 250 mean age matched and proportion of African-American race/ethnicity matched controls were selected who had a prior available prostate specific antigen and digital rectal examination. Serum samples were obtained, and free prostate specific antigen, [-2]proenzyme prostate specific antigen, Dickkopf-1 and neuroendocrine marker were measured. AUC, sensitivities and specificities were calculated, and multivariable logistic regression was used to assess the independent predictive value compared to prostate specific antigen, digital rectal examination, family history, prior biopsy history, race/ethnicity and age.

RESULTS

The AUCs (95% CI) were 0.76 (0.71, 0.8) for free prostate specific antigen, 0.72 (0.67, 0.76) for [-2]proenzyme prostate specific antigen, 0.76 (0.72, 0.8) for %free prostate specific antigen, 0.61 (0.56, 0.66) for %[-2]proenzyme prostate specific antigen, 0.73 (0.68, 0.77) for prostate health index, 0.53 (0.48, 0.58) for Dickkopf-1 and 0.53 (0.48, 0.59) for neuroendocrine marker. In the 2 to 10 ng/ml prostate specific antigen range the AUCs (95% CI) were 0.58 (0.49, 0.67) for free prostate specific antigen, 0.53 (0.44, 0.62) for [-2]proenzyme prostate specific antigen, 0.67 (0.59, 0.75) for %free prostate specific antigen, 0.57 (0.49, 0.65) for %[-2]proenzyme prostate specific antigen and 0.59 (0.51, 0.67) for phi. Only %free prostate specific antigen retained independent predictive value compared to the traditional risk factors.

CONCLUSIONS

Free prostate specific antigen retained independent diagnostic usefulness for prostate cancers detected through prostate specific antigen and digital rectal examination screening. Prostate specific antigen isoforms are highly correlated with prostate specific antigen. Future research is needed to identify new markers associated with prostate cancer through different mechanisms.

Analysis of the expression profile of Dickkopf-1 gene in human glioma and the association with tumor malignancy

BACKGROUND

Gliomas represent the most common primary malignant brain tumors, yet little is known about the molecular pathogenesis of these tumors. The highly-regulated Wnt signal transduction pathway is essential for normal developmental processes, and defects in the pathway are closely linked to oncogenesis. Dickkopf-1 (DKK-1) is a secreted protein that acts as a potent inhibitor of the Wnt pathway. The aim of this study was to examine the expression profile of DKK-1 gene in human glioma and its association with tumor malignancy.

METHODS

We determined the expression levels of DKK-1 transcript and protein in 12 glioblastoma cell lines, medulloblastoma cells, low-grade glioma cells, and human astrocyte cells by semiquantitative RT-PCR and ELISA. A total of 47 tumor biopsy specimens and 11 normal brain tissue samples from patients with cerebral trauma internal decompression were embedded in paraffin blocks and used for immunostaining. Twenty-six primary tumors and 7 corresponding brain samples were stored in liquid nitrogen and used for RT-PCR. We further examined serologic concentrations and cerebral fluid levels of DKK-1 in patients with tumors.

RESULTS

DKK-1 could only be detected in 12 human glioblastoma cell lines, not in a panel of other tumor and normal cell lines. The difference between glioma patients and healthy individuals was significant. Kendall's tau-c association analysis also revealed the increased DKK-1 protein expression in tumor tissues of higher pathologic classification. The levels of cerebral fluid DKK-1 protein were significantly higher in glioma patients than in healthy donors or in neuronal benign tumor patients, suggesting that the DKK-1 molecule in cerebral fluids can be applicable to detect the presence of glioma and be developed as a novel prognostic treatment.

CONCLUSION

The Wnt antagonist DKK-1 gene may have important roles in glioma tumorigenesis and act as a novel biomarker in human malignant glioblastoma.

Elevated expression of Dickkopf-1 increases the sensitivity of human glioma cell line SHG44 to BCNU

BACKGROUND

Studies have shown that Dickkopf-1 (DKK-1) is involved in tumorigenesis. Recently, we found that 9 out of 12 human glioma cell lines had high level of DKK-1 protein while the other 3 had very low or non-detectable level of DKK-1. The aim of this study is to further examine the function of DKK-1 in glioma cells.

MATERIALS AND METHODS

The glioma cell line SHG44 was obtained from a patient with grade II-III astrocytoma. SHG44 cells were transfected with a human DKK-1 gene. Transfection of the empty vector pcDNA3.1 was used as negative control. Sensitivity to BCNU was measured by Annexin-V staining. Expression of bax, bcl-2 and caspase-3 of three groups was determined by immunohistochemistry.

RESULTS

The tranfection was confirmed by PCR, RT-PCR and Western blot. More apoptotic cell death was observed in the DKK-1 transfected cells, comparing to the non-transfected cells, or cells with empty vector. The expression of bax and caspase-3 of the SHG44 -DDK-1 increased, whereas the expression of bcl-2 decreased

CONCLUSION

Our results indicated that DKK-1 has a pro-apoptotic function of in glioma.

