The role of DAPK2 as a key regulatory element in various human cancers: a systematic review.

Cancer is considered the uncontrolled growth and spread of cells into neighboring tissues, a process governed at the molecular level by many different factors, including abnormalities in the protein family's death-associated kinase (DAPK). DAPK2 is a member of the DAPK protein family, which plays essential roles in several cellular processes. DAPK2 acts as a tumor suppressor, interacting with several proteins, such as TNF, IFN, etc. during apoptosis and autophagy. Expression of DAPK2 causes changes in the structure of the cell, ultimately leading to cell death by apoptosis. In this essay, studies are obtained from Scopus, PubMed, and the Web of Science. According to these investigations, DAPK2 activates autophagy by interacting with AMPK, mTORC1, and p73. Furthermore, DAPK2 induces apoptosis pathway via interacting with the p73 family and JNK. In general, due to the vital role of DAPK2 in cell physiology and its effect on various factors and signaling pathways, it can be a potent target in the treatment of various cancers, including gastric, ovarian, breast, and other prominent cancers.

Mechanism of DAPK1 for Regulating Cancer Stem Cells in Thyroid Cancer.

Death-associated protein kinase 1 (DAPK1) is a calcium/calmodulin (Ca2+/CaM)-dependent serine/threonine (Ser/Thr) protein kinase and is characteristically downregulated in metastatic cancer. Several studies showed that DAPK1 is involved in both the early and late stages of cancer. DAPK1 downregulation is elaborately controlled by epigenetic, transcriptional, posttranscriptional, and posttranslational processes. DAPK1 is known to regulate not only cancer cells but also stromal cells. Recent studies showed that DAPK1 was involved not only in tumor suppression but also in epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC) formation in colon and thyroid cancers. CSCs are major factors in determining cancer aggressiveness in cancer metastasis and treatment prognosis by influencing EMT. However, the molecular mechanism involved in the regulation of cancer cells by DAPK1 remains unclear. In particular, little is known about the existence of CSCs and how they are regulated in papillary thyroid carcinoma (PTC) among thyroid cancers. In this review, we describe the molecular mechanism of CSC regulation by DAPK1 in PTC progression.

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.

Frequent CDKN2B/P15 and DAPK1 methylation in duodenal follicular lymphoma is related to duodenal reactive lymphoid hyperplasia.

Duodenal type follicular lymphoma (DFL), a rare entity of follicular lymphoma (FL), is clinically indolent and is characterized by a low histological grade compared with nodal follicular lymphoma (NFL). Our previous reports revealed that DFL shares characteristics of both NFL and mucosa-associated lymphoid tissue (MALT) lymphoma in terms of clinical and biological aspects, suggesting its pathogenesis may involve antigenic stimulation. In contrast to NFL, the genomic methylation status of DFL is still challenging. Here, we determined the methylation profiles of DNAs from patients with DFL (n = 12), NFL (n = 10), duodenal reactive lymphoid hyperplasia (D-RLH) (n = 7), nodal reactive lymphoid hyperplasia (N-RLH) (n = 5), and duodenal samples from normal subjects (NDU) (n = 5) using methylation specific PCR of targets previously identified in MALT lymphoma (CDKN2B/P15, CDKN2A/P16, CDKN2C/P18, MGMT, hMLH-1, TP73, DAPK, HCAD). DAPK1 was frequently methylated in DFL (9/12; 75%), NFL (9/10; 90%), and D-RLH (5/7; 71%). CDKN2B/P15 sequences were methylated in six DFL samples and in only one NFL sample. Immunohistochemical analysis showed that p15 expression inversely correlated with methylation status. Genes encoding other cyclin-dependent kinase inhibitors (CDKN2A/P16, CDKN2C/P18) were not methylated in DFL samples. Methylation of the genes of interest was not detected in DNAs from D-RLH, except for DAPK1, and the difference in the extent of methylation between NDU and D-RLH was statistically significant (P = 0.013). Our results suggest that D-RLH serves as a reservoir for the development of DFL and that methylation of CDKN2B/P15 plays an important role in this process.

Is autism a PIN1 deficiency syndrome? A proposed etiological role for glyphosate.

