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 apoptosisand tumor suppression. DAPK1 is frequently lost in many different tumor types including breast cancer. The aim ofthis study was to evaluate the promoter methylation status of DAPK1 and a possible correlation with the expressionof 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 128breast 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 methylationfrequency among breast tumors when compared with the corresponding normal tissues. Hypermethylation of DAPK1is significantly correlated with the loss of DAPK1 protein expression (P < .001, rs= -0.361). The loss of DAPK1 proteinwas 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), ERnegativity (p= 0.004) and TNB cancers (p=0.003) correlated significantly with the hypermethylation of the DAPK1promoter. Coclusion: This study indicates that DAPK1 is methylated in IDC and promoter hypermethylation could beattributed to silencing of DAPK1 gene expression in breast cancer. Thus, we consider DAPK1 inactivation by promoterhypermethylation likely plays a role in the development and progression of breast cancer.