Abstract:
Objective This study aimed to investigate the methylation and protein expression of death-associated protein kinase(DAPK) promoter in epithelial ovarian carcinoma(EOC).This study also aimed to evaluate the functions of DAPK methylation and protein expression in EOC development.
Methods Methylation-specific polymerase chain reaction was performed to detect DAPK promoter methylation in paraffin-embedded tissue specimens.The following specimens were examined: 55 cases of EOC tissues(malignant group); 25 borderline epithelial ovarian neoplasms(borderline group); 30 cases of benign epithelial ovarian neoplasms(benign group); and 25 cases of normal epithelial ovarian tissue(normal group).Immunohistochemical streptavidin-peroxidase method was also performed to assess DAPK expression in the aforementioned specimens.
Results The rate of DAPK promoter methylation was 0%(0/25), 6.7%(2/30), 16.0%(4/25), and 47.3%(26/55) in normal, benign, borderline, and malignant groups, respectively.This rate was significantly higher in the malignant group than in the three groups(P < 0.008 3).The rate of DAPK-positive protein expression was 96.0%(24/25), 90.0%(27/30), 48.0%(12/25), and 30.9%(17/55) in normal, benign, borderline, and malignant groups, respectively.This rate was significantly lower both in malignant and borderline groups than that in benign and normal groups, respectively(P < 0.008 3).Thus, DAPK promoter methylation was negatively correlated with its protein expression.
Conclusion DAPK promoter methylation caused gene silencing and inactivity, thereby resulting in downregulation or loss of DAPK promoter protein expression, which contributed to oncogenesis and progression of EOCs.