Autism is a neurodevelopmental disorder, the prevalence of which has increased dramatically in the United States over the past two decades. It is characterized by stereotyped behaviors and impairments in social interaction and communication. In this paper, we present evidence that autism can be viewed as a PIN1 deficiency syndrome. Peptidyl-prolyl cis/trans isomerase, NIMA-Interacting 1 (PIN1) is a peptidyl-prolyl cis/trans isomerase, and it has widespread influences in biological organisms. Broadly speaking, PIN1 deficiency is linked to many neurodegenerative diseases, whereas PIN1 over-expression is linked to cancer. Death-associated protein kinase 1 (DAPK1) strongly inhibits PIN1, and the hormone melatonin inhibits DAPK1. Melatonin deficiency is strongly linked to autism. It has recently been shown that glyphosate exposure to rats inhibits melatonin synthesis as a result of increased glutamate release from glial cells and increased expression of metabotropic glutamate receptors. Glyphosate's inhibition of melatonin leads to a reduction in PIN1 availability in neurons. In this paper, we show that PIN1 deficiency can explain many of the unique morphological features of autism, including increased dendritic spine density, missing or thin corpus callosum, and reduced bone density. We show how PIN1 deficiency disrupts the functioning of powerful high-level signaling molecules, such as nuclear factor erythroid 2-related factor 2 (NRF2) and p53. Dysregulation of both of these proteins has been linked to autism. Severe depletion of glutathione in the brain resulting from chronic exposure to oxidative stressors and extracellular glutamate leads to oxidation of the cysteine residue in PIN1, inactivating the protein and further contributing to PIN1 deficiency. Impaired autophagy leads to increased sensitivity of neurons to ferroptosis. It is imperative that further research be conducted to experimentally validate whether the mechanisms described here take place in response to chronic glyphosate exposure and whether this ultimately leads to autism.

In Silico Prediction of Quercetin Analogs for Targeting Death-Associated Protein Kinase 1 (DAPK1) Against Alzheimer's Disease.

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder that greatly affects the health and life quality of the elderly population. Existing drugs mainly alleviate symptoms but fail to halt disease progression, underscoring the urgent need for the development of novel drugs. Based on the neuroprotective effects of flavonoid quercetin in AD, this study was designed to identify potential AD-related targets for quercetin and perform in silico prediction of promising analogs for the treatment of AD. Database mining suggested death-associated protein kinase 1 (DAPK1) as the most promising AD-related target for quercetin among seven protein candidates. To achieve better biological effects for the treatment of AD, we devised a series of quercetin analogs as ligands for DAPK1, and molecular docking analyses, absorption, distribution, metabolism, and excretion (ADME) predictions, as well as molecular dynamics (MD) simulations, were performed. The energy for drug-protein interaction was predicted and ranked. As a result, quercetin-A1a and quercetin-A1a1 out of 19 quercetin analogs exhibited the lowest interaction energy for binding to DAPK1 than quercetin, and they had similar dynamics performance with quercetin. In addition, quercetin-A1a and quercetin-A1a1 were predicted to have better water solubility. Thus, quercetin-A1a and quercetin-A1a1 could be promising agents for the treatment of AD. Our findings paved the way for further experimental studies and the development of novel drugs.

DAPK1 mediates cognitive dysfunction and neuronal apoptosis in PSD rats through the ERK/CREB/BDNF signaling pathway.

Post-stroke depression (PSD) is one of the most common mental sequelae after a stroke and can damage the brain. Although PSD has garnered increasing attention in recent years, the precise mechanism remains unclear. Studies have indicated that the expression of DAPK1 is elevated in various neurodegenerative conditions, including depression, ischemic stroke, and Alzheimer's disease. However, the specific molecular mechanism of DAPK1-mediated cognitive dysfunction and neuronal apoptosis in PSD rats is unclear. In this study, we established a rat model of PSD, and then assessed depression-like behaviors and cognitive dysfunction in rats using behavioral tests. In addition, we detected neuronal apoptosis and analyzed the expression of DAPK1 protein and proteins related to the ERK/CREB/BDNF signaling pathway. The findings revealed that MCAO combined with CUMS can induce more severe depression-like behaviors and cognitive dysfunction in rats, while overexpression of DAPK1 may hinder the downstream ERK/CREB/BDNF signaling pathways, resulting in neuronal loss and exacerbation of brain tissue damage. In this study, we will focus on DAPK1 and explore its role in PSD.

