Death-associated Protein Kinase Promoter Methylation Research Articles

Comparative study of death-associated protein kinase promoter methylation between nonsquamous and squamous subtypes of nonsmall cell lung cancer

Background Lung cancer is a leading cause of cancer-related mortality in the world. Nonsmall cell lung cancer (NSCLC) can be classified as nonsquamous cell carcinoma (non-SCC) and squamous cell carcinoma (SCC). NSCLC pathogenesis includes altered methylation patterns in multiple genes. Promotor methylation of death-associated protein kinase (DAPK) has been documented in various tumors. Aim To compare DAPK promoter methylation and clinical characteristics in patients of nonsquamous cell lung cancer with those of SCC. Patients and methods A case–control study was conducted on fresh-frozen tumor samples from 81 patients with primary NSCLC, including 43 non-SCC cases and 38 SCC cases, investigated in the Chest Department, Mansoura University Hospital, in the period from June 2017 to January 2020. A total of 40 patients matched for age and sex with nonmalignant lung lesions served as controls. Patients with age more than 18 years, radiological suggestions of lung cancer, and histologically diagnosed NSCLC were included, whereas patients with malignancies other than NSCLC or unfit for bronchoscopy were excluded. A pathologist histologically examined each lung tumor to define the type and other clinical characteristics of the tumor. DNA was isolated from fresh-frozen tissues, and the detection of DNA methylation was performed using methylation-specific PCR. Results NSCLC case groups included 43 nonsquamous cells and 38 squamous cells, with a mean age of 62.89±5.5 and 64.19±5.87 years, respectively. The control group included 40 patients, with a mean age of 61.37±6.64 years. There were statistically significant differences regarding smoking status (P=0.002) and the clinical characteristics suggestive of lung cancer between both patients with NSCLC and controls, but the differences between SCC and non-SCC were not significant. The results were significantly different between the two groups concerning chest radiograph and computed tomographic finding, where the peripheral mass was significantly higher in non-SCC than SCC (P<0.001). DAPK promoter methylation was significantly higher for NSCLC (both SCC and non-SCC) as compared with controls (P≤0.001), but there was no significant difference between SCC and non-SCC groups. Conclusion Detection of the aberrant DAPK hypermethylation in tumor DNA from patients with NSCLC may provide an effective means for early auxiliary diagnosis of the malignancy but cannot distinguish between the histopathological types.

Meta-analysis: Assocation between promoter hypermethylation of DAPK (Death-Associated Protein Kinase) and cervical cancer

Purpose: Death-associated protein kinase (DAPK or DAPK1) is an important tumor suppressor protein that involved in the regulation of cell activities. The aberrant methylation of DAPK promoter has been reported in patients with cervical cancer. However, the association between of DAPK1 and cervical cancer was not always unification, in previous studies. Therefore, in current study, a meta-analysis was performed for association of between DAPK gene’s promoter hypermethylated and cervical cancer.
 Methods: A systematic literature analysis was conducted based on the previous studies published in PubMed, PubMed Central (NCBI), Google by using following keywords: cervical cancer, cervical carcinoma, Methylation, by the end of January, 2018. The association between DAPK promoter methylation and cervical cancer was evaluated by odds ratio (ORs) and 95% confidence intervals (CI). To evaluate the potential sources of heterogeneity, the meta-regression analysis and subgroup analysis were conducted.
 Results: A total of 21 case-control studies which relevant to the association between DAPK1 gene’s promoter methylation frequency and cervical cancer, that including 1600 cancer cases and 1011 control cases (non-cancerous cases). The analysis results indicated that the characteristic of candidate gene’s promoter methylation increased the cervical cancer risk through the calculation of OR value (OR = 21.25; 95% CI = 8.73 – 52.97; p < 0.001; Random effect model). The association between DAPK1 gene’s promoter hypermethylation was confirmed in all the subgroups analyses, including materials and assays methods, ethnicity. Furthermore, this association is higher in cervical squamous cell carcinoma than cervical adenocarcinoma and is a characteristic of late-stage disease.
 Conclusion: The hypermethylated DAPK1 gene’s promoter was also one of etiological factor, lead to the cervical tumorigenesis.

