Cell Repair Processes Research Articles

Low-dose photodynamic therapy effect on closure of scratch wounds of normal and diabetic fibroblast cells: An in vitro study.

Chronic wounds such as diabetic ulcers are a serious public health problem. Extensive research is needed to find new alternatives for wound treatment. Photodynamic therapy (PDT) is a non-invasive method, which has been studied for several decades to treat cancer, infections, and other diseases. PDT involves the administration of a photosensitizer compound followed by irradiation with using light at specific wavelength to produce reactive oxygen species (ROS) using molecular oxygen. It is possible that low dose photodynamic therapy (LDPDT) could improve wound healing and stimulates the cell repair process. This study we explored the effect of LDPDT on wound healing in vitro using normal and diabetic cellular wound models. The effects of different concentrations of 5-ALA and different energy densities (dark or light) on the cell viability of human fibroblast cells were studied using the MTT assay. After ascertaining the optimum parameters, a scratch wound assay was performed on both normal and diabetic cells and then cells treated with 1 and 5μg/mL of 5-ALA at 1J/cm2 energy density. ROS production and morphological alteration of the cells were studied. The mortality of normal fibroblast cells increased with increasing 5-ALA concentration and also increasing energy density (up to 3J/cm2 ). However, in diabetic cells, the mortality rate did not decrease. Diabetic cells showed increased migration and closure of the scratch compared to normal cells under similar conditions. A low concentration of 5-ALA (5μg/mL) and low energy density of 1J/cm2 in both normal and diabetic cells gave a small increase in ROS levels compared to controls. This may explain the positive effects of LDPDT on wound healing. The findings of this study suggest that LDPDT may have a potential effect on the wound healing of diabetic wounds.

Membrane Particles Derived From Adipose Tissue Mesenchymal Stromal Cells Improve Endothelial Cell Barrier Integrity.

Proinflammatory stimuli lead to endothelial injury, which results in pathologies such as cardiovascular diseases, autoimmune diseases, and contributes to alloimmune responses after organ transplantation. Both mesenchymal stromal cells (MSC) and the extracellular vesicles (EV) released by them are widely studied as regenerative therapy for the endothelium. However, for therapeutic application, the manipulation of living MSC and large-scale production of EV are major challenges. Membrane particles (MP) generated from MSC may be an alternative to the use of whole MSC or EV. MP are nanovesicles artificially generated from the membranes of MSC and possess some of the therapeutic properties of MSC. In the present study we investigated whether MP conserve the beneficial MSC effects on endothelial cell repair processes under inflammatory conditions. MP were generated by hypotonic shock and extrusion of MSC membranes. The average size of MP was 120 nm, and they showed a spherical shape. The effects of two ratios of MP (50,000; 100,000 MP per target cell) on human umbilical vein endothelial cells (HUVEC) were tested in a model of inflammation induced by TNFα. Confocal microscopy and flow cytometry showed that within 24 hours >90% of HUVEC had taken up MP. Moreover, MP ended up in the lysosomes of the HUVEC. In a co-culture system of monocytes and TNFα activated HUVEC, MP did not affect monocyte adherence to HUVEC, but reduced the transmigration of monocytes across the endothelial layer from 138 ± 61 monocytes per microscopic field in TNFα activated HUVEC to 61 ± 45 monocytes. TNFα stimulation induced a 2-fold increase in the permeability of the HUVEC monolayer measured by the translocation of FITC-dextran to the lower compartment of a transwell system. At a dose of 1:100,000 MP significantly decreased endothelial permeability (1.5-fold) respect to TNFα Stimulated HUVEC. Finally, MP enhanced the angiogenic potential of HUVEC in an in vitro Matrigel assay by stimulating the formation of angiogenic structures, such as percentage of covered area, total tube length, total branching points, total loops. In conclusion, MP show regenerative effects on endothelial cells, opening a new avenue for treatment of vascular diseases where inflammatory processes damage the endothelium.

Genomics of aging: Glycosylation.