Inhibition of DAPK3 Suppresses Radiation-Induced Cellular Senescence by Activation of a PGC1α-Dependent Metabolism Pathway in Brain Endothelial Cells.

In the brain, environmental changes, such as neuroinflammation, can induce senescence, characterized by the decreased proliferation of neurons and dendrites and synaptic and vascular damage, resulting in cognitive decline. Senescence promotes neuroinflammatory disorders by senescence-associated secretory phenotypes and reactive oxygen species. In human brain microvascular endothelial cells (HBMVECs), we demonstrate that chronological aging and irradiation increase death-associated protein kinase 3 (DAPK3) expression. To confirm the role of DAPK3 in HBMVEC senescence, we disrupted DAPK3 activity using small interfering RNA (siRNA) or a dominant-negative mutant (DAPK3-P216S), which reduced cellular senescence phenotypes, as assessed by changes in tube formation, senescence-associated beta-galactosidase activity, and cell proliferation. In endothelial cells, DAPK3 promotes cellular senescence by regulating the phosphorylation and inactivation of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1α) via the protein kinase B pathway, resulting in the decreased expression of mitochondrial metabolism-associated genes, such as ATP5G1, BDNF, and COX5A. Our studies show that DAPK3 is involved in cellular senescence and PGC1α regulation, suggesting that DAPK3 regulation may be important for treating aging-related brain diseases or the response to radiation therapy.

The effect of phosphorylation on the conformational dynamics and allostery of the association of death-associated protein kinase with calmodulin.

Protein phosphorylation plays an important role in the signal transduction and is capable of regulation of cell activity. The death-associated protein kinase 1 (DAPK1), as a Ser/Thr kinase, interacts with calmodulin (CaM) to regulate apoptotic and autophagic signaling. Autophosphorylation of DAPK1 at Ser308 located at the autoregulatory domain (ARD) blocks CaM binding and inhibits kinase catalytic activity. However, the mechanism underlying the influence of Ser308 phosphorylation (pS308) on the DAPK1 activity remains unclear. Here, we performed multiple, microsecond length molecular dynamics (MD) simulations, the molecular mechanics generalized Born/surface area (MM-GBSA) binding free energy calculations, principal component analysis, and dynamic cross-correlation analysis to unravel the conformational dynamics and allostery of the DAPK1 - CaM interaction triggered by the pS308 at the ARD. MD simulations showed that pS308 affected the conformational stability of the DAPK1 - CaM complex. Further energetic and structural exploration revealed that pS308 weakened the association of the phosphorylated DAPK1 to CaM, which lowered the susceptibility of DAPK1 to be activated by CaM. This result can provide mechanistic insights into the molecular underpinning through which the DAPK1 kinase activity is modulated by the auto-phosphorylation.Communicated by Ramaswamy H. Sarma.

Anoikis-related signature predicts prognosis and characterizes immune landscape of ovarian cancer.

Ovarian cancer (OV) is the most lethal gynecological malignancy worldwide, with high recurrence rates. Anoikis, a newly-acknowledged form of programmed cell death, plays an essential role in cancer progression, though studies focused on prognostic patterns of anoikis in OV are still lacking. We filtered 32 potential anoikis-related genes (ARGs) among the 6406 differentially expressed genes (DEGs) between the 180 normal controls and 376 TCGA-OV samples. Through the LASSO-Cox analysis, a 2-gene prognostic signature, namely AKT2, and DAPK1, was finally distinguished. We then demonstrated the promising prognostic value of the signature through the K-M survival analysis and time-dependent ROC curves (p-value < 0.05). Moreover, based on the signature and clinical features, we constructed and validated a nomogram model for 1-year, 3-year, and 5-year overall survival, with reliable prognostic values in both TCGA-OV training cohort (p-value < 0.001) and ICGC-OV validation cohort (p-value = 0.030). We evaluated the tumor immune landscape through the CIBERSORT algorithm, which indicated the upregulation of resting Myeloid Dendritic Cells (DCs), memory B cells, and naïve B cells and high expression of key immune checkpoint molecules (CD274 and PDCD1LG2) in the high-risk group. Interestingly, the high-risk group exhibited better sensitivity toward immunotherapy and less sensitivity toward chemotherapies, including Cisplatin and Bleomycin. Especially, based on the IHC of tissue microarrays among 125 OV patients at our institution, we reported that aberrant upregulation of DAPK1 was related to poor prognosis. Conclusively, the anoikis-related signature was a promising tool to evaluate prognosis and predict therapy responses, thus assisting decision-making in the realm of OV precision medicine.

