An alternative transcript from the death-associated protein kinase 1 locus encoding a small protein selectively mediates membrane blebbing

Investigation of the Vascular-Endothelial Pattern of Expression of DAPK-1 in Oral Squamous Cell Carcinoma and Oral Potentially Malignant Disorders Through Immunohistochemistry

Introduction Potentially malignant disorders, like oral lichen planus (OLP) and oral leukoplakia (OL) of several degrees of dysplasia, manifest a significant potential of malignant transformation being a precursor of oral squamous cell carcinoma (OSCC). The role of microvascularization in carcinogenesis is critical; therefore, microvascularization constitutes a major therapeutic target. DAPK-1 constitutes a possible cancer marker, with proven implications in other human cancers, and there isn't any study on its vascular endothelial expression in the oral cavity, particularly in oral cancer and oral potentially malignant diseases. The present study aims to investigate the vascular endothelial expression of the DAPK-1 in paraffin-embedded tissue samples of oral leukoplakia, oral squamous cell carcinoma, and oral lichen planus. Materials and methods The study focuses on the immunohistochemical, vascular-endothelial, expression pattern of biomarker DAPK-1 (NBP2-38468, Novus Biologicals, Centennial, CO, US). Tissue samples were obtained from six cases of oral lichen planus (OLP) (3 of reticular and 3 of erosive form), 30 cases of oral leukoplakia (OL) (10 with no dysplasia, 10 with mild dysplasia, and 10 with moderate/severe dysplasia), 22 cases of OSCC (2 well-differentiated, 17 moderately differentiated, and 3 poorly differentiated), as well as 5 cases of normal oral epithelium. The tissue samples were retrieved from the archives of the Department of Oral Medicine/Pathology, School of Dentistry, Aristotle University of Thessaloniki, as well as from St Lukas Hospital of Thessaloniki, Greece, from 2004-2019. In accordance with the Research and Ethics Committee guidelines of the Aristotle University, School of Dentistry, and the Helsinki II declaration, the study was conducted. The primary inclusion criteria for the study focused on the presence of sufficient precancerous or cancerous tissue. Conversely, inadequate tissue served as the exclusion criteria. The staining was evaluated exclusively in a quantitative manner. The vascular endothelial staining was evaluated as either positive or negative. If at least one endothelial cell exhibited positive staining, the section was classified as positive. Statistical analysis was carried out using SPSS Statistics v25.0 (IBM Corp., Armonk, NY, US) utilizing Pearson's chi-square or Fisher's exact test, depending on the sample size, to compare OLP to OL, OLP to OSCC, OLP to normal, OL to OSCC, OL to normal, and OSCC to normal. The significance level was established at 0.05 (p=0.05). Results A prevalence of positive OL cases may be noticed. The comparison between OLP and OL yielded Fisher's exact test of p>0.999, OLP and OSCC p=0.389, OLP and normal oral epithelium p>0.999, OL and OSCC p=0.226, OL and normal oral epithelium p>0.999, as well as OSCC and normal oral epithelium p=0.342. Conclusions The role of DAPK in tumorigenesis is already supported by limited literature. However, its implication in the development of OSCC and oral potentially malignant disorders (OPMDs) has yet to be elucidated. Its elevated expression in OL suggests a role in affecting the microenvironment, the vessels, in particular, surrounding oral potentially malignant lesions, possibly assisting their transition into cancer. The evaluation of the vascular-endothelial immunohistochemical profile of DAPK-1 in OL, OLP, and OSCC requires further studies in more tissue samples to illustrate its possible implications.