DUSP1/MKP1 promotes angiogenesis, invasion and metastasis in non-small-cell lung cancer

DUSP1/MKP1 is a dual-specific phosphatase that regulates MAPKs activity, with an increasingly recognized role in tumor biology. To understand more about the involvement of DUSP1 in lung cancer, we performed gene expression analyses of parental and DUSP1-interfered H460 non-small-cell lung cancer (NSCLC) cells. Downregulation of DUSP1 induced changes in the expression levels of genes involved in specific biological pathways, including angiogenesis, MAP kinase phosphatase activity, cell-cell signaling, growth factor and tyrosine-kinase receptor activity. Changes in the expression of some of these genes were due to modulation of c-Jun-N-terminal kinase and/or p38 activity by DUSP1. Complementary functional assays were performed to focus on the implication of DUSP1 in angiogenesis and metastasis. In H460 cells, interference of DUSP1 resulted in a diminished capacity to invade through Matrigel, to grow tumors in nude mice and also to induce metastasis through tail-vein injection. Furthermore, the angiogenic potential of H460 cells was also impaired, correlating with a decrease in VEGFC production and indicating that DUSP1 could be required to induce angiogenesis. Finally, we studied whether a similar relationship occurred in patients. In human NSCLC specimens, DUSP1 was mainly expressed in those tumor cells close to CD31 vascular structures and a statistically significant correlation was found between VEGFC and DUSP1 expression. Overall, these results provide evidence for a role of DUSP1 in angiogenesis, invasion and metastasis in NSCLC.

High Dickkopf-1 expression is associated with poor prognosis in patients with advanced urothelial carcinoma

Although Dickkopf-1 (DKK1) has been demonstrated to be associated with tumorigenesis in various types of human tumors, a correlation between DKK1 and urothelial carcinoma (UC) has not been reported. In the present study, the correlation between DKK1 expression and UC progression was investigated. Seventy-five UC patients were enrolled. The expression of DKK1 in serum and UC tissue was detected by ELISA, real-time PCR and Western blotting. Prognostic significance was assessed by using Kaplan-Meier survival estimates and log-rank tests. The results showed that serum levels of DKK1 were significantly higher in the UC patients with muscle-invasive (p=0.0001) and high-grade tumors (p=0.00001) as compared to the controls. A high-serum DKK1 was also associated with poor disease-free survival in the UC patients (hazard ratio=2.44; 95% CI 1.10-5.40; p=0.028). Furthermore, DKK1 was also overexpressed in 93% (41/44) of the UC tissues. Therefore, the findings indicate that the expression of DKK1 is associated with UC progression.

Phosphorylation and activation of cell division cycle associated 5 by mitogen-activated protein kinase play a crucial role in human lung carcinogenesis

We analyzed the gene expression profiles of clinical lung carcinomas using a cDNA microarray containing 27,648 genes or expressed sequence tags, and identified CDCA5 (cell division cycle associated 5) to be upregulated in the majority of lung cancers. Tumor tissue microarray analysis of 262 non-small cell lung cancer patients revealed that CDCA5 positivity was an independent prognostic factor for lung cancer patients. Suppression of CDCA5 expression with siRNAs inhibited the growth of lung cancer cells; concordantly, induction of exogenous expression of CDCA5 conferred growth-promoting activity in mammalian cells. We also found that extracellular signal-regulated kinase (ERK) kinase phosphorylated CDCA5 at Ser79 and Ser209 in vivo. Exogenous expression of phospho-mimicking CDCA5 protein whose Ser209 residue was replaced with glutamine acid further enhanced the growth of cancer cells. In addition, functional inhibition of the interaction between CDCA5 and ERK kinase by a cell-permeable peptide corresponding to a 20-amino-acid sequence part of CDCA5, which included the Ser209 phosphorylation site by ERK, significantly reduced phosphorylation of CDCA5 and resulted in growth suppression of lung cancer cells. Our data suggest that transactivation of CDCA5 and its phosphorylation at Ser209 by ERK play an important role in lung cancer proliferation, and that the selective suppression of the ERK-CDCA5 pathway could be a promising strategy for cancer therapy.

Wnt inhibitor Dickkopf-1 as a target for passive cancer immunotherapy

Dickkopf-1 (DKK1) is an inhibitor of Wnt/beta-catenin signaling that is overexpressed in most lung and esophageal cancers. Here, we show its utility as a serum biomarker for a wide range of human cancers, and we offer evidence favoring the potential application of anti-DKK1 antibodies for cancer treatment. Using an original ELISA system, high levels of DKK1 protein were found in serologic samples from 906 patients with cancers of the pancreas, stomach, liver, bile duct, breast, and cervix, which also showed elevated expression levels of DKK1. Additionally, anti-DKK1 antibody inhibited the invasive activity and the growth of cancer cells in vitro and suppressed the growth of engrafted tumors in vivo. Tumor tissues treated with anti-DKK1 displayed significant fibrotic changes and a decrease in viable cancer cells without apparent toxicity in mice. Our findings suggest DKK1 as a serum biomarker for screening against a variety of cancers, and anti-DKK1 antibodies as potential theranostic tools for diagnosis and treatment of cancer.