The targeting of DAPK1 with miR-190a-3p promotes autophagy in trophoblast cells.

Pre-eclampsia (PE) is a dangerous pathological status that occurs during pregnancy and is a leading reason for both maternal and fetal death. Autophagy is necessary for cellular survival in the face of environmental stress as well as cellular homeostasis and energy management. Aberrant microRNA (miRNA) expression is crucial in the pathophysiology of PE. Although studies have shown that miRNA (miR)-190a-3p function is tissue-specific, the precise involvement of miR-190a-3p in PE has yet to be determined. We discovered that miR-190a-3p was significantly lower and death-associated protein kinase 1 (DAPK1) was significantly higher in PE placental tissues compared to normal tissues, which is consistent with the results in cells. The luciferase analyses demonstrated the target-regulatory relationship between miR-190a-3p and DAPK1. The inhibitory effect of miR-190a-3p on autophagy was reversed by co-transfection of si-DAPK1 and miR-190a-3p inhibitors. Thus, our data indicate that the hypoxia-dependent miR-190a-3p/DAPK1 regulatory pathway is implicated in the development and progression of PE by promoting autophagy in trophoblast cells.

Quantitative Proteomic and Phosphoproteomic Analyses Reveal a Role of Death-Associated Protein Kinase 1 in Regulating Hippocampal Synapse.

Death-associated protein kinase 1 (DAPK1) is a stress-responsive calcium/calmodulin (CaM)-regulated serine/threonine protein kinase that is actively involved in stress-induced cell death. The dysregulation of DAPK1 has been established in various neurological disorders such as epilepsy, Alzheimer's disease (AD), and Parkinson's disease (PD). Recent research indicates a synaptic localization of DAPK1 in neurons, suggesting a potential role of DAPK1 in modulating synaptic structure and function. However, the key molecules and pathways underlying the influence of DAPK1 on synapses remain elusive. We utilized quantitative proteomic and phosphoproteomic analyses to compare the differences in protein expression and phosphorylation in hippocampal tissues of wild-type (WT) and DAPK1-knockout (KO) mice. Bioinformatic analysis of differentially expressed proteins and phosphoproteins revealed a preferential enrichment of proteins involved in regulating synaptic function, cytoskeletal structure, and neurotransmission. Gene set enrichment analysis (GESA) highlighted altered presynaptic functions including synaptic vesicle priming and glutamate secretion in KO mice. Besides, we observed that proteins with potential phosphorylation motifs of ERK and DAPK1 were overrepresented among the differential phosphoproteins and were highly enriched in neuronal function-related pathways. Furthermore, Western blot analysis validated differences in the expression of several proteins closely associated with presynaptic organization, dendrites and calcium transmembrane transport between KO and WT mice, further corroborating the potential involvement of DAPK1 in the regulation of synaptic functions. Overall, our data provide molecular evidence to elucidate the physiological links between DAPK1 and neuronal functions and help clarify the role of DAPK1 in the pathogenesis of neurodevelopmental and neurodegenerative diseases.

CircMAP3K5 promotes cardiomyocyte apoptosis in diabetic cardiomyopathy by regulating miR-22-3p/DAPK2 Axis.

