Methylation of BNIP3 and DAPK indicates lower response to chemotherapy and poor prognosis in gastric cancer.
ABSTRACT Aberrant promoter hypermethylation (methylation) is an epigenetic change that silences the expression of crucial genes, thus inactivating the apoptotic pathway in various cancers. Inactivation of the apoptotic pathway has been considered to be associated with chemoresistance. The objective of the present study was to clarify the effect of the methylation of the apoptosis-related genes, Bcl-2/adenovirus E1B 19 kDa-interacting protein 3 (BNIP3) and death-associated protein kinase (DAPK), on the response to chemotherapy in metastatic or recurrent gastric cancers. Tumor samples were obtained from 80 gastric cancer patients who were treated with fluoropyrimidine-based chemotherapy for distant metastatic or recurrent disease, after surgical resection of the primary tumor. The methylation status of the apoptosis-related genes, BNIP3 and DAPK, was investigated by methylation-specific PCR. Methylation in BNIP3 was detected in 31 tumors (39%) and in DAPK in 33 tumors (41%). There was no correlation between the methylation status of BNIP3 and that of DAPK. The response rate was significantly lower in patients with methylation of DAPK, than in those without (21 vs. 49% p=0.012). Progression-free survival time (PFS) was shorter in patients with methylation of DAPK than in those without (p=0.007). The overall survival time (OS) was shorter in patients with methylation of BNIP3 than in those without (p=0.031). The response rate was significantly lower in patients with methylation of either DAPK or BNIP3, or both, than in those without methylation (p=0.003). PFS and OS were significantly shorter in patients with methylation of either or both of these genes than in those without (p=0.002, p=0.001). The methylation of BNIP3 and DAPK can predict lower response to chemotherapy and poor prognosis in gastric cancer.
- SourceAvailable from: Abhishek D Garg[Show abstract] [Hide abstract]
ABSTRACT: BNIP3 is an atypical BH3-only member of the BCL-2 family of proteins with reported pro-death as well as pro-autophagic and cytoprotective functions, depending on the type of stress and cellular context. In line with this, the role of BNIP3 in cancer is highly controversial and increased BNIP3 levels in cancer patients have been linked with both good as well as poor prognosis. In this study, using small hairpin RNA (shRNA) lentiviral transduction to stably knockdown BNIP3 (BNIP3-shRNA) expression levels in melanoma cells, we show that BNIP3 supports cancer cell survival and long-term clonogenic growth. Although BNIP3-shRNA increased mitochondrial mass and baseline levels of reactive oxygen species production, which are features associated with aggressive cancer cell behavior, it also prevented cell migration and completely abolished the ability to form a tubular-like network on matrigel, a hallmark of vasculogenic mimicry (VM). We found that this attenuated aggressive behavior of these melanoma cells was underscored by severe changes in cell morphology and remodeling of the actin cytoskeleton associated with loss of BNIP3. Indeed, BNIP3-silenced melanoma cells displayed enhanced formation of actin stress fibers and membrane ruffles, while lamellopodial protrusions and filopodia, tight junctions and adherens junctions were reduced. Moreover, loss of BNIP3 resulted in re-organization of focal adhesion sites associated with increased levels of phosphorylated focal adhesion kinase. Remarkably, BNIP3 silencing led to a drop of the protein levels of the integrin-associated protein CD47 and its downstream signaling effectors Rac1 and Cdc42. These observations underscore that BNIP3 is required to maintain steady-state levels of intracellular complexes orchestrating the plasticity of the actin cytoskeleton, which is integral to cell migration and other vital processes stimulating cancer progression. All together these results unveil an unprecedented pro-tumorigenic role of BNIP3 driving melanoma cell's aggressive features, like migration and VM.Cell Death & Disease 01/2014; 5:e1127. · 6.04 Impact Factor
Article: Transcription control of DAPK.[Show abstract] [Hide abstract]
ABSTRACT: Imbalanced cell death is a common phenomenon in many human diseases, including cancer. DAPK's essential function is in promoting apoptosis. DAPK interacts with stress-induced receptors through its death domain to initiate an apoptosis cascade. In addition, DAPK phosphorylates multiple cytosolic substrates and can mediate transfer of signaling pathways to the effector caspases. A series of studies demonstrated that, depending on stimuli, DAPK expression is regulated on both the transcriptional and posttranscriptional levels. Silencing of DAPK due to hypermethylation of its promoter was reported in many types of cancer. STAT3 and p52-NFkB transcription factors have been shown to down-regulate DAPK expression. In contrast, p53, C/EBP-β and Smad transcription factors bind to their specific response elements within the DAPK promoter and induce its transcription. Post-transcriptionally, DAPK undergoes alternative splicing, which results in the production of two functionally different isoforms. Moreover, miRNA 103 and miRNA 107 recently were shown to inhibit DAPK in colorectal cancer. Here we summarize our recent knowledge about transcriptional regulation of DAPK expression.Apoptosis 11/2013; · 4.07 Impact Factor
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ABSTRACT: Abstract A wide range of protein cancer biomarkers is currently recommended in international guidelines for monitoring the growth and regression of solid tumors. However, a number of these markers are also present in low concentrations in blood obtained from healthy individuals and from patients with benign diseases. In contrast, evidence has accumulated that suggests that modified methylated DNA is strongly related to the cancer phenotype. The modifications found in modified methylated DNA include a global loss of methylation in the genomes of the tumor cells as well as focal hypermethylation of gene promoters. Because tumor cells naturally secrete DNA and upon cell death leak DNA, modified methylated DNA can be detected in blood, urine, sputum and other body fluids. At present international guidelines do not include recommendations for monitoring modified methylated DNA. The low level of evidence can partly be explained by incomplete collection of serial blood samples, by analytical challenges, and by lack of knowledge of how monitoring studies should be designed and how serial marker data obtained from individual patients should be interpreted. Here, we review the clinical validity and utility of methylated DNA for monitoring the activity of malignant disease.Critical Reviews in Clinical Laboratory Sciences 03/2014; · 3.78 Impact Factor