Activation of an oncogenic TBC1D7 (TBC1 domain family, member 7) protein in pulmonary carcinogenesis

To develop novel biomarkers and therapeutic agents for lung cancers, we screened molecules that were highly expressed in lung cancers by means of cDNA microarray analysis and found an elevated expression of TBC1 domain family, member 7 (TBC1D7) in the majority of lung cancers. Northern-blot analysis using mRNAs from 16 normal tissues detected its expression only in testis. Immunohistochemical staining using tumor tissue microarrays consisting of 261 archived non-small cell lung cancer (NSCLC) specimens suggested an association of TBC1D7 expression with poor prognosis for NSCLC patients (P = 0.0063). Treatment of lung cancer cells using siRNA against TBC1D7, suppressed its expression and resulted in inhibition of the cell growth. Furthermore, the induction of exogenous expression of TBC1D7 conferred growth-promoting activity at in vitro and in vivo conditions. We also identified TBC1D7 to interact with TSC1 protein in lung cancer cells. TSC1 introduction into cells increased the level of TBC1D7 protein, whereas knockdown of TSC1 expression decreased the level of TBC1D7 protein, suggesting that TBC1D7 is stabilized probably through interaction with TSC1. In addition, inhibition of the binding between TBC1D7 and TSC1 by a TBC1D7-derived 20-amino acid cell-permeable peptide (11R-TBC1D7(152-171)), which corresponded to the binding domain to TSC1, effectively suppressed growth of lung cancer cells. Selective suppression of TBC1D7 and/or inhibition of the TBC1D7-TSC1 complex formation could be promising therapeutic strategies for lung cancer therapy.

Dickkopf-1 autoantibody is a novel serological biomarker for non-small cell lung cancer

OBJECTIVE

We investigated whether or not there are autoantibodies for DKK1 (Dickkopf-1) in patients with non-small cell lung cancer (NSCLC) and whether this autoantibody can be used for cancer detection.

METHODS

The levels of DKK1 autoantibodies were determined in 93 NSCLC patients and 87 healthy controls.

RESULTS

We found that, in the sera, the presence of autoantibody against DKK1 was highly correlated with NSCLC. High anti-DKK1 autoantibody titres were found in the sera of NSCLC patients, whereas low or negative titres were found in the control group. The ROC curve results showed that autoantibody immunoassay exhibited 62% sensitivity and 84% specificity. The sensitivity for the detection of NSCLC in stage I also reach 64.3%. Furthermore, a combined ELISA assays for both DKK1 and autoantibody DKK1 increased sensitivity and classified 81.7% (76/93) of the NSCLC patients as positive, whereas only 13.8 % (12/87) of healthy volunteers were falsely diagnosed as positive.

CONCLUSIONS

Our results suggest that the detection of circulating DKK1 autoantibody could potentially serve as a useful non-invasive marker for determining lung cancer status.

Dickkopf-1 is overexpressed in human pancreatic ductal adenocarcinoma cells and is involved in invasive growth

The protein products of the Dickkopf (DKK) genes are antagonists of Wnt glycoproteins, which participate in tumor development and progression by binding to frizzled receptors. In this study, the expression of DKK-1 was analyzed in a panel of 43 human cultured carcinoma cell lines. DKK-1 expression was consistently and significantly upregulated in pancreatic carcinoma cell lines. Low level of DKK-3 expression was also seen. In contrast, the expression of DKK-2 and -4 was not detectable in most pancreatic carcinoma cell lines. The overexpression of DKK-1 was confirmed in surgically resected human pancreatic cancer tissues, in which the mRNA level was evaluated in paired samples from cancerous and noncancerous pancreatic tissues. In ductal adenocarcinomas (23 cases), DKK-1 mRNA levels were significantly upregulated compared to corresponding noncancerous tissues in a statistically significant level. To test the biological role of DKK-1 in pancreatic carcinoma cells, we performed a knockdown of DKK-1 in SUIT-2 human pancreatic adenocarcinoma cell line and S2-CP8, its metastatic subline, using a retroviral short hairpin RNA expression vector. DKK-1 knockdown resulted in reduced migratory activity of SUIT-2 in vitro. The in vitro growth rate and Matrigel invasion were also suppressed by DKK-1 knockdown in S2-CP8 cells. Collectively, the evidence suggests that, despite of its presumed antagonistic role in Wnt signaling, DKK-1 may have a role in the aggressiveness of pancreatic carcinoma cells and could, therefore, serve as a novel biomarker of pancreatic cancer.