BACKGROUND: Diabetic cardiomyopathy (DCM) is one of the serious complications of the accumulated cardiovascular system in the long course of diabetes. To date, there is no effective treatment available for DCM. Circular RNA (circRNA) is a novel r2egulatory RNA that participates in a variety of cardiac pathological processes. However, the regulatory role of circular RNA MAP3K5 (circMAP3K5) in DCM is largely unclear. METHODS AND RESULTS: Microarray analysis of DCM rats' heart circular RNAs was performed and the highly species-conserved circRNA mitogen-activated protein kinase kinase kinase 5 (circMAP3K5) was identified, which participates in DCM processes. High glucose-provoked cardiotoxicity leads to the up-regulation of circMAP3K5, which mechanistically contributes to cardiomyocyte cell death. Also, in high glucose-induced H9c2 cardiomyocytes, the level of apoptosis was significantly increased, as well as the expression of circMAP3K5. In contrast, the depletion of circMAP3K5 could reduce high glucose-induced apoptosis in cardiomyocytes. In terms of mechanism, circMAP3K5 acts as a miR-22-3p sponge and miR-22-3p directly target death-associated protein kinase 2 (DAPK2) in H9c2 cardiomyocytes, where in circMAP3K5 upregulates DAPK2 expression by targeting miR-22-3p. Moreover, we also found that miR-22-3p inhibitor and pcDNA DAPK2 could antagonize the protective effects brought by the depletion of circMAP3K5. CONCLUSION: CircMAP3K5 is a highly conserved noncoding RNA that is upregulated during DCM process. We concluded that circMAP3K5 promotes high glucose-induced cardiomyocyte apoptosis by regulating the miR-22-3p/DAPK2 axis. The results of this study highlight a novel and translationally important circMAP3K5-based therapeutic approach for DCM.

BNIP3 and DAPK1 methylation in peripheral blood leucocytes are noninvasive biomarkers for gastric cancer.

OBJECTIVE: The objective of this study is to comprehensively investigate the potential value of BNIP3 and DAPK1 methylation in peripheral blood leukocytes as a non-invasive biomarker for the detection of gastric cancer (GC), prediction of chemotherapy efficacy, and prognosis assessment. PATIENTS AND METHODS: Initially, multiple bioinformatic analyses were employed to explore the genetic landscape and biological effects of BNIP3 and DAPK1 in GC tissues. Subsequently, case-control and prospective follow-up studies were conducted to compare the differences in BNIP3 and DAPK1 methylation levels in peripheral blood leukocytes among GC patients and healthy controls, as well as between patients exhibiting sensitivity and resistance to platinum plus fluorouracil treatment, and between patients with varying survival outcomes of GC. Additionally, several predictive nomograms were constructed based on the identified CpG sites and relevant clinical parameters to forecast the occurrence of GC, chemotherapy efficacy, and prognosis. RESULTS: The upregulation of BNIP3 and DAPK1 was found to be associated with the development and poorer survival outcomes of GC. Furthermore, the expression of BNIP3/DAPK1 exhibited an inverse relationship with their DNA methylation levels and demonstrated a positive correlation with immune cell infiltration, as well as the IC50 values of 5-Fluorouracil and Cisplatin in GC tissues. Increased infiltration of macrophages in the high-expression groups was observed to be linked to unfavorable GC survival. In the case-control and follow-up studies, lower methylation levels of BNIP3 and DAPK1 were identified in the peripheral leukocytes of GC patients compared to healthy controls. Hypomethylation was also associated with more aggressive subtypes, diminished chemotherapy efficacy, and poorer survival outcomes in GC. CONCLUSION: The DNA methylation of BNIP3 and DAPK1 in peripheral blood leukocytes holds promise as a novel non-invasive biomarker for predicting the occurrence of GC, chemotherapy efficacy, and prognosis assessment.

Knockdown of DAPK1 inhibits IL-1ß-induced inflammation and cartilage degradation in human chondrocytes by modulating the PEDF-mediated NF-κB and NLRP3 inflammasome pathway.