Death-associated protein kinases and intestinal epithelial homeostasis

The family of death-associated protein kinases (DAPKs) and DAPK-related apoptosis-inducing protein kinases (DRAKs) act as molecular switches for a multitude of cellular processes, including apoptotic and autophagic cell death events. This review summarizes the mechanisms for kinase activity regulation and discusses recent molecular investigations of DAPK and DRAK family members in the intestinal epithelium. In general, recent literature convincingly supports the importance of this family of protein kinases in the homeostatic processes that govern the proper function of the intestinal epithelium. Each of the DAPK family of proteins possesses distinct biochemical properties, and we compare similarities in the information available as well as those cases where functional distinctions are apparent. As the prototypical member of the family, DAPK1 is noteworthy for its tumor suppressor function and association with colorectal cancer. In the intestinal epithelium, DAPK2 is associated with programmed cell death, potential tumor-suppressive functions, and a unique influence on granulocyte biology. The impact of the DRAKs in the epithelium is understudied, but recent studies support a role for DRAK1 in inflammation-mediated tumor growth and metastasis. A commentary is provided on the potential importance of DAPK3 in facilitating epithelial restitution and wound healing during the resolution of colitis. An update on efforts to develop selective pharmacologic effectors of individual DAPK members is also supplied.

Evaluation of the prognostic and physiological functions of death associated protein kinase 1 in breast cancer

Death associated protein kinase 1 (DAPK1) is a notable serine/threonine kinase involved in the regulation of multiple cellular pathways, including apoptosis and autophagy. Although DAPK1 is usually considered to be a tumor suppressor, it was previously reported to promote the viability of p53 mutant cancer cell lines and possess physiological oncogenic functions in breast cancer. However, the ability of endogenous DAPK1 to suppress breast cancer cell mobility has not been assessed. In the present study, the prognostic function of DAPK1 in a Chinese patient cohort was evaluated, and no significant association was observed between DAPK1 expression and patient survival or lymph node metastasis. In order to investigate the physiological function of endogenous DAPK1, stable inducible DAPK1 knockdown MCF7 and MDA-MB-231 cell lines were established. Consistent with previous studies, endogenous DAPK1 only regulated cell viability in p53 mutant MDA-MB-231 cells. However, knockdown of DAPK1 did not significantly affect cell motility of either MCF7 or MDA-MB-231 cells. Altogether, these results further explored the function of endogenous DAPK1 in breast cancer and may shed light in understanding the molecular signaling pathways regulating the physiological function of DAPK1.

Quantitative and correlation analysis of the DNA methylation and expression of DAPK in breast cancer

Background

Death-associated protein kinase 1 (DAPK) is an important tumor suppressor kinase involved in the regulation of multiple cellular activities such as apoptosis and autophagy. DNA methylation of DAPK gene was found in various types of cancers and often correlated with the clinicopathological characteristics. However, the mRNA and protein expression of DAPK in the same sample was rarely measured. Thus, it was unclear if the correlation between DAPK gene methylation and clinicopathological parameters was due to the loss of DAPK expression.

Methods

In this study, the DNA methylation rate, mRNA and protein expression of DAPK was quantitatively detected in 15 pairs of breast cancer patient samples including tumor (T) and adjacent non-tumor (N) tissues.

Results

The correlation between DNA methylation rate and mRNA expression, together with the correlation between mRNA and protein expression, was calculated. No correlation was observed between any levels using either the measurement value of each sample or the T/N ratio of each pair.

Discussion

These data suggested that the DNA methylation status of DAPK did not correlate well with its mRNA or protein expression. Extra caution is needed when interpreting the DNA methylation data of DAPK gene in clinical studies.

Death associated protein kinases: molecular structure and brain injury

Perinatal brain damage underlies an important share of motor and neurodevelopmental disabilities, such as cerebral palsy, cognitive impairment, visual dysfunction and epilepsy. Clinical, epidemiological, and experimental studies have revealed that factors such as inflammation, excitotoxicity and oxidative stress contribute considerably to both white and grey matter injury in the immature brain. A member of the death associated protein kinase (DAPk) family, DAPk1, has been implicated in cerebral ischemic damage, whereby DAPk1 potentiates NMDA receptor-mediated excitotoxicity through interaction with the NR2BR subunit. DAPk1 also mediate a range of activities from autophagy, membrane blebbing and DNA fragmentation ultimately leading to cell death. DAPk mRNA levels are particularly highly expressed in the developing brain and thus, we hypothesize that DAPk1 may play a role in perinatal brain injury. In addition to reviewing current knowledge, we present new aspects of the molecular structure of DAPk domains, and relate these findings to interacting partners of DAPk1, DAPk-regulation in NMDA-induced cerebral injury and novel approaches to blocking the injurious effects of DAPk1.