Clinical significance of serum DKK-1 in patients with gynecological cancer

Dickkopf-1 (DKK-1) is a secreted protein involved in embryonic development. Dickkopf-1 is also implicated in osteoporosis, arthritis, and cancer and represents a potential therapeutic target for the treatment of these diseases. Because DKK-1 encodes a secreted protein, we investigated whether the DKK-1 protein is secreted into the sera of patients with gynecological cancer. The levels of DKK-1 protein were assessed by enzyme-linked immunosorbent assay in the sera of 104 patients with gynecological cancer including 36 with ovarian, 40 with cervical, and 28 with endometrial cancers. The serum levels of DKK-1 protein were higher in patients with cervical (314.13 [385.02] pg/mL, P = 0.000) and endometrial (46.95 [21.62] pg/mL, P = 0.000) cancers than in healthy individuals (29.45 [11.86] pg/mL). The serum levels of DKK-1 protein were associated with clinical stage in all patients with gynecological cancer. In patients with cervical cancer, the serum levels of DKK-1 protein were also associated with histological type and lymphatic metastasis. Dickkopf-1 protein detection using enzyme-linked immunosorbent assay as a molecular marker can contribute to the detection and the diagnosis of cervical and endometrial cancers, especially for cervical squamous cell cancer.

Activation of WD repeat and high-mobility group box DNA binding protein 1 in pulmonary and esophageal carcinogenesis

PURPOSE

We attempted to identify novel biomarkers and therapeutic targets for lung and esophageal cancers.

EXPERIMENTAL DESIGN

We screened for genes that were overexpressed in a large proportion of lung and esophageal carcinomas using a cDNA microarray representing 27,648 genes or expressed sequence tags. A gene encoding WDHD1, a WD repeat and high-mobility group box DNA binding protein 1, was selected as a candidate. Tumor tissue microarray containing 267 archival non-small cell lung cancers and 283 esophageal squamous cell carcinomas (ESCC) was used to investigate the clinicopathologic significance of WDHD1 expression. The role of WDHD1 in cancer cell growth and/or survival was examined by small interfering RNA experiments and cell growth assays. The mechanism of WDHD1 activation through its phosphorylation in cancer cells was examined by immunoprecipitation and kinase assays.

RESULTS

Positive WDHD1 immunostaining was associated with a poor prognosis for patients with non-small cell lung cancer (P = 0.0403) as well as ESCC (P = 0.0426). Multivariate analysis indicated it to be an independent prognostic factor for ESCC (P = 0.0104). Suppression of WDHD1 expression with small interfering RNAs effectively suppressed lung and esophageal cancer cell growth. In addition, induction of the exogenous expression of WDHD1 promoted the growth of mammalian cells. AKT1 kinase seemed to phosphorylate and stabilize the WDHD1 protein in cancer cells.

CONCLUSIONS

WDHD1 expression is likely to play an important role in lung and esophageal carcinogenesis as a cell cycle regulator and a downstream molecule in the phosphoinositide 3-kinase/AKT pathway, and that WDHD1 is a candidate biomarker and a promising therapeutic target for cancer.

Dickkopf-1 promotes hyperglycemia-induced accumulation of mesangial matrix and renal dysfunction

Wnt/beta-catenin signaling mediates renal fibrosis in several model systems including diabetic nephropathy. Dickkopf-1 (DKK-1) is an endogenous inhibitor of Wnt/beta-catenin signaling, but whether DKK-1 modulates diabetic nephropathy is unknown. Here, we studied whether DKK-1 participates in high glucose (HG)-induced expression of profibrotic factors and renal damage. In vitro, HG increased expression of DKK1, receptor Kremen-2, TGF-beta1, and fibronectin in mesangial cells. Loss and gain of DKK1 function modulated HG-mediated c-Jun, TGF-beta1, and fibronectin expression. DKK1 mediated HG-induced phosphorylation of Ser45-beta-catenin and reduction of nuclear beta-catenin levels, but not phosphorylation of ERK kinase. Wnt3a protein and the beta-catenin (Delta45) mutation increased nuclear beta-catenin but abrogated HG-induced DKK1 and fibronectin expression. Exogenous DKK1 antisense oligonucleotide attenuated the increase in both serum DKK1 and urinary protein excretion in streptozotocin-induced diabetic rats. Knocking down DKK1 inhibited mesangial expression of TGF-beta1 and fibronectin and reduced both the glomerular volume and deposition of mesangial matrix in diabetic kidneys. Taken together, DKK1 mediates HG-induced destabilization of beta-catenin and matrix accumulation in mesangial cells. Knocking down DKK1 prevents diabetes-induced renal dysfunction and microstructure deterioration, suggesting that inhibition of DKK1offers therapeutic potential for diabetic nephropathy.

Identification of nectin-4 oncoprotein as a diagnostic and therapeutic target for lung cancer

Gene expression profile analysis of lung cancers revealed the transactivation of an immunoglobulin-like molecule Nectin-4 in the majority of non-small cell lung cancers (NSCLC). Immunohistochemical staining of 422 NSCLCs showed that a high level of Nectin-4 expression was associated with poor prognosis for NSCLC patients (P < 0.0001), and multivariate analysis confirmed its independent prognostic value (P < 0.0001). We established an ELISA to measure serum Nectin-4 and found that serum Nectin-4 levels were significantly higher in NSCLC patients than in healthy volunteers. The proportion of the serum Nectin-4-positive cases was 88 of 164 (53.7%) NSCLCs, whereas only 3 of 131 (2.3%) healthy volunteers were falsely diagnosed as positive, which was superior to carcinoembryonic antigen (CEA) and cytokeratin 19-fragment (CYFRA21-1) in sensitivity and specificity. A combined ELISA for both Nectin-4 and CEA increased sensitivity and classified 65.0% of lung adenocarcinomas as positive with false-positive rate of 4.6%. The use of both Nectin-4 and CYFRA21-1 classified 68.3% of lung squamous cell carcinomas as positive with false-positive rate of 6.1%. Treatment of lung cancer cells with small interfering RNAs against Nectin-4 suppressed its expression and cell growth. In addition, exogenous expression of Nectin-4 increased the lamellipodia formation and the invasive ability of mammalian cells through activation of small GTPase Rac1. Nectin-4 might play a significant role in lung carcinogenesis, and it should be a new candidate serum and tissue biomarker, as well as a therapeutic target.

