Death-associated Protein Kinase Hypermethylation 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 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.

Analysis of Promoter Hypermethylation of DAPK and BAX Apoptotic Genes in Iranian Gastric Cancer Patients Undergoing Chemotherapy

Background: The apoptotic route is mostly damaged in gastric cancer tumor cells. DNA methylation of promoter associated CpG islands inactivates tumor suppressor genes. The objective of the present study was to analyze the hypermethylation of death-associated protein kinase (DAPK) and Bcl-2-associated X protein (BAX) genes in individuals suffering from gastric cancer and undergoing chemotherapy. Methods: Genomic DNA was extracted from blood samples and the tissue fixed in the paraffin of 30 patients and normal individuals. Hypermethylation investigation of DAPK and BAX genes was conducted via methylation specific PCR technique, the outcomes of which were analyzed through electrophoresis and SPSS software version 20. Results: Methylation of both BAX and DAPK genes with a frequency of (28.3%, 21.7%) in blood and (23.3%, 23.3%) in tissue, respectively, had a significant relationship with gastric cancer (P˂0.01). A significant relationship was also observed between the methylation of BAX gene in tissue and tumor type (12, 35.3% and P˂0.01). No relationship was found between methylation and grade, stage, node, age, sex, and other pathologic and clinical data of the patients (P>0.05). There was a significant association between simultaneous methylation of DAPK and BAX genes in tumor and typical tissues with methylation a frequency of 40% and 95.83%, respectively (P˂ 0.01). Conclusion: Methylation of the BAX and DAPK genes can be used as a biomarker in bloodand an approach in the early detection of malignity and illness management. Methylation inhibitors with the potential for drug targeting of DAPK and BAX can further be employed in pharmacotherapy.

IDENTIFICATION OF FREQUENT PROMOTER METHYLATION OF DEATH-ASSOCIATED PROTEIN KINASE IN LIQUID-BASED PAPANICOLAOUS TEST SAMPLES IN VIETNAMESE POPULATION

Objective: The infection of high-risk human papillomavirus (HPV) genotypes, particularly HPV-16 and HPV-18, is known to cause cervical cancer (CC); however, aberrant DNA methylation of death-associated protein kinase (DAPK), a member of tumor suppressor gene family, are required for cervical tumorigenesis. The aim of our study was to evaluate the hypermethylation frequency of CpG belonged to DAPK promoter, in Vietnamese patients, as well as to study about the association between hypermethylation, and high-risk HPV infection leading to CC.Methods: Methylation-specific-polymerase chain reaction (MSP) was performed to analyze methylation status from 109 liquid-based papanicolaous test samples, collected from local hospital and were identified whether HPV/or non-HPV, high-risk/low-risk HPV infection, then was confirmed by sequencing.Results: In the case of high-risk HPV infection, the frequency of DAPK gene hypermethylation was 66.67% (24 of 36 cases). Meanwhile, low hypermethylation status was found in low-risk and non-HPV infection, counting for 12.0% (3 of 25 cases), 2.1% (1 of 48 cases), respectively. Significant association of DAPK hypermethylation with high-risk, low-risk, and non-HPV infection was observed (p<0.0001). The DAPK hypermethylation increased the possibility to CC in the case of high-risk HPV infected with high incidence: Odds ratio=34.5 (95% confidence interval [CI]=10.15-117.23, p<0.01), relative risk=12.2 (95% CI=4.56-32.42, p<0.01).Conclusion: Based on those data, it suggested that MSP carried out on noninvasive samples will lead to potential method to screening, diagnosis and early diagnosis of cervical carcinoma in Vietnamese population.

Hypermethylation of Death-Associated Protein Kinase (DAPK1) and its association with oral carcinogenesis - An experimental and meta-analysis study

ObjectivesThe value of abnormal DNA methylation of DAPK1 promoter and its association with various cancers have been suggested in the literature. To establish the significance of DNA methylation of DAPK1 promoter in oral squamous cell carcinoma (OSCC), we a) performed a case-control study, b) evaluated published data for its utility in the diagnosis and prognosis of OSCC and c) identified the association of DAPK1 gene expression with promoter DNA methylation status. DesignBisulfite gene sequencing of DAPK1 promoter region was performed on non-malignant and malignant oral samples. Further, using a systematic search, 330 publications were retrieved from PubMed, Scopus, and Google Scholar and 11 relevant articles were identified. ResultsSignificant association of DAPK1 promoter methylation with OSCC (p<0.0001) was observed in the case-control study. The studies chosen for meta-analysis showed prognostic and predictive significance of DAPK1 gene promoter, despite defined inconsistencies in few studies. Overall, we obtained a statistically significant (p-value<0.001) association for both sensitivity and specificity of DAPK1 DNA promoter methylation in oral cancer cases, without publication bias. ConclusionDNA hypermethylation of DAPK1 gene promoter is a promising biomarker for OSCC prediction/prognostics and suggests further validation in large distinct cohorts to facilitate translation to clinics.