Promoter methylation of tumor suppressor genes induced by human papillomavirus in cervical cancer.

Cervical cancer is the most fourth common cancer in women worldwide. The E6 and E7 high-risk human papillomavirus (HPV) types are the main cause of this cancer. Several studies have revealed that promoter methylation of tumor suppressor genes is induced by HPV E7. Recently, it was found that HPV16-E7 and the DNA methyltransferase 1 complex could bind at the cyclin A1 (CCNA1) promoter, resulting in CCNA1 promoter methylation. Therefore, there is a need to study other tumor suppressor genes for which HPV may induce promoter methylation. The present study investigated whether HPV induced cell adhesion molecule 1 (CADM1) and death associated protein kinase 1 (DAPK1) promoter methylation. C33a (no HPV infection) and SiHa (HPV 16 infection) cell lines were used for methylation status and expression observation. It was found that CADM1 and DAPK1 promoter methylation, no expression of CADM1 and decreased expression of DAPK1, was presented in SiHa cells. While no promoter methylation of these two genes was observed in C33a cells, with positive expression of the genes. It was subsequently investigated whether E6 and/or E7 could induce promoter methylation and decrease the expression of these two genes. Methylation-specific primer PCR and quantitative PCR were performed to elucidate the promoter methylation status and expression of CADM1 and DAPK1 in C33a cells transfected with HPV16 E6-PCDNA3 or HPV16 E7-PCDNA3.1 myc-his, compared to empty vector-transfected cells. The results showed that HPV E7 could induce CADM1 promoter methylation and decrease the gene expression in HPV E7 transfected C33a cells, while HPV E6 could induce DAPK1 promoter methylation and decrease its expression in C33a cells transfected with HPV E6. Finally, the mechanism by which HPV E7 induced CADM1 promoter methylation was observed by performing chromatin immunoprecipitation; the data showed that E7 induced CADM1 methylation by the same mechanism as that for CCNA1, by binding at the CADM1 promoter, resulting in the subsequent reduction of its expression in cervical cancer.

Association of Protein Expression and Methylation of DAPK1 with Clinicopathological Features in Invasive Ductal Carcinoma Patients from Kashmir

Aims:Death-associated protein kinase-1 (DAPK1) is a pro-apoptotic Ser/Thr kinase that participates in cell apoptosis and tumor suppression. DAPK1 is frequently lost in many different tumor types including breast cancer. The aim of this study was to evaluate the promoter methylation status of DAPK1 and a possible correlation with the expression of DAPK1 and standard clinicopathological features in invasive ductal breast carcinoma patients (IDC).Methods:Methylation Specific PCR (MSP) was carried out to investigate the promoter methylation status of DAPK1 from 128 breast cancer patients. The effect of promoter methylation on protein expression was evaluated by immunohistochemistry (n=128) and western blotting (n=56).Results:We found significant difference in DAPK1 promoter methylation frequency among breast tumors when compared with the corresponding normal tissues. Hypermethylation of DAPK1 is significantly correlated with the loss of DAPK1 protein expression (P < .001, rs= -0.361). The loss of DAPK1 protein was significantly associated with estrogen receptor (ER) negativity (p= 0.003), triple negative breast cancer (TNB) (p= 0.024) and advanced tumor stages (P = 0.001). Moreover, age at diagnosis (p= 0.041), tumor stage (p= 0.034), ER negativity (p= 0.004) and TNB cancers (p=0.003) correlated significantly with the hypermethylation of the DAPK1 promoter.Coclusion:This study indicates that DAPK1 is methylated in IDC and promoter hypermethylation could be attributed to silencing of DAPK1 gene expression in breast cancer. Thus, we consider DAPK1 inactivation by promoter hypermethylation likely plays a role in the development and progression of breast cancer.

Prognostic significance of DAPK promoter methylation in lymphoma: A meta-analysis.

