Prospecting for Breast Cancer Blood Biomarkers: Death-Associated Protein Kinase 1 (DAPK1) as a Potential Candidate.

BACKGROUND: Breast cancer is the commonest malignancy in women worldwide. It is estimated to affect approximately 1.5 million women annually and responsible for the greatest number of cancer-related mortalities among women. In 2018, breast cancer mortalities stood at 627,000 women representing approximately 15% of all cancer deaths among women. In Ghana, breast cancer is the second leading cause of cancer deaths, with an incidence of 2,900 cases annually; one of eight women with the disease die. This gives impetus to the fight for improved early detection, treatment, and/management. In this light, we investigated the potential of death-associated protein kinase 1 (DAPK1) as a biomarker for breast cancer. As a tumour suppressor, its expression is activated by several carcinogens to influence cellular pathways that result in apoptosis, autophagy, immune response, and proliferation. AIM: To investigate DAPK1 as a blood biomarker for breast cancer. METHODS: Blood samples of participants diagnosed with breast cancer and healthy controls were collected and processed to obtain serum. Information on age, treatment, diagnosis, and pathology numbers was retrieved from folders. Pathology numbers were used to retrieve breast tissue blocks of patients at the Department of Pathology of the KBTH. Tissue blocks were sectioned and immunohistochemically stained with anti-DAPK1 and counterstained with hematoxylin to determine the DAPK1 expression levels. DAKP1 levels in blood sera were quantified using a commercial anti-DAPK1 ELISA kit. Case and control group means were compared using one-way ANOVA and Chi-square test. Statistical significance was set at p ≤ 0.05. Results and Discussion. DAPK1 levels were higher in sera and breast tissues of breast cancer patients than controls. The augmented DAPK1 expression can be interpreted as a stress response survival mechanism to remediate ongoing deleterious events in the cells orchestrated by carcinogenesis. In the presence of abundant DAPK1, the proliferative power of cells (both cancerous and noncancerous) is increased. This may explain why high DAPK1 expression strongly associates with aggressive breast cancer phenotypes like the ER-negative breast cancers, especially the triple-negative breast cancers (TNBC) which are the most aggressive, fast-growing, and highly metastatic. CONCLUSION: DAPK1 is highly expressed in sera and breast tissues of breast cancer patients than nonbreast cancer participants. The elevated expression of DAKP1 in circulation rather than in breast tissues makes it a candidate for use as a blood biomarker and potential use as therapeutic target in drug development.

Death associated protein kinase 1 (DAPK-1) is increased in preeclampsia.

INTRODUCTION: Death associated protein kinase-1 (DAPK-1) is highly expressed in the placenta relative to all other human tissues. We examine whether it is differentially expressed with preeclampsia. METHODS: We examined samples from a large prospective collection of plasma from 2002 women. We split the samples into two cohorts: Cohort 1 (n = 1000) and Cohort 2 (n = 1002). We first measured circulating DAPK-1 at 36 weeks' gestation in a nested case-control group (from Cohort 1) of 39 women who developed preeclampsia and 98 controls. We then validated our findings by measuring circulating levels in all samples from both cohorts. We also measured DAPK-1 in the circulation and placentas of women who were diagnosed with preterm preeclampsia or delivered a growth restricted infant at <34 weeks' gestation. RESULTS: In the case-control study, circulating DAPK-1 was significantly increased in women destined to develop preeclampsia (p < 0.01). We validated this by measuring circulating levels in Cohorts 1 and 2. Again, circulating DAPK-1 was significantly higher (p < 0.001) among women destined to develop preeclampsia (Cohort 1, Area under the receiver operator characteristic curve (AUC) = 0.66; Cohort 2 AUC = 0.67). Circulating DAPK-1 was also significantly elevated in women with established preterm preeclampsia. Placental DAPK-1 mRNA and protein expression were elevated in women with established preeclampsia. DISCUSSION: DAPK-1 is a novel placenta-enriched molecule that is elevated in the circulation of women preceding the diagnosis of preeclampsia and is likely to be secreted from the placenta.

Promoter hypermethylation of tumor suppressor genes in serum as potential biomarker for the diagnosis of nasopharyngeal carcinoma.

PURPOSE: Promoter hypermethylation of tumor suppressor genes may serve as a promising biomarker for the diagnosis of cancer. Cell-free circulating DNA (cf-DNA) shares hypermethylation status with primary tumors. This study investigated promoter hypermethylation of five tumor suppressor genes as markers in the detection of nasopharyngeal carcinoma (NPC) in serum samples. METHODS: cf-DNA was extracted from serum collected from 40 NPC patients and 41 age- and sex-matched healthy subjects. The promoter hypermethylation status of the five genes (RASSF1, CDKN2A, DLEC1, DAPK1 and UCHL1) was assessed by methylation-specific PCR after sodium bisulfite conversion. Differences in the methylation status of these five genes between NPC patients and healthy subjects were compared. RESULTS: The concentration of cf-DNA in the serum of NPC patients was significantly higher than that in normal controls. The five tumor suppressor genes - RASSF1, CDKN2A, DLEC1, DAPK1 and UCHL1 - were found to be methylated in 17.5%, 22.5%, 25.0%, 51.4% and 64.9% of patients, respectively. The combination of four-gene marker - CDKN2A, DLEC1, DAPK1 and UCHL1 - had the highest sensitivity and specificity in predicting NPC. CONCLUSION: Screening DNA hypermethylation of tumor suppressor genes in serum was a promising approach for the diagnosis of NPC.