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.
Keywords: Breast cancer; DAPK1; hypermethylation; immunohistochemistry; MSP.
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