Clinical significance and prognostic value of serum Dickkopf-1 concentrations in patients with lung cancer

BACKGROUND

Dickkopf-1 (DKK1), a secreted protein, is known as a negative regulator of the Wnt signaling pathway, which has been implicated in the development of several types of cancers. Clinical significance of serum DKK1 in lung cancer remains to be determined.

METHODS

A novel time-resolved immunofluorometric assay was developed. By use of this method, we investigated the serum concentrations of DKK1 in 592 patients with malignancies, 72 patients with benign lung disease, and 120 healthy controls. Serum cytokeratin 19 fragment and neuron-specific enolase values were obtained.

RESULTS

Serum DKK1 concentrations were significantly higher in patients with lung cancer than in patients with other malignant tumors or benign lung diseases and healthy controls. Serum concentrations of DKK1 were decreased significantly in groups of patients with gastric cancer, colorectal cancer, ovarian cancer, and cervical adenocarcinoma compared with healthy controls. Application of both DKK1 and cytokeratin 19 fragment increased sensitivity, correctly identifying 89.6% of the non-small cell lung cancer patients as positive. The use of both DKK1 and neuron-specific enolase increased sensitivity to detect small cell lung cancer to 86.2%. DKK1 concentrations increased with stage, tumor class, and presence of lymph node and distant metastases, regardless of histology and patient age and sex. Patients with a DKK1 concentration of 22.6 microg/L or higher had a statistically significantly diminished survival compared with patients whose DKK1 values were lower.

CONCLUSIONS

DKK1 was preferentially expressed in lung cancer. Increasing concentrations of DKK1were significantly associated with tumor progression and decreased survival in patients with lung cancer. .

Research and application of tumor markers in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC), the main type of esophageal cancer, is one of the most common gastrointestinal malignant cancers. Tumor markers detection are easy, economical, fast and non-invasive. Some tumor markers can be expressed before morphological changes occurred in tissues and organs; therefore, they can be used for the diagnosis of disease in the asymptomatic stage, thus making the research into tumor marker discovery even more meaningful. This paper summarizes several known tumor makers' expression detected in ESCC in recent years, and illustrates them from the aspects of genes, proteins, autoimmune antibodies, antigens and prognostic factors.

Association of breast cancer stem cells identified by aldehyde dehydrogenase 1 expression with resistance to sequential Paclitaxel and epirubicin-based chemotherapy for breast cancers

PURPOSE

Breast cancer stem cells have been shown to be associated with resistance to chemotherapy in vitro, but their clinical significance remains to be clarified. The aim of this study was to investigate whether cancer stem cells were clinically significant for resistance to chemotherapy in human breast cancers.

EXPERIMENTAL DESIGN

Primary breast cancer patients (n = 108) treated with neoadjuvant chemotherapy consisting of sequential paclitaxel and epirubicin-based chemotherapy were included in the study. Breast cancer stem cells were identified by immunohistochemical staining of CD44/CD24 and aldehyde dehydrogenase 1 (ALDH1) in tumor tissues obtained before and after neoadjuvant chemotherapy. CD44(+)/CD24(-) tumor cells or ALDH1-positive tumor cells were considered stem cells.

RESULTS

Thirty (27.8%) patients achieved pathologic complete response (pCR). ALDH1-positive tumors were significantly associated with a low pCR rate (9.5% versus 32.2%; P = 0.037), but there was no significant association between CD44(+)/CD24(-) tumor cell proportions and pCR rates. Changes in the proportion of CD44(+)/CD24(-) or ALDH1-positive tumor cells before and after neoadjuvant chemotherapy were studied in 78 patients who did not achieve pCR. The proportion of ALDH1-positive tumor cells increased significantly (P < 0.001) after neoadjuvant chemotherapy, but that of CD44(+)/CD24(-) tumor cells did not.

CONCLUSIONS

Our findings suggest that breast cancer stem cells identified as ALDH1-positive, but not CD44(+)/CD24(-), play a significant role in resistance to chemotherapy. ALDH1-positive thus seems to be a more significantly predictive marker than CD44(+)/CD24(-) for the identification of breast cancer stem cells in terms of resistance to chemotherapy.

