Engineering a waste management enzyme to overcome cancer resistance to apoptosis: adding DNase1 to the anti-cancer toolbox

DNA methylation landscape of triple-negative ductal carcinoma in situ (DCIS) progressing to the invasive stage in canine breast cancer

Triple-negative breast cancer (TNBC) is a subtype of breast cancer unresponsive to traditional receptor-targeted treatments, leading to a disproportionate number of deaths. Invasive breast cancer is believed to evolve from non-invasive ductal carcinoma in situ (DCIS). Detection of triple-negative DCIS (TN-DCIS) is challenging, therefore strategies to study molecular events governing progression of pre-invasive TN-DCIS to invasive TNBC are needed. Here, we study a canine TN-DCIS progression and investigate the DNA methylation landscape of normal breast tissue, atypical ductal hyperplasia (ADH), DCIS and invasive breast cancer. We report hypo- and hypermethylation of genes within functional categories related to cancer such as transcriptional regulation, apoptosis, signal transduction, and cell migration. DNA methylation changes associated with cancer-related genes become more pronounced at invasive breast cancer stage. Importantly, we identify invasive-only and DCIS-specific DNA methylation alterations that could potentially determine which lesions progress to invasive cancer and which could remain as pre-invasive DCIS. Changes in DNA methylation during TN-DCIS progression in this canine model correspond with gene expression patterns in human breast tissues. This study provides evidence for utilizing methylation status of gene candidates to define late-stage (DCIS and invasive), invasive stage only or DCIS stage only of TN-DCIS progression.

Circulating cell-free DNA fragment analysis by microchip electrophoresis and its relationship with DNase I in cardiac diseases

Circulating cell-free DNA (cfDNA) has been directly related to cancer, diabetes, stroke, systemic lupus erythematosus, trauma, rheumatoid arthritis, inflammation, infection, and myocardial infarction (MI). In this study, plasma cfDNA was extracted from the plasma of cardiac disease patients and the cfDNA fragment distribution as well as the relationships between cfDNA concentration and deoxyribonuclease I (DNase I) activity enzyme implicated in double-stranded DNA processing were examined. Results revealed that the cfDNA concentrations in patients with MI and cardiac angina were significantly higher than that in healthy control subjects. Microchip electrophoresis of plasma cfDNA revealed a single fragment (150-200 bp) in some healthy control subjects and three fragments (150-200 bp, 300-400 bp, and 500-600 bp) in all cardiac patient samples. Moreover, a cfDNA ratio of 150-200 bp/500-600 bp was significantly more prevalent in MI patients than in patients with other cardiac diseases (chest pain, cardiac angina, atrial fibrillation and cardiac failure). In addition, a positive correlation between DNase I activity and cfDNA concentration was observed. These results suggest that the plasma cfDNA in cardiac disease patients may originate from apoptosis and that the 150-200 bp/500-600 bp ratio for cfDNA may be a novel diagnostic indicator for MI.

Deoxyribonuclease I Activity, Cell-Free DNA, and Risk of Liver Cancer in a Prospective Cohort

BACKGROUND

Circulating cell-free DNA (cfDNA) is a proposed latent biomarker for several cancers, including liver cancer. Deoxyribonucleases (DNases) facilitate the timely and efficient degradation of cfDNA, leading us to hypothesize that DNase I and/or II might be a more sensitive early biomarker than cfDNA. To test this hypothesis, a study was conducted in a large, prospective cohort.

METHODS

A nested case-control study (224 liver cancer case patients and 224 matched control subjects) was conducted in a cohort of Finnish male smokers, followed from baseline (1985-1988) to 2014. The associations among DNase I activity, cfDNA, and the risk of liver cancer were assessed using multivariable-adjusted conditional logistic regression.

RESULTS

DNase I activity, whether measured as radius (mm) or as units per milliliter, was statistically significantly associated with increased risk of liver cancer (P trend <.01). DNase I activity in the highest quartile was associated with a greater than threefold risk of developing liver cancer (DNase I activity radius >2.7 mm, hazard ratio [HR] = 3.03, 95% confidence interval [CI] = 1.59 to 5.77; DNase I activity >2.72 units/mL, HR = 3.30, 95% CI = 1.64 to 6.65). The strength of this association was not substantially altered by exclusion of cases diagnosed within the first five years of follow-up or those with hepatitis C virus (HCV) infection. In contrast, cfDNA and DNase II was not statistically significantly associated with risk of liver cancer.

CONCLUSIONS

DNase I activity was a superior latent biomarker of liver cancer than cfDNA. These findings advance the goal of developing a means to detect liver cancer years well before the development of clinical manifestations.

Modulating secreted components of tumor microenvironment: A masterstroke in tumor therapeutics

The microenvironment in which cancer resides plays an important role in regulating cancer survival, progression, malignancy and drug resistance. Tumor microenvironment (TME) consists of heterogeneous number and types of cellular and non-cellular components that vary in relation to tumor phenotype and genotype. In recent, non-cellular secreted components of microenvironmental heterogeneity have been suggested to contain various growth factors, cytokines, RNA, DNA, metabolites, structural matrix and matricellular proteins. These non-cellular components have been indicated to orchestrate numerous ways to support cancer survival and progression by providing metabolites, energy, growth signals, evading immune surveillance, drug resistance environment, metastatic and angiogenesis cues. Thus, switching action from pro-cancer to anti-cancer activities of these secreted components of TME has been considered as a new avenue in cancer therapeutics and drug resistance. In this report, we summarize the recent pre-clinical and clinical evidences to emphasize the importance of non-cellular components of TME in achieving precision therapeutics and biomarker study.