Increased hypermethylation of glutathione S-transferase P1, DNA-binding protein inhibitor, death associated protein kinase and paired box protein-5 genes in triple-negative breast cancer Saudi females.

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer (BC) with higher metastatic rate and both local and systemic recurrence compared to non-TNBC. The generation of reactive oxygen species (ROS) secondary to oxidative stress is associated with DNA damage, chromosomal degradation and alterations of both hypermethylation and hypomethylation of DNA. This study concerns differential methylation of promoter regions in specific groups of genes in TNBC and non-TNBC Saudi females in an effort to understand whether epigenetic events might be involved in breast carcinogenesis, and whether they might be used as markers for Saudi BCs. Methylation of glutathione S-transferase P1 (GSTP1), T-cadherin (CDH13), Paired box protein 5 (PAX5), death associated protein kinase (DAPK), twist-related protein (TWIST), DNA-binding protein inhibitor (ID4), High In Normal-1 (HIN-1), cyclin-dependent kinase inhibitor 2A (p16), cyclin D2 and retinoic acid receptor-β (RARβ1) genes was analyzed by methylation specific polymerase chain reaction (MSP) in 200 archival formalin- fixed paraffin embedded BC tissues divided into 3 groups; benign breast tissues (20), TNBC (80) and non-TNBC (100). The relationships between methylation status, and clinical and pathological characteristics of patients and tumors were assessed. Higher frequencies of GSTP1, ID4, TWIST, DAPK, PAX5 and HIN-1 hypermethylation were found in TNBC than in non-TNBC. Hypermethylation of GSTP1, CDH13, ID4, DAPK, HIN-1 and PAX5 increased with tumor grade increasing. Other statistically significant correlations were identified with studied genes. Data from this study suggest that increased hypermethylation of GSTP1, ID4, TWIST, DAPK, PAX5 and HIN-1 genes in TNBC than in non-TNBC can act as useful biomarker for BCs in the Saudi population. The higher frequency of specific hypermethylated genes paralleling tumor grade, size and lymph node involvement suggests contributions to breast cancer initiation and progression.

Promoter hypermethylation patterns of P16, DAPK and MGMT in oral squamous cell carcinoma: a systematic review and meta-analysis.

Oral squamous cell carcinoma (OSCC) is a common cancer world-wide that is highly lethal due to its recurrence and metastasis. Methylation is a common epigenetic mechanism that leads to gene silencing in tumors and could be a useful biomarker in OSCC. The prevalence of P16, death-associated protein kinase (DAPK) and O6-methylguanine-DNA-methyltransferase (MGMT) promoter hypermethylation in OSCC has been evaluated for several years while the results remain controversial. The aim of this systematic review is to critically analyze and perform a meta-analysis on the various studies in the literature that have reported the promoter hypermethylation of P16, DAPK and MGMT genes in OSCC. Articles were searched and selected through PubMed. Hand search from the relevant journals was also performed. Articles were reviewed and analyzed. The estimated prevalence of P16 methylation was 43%, DAPK methylation was 39.7% and MGMT methylation was 39.8%. Heterogeneity in methylation prevalences and correlations with the clinical outcomes of the disease prevailed in various studies. We can conclude from our systematic review that a higher prevalence of methylation of P16, DAPK and MGMT occur in OSCC. Further studies are required to substantiate the role of methylation of P16, DAPK and MGMT as a marker in OSCC.