We aimed to characterize the clinical significance of epigenetic loss of death-associated protein kinase (DAPK) gene function through promoter methylation in the development and prognosis of lymphoma. PubMed, Web of Science and ProQuest databases were searched for relevant studies. Twelve studies involving 709 patients with lymphoma were identified. The prognostic value of DAPK methylation was expressed as risk ratio (RR) and its corresponding 95% confidence interval (CI), while the associations between DAPK methylation and the clinical characteristics of patients with lymphoma were expressed as odd ratios (ORs) and their corresponding 95% CIs. Meta-analysis showed that the 5-year survival rate was significantly lower in lymphoma patients with hypermethylated DAPK (RR = 0.85, 95% CI (0.73, 0.98), P = 0.025). Sensitivity analysis demonstrated consistent result. However, no associations were found between DAPK methylation and clinicopathological features of lymphoma, in relation to gender (OR = 1.07, 95% CI (0.72, 1.59), P = 0.751), age (OR = 1.01, 95% CI (0.66, 1.55), P = 0.974), international prognostic index (OR = 1.20, 95% CI (0.63, 2.27), P = 0.575), B symptoms (OR = 0.76, 95% CI (0.38, 1.51), P = 0.452), serum lactate dehydrogenase (OR = 1.13, 95% CI (0.62, 2.05), P = 0.683), and BCL-2 expression (OR = 1.55, 95% CI (0.91, 2.66), P = 0.106). Lymphoma patients with hypermethylated DAPK are at risk for poorer 5-year survival rate. DAPK methylation may serve as a negative prognostic biomarker among lymphoma patients, although it may not be associated with the progression of lymphoma.

Clinicopathological significance of DAPK promoter methylation in non-small-cell lung cancer: a systematic review and meta-analysis.

BackgroundLung carcinogenesis is related to silencing of tumor suppressor genes and activation of oncogenes. The aim was to investigate the significance of death-associated protein kinase (DAPK) methylation in non-small-cell lung cancer (NSCLC) through a meta-analysis.MethodsA detailed literature search was made in PubMed, Embase, and Web of Science databases. All analysis was performed with Review Manager 5.2.ResultsIn total, 28 studies with a total of 2,148 patients were involved. The frequency of DAPK promoter hypermethylation was 40.50% in NSCLC, significantly higher than in nonmalignant lung tissue; the pooled OR was 5.69, P<0.00001. Additionally, DAPK promoter hypermethylation was significantly correlated with poor overall survival in patients with NSCLC. However, there was no significant difference found while comparing the rate of DAPK promoter hypermethylation in adenocarcinoma and squamous cell cancer. The rate of DAPK promoter hypermethylation was similar between stage III/IV and stage I/II. In addition, the data showed that DAPK promoter hypermethylation was not associated with smoking behavior in patients with NSCLC.ConclusionDAPK promoter hypermethylation is correlated with risk of NSCLC and is a potential biomarker for prediction of poor prognosis in patients with NSCLC.

Death-associated protein kinase promoter methylation correlates with clinicopathological and prognostic features in nonsmall cell lung cancer patients: A cohort study.

The objective was to study the correlation between death-associated protein kinase (DAPK) promoter methylation and the clinicopathological and prognostic features in nonsmall cell lung cancer (NSCLC) patients. A total of 117 NSCLC patients were recruited into our study between December 2012 and December 2014. Methylation-specific polymerase chain reaction was employed to detect the methylation status of DAPK in cancer tissues, peficancerous tissues, and serum samples of 117 NSCLC patients. In addition, serum samples of 115 healthy subjects were analyzed as controls. A literature search of English and Chinese databases, based on predefined criteria, identified published studies closely related to this study. Data were extracted, and meta-analysis was performed using STATA 12.0 software (STATA Corporation, College Station, TX, USA). Our study results showed that DAPK promoter methylation frequency was significantly higher in NSCLC tissues compared to peficancerous normal tissues (58.1% vs. 12.8%, χ2 = 52.45, P < 0.001). When serum samples were compared, DAPK methylation frequency in NSCLC patients was higher than the control group (27.4% vs. 0, χ2 = 37.07, P < 0.001). Our meta-analysis results demonstrated that DAPK methylation frequency was lower in tumor node metastasis (TNM) stage I-II compared to TNM stage III-IV (relative risk [RR] =0.87, 95% confidence interval [CI] =0.76-0.99, P = 0.041). DAPK promoter methylation frequency in NSCLC patients with lymph node metastasis was significantly higher compared to the patients with no metastases (RR = 1.26, 95% CI = 1.04-1.52, P = 0.020). Finally, the 5-year survival rate was lower in NSCLC patient group with high frequency of DAPK methylation, compared to the patient group with unmethylated DAPK (RR = 0.71, 95% CI = 0.56-0.89, P = 0.004). Our results showed that DAPK promoter methylation is tightly correlated with clinicopathological features of NSCLC and is associated with poor prognosis in patients.