DNase I aggravates islet β-cell apoptosis in type 2 diabetes

Deoxyribonuclease I (DNase I) is an endonuclease responsible for the destruction of chromatin during apoptosis. However, its role in diabetes remains unclear. The aim of the current study was to investigate the role of DNase I combined with high glucose levels in β-cell apoptosis. Human samples were collected and the DNase I activity was examined. High glucose-cultured INS-1 cells were transfected with DNase I small interfering RNA (siRNA) and the cell apoptosis was examined by western blotting and flow cytometry. Cell viability was analyzed by the Cell Counting Kit-8 assay. Cell apoptosis resulting from 50 mU/μl DNase I was also observed by flow cytometry, terminal deoxynucleotidyl transferase dUTP nick-end labeling stain and western blotting. Compared with healthy controls, the serum DNase I activity of patients with diabetes was significantly increased (P<0.05). In addition, DNase I expression was observed to be significantly increased in human pancreatic tissues. The addition of high glucose upregulated the cell apoptotic rate, whereas DNase I knockdown significantly reduced apoptosis in cells treated with high glucose. In addition, the western blotting results indicated that caspase-3 was increased subsequent to treatment of cells with 30 mM high glucose, however, this increase can be reversed by transfection with DNase I siRNA (P<0.05). Compared with cells cultured in normal conditions and high glucose, 50 mU/μl DNase I was able to significantly increase the cell apoptotic rate and level of caspase-3. DNase I activity was observed to be increased in type 2 diabetes, and high glucose combined with increased DNase I is suggested to aggravate β-cell apoptosis.

Extracellular DNA: A Bridge to Cancer

DNase I is a secreted enzyme whose function has been presumed to control "waste management" in the human system, by degrading DNA that leaks from dead and dying cells. Emerging studies have instead yielded evidence that DNase I plays a central role in newly defined dynamics of immune and autoimmune diseases, as well as cancer and vascular disorders, including thrombosis. Cancer cells have been reported to be associated with distinctive extracellular structures that facilitate aggregation and implantation. The fact that DNA is a component of such structures and that it plays a role in cancer development is illustrated by direct evidence: DNase I added to tumor cells eliminates the structures and inhibits tumorigenicity of some cancer cell lines. DNase I injected into experimental animals, moreover, results in significant inhibition of metastasis. Despite independent observations of such phenomena in diverse cancers for over 50 years, the potential for using DNase I as a clinical tool to prevent or treat cancer remains unexplored. The discovery of neutrophil extracellular traps has yielded a conceptual framework for interpreting how extracellular DNA may function in cancer development and why it may prove to be an important clinical target in stopping cancer outside the cell.

Cofilin: a redox sensitive mediator of actin dynamics during T-cell activation and migration

Cofilin is an actin-binding protein that depolymerizes and/or severs actin filaments. This dual function of cofilin makes it one of the major regulators of actin dynamics important for T-cell activation and migration. The activity of cofilin is spatio-temporally regulated. Its main control mechanisms comprise a molecular toolbox of phospho-, phospholipid, and redox regulation. Phosphorylated cofilin is inactive and represents the dominant cofilin fraction in the cytoplasm of resting human T cells. A fraction of dephosphorylated cofilin is kept inactive at the plasma membrane by binding to phosphatidylinositol 4,5-bisphosphate. Costimulation via the T-cell receptor/CD3 complex (signal 1) together with accessory receptors (signal 2) or triggering through the chemokine SDF1α (stromal cell-derived factor 1α) induce Ras-dependent dephosphorylation of cofilin, which is important for immune synapse formation, T-cell activation, and T-cell migration. Recently, it became evident that cofilin is also highly sensitive for microenvironmental changes, particularly for alterations in the redox milieu. Cofilin is inactivated by oxidation, provoking T-cell hyporesponsiveness or necrotic-like programmed cell death. In contrast, in a reducing environment, even phosphatidylinositol 4,5-bisphosphate-bound cofilin becomes active, leading to actin dynamics in the vicinity of the plasma membrane. In addition to the well-established three signals for T-cell activation, this microenvironmental control of cofilin delivers a modulating signal for T-cell-dependent immune reactions. This fourth modulating signal highly impacts both initial T-cell activation and the effector phase of T-cell-mediated immune responses.

Laser scanning cytometry: principles and applications-an update

Laser scanning cytometer (LSC) is the microscope-based cytofluorometer that offers a plethora of unique analytical capabilities, not provided by flow cytometry (FCM). This review describes attributes of LSC and covers its numerous applications derived from plentitude of the parameters that can be measured. Among many LSC applications the following are emphasized: (a) assessment of chromatin condensation to identify mitotic, apoptotic cells, or senescent cells; (b) detection of nuclear or mitochondrial translocation of critical factors such as NF-κB, p53, or Bax; (c) semi-automatic scoring of micronuclei in mutagenicity assays; (d) analysis of fluorescence in situ hybridization (FISH) and use of the FISH analysis attribute to measure other punctuate fluorescence patterns such as γH2AX foci or receptor clustering; (e) enumeration and morphometry of nucleoli and other cell organelles; (f) analysis of progeny of individual cells in clonogenicity assay; (g) cell immunophenotyping; (h) imaging, visual examination, or sequential analysis using different probes of the same cells upon their relocation; (i) in situ enzyme kinetics, drug uptake, and other time-resolved processes; (j) analysis of tissue section architecture using fluorescent and chromogenic probes; (k) application for hypocellular samples (needle aspirate, spinal fluid, etc.); and (l) other clinical applications. Advantages and limitations of LSC are discussed and compared with FCM.