Osteoarthritis (OA) is a common joint disease that is characterized by inflammation and cartilage degradation. Death-associated protein kinase 1 (DAPK1) is a multi-domain serine/threonine kinase and has been reported to be involved in the progression of OA. However, its role and mechanism in OA remain unclear. Here, we found the expression of DAPK1 in OA cartilage tissues was higher than that in normal cartilage tissues. The expression of DAPK1 in chondrocytes was up-regulated by IL-1ß. Knockdown of DAPK1 promoted cell viability and anti-apoptotic protein expression, while it inhibited the apoptosis rate and pro-apoptotic protein expressions in IL-1ß-induced chondrocytes. In addition, DAPK1 inhibition reduced the levels of inflammatory cytokines and expressions of matrix metalloproteinases (MMPs), and increased the expressions of collagen II and aggrecan. The data of mechanistic investigation indicated that the expression of pigment epithelium-derived factor (PEDF) was positively regulated by DAPK1. Overexpression of PEDF attenuated the effects of DAPK1 knockdown on IL-1ß-induced cell viability, apoptosis, inflammation, and cartilage degradation. Furthermore, PEDF overexpression restored the activity of the NF-κB pathway and NLRP3 inflammasome after DAPK1 knockdown. Collectively, down-regulation of DAPK1 inhibited IL-1ß-induced inflammation and cartilage degradation via the PEDF-mediated NF-κB and NLRP3 inflammasome pathways.

Death-associated protein kinase 1 phosphorylates MDM2 and inhibits its protein stability and function.

Breast cancer is one of the major malignancies in women, and most related deaths are due to recurrence, drug resistance, and metastasis. The expression of the mouse double minute 2 (MDM2) oncogene is upregulated in breast cancer; however, its regulatory mechanism has yet to be fully elucidated. Herein, we identified the tumor suppressor death-associated protein kinase 1 (DAPK1) as a novel MDM2 regulator by unbiased peptide library screening. DAPK1 is directly bound to MDM2 and phosphorylates it at Thr419. DAPK1-mediated MDM2 phosphorylation promoted its protein degradation via the ubiquitin-proteasome pathway, resulting in upregulated p53 expression. DAPK1 overexpression, but not its kinase activity-deficient form, decreased colony formation and increased doxorubicin-induced cell death; however, DAPK1 knockdown produced the opposite effects in human breast cancer cells. In a xenograft tumorigenesis assay, DAPK1 overexpression significantly reduced tumor formation, whereas inhibition of DAPK1 kinase activity reduced its antitumorigenic effect. Finally, DAPK1 expression was negatively correlated with MDM2 levels in human breast cancer tissues. Thus, these results suggest that DAPK1-mediated MDM2 phosphorylation and its protein degradation may contribute to its antitumorigenic function in breast cancer.

Diagnostic Value of DAPK Methylation for Nasopharyngeal Carcinoma: Meta-Analysis.

BACKGROUND: Methylation of DAPK has been reported to play a key role in the initiation and progression of nasopharyngeal cancer. However, there are differences between the studies on it. This meta-analysis was performed to evaluate the diagnostic value of DAPK promoter methylation for NPC. METHOD: The study method involves the systematic research of eligible studies based on criteria. The frequency, odds ratios (OR), sensitivity as well as specificity with the corresponding 95% confidence intervals (CIs) were used to assess the effect sizes. RESULTS: A total of 13 studies, including 1048 NPC samples and 446 non-cancerous samples, were used for the meta-analysis. The overall frequencies of DAPK methylation were 56.94% and 9.28% in NPC samples and non-cancerous samples, respectively. The association between DAPK methylation and risk of NPC was also confirmed by calculating the OR value which was 13.13 (95%CI = 54.24-40.72) based on a random-effect model (Q = 64.74; p < 0.0001; I2 = 81.47% with 95%CI for I2 = 69.39-88.78). Additionally, the study results suggest that testing for DAPK methylation in tissue samples or brushing may provide a promising method for diagnosing NPC. CONCLUSION: This is the first meta-analysis that provided scientific evidence that methylation of the DAPK gene could serve as a potential biomarker for diagnosis, prognosis, and early screening of NPC patients.

YTHDF2 promotes gallbladder cancer progression and gemcitabine resistance via m6A-dependent DAPK3 degradation.