Promoter methylation and expression of death-associated protein kinase gene in acute leukemia

To study the clinical implications of death-associated protein kinase (DAPK) promoter methylation and DAPK gene expression in untreated patients with acute leukemia. Methylation-specific PCR and RT-PCR were employed to detect the DAPK gene methylation and mRNA expression in the bone marrow of 60 patients with acute myeloid leukemia (AML), 55 patients with acute lymphocytic leukemia (ALL), and 17 normal subjects. The positivity rate of DAPK methylation was significantly higher in ALL patients (29.1%) than in AML patients group (5%) and normal subjects (0%) (P<0.01). No correlation was found between DAPK gene methylation and the clinical features in ALL patients (P>0.05). DAPK mRNA expression level differed significantly among the 3 groups (P=0.000), and was the highest in normal subjects and the lowest in ALL patients. In ALL patients, the expression level of DAPK mRNA showed a significant inverse correlation with DAPK promoter methylation (P<0.05). The methylation rate of DAPK gene is higher in untreated ALL patients than in AML patients and normal subjects. DAPK gene methylation is not correlated with the clinical features of ALL patients but is probably related with the low gene expression level of DAPK in these patients.

Association between promoter methylation of DAPK gene and HNSCC: A meta-analysis.

BackgroundThe death-associated protein kinase (DAPK) is a tumor suppressor gene, which is a mediator of cell death of INF-γ–induced apoptosis. Aberrant methylation of DAPK promoter has been reported in patients with head and neck squamous cell carcinoma (HNSCC). However, the results of these studies are inconsistent. Hence, the present study aimed to evaluate the association between the promoter methylation of DAPK gene and HNSCC.MethodsRelevant studies were systematically searched in PubMed, Web of Science, Ovid, and Embase. The association between DAPK promoter methylation and HNSCC was assessed by odds ratio (ORs) and 95% confidence intervals (CI). To evaluate the potential sources of heterogeneity, we conducted the meta-regression analysis and subgroup analysis.ResultsEighteen studies were finally included in the meta-analysis. The frequency of DAPK promoter methylation in patients with HNSCC was 4.09-fold higher than the non-cancerous controls (OR = 3.96, 95%CI = 2.26–6.95). A significant association between DAPK promoter methylation and HNSCC was found among the Asian region and the Non-Asia region (Asian region, OR = 4.43, 95% CI = 2.29–8.58; Non-Asia region, OR = 3.39, 95% CI = 1.18–9.78). In the control source, the significant association between DAPK promoter methylation and HNSCC was seen among the autologous group and the heterogeneous group (autologous group, OR = 2.71, 95% CI = 1.49–4.93; heterogeneous group, OR = 9.50, 95% CI = 2.98–30.27). DAPK promoter methylation was significantly correlated with alcohol status (OR = 1.85, 95% CI = 1.07–3.21).ConclusionThe results of this meta-analysis suggested that aberrant methylation of DAPK promoter was associated with HNSCC.

Promoter methylation of p16 and DAPK genes in brushing, blood, and tissue samples from patients with nasopharyngeal carcinoma: a systematic meta-analysis

Background: Promoter methylation of tumor suppressor genes (TSGs) p16 and death-associated protein kinase ( DAPK ) has been reported in various carcinomas. However, the correlation between p16 or DAPK promoter methylation and the detection of nasopharyngeal carcinoma (NPC) in different sample types remains unclear. Methods: A systematic literature research was conducted to identify available studies. The pooled odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated and analyzed. Results: Eleven eligible papers on p16 promoter methylation and seven eligible papers on DAPK promoter methylation were included in this analysis. The pooled OR of p16 and DAPK promoter methylation was significantly higher in samples of NPC tissues than in nontumorous (OR =5.49, P 0.1). Conclusions: Our findings suggested that p16 and DAPK promoter methylation may be associated with the carcinogenesis of NPC. Promoter methylation of p16 or DAPK may become a noninvasive biomarker for NPC detection in blood and brushing samples. DAPK or p16 promoter methylation was not correlated with tumor stage. Conducting additional studies is essential in the future to confirm our results.