Inhibition of STAT5 induces G1 cell cycle arrest and reduces tumor cell invasion in human colorectal cancer cells

Abnormalities in the signal transducer and activator of transcription (STAT) pathway are involved in the oncogenesis of several cancers. However, the mechanism by which dysregulated STAT5 signaling contributes to the progression of human colorectal cancer (CRC) has not been elucidated. To investigate the role of STAT5 in CRC progression, we depleted STAT5 with a small interfering RNA (siRNA). Our results demonstrate that STAT5 is involved in CRC cell growth, cell cycle progression, invasion and migration through regulation of gene expression, such as Bcl-2, p16(ink4a), p21(waf1/cip1), p27(kip1), E-cadherin, the focal adhesion kinase (FAK), vascular endothelial growth factor (VEGF) and matrix metalloproteinases. In addition, immunohistochemical staining reveals upregulation of STAT5 during CRC tumorigenesis. Moreover, phospho-STAT5 (pSTAT5) is predominantly localized in the cytoplasm of adenomas cells and colon adenocarcinoma cells, but primarily presented in the nucleus of normal colonic epithelium cells. Thus, pSTAT5 protein is shuttled from the nucleus to the cytoplasm in the oncogenesis of CRC, suggesting that activated STAT5 may also have cytoplasmic functions. In support of this hypothesis, we found that STAT5 formed a complex with p44/42 MAPK and SAPK/JNK in CRC cells, suggesting cross talk between STAT5 signaling and the MAPK pathway in the development of human CRC. Our findings illustrate the biological significance of STAT5 signaling in CRC progression, and provide novel evidence that intervention in STAT5 signaling may have potential therapeutic value in the prevention of human colorectal cancer.

Involvement of epithelial cell transforming sequence-2 oncoantigen in lung and esophageal cancer progression

PURPOSE

This study aims to isolate potential molecular targets for diagnosis, treatment, and/or prevention of lung and esophageal carcinomas.

EXPERIMENTAL DESIGN

We screened for genes that were frequently overexpressed in the tumors through gene expression profile analyses of 101 lung cancers and 19 esophageal squamous cell carcinomas (ESCC) by cDNA microarray consisting of 27,648 genes or expressed sequence tags. In this process, we identified epithelial cell transforming sequence 2 (ECT2) as a candidate. Tumor tissue microarray was applied to examine the expression of ECT2 protein in 242 archived non-small-cell lung cancers (NSCLC) and 240 ESCC specimens and to investigate its prognostic value. A role of ECT2 in lung and esophageal cancer cell growth and/or survival was examined by small interfering RNA experiments. Cellular invasive activity of ECT2 in mammalian cells was examined using Matrigel assays.

RESULTS

Northern blot and immunohistochemical analyses detected expression of ECT2 only in testis among 23 normal tissues. Immunohistochemical staining showed that a high level of ECT2 expression was associated with poor prognosis for patients with NSCLC (P = 0.0004) as well as ESCC (P = 0.0088). Multivariate analysis indicated it to be an independent prognostic factor for NSCLC (P = 0.0005). Knockdown of ECT2 expression by small interfering RNAs effectively suppressed lung and esophageal cancer cell growth. In addition, induction of exogenous expression of ECT2 in mammalian cells promoted cellular invasive activity.

CONCLUSIONS

ECT2 cancer-testis antigen is likely to be a prognostic biomarker in clinic and a potential therapeutic target for the development of anticancer drugs and cancer vaccines for lung and esophageal cancers.

Anti-DKK1 mAb (BHQ880) as a potential therapeutic agent for multiple myeloma

Decreased activity of osteoblasts (OBs) contributes to osteolytic lesions in multiple myeloma (MM). The production of the soluble Wnt inhibitor Dickkopf-1 (DKK1) by MM cells inhibits OB activity, and its serum level correlates with focal bone lesions in MM. Therefore, we have evaluated bone anabolic effects of a DKK1 neutralizing antibody (BHQ880) in MM. In vitro BHQ880 increased OB differentiation, neutralized the negative effect of MM cells on osteoblastogenesis, and reduced IL-6 secretion. In a severe combined immunodeficiency (SCID)-hu murine model of human MM, BHQ880 treatment led to a significant increase in OB number, serum human osteocalcin level, and trabecular bone. Although BHQ880 had no direct effect on MM cell growth, it significantly inhibited growth of MM cells in the presence of bone marrow stromal cells (BMSCs) in vitro. This effect was associated with inhibition of BMSC/MM cell adhesion and production of IL-6. In addition, BHQ880 up-regulated beta-catenin level while down-regulating nuclear factor-kappaB (NF-kappaB) activity in BMSC. Interestingly, we also observed in vivo inhibition of MM cell growth by BHQ880 treatment in the SCID-hu murine model. These results confirm DKK1 as an important therapeutic target in myeloma and provide the rationale for clinical evaluation of BHQ880 to improve bone disease and to inhibit MM growth.

Elevated expression of DKK1 is associated with cytoplasmic/nuclear beta-catenin accumulation and poor prognosis in hepatocellular carcinomas

BACKGROUND/AIMS

To assess the value of Dickkopf-1 (DKK1) for predicting clinical outcome of human hepatocellular carcinoma (HCC) in patients with HCC.