This third article in the Genomics of Aging series explores the process of glycosylation and how abnormal glycosylation contributes to aging and disease (i.e., diabetes, cardiovascular disease [CVD], neurological disorder, and cancer). Glycosylation is an important posttranslational process that contributes to normal protein folding, cell adhesion, protein stability, and motility. Gradual accumulation of molecular errors contributes to the aging process, and specific genetic variants in this pathway have been identified in cancer, CVD, aging, and vulnerability to disease progression. Manipulating glycosylation pathways may be beneficial in reducing disease risk in the future. Smoking cessation has been shown to reverse epigenetic changes in glycosylation pathways that increase cancer, CVD, and all-cause mortality risk, and CVD risk may be reduced if a dimeric glycosylated fusion protein pathway can be regulated. Selective food sources and synthetic vitamins and antioxidants have been shown to support normal glycosylation and help in the cell repair process.

Geomagnetic Shielding Enhances Radiation Resistance by Promoting DNA Repair Process in Human Bronchial Epithelial Cells.

With the advent of long-duration space explorations, ionizing radiation (IR) may pose a constant threat to astronauts without the protection of Earth’s magnetic field, or hypomagnetic field (HMF). However, the potential biological effects of a HMF on the cellular response to IR have not been well characterized so far. In this study, immortalized human bronchial epithelial cells were exposed to X-rays under either a geomagnetic field (GMF, ~50 uT) or HMF (<50 nT) culture condition. A significant increase of the cell survival rate in HMF after radiation was observed by colony formation analysis. The kinetics of DNA double-strand breaks (DSBs), determined by γH2AX foci formation and disappearance, presented a faster decrease of foci-positive cells and a significantly lower mean number of γH2AX foci per nucleus in HMF-cultured cells than in GMF-cultured cells after radiation. In addition, a γH2AX/53BP1 colocalization assay showed an upregulated DSB recovery rate in HMF cultured cells. These findings provided the first evidence that HMF exposure may enhance the cellular DSB repair efficiency upon radiation, and consequently modulate the genotoxic effects of IR.

New In Vitro Model of Oxidative Stress: Human Prostate Cells Injured with 2,2-diphenyl-1-picrylhydrazyl (DPPH) for the Screening of Antioxidants.

The antioxidant activity of natural compounds consists in their ability to modulate gene and protein expression, thus inducing an integrated cell protective response and repair processes against oxidative stress. New screening tools and methodologies are crucial for the actual requirement of new products with antioxidant activity to boost endogenous oxidative stress responsive pathways, Reactive Oxygen Species (ROS) metabolism and immune system activity, preserving human health and wellness. In this study, we performed and tested an integrated oxidative stress analysis, using DPPH assay and PNT2 cells injured with DPPH. We firstly investigated the mechanism of action of the oxidising agent (DPPH) on PNT2 cells, studying the variation in cell viability, oxidative stress genes, inflammatory mediator and ROS levels. The results reveal that DPPH activated ROS production and release of Prostaglandin E2 in PNT2 at low and intermediate doses, while cells switched from survival to cell death signals at high doses of the oxidising agent. This new in vitro oxidative stress model was validated by using Trolox, β-carotene and total extract of the green microalga Testraselmis suecica. Only the T. suecica extract can completely counteract DPPH-induced injury, since its chemical complexity demonstrated a multilevel protecting and neutralising effect against oxidative stress in PNT2.

Ultrastructural investigation of acidocalcisomes and ATPase activity in yeast Candida guilliermondii NP-4 as 'complementary' stress-targets.

As a result of electron microscopic studies of morphogenesis in yeast Candida guilliermondii NP-4, the formation of new structures of volutin acidocalcisomes has been established within the cell cytoplasm. Under influence of X-irradiation, the changes in morphometric and electron-dense properties of yeast cells were identified: in yeast cytoplasm, the electron-dense volutin granules were increased up to 400nm in size. After 24-h post-irradiation incubation of yeasts, the large volutin pellets are fragmented into smaller number particles in size up to 25-150nm. The ATPase activity in yeast mitochondria was changed under X-irradiation. In latent phase of growth, ATPase activity was decreased 1·35-fold in comparison with non-irradiated yeasts. In logarithmic phase of growth, ATPase activity was three times higher than in latent phase, and in stationary phase of growth it has a value similar to the latent phase. Probably, the cells receive the necessary energy from alternative energy sources, such as volutin. Electron microscopy of volutin granule changes might serve as convenient method for evaluation of damages and repair processes in cells under influence of different environmental stress-factors.