DAPK Promoter Methylation and Bladder Cancer Risk: A Systematic Review and Meta-Analysis.

BackgroundMethylation of tumor suppressor gene promoter leads to transcription inactivation and is involved in tumorigenesis. Several studies demonstrate a potential association between the Death-Associated Protein Kinase (DAPK) gene promoter methylation and bladder cancer risk, tumor stage and histological grade. Due to inconsistent results of these studies, we performed this meta-analysis to ascertain the association.MethodsStudies were retrieved from the PubMed, Embase, Web of Science and the Cochrane Library databases. Study selection and data extraction were executed by two reviewers independently. Meta-analysis was performed using Stata 13.0 and Review Manager 5.3 software.ResultsA total of 21 articles involving 15 case control and 8 case series studies were included in this meta-analysis. DAPK promoter methylation was associated with bladder cancer risk (OR: 5.81; 95%CI = 3.83–8.82, P<0.00001). The frequency of DAPK promoter methylation was equal in bladder cancer tissue and paired adjacent normal tissue (OR: 0.87; 95%CI = 0.31–2.48, P = 0.794). Furthermore, DAPK promoter methylation was associated with higher histological grade (OR: 1.52; 95%CI = 1.10–2.09, P = 0.011) but not associated with tumor stage (OR: 1.12; 95%CI = 0.67–1.87, P = 0.668).ConclusionsThe result suggests that DAPK promoter methylation is significantly increased in bladder cancer patients compared to normal controls. DAPK promoter methylation could serve as a biomarker for bladder cancer detection and management.

Clinical effect of DAPK promoter methylation in gastric cancer: A systematic meta-analysis.

Background:The loss of death-associated protein kinase (DAPK) gene expression through promoter methylation is involved in many tumors. However, the relationship between DAPK promoter methylation and clinicopathological features of gastric cancer (GC) remains to be done. Therefore, we performed a meta-analysis to assess the role of DAPK promoter methylation in GC.Methods:Literature databases were searched to retrieve eligible studies. The pooled odds ratios (ORs) with its 95% confidence intervals (CIs) were calculated using the Stata 12.0 software.Results:Final 22 available studies with 1606 GC patients and 1508 nonmalignant controls were analyzed. A significant correlation was found between DAPK promoter methylation and GC (OR = 3.23, 95% CI = 1.70–6.14, P < 0.001), but we did not find any significant association in Caucasian population, and in blood samples in subgroup analyses. DAPK promoter methylation was associated with tumor stage and lymph node status (OR = 0.69, 95% CI = 0.49–0.96, P = 0.03; OR = 1.50, 95% CI = 1.12–2.01, P = 0.007; respectively). However, we did not find that DAPK promoter methylation was associated with gender status and tumor histology.Conclusion:Our findings suggested that DAPK promoter methylation may play a key role in the carcinogenesis and progression of GC. In addition, methylated DAPK was a susceptible gene for Asian population. However, more studies with larger subjects should be done to further evaluate the effect of DAPK promoter methylation in GC patients, especially in blood and Caucasian population subgroup.