Promoter Hypermethylation of Death-Associated Protein Kinase and p16 Genes in Vulvar Lichen Sclerosus

The purpose of this study was to discuss our investigation of the hypermethylation of promoter regions of tumor suppressor genes, such as death-associated protein kinase (DAPK) and p16, in vulvar lichen sclerosus (LS), in comparison with a control group. Promoter hypermethylation of DAPK and p16 was investigated using 24 vulvar biopsies of patients with LS who had received no previous treatment. The control group was composed of 15 patients with no vulvar disease. The DNA of subjects was treated with sodium bisulphate, and the genes under study were subjected to methylation-specific polymerase chain reaction. The resulting polymerase chain reaction products were amplified and analyzed using a 10% polyacrylamide gel. The mean age of the patients with LS was 57 years (the majority were postmenopausal). In the control group, the mean age of the patients was 50 years (p = .151). Methylation of the promoter region of DAPK was found in 4 (17%) of the 23 patients analyzed, and p16 promoter region methylation was found in 8 patients (35%). Two cases of methylation of the DAPK gene were also found to be methylated for the p16 gene. In the control group, no methylation was found in the patients analyzed for the DAPK gene and methylation was found in 3 (21%) of the 14 patients analyzed for the p16 gene (p = .190 and p = .316, respectively). Methylation of the DAPK and p16 genes, although not sufficient to dictate prognosis of the disease, should not be underestimated because it may form part of a process of genetic and epigenetic alterations that in the future could become relevant to malignant transformation.

Hypermethylation of MGMT and DAPK gene promoters is associated with tumorigenesis and metastasis in oral squamous cell carcinoma

Background/purpose Oral squamous cell carcinoma (OSCC) is the fourth major cause of mortality among males in Asia. The tumorigenesis of OSCC is a multi-step process characterized by sequential morphological changes. The extent of lymph node metastasis is a major determinant in the prognosis of cancer. Hypermethylation is an important pathway for repression of gene transcription in cancer cells and a promising marker for cancer detection. It is also found in early metastatic cancer patients. Materials and methods Sixty-four histologically confirmed OSCC tissues and corresponding nontumorous tissues were enrolled in this study. DNA was extracted. The promoter methylation status of the p16, death-associated protein kinase (DAPK), MGMT, and glutathione S-transferase genes in OSCC tissues was evaluated by a methylation-specific polymerase chain reaction analysis. Results Frequencies of promoter hypermethylation of p16, DAPK, and MGMT in OSCC tissue were 67.2%, 45.3%, and 31.3%, respectively. No methylation was found in normal oral mucosa. Methylation rates of MGMT (50%) and DAPK (55.6%) in metastasized OSCC were higher than those of MGMT (23.9%) and DAPK (41.3%) in nonmetastasized OSCC. No glutathione S-transferase P methylation was found in any tissue samples. Conclusions Our study supports the hypothesis that hypermethylation of p16 gene promoters may indicate a high risk of oral cancer, and hypermethylation of the MGMT and DAPK genes may be a major indicator of early OSCC metastasis.

DAPK promoter hypermethylation in tissues and body fluids of oral precancer patients

Death-associated protein kinase (DAPK) has been suggested as a tumor suppressor gene. A high frequency of DAPK promoter hypermethylation has been noted in head and neck cancers and other solid tumors, and it has been used as a tumor marker in molecular detection strategies. Our aim was to examine DAPK promoter hypermethylation in tissue, blood, and salivary rinse samples of oral precancer patients (OPs) and to explore the potential role in oral carcinogenesis. DAPK hypermethylation was analyzed in 77 OPs and 32 oral squamous cell carcinomas (OSCCs) by real-time quantitative methylation-specific PCR (QMSP). We compared the hypermethylation expression between two groups and analyzed the associations with clinicopathologic parameters. The promoter hypermethylation frequency of DAPK in tissue (46.9%) and blood (52.2%) of OSCCs was significantly higher than those in OPs (19.5%, P = 0.004; 22.4%, P = 0.007, respectively). DAPK promoter hypermethylation expression in blood was correlated with its expression in tissue (r = 0.49, P < 0.000). The OP patients who smoked more than 20 years were found 40.0% tissue DAPK hypermethylation in contrast with 10.7% tissue DAPK hypermethylation in the patients whose smoking duration ≦20 years (P = 0.010). Our results suggest that DAPK hypermethylation is an early event in oral carcinogenesis and blood DAPK hypermethylation might be a potential minimal invasive biomarker for OSCC early detection.