Discovery of Exosomes From Tick Saliva and Salivary Glands Reveals Therapeutic Roles for CXCL12 and IL-8 in Wound Healing at the Tick-Human Skin Interface.

Ticks secrete various anti-coagulatory, anti-vasoconstrictory, anti-inflammatory, and anti-platelet aggregation factors in their saliva at the bite site during feeding to evade host immunological surveillance and responses. For the first time, we report successful isolation of exosomes (small membrane-bound extracellular signaling vesicles) from saliva and salivary glands of partially fed or unfed ixodid ticks. Our data showed a novel role of these in vivo exosomes in the inhibition of wound healing via downregulation of C-X-C motif chemokine ligand 12 (CXCL12) and upregulation of interleukin-8 (IL-8). Cryo-electron microscopy (cryo-EM) analysis revealed that tick saliva and salivary glands are composed of heterogeneous populations of in vivo exosomes with sizes ranging from 30 to 200 nm. Enriched amounts of tick CD63 ortholog protein and heat shock protein 70 (HSP70) were evident in these exosomes. Treatment of human skin keratinocytes (HaCaT cells) with exosomes derived from tick saliva/salivary glands or ISE6 cells dramatically delayed cell migration, wound healing, and repair process. Wound healing is a highly dynamic process with several individualized processes including secretion of cytokines. Cytokine array profiling followed by immunoblotting and quantitative-PCR analysis revealed that HaCaT cells treated with exosomes derived from tick saliva/salivary glands or ISE6 cells showed enhanced IL-8 levels and reduced CXCL12 loads. Inhibition of IL-8 or CXCL12 further delayed exosome-mediated cell migration, wound healing, and repair process, suggesting a skin barrier protection role for these chemokines at the tick bite site. In contrast, exogenous treatment of CXCL12 protein completely restored this delay and enhanced the repair process. Taken together, our study provides novel insights on how tick salivary exosomes secreted in saliva can delay wound healing at the bite site to facilitate successful blood feeding.

The significance of m6A RNA methylation regulators in predicting the prognosis and clinical course of HBV-related hepatocellular carcinoma

BackgroundHepatocarcinogenesis is reportedly correlated with abnormal m6A modifications; however, it is unknown whether m6A RNA methylation regulators facilitate the occurrence of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). Thus, we constructed an m6A-related model that may enhance HBV-related HCC prognosis.MethodsGene signatures of HNRNPA2B1 and RBM15 were generated by univariate and Lasso Cox regression analyses using the gene set and clinical information from The Cancer Genome Atlas (TCGA) database. High-risk and low-risk groups were confirmed based on the gene signature model. Furthermore, we validated the predictive roles of the two genes for overall survival (OS) in the GSE14520 dataset. The relative expression of 22 paired mRNAs was measured using quantitative real-time polymerase chain reaction (qRT-PCR) analysis to determine whether the two genes had a predictive role in our Guilin cohort.ResultsThe differences in OS between the high-risk and low-risk groups were statistically significant in the TCGA (p = 0.003) and GSE14520 (p = 0.045) datasets, but not in the Guilin cohort, owing to differences in clinical information among the three cohorts (mainly the TNM stage and survival state). Stratified analysis of TNM stages showed that the two-gene signature acted as a prognostic indicator of HBV-related HCC patients in the early TNM stage; both TCGA and GSE14520 cohorts showed statistical significance. Moreover, multivariate Cox regression analysis indicated that the two-gene signature was an independent factor for predicting prognosis (HR = 1.087, 95% CI: 1.007–1.172). Correlation analysis between the gene signature and clinical features revealed that the risk stratification was significantly correlated with grade and survival state. Finally, Gene Set Enrichment Analysis (GSEA) revealed that the KEGG pathways associated with the cell cycle, DNA replication, the spliceosome, repair, and metabolism-related processes were all significantly enriched in the high-risk group. Among the enriched genes, the expression levels of the replication protein RPA1 and the pre-mRNA splicing factor SF3B1 were significantly upregulated in the high-risk group. These results might help in elucidating the underlying molecular mechanisms of HBV-related HCC.ConclusionsOur data may provide new predictive signatures and potential therapeutic targets to identify and treat HBV-related HCC patients in the early disease stage.