DAPK promoter methylation status correlates with tumor metastasis and poor prognosis in patients with non-small cell lung cancer

This meta-analysis investigated the correlation between the promoter methylation of death-associated protein kinase (DAPK) and the clinicopathological features in patients with non-small cell lung cancer (NSCLC). Scientific literature databases were exhaustively searched to retrieve published studies relevant to DAPK methylation and NSCLC. Retrieved studies published in English and Chinese languages were screened according to the stringent predefined inclusion and exclusion criteria, and high quality studies were selected for meta-analysis. All statistical analyses were performed utilizing STATA software (Version 12.0, Stata Corporation, College Station, TX, USA). A total of 14 published studies (5 in English and 9 in Chinese) were enrolled in the present meta-analysis, and contained 1238 patients with NSCLC. The results indicated that NSCLC patients with metastatic phenotype were strongly associated with significantly higher methylation rate of DAPK compared to NSCLC patients without metastasis. Additionally, in NSCLC patients carrying tumors with DAPK methylation, the 5-year survival rate was remarkedly lower than NSCLC patients without DAPK methylation. However, we did not find significant correlation between DAPK methylation and histological stage or tumor node metastasis (TNM) stage in NSCLC patients. Our meta-analysis results reveal that DAPK promoter methylation might be associated with tumor metastasis and poor prognosis in NSCLC patients, although no correlation with histological types and TNM stage in NSCLC patients were found.

Retraction Note to: Promoter methylation of DAPK gene may contribute to the pathogenesis of nonsmall cell lung cancer: a meta-analysis.

We performed a meta-analysis of cohort studies to determine whether promoter methylation of the death-associated protein kinase (DAPK) gene contributes to the pathogenesis of nonsmall cell lung cancer (NSCLC). A range of electronic databases were searched: MEDLINE (1966 ∼ 2013), the Cochrane Library Database (Issue 12, 2013), EMBASE (1980 ∼ 2013), CINAHL (1982 ∼ 2013), Web of Science (1945 ∼ 2013), and the Chinese Biomedical Database (CBM; 1982 ∼ 2013) without any language restrictions. Meta-analysis was conducted using the STATA 12.0 software. Crude odds ratio (OR) with 95 % confidence interval (95 % CI) was calculated. Our meta-analysis integrated results from 12 clinical cohort studies that met all inclusion criteria with a total of 1,027 NSCLC patients. We observed that the frequency of DAPK gene methylation in cancer tissues were significantly higher than that in the adjacent normal and benign tissues (cancer tissues vs. benign tissues: OR = 8.50, 95 % CI = 5.88 ∼ 12.28, P < 0.001; cancer tissues vs. adjacent tissues: OR = 5.95, 95 % CI = 4.11 ∼ 8.60, P < 0.001; cancer tissues vs. normal tissues: OR = 4.75, 95 % CI = 3.28 ∼ 6.87, P < 0.001; respectively). Subgroup analysis by ethnicity demonstrated that DAPK gene methylation was closely associated with the development and progression of NSCLC among both Asians and Caucasians (all P < 0.05). Furthermore, we conducted a subgroup analysis based on sample source and discovered that DAPK gene methylation was implicated in the pathogenesis of NSCLC in both blood and tissue subgroups (all P < 0.05). Our results suggest that DAPK promoter methylation may be involved in NSCLC carcinogenesis. Thus, the detection of aberrant DAPK methylation may be helpful in the diagnosis and prognosis of NSCLC.

DAPK1 Promoter Methylation and Cervical Cancer Risk: A Systematic Review and a Meta-Analysis.

ObjectiveThe Death-Associated Protein Kinase 1 (DAPK1) gene has been frequently investigated in cervical cancer (CC). The aim of the present study was to carry out a systematic review and a meta-analysis in order to evaluate DAPK1 promoter methylation as an epigenetic marker for CC risk.MethodsA systematic literature search was carried out. The Cochrane software package Review Manager 5.2 was used. The fixed-effects or random-effects models, according to heterogeneity across studies, were used to calculate odds ratios (ORs) and 95% Confidence Intervals (CIs). Furthermore, subgroup analyses were conducted by histological type, assays used to evaluate DAPK1 promoter methylation, and control sample source.ResultsA total of 20 papers, published between 2001 and 2014, on 1929 samples, were included in the meta-analysis. DAPK1 promoter methylation was associated with an increased CC risk based on the random effects model (OR: 21.20; 95%CI = 11.14–40.35). Omitting the most heterogeneous study, the between study heterogeneity decreased and the association increased (OR: 24.13; 95% CI = 15.83–36.78). The association was also confirmed in all the subgroups analyses.ConclusionsA significant strong association between DAPK1 promoter methylation and CC was shown and confirmed independently by histological tumor type, method used to evaluate methylation and source of control samples. Methylation markers may have value in early detection of CC precursor lesions, provide added reassurances of safety for women who are candidates for less frequent screens, and predict outcomes of women infected with human papilloma virus.