METHODS

Expression of DKK1 and beta-catenin was investigated in HCC cell lines using qRT-PCR, Western blotting and immunofluorescence. Tissue microarrays representing 314 HCC patients were used to determine the expression patterns of DKK1 and beta-catenin by immunohistochemistry, and prognostic significance was assessed by using Kaplan-Meier survival estimates and log-rank tests.

RESULTS

The expression level of DKK1 was associated with the staining pattern of beta-catenin in HCC cell lines, and DKK1 overexpression correlated with beta-catenin cytoplasmic/nuclear accumulation in clinical HCC samples (P=0.011, correlation coefficient=0.144). High DKK1 expression predicted unfavorable prognosis in HCC patients, especially in early stage patients and those with normal AFP levels. In multivariate analyses, DKK1 was an independent predictor for overall survival (OS) (P=0.002) and disease-free survival (DFS) (P=0.002) of HCC patients. Furthermore, the HCC patients with high DKK1 expression and cytoplasmic/nuclear beta-catenin accumulation had very poor prognosis.

CONCLUSIONS

Elevated expression of DKK1 is a critical event in patients with HCC that indicates poor clinical outcome. DKK1, alone or combined with beta-catenin, is a novel prognostic predictor for HCC patients.

Assessment of circulating Dickkopf-1 with a new two-site immunoassay in healthy subjects and women with breast cancer and bone metastases

The aim of our study was to investigate the sex- and age-related changes of serum Dickkopf-1 (Dkk-1), a soluble inhibitor of the Wnt signaling pathway, in healthy individuals and in patients with breast cancer (BC) and bone metastases (BM) using a new ELISA. Association of serum Dkk-1 with markers of bone turnover was also investigated. Serum Dkk-1 measurements were performed using a commercial sandwich ELISA in 150 healthy men, 175 healthy pre- and postmenopausal women (20-65 years), 22 women with BC and BM (mean age 63 years), and 16 women with BC and metastases at sites other than bone (mean age 53 years). Intra- and interassay coefficients of variation were below 7% and 12%, respectively. The detection limit was determined to be 0.018 microg/L. In healthy women and men, Dkk-1 did not change with age. Serum Dkk-1 modestly correlated with serum bone alkaline phosphatase (r = 0.19, P = 0.013) and serum C-terminal cross-linking telopeptide of type I collagen (r = 0.19, P = 0.014) in women but not in men. Dkk-1 levels were higher in women with BC and BM (5.57 +/- 5.50 microg/L) than in healthy age-matched controls (3.47 +/- 1.47 microg/L, P < 0.0001) and women with metastases at sites other than bone (3.57 +/- 1.66 microg/L, P = 0.0003). In conclusion, serum Dkk-1 is stable with age in healthy women and men and increases in patients with BC and BM. Measurements of circulating Dkk-1 with this new ELISA may be useful for the clinical investigation of patients with malignant bone diseases.

Dickkopf-1 expression as a marker for predicting clinical outcome in esophageal squamous cell carcinoma

BACKGROUND AND OBJECTIVES

Dickkopf-1 (DKK1) is the inhibitor of the canonical Wnt signaling pathway, however it is highly transactivated in various cancers, suggesting the presence of unknown mechanism. Its implication in human esophageal squamous cell carcinoma (ESCC) has not been sufficiently investigated.

PATIENTS AND METHODS

We evaluated DKK1 protein expression in resected specimens from 170 patients with ESCC by immunohistochemistry. Tumors were categorized as positive or negative for DKK1. The relationships between DKK1 expression in ESCC and various clinicopathological parameters and prognosis (disease-free survival; DFS) were analyzed separately.

RESULTS

Immunohistochemically, 72 (42.4%) tumors were DKK1 positive while no significant staining was observed in the normal squamous epithelium except for few basal cells. There was no significant relationship between DKK1 expression in ESCC and any of the clinicopathological parameters tested in this study. Patients with DKK1-positive tumors had poorer DFS than those with negative ESCC (5-year DFS; 31.5% versus 53.6%, P = 0.0062). Univariate analysis showed a significant relationship between pT [hazard ratio (HR) = 2.944, 95% confidence interval (CI) = 1.713-5.059, P < 0.0001], number of pN (HR = 2.836, 95% CI = 1.866-4.309, P < 0.0001), lymphatic invasion (HR = 2.892, 95% CI = 1.336-6.262, P = 0.0070), and DKK1 expression (HR = 1.763, 95% CI = 1.167-2.663, P = 0.0071) and DFS. Multivariate analysis including the above four parameters identified pT (HR = 2.053, 95% CI = 1.157-3.645, P = 0.0140), pN number (HR = 2.107, 95% CI = 1.362-3.260, P = 0.0008), and DKK1 expression (HR = 1.813, 95% CI = 1.195-2.751, P = 0.0052) as independent and significant prognostic factors for DFS.

CONCLUSION

Our data suggest the usefulness of DKK1 as a novel predictor of poor prognosis of patients with ESCC after curative resection and also as a therapeutic target for future tailored therapies against ESCC.