Promoter Hypermethylation Patterns of Death-Associated Protein Kinase and p16 Genes in Vulvar Lichen Sclerosus

This article aimed to investigate the hypermethylation of promoter regions of tumor suppressor genes, such as death-associated protein kinase (DAPK) and p16, in vulvar lichen sclerosus (LS). The promoter hypermethylation of DAPK and p16 was investigated from 15 vulvar biopsies of patients with LS who had had no previous treatment. DNA was treated with sodium bisulfate and underwent methylation-specific polymerase chain reaction of these genes. The amplified polymerase chain reaction products were analyzed by 10% polyacrylamide gel. The mean age of the patients was 57 years (most were postmenopausal). Methylation of the promoter region of DAPK was found in 2 (13%) of 15 patients analyzed, and p16 promoter region methylation was found in 7 patients (47%). The samples that showed DAPK methylation also showed p16 methylation. Methylation of DAPK and p16 represent alterations that might occur in cell cycle control in LS. The hypothesis is that patients who had methylated genes in this study, mainly the 2 cases in which there has been methylation in both studied genes, may be more susceptible to the development of differentiated vulvar intraepithelial neoplasia or vulvar cancer. Methylation may play a role in progress of vulvar carcinogenesis.

Aberrant methylation of DAPK in long-standing ulcerative colitis and ulcerative colitis-associated carcinoma

Death-associated protein kinase (DAPK) has pro-apoptotic functions and participates in various apoptotic systems. DAPK acts as a tumor suppressor, and its inactivation by promoter hypermethylation has been frequently observed in various human cancers. As alterations of pro-apoptotic genes might cause instability in the balance of cell-turnover during chronic inflammatory processes, epigenetic silencing of DAPK might be involved in the carcinogenesis of ulcerative colitis-associated carcinoma (UCC). To evaluate the role of DAPK in the inflammation-driven carcinogenesis of ulcerative colitis (UC), we analyzed promoter hypermethylation and protein expression of DAPK using methylation-specific PCR and immunohistochemistry in 43 UCCs and paired UC-background mucosa, as well as in UC-background mucosa of 50 patients without UCC. The frequency of methylation of DAPK in UCCs was low (27.6%) compared to overall non-neoplastic UC-background mucosa (48.3%; p = 0.02) and sporadic colorectal carcinoma (57.4%, p = 0.019). The difference in the methylation frequency in UC-background mucosa in patients without UCC (54.2%), compared to those with UCC (40.0%), was not significant ( p = 0.141). Promoter methylation correlated significantly with decreased DAPK protein expression ( p < 0.001) and severity of inflammatory activity ( p = 0.024). In unmethylated UC-background mucosa, DAPK protein expression increased with activity of UC-associated inflammation, suggesting a protective role of the pro-apoptotic DAPK during the chronic inflammatory process of UC. Thus, inactivation of DAPK by promoter hypermethylation might be crucial for accumulation of DNA damage in inflamed mucosa of UC, and might therefore contribute to the initiation of the neoplastic process and development of UC-associated carcinoma.

Gene promoter hypermethylation in leukoplakia of the oral mucosa

Gene promoter hypermethylation in leukoplakia of the oral mucosa Mingli Liu1, Lei Feng2, Ximing Tang3, Shanchun Guo41Department of Physics, Tufts University School of Medicine, Boston, Massachussetts; 2Department of Thoracic/Head and Neck Medical Oncology, 3Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas; 4Sylvester Cancer Center, University of Miami School of Medicine, Florida, USAAbstract: To examine whether aberrant DNA methylation in the promoter region might occur earlier in tumorigenesis, particularly in premalignant lesions, we examined biopsies from 111 participants in a chemoprevention trial aimed at reversal of oral leukoplakia, using methylation-specific polymerase chain reaction for the promoter regions of the tumor suppressor gene CDKN2A (p16), the putative metastasis suppressor gene for death-associated protein kinase (DAP-K), the DNA repair gene O6-methyguanine-DNA-methyltransferase (MGMT), and the detoxification gene glutathione S-transferase p1(GSTP1). p16 promoter hypermethylation was detected in 21 of 82 (25.6%), DAP-K hypermethylation in 28 of 87 (32.2%), and MGMT hypermethylation in 32 of 106 (30.2%) oral leukoplakia lesions analyzed. No aberrant methylation was found at the GSTP1 gene in 110 lesions examined. Among 68 biopsies analyzed for all three genes (p16, DAP-K, MGMT), 17 biopsies were detected with an abnormal methylation pattern at only one gene, 15 at two genes, and 8 at all three genes. Among clinical characteristics and their correlation with methylation, only alcohol consumption was correlated with DAP-K methylation (P = 0.027), while MGMT methylation was more frequent in females (P = 0.003) and nonsmokers (P = 0.0005). A significant correlation was found between p16 and DAP-K hypermethylation; p16 promoter was methylated in 14 (56%) of 25 lesions with DAP-K methylation, and only 5 (11.1%) of 45 DAP-K methylation-negative lesions (P = 0.0001). DAP-K aberrant methylation was also significantly correlated with MGMT methylation (16 of 31 in MGMT methylation-positive lesions versus 12 of 52 MGMT methylation-negative lesions, P = 0.0016). Our results suggest that epigenetic mechanisms of inactivation, such as aberrant methylation of p16, DAP-K, and MGMT genes, occur early in head and neck tumorigenesis, and might play a role in the progression of these lesions.Keywords: p16, DAP-K, MGMT, GSTP1 genes, methylation, leukoplakia