Association between DAPK1 Promoter Methylation and Cervical Cancer: a Systematic Review and a Meta‐analysis

DNA methylation, a major epigenetic mechanism, is involved in various biological processes including cancer. Particularly, promoter methylation can inactivate Death‐Associated Protein Kinase1 (DAPK1), a tumor suppressor gene which is often methylated during the carcinogenesis of cervical cancer. In the present systematic review and meta‐analysis, we evaluated the association between DAPK1 promoter methylation and cervical cancer risk. A literature search, using the PubMED database, was performed to select studies published up to July 2014. Subgroups analyses were performed. A total of 27 studies were included. All studies evaluated DAPK1 promoter methylation in squamous cell carcinoma and 12 studies also in adenocarcinoma. The “gold standard” method of promoter methylation evaluation was methylation specific PCR. Twenty studies, evaluating DAPK1 promoter methylation both in tumor and in healthy controls samples, were included in the meta‐analysis (1092 from cancer patients and 837 from controls). Meta‐analysis showed a significant association between DAPK1 promoter methylation and cervical cancer (pooled OR: 21.20; 95% CI: 11.14, 40.35) with the random effects model. The association was confirmed in specific subgroups. In conclusion DAPK1 promoter methylation might play an important role in the pathogenesis of cervical cancer. The promoter methylation of DAPK1 is a frequent event in cervical carcinogenesis and may have potential clinical application as a cancer biomarker.This work was conducted with the research support of Bench Srl, University of Catania.

RETRACTED ARTICLE: Promoter methylation of DAPK gene may contribute to the pathogenesis of nonsmall cell lung cancer: a meta-analysis

We performed a meta-analysis of cohort studies to determine whether promoter methylation of the death-associated protein kinase (DAPK) gene contributes to the pathogenesis of nonsmall cell lung cancer (NSCLC). A range of electronic databases were searched: MEDLINE (1966 ∼ 2013), the Cochrane Library Database (Issue 12, 2013), EMBASE (1980 ∼ 2013), CINAHL (1982 ∼ 2013), Web of Science (1945 ∼ 2013), and the Chinese Biomedical Database (CBM; 1982 ∼ 2013) without any language restrictions. Meta-analysis was conducted using the STATA 12.0 software. Crude odds ratio (OR) with 95 % confidence interval (95 % CI) was calculated. Our meta-analysis integrated results from 12 clinical cohort studies that met all inclusion criteria with a total of 1,027 NSCLC patients. We observed that the frequency of DAPK gene methylation in cancer tissues were significantly higher than that in the adjacent normal and benign tissues (cancer tissues vs. benign tissues: OR=8.50, 95 % CI=5.88 ∼ 12.28, P<0.001; cancer tissues vs. adjacent tissues: OR=5.95, 95 % CI=4.11 ∼ 8.60, P<0.001; cancer tissues vs. normal tissues: OR=4.75, 95 % CI=3.28 ∼ 6.87, P<0.001; respectively). Subgroup analysis by ethnicity demonstrated that DAPK gene methylation was closely associated with the development and progression of NSCLC among both Asians and Caucasians (all P<0.05). Furthermore, we conducted a subgroup analysis based on sample source and discovered that DAPK gene methylation was implicated in the pathogenesis of NSCLC in both blood and tissue subgroups (all P<0.05). Our results suggest that DAPK promoter methylation may be involved in NSCLC carcinogenesis. Thus, the detection of aberrant DAPK methylation may be helpful in the diagnosis and prognosis of NSCLC.