A novel activity of the Dickkopf-1 amino terminal domain promotes axial and heart development independently of canonical Wnt inhibition

The secreted Dickkopf-1 (Dkk1) protein mediates numerous cell fate decisions and morphogenetic processes. Its carboxyl terminal cysteine-rich region (termed C1) binds LRP5/6 and inhibits canonical Wnt signaling. Paradoxically, the isolated C1 domain of Dkk1 as well as Wnt antagonists that act by sequestering Wnts, such as Frz-B, WIF-1 and Crescent, are poor mimics of the inductive and patterning activities of Dkk1 critical for heart and axial development. To understand the basis for the unique properties of Dkk1, we investigated the function of its amino terminal cysteine-rich region (N1). N1 does not bind LRP or Kremen nor inhibit Wnt signaling and has had no known function. We show that it can synergize with BMP antagonism to induce prechordal and axial mesoderm when expressed as an independent protein in Xenopus embryos. Moreover, we show that it can function in trans to complement the activity of C1 protein to mediate two embryologic functions of Dkk1: induction of chordal and prechordal mesoderm and specification of heart tissue from non-cardiogenic mesoderm. Remarkably, N1 also synergizes with WIF-1 and Crescent, indicating that N1 signals independently of C1 and its interactions with LRP. Since cleavage of Dkk1 is not detected, these results define N1 as a novel signaling domain within the intact protein that is responsible for the potent effects of Dkk1 on the induction and patterning of the body axis and heart. We conclude that this new activity is also likely to synergize with canonical Wnt inhibitory in the numerous developmental and disease processes that involve Dkk1.

Biomarkers for osteoporosis management: utility in diagnosis, fracture risk prediction and therapy monitoring

Osteoporosis is a systemic disease characterized by low bone mass and microarchitectural deterioration of bone tissue, resulting in an increased risk of fracture. While the level of bone mass can be estimated by measuring bone mineral density (BMD) using dual X-ray absorptiometry (DXA), its measurement does not capture all the risk factors for fracture. Quantitative changes in skeletal turnover can be assessed easily and non-invasively by the measurement of serum and urinary biochemical markers; the most sensitive markers include serum osteocalcin, bone specific alkaline phosphatase, the N-terminal propeptide of type I collagen for bone formation, and the crosslinked C- (CTX) and N- (NTX) telopeptides of type I collagen for bone resorption. Advances in our knowledge of bone matrix biochemistry, most notably of post-translational modifications in type I collagen, are likely to lead to the development of new biochemical markers that reflect changes in the material property of bone, an important determinant of bone strength. Among those, the measurement of the urinary ratio of native (alpha) to isomerized (beta) CTX - an index of bone matrix maturation - has been shown to be predictive of fracture risk independently of BMD and bone turnover. In postmenopausal osteoporosis, levels of bone resorption markers above the upper limit of the premenopausal range are associated with an increased risk of hip, vertebral, and nonvertebral fracture, independent of BMD. Therefore, the combined use of BMD measurement and biochemical markers is helpful in risk assessment, especially in those women who are not identified as at risk by BMD measurement alone. Levels of bone markers decrease rapidly with antiresorptive therapies, and the levels reached after 3-6 months of therapy have been shown to be more strongly associated with fracture outcome than changes in BMD. Preliminary studies indicate that monitoring changes of bone formation markers could also be useful to monitor anabolic therapies, including intermittent parathyroid hormone administration and, possibly, to improve adherence to treatment. Thus, repeated measurements of bone markers during therapy may help improve the management of osteoporosis in patients.

The role of Dickkopf-1 in bone development, homeostasis, and disease

Wnt/beta-catenin signaling is central to bone development and homeostasis in adulthood and its deregulation is associated with bone pathologies. Dickkopf-1 (DKK1), a soluble inhibitor of Wnt/beta-catenin signaling required for embryonic head development, regulates Wnt signaling by binding to the Wnt coreceptor lipoprotein-related protein-5 (LRP5)/Arrow. LRP5 mutations causing high bone mass syndromes disrupt DKK1-mediated regulation of LRP5. Forced overexpression of Dkk1 in osteoblasts causes osteopenia, disruption of the hematopoietic stem cell (HSC) niche, and defects in HSC function. Dkk1 also inhibits fracture repair. Studies suggest that DKK1 activation in osteoblasts is the underlying cause of glucocorticoid- and estrogen deficiency-mediated osteoporosis, and at least partially underlies the teratogenic effects of thalidomide on limb development. DKK1 induces proliferation of mesenchymal stem cells (MSC) in vitro and may play a role in the development of high-grade undifferentiated pleomorphic sarcomas derived from MSC and osteosarcomas. DKK1 has been implicated in causing erosive arthritis, the osteolytic phenotypes of multiple myeloma and metastatic breast cancer, and osteoblastic metastases of prostate cancer. Preclinical studies have shown that neutralizing DKK1/Dkk1 and/or enhancing Wnt/beta-catenin signaling may prove effective in treating bone pathologies. Here, we review the rapidly growing body of literature defining a pivotal role for DKK1 in bone health and disease.