Correlation of promoter hypermethylation in hTERT, DAPK and MGMT genes with cervical oncogenesis progression

DNA hypermethylation occurs during the multistep process of cervical carcinogenesis. We investigated whether the methylation status in the promoter region of a potential oncogene, the human telomerase reverse transcriptase (hTERT), and the tumor suppressor genes death-associated protein kinase (DAPK) and O6-methylguanine DNA methyltransferase (MGMT), were able to distinguish the early from late stages of cervical oncogenesis. The methylation status in the promoter of these genes was analyzed using real-time MethyLight analysis in 115 cervical specimens, including normal, premalignant [atypical squamous epithelial cells (ASCUS), low-grade squamous intraepithelial lesions (LGSIL), high-grade squamous intraepithelial lesions (HGSIL)] and cancer specimens. Clinicopathological parameters (cytology, histology, grade, stage) were compared to the levels of promoter hypermethylation. We found that hTERT, MGMT and DAPK hypermethylation levels were increased during cervical oncogenesis progression. hTERT promoter hypermethylation was able to distinguish normal from cancer (p=0.008), normal from premalignant (p=0.036), as well as premalignant from cervical cancer cases (p=0.003). A significant association was also observed between all three genes and the grade of cervical cancer, with hTERT showing a better association (p<0.0001). Our data suggest that the combination of hTERT, MGMT, DAPK promoter hypermethylation could have a potential function as molecular biomarker of cervical oncogenesis progression.

Hypermethylation of Death-Associated Protein Kinase 1 differentiates natural killer cell lines from cell lines derived from T-acute lymphoblastic leukemia

Hypermethylation of Death-Associated Protein Kinase 1 differentiates natural killer cell lines from cell lines derived from T-acute lymphoblastic leukemia

Promoter methylation of death-associated protein kinase and its role in irradiation response in cervical cancer

This study was aimed at investigating the death-associated protein kinase (DAPK) promoter methylation and its clinical relevance in cervical cancer. The DAPK promoter methylation was detected by methylation-specific PCR (MSP) and correlated with DAPK mRNA and protein expression. The effect of DAPK expression on the radiosensitivity of the cervical cancer cell line was assessed by overexpressing DAPK in the radioresistant cell line SiHa. DAPK hypermethylation was found in 56.08% of the cervical cancer samples and was associated with the tumor histological cell type of squamous cell carcinoma (p=0.002) and advanced tumor stage (p=0.005). Subsequently, DAPK protein expression was found to significantly decrease in cervical cancer samples when compared to normal tissues. The DAPK mRNA and protein expression levels were absent or remarkably reduced in SiHa and HeLa in which the DAPK promoter was hypermethylated. The expression levels of DAPK could be restored after demethylation treatment with 5-aza-2'-deoxycytidine. Overexpressing DAPK in vitro had no significant influence to the survival of the radioresistant SiHa cell after being challenged by irradiation. Our findings suggest that DAPK might not directly be responsible for the cellular radiosensitivity, however, DAPK hypermethylation appeared to be of prognostic significance in the advanced stages of cervical cancer.

Urothelial carcinomas arising in arsenic‐contaminated areas are associated with hypermethylation of the gene promoter of the death‐associated protein kinase

The mechanisms of urothelial carcinogenesis in areas highly contaminated with arsenic remain unclear. The aim was to determine whether hypermethylation of death-associated protein kinase (DAPK) gene is associated with chronic arsenic exposure. The frequency of aberrant promoter methylation of DAPK in 17 urothelial carcinomas from an arsenic-contaminated area and 21 urothelial carcinomas from a non-arsenic-contaminated area was determined by methylation-specific polymerase chain reaction. DAPK hypermethylation status was significantly higher in urothelial cancers arising in arsenic-contaminated areas when compared with tumours from patients from non-contaminated areas (P = 0.018). In the subset of patients from living environments which were contaminated with arsenic, there was a statistically significant association between DAPK hypermethylation and patient's age, tumour invasiveness, histological grade and recurrence. This was not seen for urothelial carcinoma from patients from non-contaminated areas. A close correlation was also found between DAPK promoter methylation and low-intensity DAPK expression, as detected by immunohistochemistry (P = 0.037). Exposure to arsenic may induce DAPK promoter hypermethylation and inactivate the function of DAPK in urothelial carcinoma. This could prove to be a key molecular event contributing to the malignant phenotype of tumour arising in patients from arsenic-contaminated environments.