N6-methyladenosine (m6A) is the most abundant internal modification in eukaryotic RNA and involved in the carcinogenesis of various malignancies. However, the functions and mechanisms of m6A in gallbladder cancer (GBC) remain unclear. In this study, we investigated the role and underlying mechanism of the RNA-binding protein YT521-B homology domain-containing family protein 2 (YTHDF2), an m6A reader, in GBC. Herein, we detected that YTHDF2 was remarkably upregulated in GBC tissues compared to normal gallbladder tissues. Functionally, YTHDF2 overexpression promoted the proliferation, tumor growth, migration, and invasion of GBC cells while inhibiting the apoptosis in vitro and in vivo. Conversely, YTHDF2 knockdown induced opposite results. Mechanistically, we further investigated the underlying mechanism by integrating RNA immunoprecipitation sequencing (RIP-seq), m6A-modified RIP-seq, and RNA sequencing, which revealed that death-associated protein kinase 3 (DAPK3) is a direct target of YTHDF2. YTHDF2 binds to the 3'-UTR of DAPK3 mRNA and facilitates its degradation in an m6A-dependent manner. DAPK3 inhibition restores the tumor-suppressive phenotype induced by YTHDF2 deficiency. Moreover, the YTHDF2/DAPK3 axis induces the resistance of GBC cells to gemcitabine. In conclusion, we reveal the oncogenic role of YTHDF2 in GBC, demonstrating that YTHDF2 increases the mRNA degradation of the tumor suppressor DAPK3 in an m6A-dependent way, which promotes GBC progression and desensitizes GBC cells to gemcitabine. Our findings provide novel insights into potential therapeutic strategies for GBC.

Aerobic exercise mitigates hippocampal neuronal apoptosis by regulating DAPK1/CDKN2A/REDD1/FoXO1/FasL signaling pathway in D-galactose-induced aging mice.

Brain aging is the most important risk factor for neurodegenerative disorders, and abnormal apoptosis is linked to neuronal dysfunction. Specifically, studies have found that exercise effectively inhibits hippocampal neuronal apoptosis, while the molecular mechanism remains unclear. In the present study, we investigated the impact of aerobic exercise on hippocampal neuronal apoptosis in aging mice and the potential involvement of DAPK1 and its downstream pathways based on recent data that DAPK1 may be associated with neuronal death in neurodegenerative diseases. Senescent mice were subjected to 8 weeks of Aerobic training. Following behavioral testing, hippocampal samples were examined histologically and biochemically to detect pathological changes, neuronal apoptosis, and mRNA and protein levels. We found that the exercise intervention improved spatial memory and alleviated neuronal apoptosis in the brain. Notably, exercise down-regulated DAPK1 expression and inhibited Fas death receptor transactivation and the mitochondrial apoptotic pathway in the hippocampus. These results shed new light on the protective effect of regular exercise against brain aging though modulating the DAPK1 pathway.

Diagnostic value of the combination of DAPK methylation in urinary sediment and B ultrasound for recurrent urinary bladder cancer.

BACKGROUND: Urinary bladder cancer (UBC) is the most common malignancy affecting the urinary system. This study aimed to investigate the diagnostic value of combining DAPK methylation in urinary sediment and B ultrasound in the detection of recurrent UBC. METHODS: A total of 1021 cases with primary UBC who underwent electrocision of bladder tumor through urethra were included in this study and followed up. Various parameters including B ultrasound, DAPK methylation in urinary sediment, examination of exfoliated cells in the urine, and cystoscopy were performed. The data collected was analyzed using the Kappa test, and receiver operating characteristic (ROC) curve was constructed to assess the diagnostic role in recurrent UBC. RESULTS: Among the 1021 patients, 115 patients experienced recurrence confirmed by cystoscopy and biopsy within two years and were excluded from the study, resulting in an effective sample size of 906 primary UBC cases. The results of cystoscopy showed agreement with B ultrasound (Kappa = 0.785, P < 0.05), as well as with DAPK methylation in urinary sediment, and the combination of B ultrasound and DAPK methylation (Kappa = 0.517, P < 0.05, Kappa = 0.593, P < 0.05). The combination of B ultrasound with DAPK methylation yielded an area under the curve of 0.922, with a sensitivity of 92.86%, specificity of 91.63%, and a negative predictive value of 99.4%, suggesting that a negative result indicates a low risk of recurrence. CONCLUSION: The combination of DAPK methylation in urinary sediment with B ultrasound demonstrates high diagnostic performance for recurrent UBC.