Epigenetic regulation of death-associated protein kinase expression in primary gastric cancers from Chinese patients

Death-associated protein kinase (DAPK) is a novel serine/threonine kinase involved in apoptosis and tumor suppression. Promoter methylation is an important mechanism by which tumor suppressor gene transcription is repressed in cancer cells. Although reduced expression and aberrant methylation of DAPK has been reported in various human cancers, including gastric cancer (GC), the results remain discrepant. We aimed to investigate DAPK mRNA and protein expression in primary GC tissues from Chinese patients and establish a possible relationship between the promoter methylation status and the decreased expression of DAPK. The mRNA level, protein expression, and promoter methylation of DAPK were examined, in the cancer tissues and the corresponding, adjacent nontumor tissues of the 62 GC cases, by RT-PCR, western blotting and methylation-specific PCR, respectively. DAPK mRNA and protein expression in GC tissues was significantly reduced compared with corresponding nontumor tissues (P<0.0001). The methylation frequency of the DAPK promoter in primary GC tissues is significantly higher than in the corresponding nontumor tissues (54.8 vs. 17.7%, P<0.0001). Furthermore, DAPK mRNA expression in tissues containing aberrant promoter methylation was significantly reduced compared with GC tissues with unmethylated DAPK promoter (P<0.0001). Moreover, a significant correlation was demonstrated between the TNM stage and the degree of DAPK promoter methylation in primary GCs (P=0.04). DAPK protein and mRNA expression was reduced in GC tissues of Chinese patients. Diminished expression of DAPK was associated with promoter methylation.

Quantitative analyses of DAPK1 methylation in AML and MDS

Aberrant DNA methylation and concomitant transcriptional silencing of death-associated protein kinase 1 (DAPK1) have been demonstrated to be key pathogenic events in chronic lymphocytic leukemia (CLL). In acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), however, the presence of elevated DNA methylation levels has been a matter of continued controversy. Several studies demonstrated highly variable frequencies of DAPK1 promoter methylation by the use of methylation-specific PCR (MSP). By quantitative high-resolution assessment, we demonstrate that aberrant DNA methylation is an extremely rare event in this region. We observed elevated levels just in one out of 246 (0.4%) AML patients, all 42 MDS patients were unmethylated. In conclusion, we present a refined DAPK1 methylation analysis in a large representative patient cohort of AML and MDS patients proofing almost complete absence of elevated DNA methylation. Our results highlight the importance of quantitative measurements for translational research questions on primary patient specimens, particularly.

Relationship between promoter methylation of p16, DAPK and RAR beta genes and the clinical data of non-small cell lung cancer

To investigate the effects of promoter methylation of p16, death-associated protein kinase (DAPK) and retinoic acid receptor-beta (RAR beta) genes on clinical data in non-small cell lung cancers, and to study the effect of smoking on the risk of gene methylation. The promoter methylation of p16, DAPK and RAR beta genes in 200 primary non-small cell lung cancers and the corresponding nonmalignant lung tissues were determined by methylation-specific PCR. Methylation in the tumor tissues was detected in 51.0% for p16, 60.0% for DAPK, and 58.0% for RAR beta gene, with significant differences (P < 0.05) when compared with those in the corresponding nonmalignant tissues(12.5%, 11.5% and 15.0%) respectively. p16 gene methylation in tumor tissue was associated with age significantly in unconditional logistic regression analysis (P < 0.01) and histologic type (P < 0.05). DAPK gene methylation in tumor tissue was associated significantly with age (P < 0.05), gender (P < 0.05) and clinical type (P < 0.05). RAR beta gene methylation in tumor tissue was associated with clinical type (P < 0.05) and tumor stage (P < 0.05) significantly. The interaction odds ratio (OR) for the gene-gene interaction in tumor tissue between p16 and DAPK was 1.987 (95%CI:1.055-3.743). The results of the gene-smoking analyses revealed that a relationship existed between cigarette smoking and p16 gene methylation (OR = 3.139, 95%CI: 1.046-9.419), the OR for the relationship of DAPK gene methylation and cigarette smoking was 3.585(95%CI: 1.270-10.123) in tumor tissue. The RAR beta gene methylation did not differ based on the smoking status of patients in tumor tissue. The p16, DAPK and RAR beta genes methylation are strongly associated with clinical data of non-small cell lung cancer, and methylation of p16 and DAPK genes are associated with tobacco smoking.