Positive Correlation of Tissue Inhibitor of Metalloproteinase‐3 and Death‐Associated Protein Kinase Hypermethylation in Head and Neck Squamous Cell Carcinoma

Promoter hypermethylation of tumor suppressor genes is common in head and neck cancer as well as other primary cancers resulting in epigenetic gene silencing. Tissue inhibitor of metalloproteinase-3 (TIMP-3) has been shown to have promoter hypermethylation in several solid tumors, but has not been identified in head and neck squamous cell carcinoma (HNSCC). Our objective was to determine if TIMP-3 promoter was hypermethylated in HNSCC, if there was any correlation with death associated protein kinase (DAPK), a tumor suppressor whose promoter has been hypermethylated at high levels in HNSCC, and if any clinical factors influence hypermethylation of either of these genes. Prospective study. Tumor samples from 124 patients with HNSCC were evaluated for promoter hypermethylation for TIMP-3 and DAPK using quantitative methylation specific polymerase chain reaction (qMSP). We compared both TIMP-3 and DAPK hypermethylation in HNSCC with each other as well as with other clinical variables. We found that TIMP-3 was hypermethylated in approximately 71.8% of the tumor samples and DAPK was hypermethylated in 74.2%. The presence of TIMP-3 and DAPK promoter hypermethylation was significantly higher than in control specimens. More importantly, TIMP-3 and DAPK hypermethylations in these samples were highly correlated with a concordance of 78% (P < .001). DAPK was also correlated with current alcohol consumption (P < .028), but neither TIMP-3 nor DAPK hypermethylation was significantly correlated with other clinical variables or with survival. TIMP-3 promoter hypermethylation is elevated in HNSCC and is highly correlated with DAPK hypermethylation, implying a functional relationship between these genes.

Epigenetic dysregulation of the death-associated protein kinase/p14/HDM2/p53/Apaf-1 apoptosis pathway in multiple myeloma

Aim: To study the role of gene promoter hypermethylation of the putative tumour suppressor genes involved in the death-associated protein (DAP) kinase/p14/HDM2/p53/Apaf-1 apoptosis pathway in multiple myeloma (MM). Method: DNAs...

Correlation between promoter hypermethylation of GSTP1 and response to chemotherapy in diffuse large B cell lymphoma

Glutathione-S-transferase P1 (GSTP1) and O6-methylguanine DNA methyltransferase (MGMT) are involved in drug-resistant to chemotherapeutic agents such as doxorubicin. In this study, prognostic significance of promoter hypermethylation and mRNA and protein expression of GSTP1 and MGMT together with promoter hypermethylation of death-associated protein kinase (DAPK) in diffuse large B cell lymphoma (DLBCL) was analyzed. Fifty-three patients with DLBCL, 24 men and 29 women, with age ranging from 23 to 91 (median 65), were analyzed. Genomic DNA and total RNA extracted from frozen samples of DLBCL were analyzed by methylation-specific polymerase chain reaction and quantitative reverse transcription polymerase chain reaction (RT-PCR) to determine promoter hypermethylation and mRNA expression of GSTP1, MGMT, and DAPK. Immunohistochemical analysis was performed to determine GSTP1 and MGMT expression at the protein level. Promoter hypermethylation of GSTP1, MGMT, and DAPK was detected in 12 (22.6%), 21 (39.6%), and 36 (67.9%) of 53 patients, respectively. Quantitative RT-PCR and immunohistochemistry did not show a correlation between methylation status and mRNA and protein expression of GSTP1 and MGMT. Patients with GSTP1 promoter hypermethylation showed a better 5-year overall survival rate than those without (100 vs 62.2%; p < 0.05). However, GSTP1 promoter hypermethylation was not an independent prognosticator in multivariate analysis. Methylation status of GSTP1 could be an indicator of drug response and a prognosticator for DLBCL.