Ethanolic extract of Moringa oleifera leaves alleviate cyclophosphamide-induced testicular toxicity by improving endocrine function and modulating cell specific gene expression in mouse testis

Ethnopharmacological relevanceMoringa oleifera Lam. is known for its nutritional and ethno medicinal values due to the presence of wide array of phytochemicals with multiple biological activities. We have previously reported that ethanolic extract of Moringa oleifera leaves (MOE) ameliorated cyclophosphamide (CP)-induced testicular toxicity and improved functional integrity of spermatozoa as well as spermatogenic cells. Aim of the studyThe present study was planned to investigate whether the mitigation of CP-induced testicular toxicity by MOE is mediated via modulation of endocrine profile, genes associated with function of different cell types and enhancement of DNA repair response in spermatogonial cells. Materials and methodsAdult Swiss albino mice (8 week) were injected with CP (100 mg/kg, one dose in a week for 3 weeks) and MOE (100 mg/kg, 5 doses in a week for 4 weeks) either alone or in combination intraperitoneally. At 35 day post CP injection (first dose), the functional characteristics such as count, motility, head morphology and DNA integrity were assessed in epididymal spermatozoa. Key reproductive hormones like testosterone, follicle stimulating hormone (FSH) and Inhibin B concentration were analyzed in serum and testis. In addition, mRNA expression of genes pertaining to the function of Leydig, Sertoli and spermatogonial cells as well as antioxidant enzymes were evaluated in the testis. To understand the DNA damage and repair process in germ cells, prepubertal (2 week) mice were administered with single dose of CP (200 mg/kg) and/or MOE (100 mg/kg) and analyzed for expression of DNA damage (γ-H2AX, P53 and Caspase3) and repair genes (Rad51 and Ku80) in isolated spermatogonial cells at various time points after treatment. ResultsCP administration resulted in decrease in count, motility and increase in morphological defects and DNA damage in spermatozoa. Testosterone level was marginally decreased while there was a significant increase in FSH (p < 0.001) and decrease in inhibin B (p < 0.05) observed in CP treated mice. Administration of MOE prior to CP, improved sperm functional characteristics, decreased FSH and increased inhibin B levels. Expression of Abp was down-regulated while Transferrin, Fshr and Gata4 (Sertoli cell specific genes) were up-regulated in testis treated with CP. Administration of CP down-regulated the expression of Oct4 and Ddx4 (Spermatogonia specific genes). MOE administration was shown to ameliorate CP-induced damage by modulating the expression of genes specific to Sertoli and spermatogenic cells. Furthermore, MOE treatment reduced CP-induced DNA damage as evident from lower percentage of γ-H2AX positive spermatogonial cells. ConclusionAdministration of MOE mitigated CP-induced testicular damage by improving blood and, intra-testicular hormonal milieu as well as modulating the expression of genes pertaining to Sertoli and spermatogonial cells.

ORCA/LRWD1 Regulates Homologous Recombination at ALT-Telomeres by Modulating Heterochromatin Organization.

SummaryTelomeres are maintained by telomerase or in a subset of cancer cells by a homologous recombination (HR)-based mechanism, Alternative Lengthening of Telomeres (ALT). The mechanisms regulating telomere-homeostasis in ALT cells remain unclear. We report that a replication initiator protein, Origin Recognition Complex-Associated (ORCA/LRWD1), by localizing at the ALT-telomeres, modulates HR activity. ORCA's localization to the ALT-telomeres is facilitated by its interaction to SUMOylated shelterin components. The loss of ORCA in ALT-positive cells elevates the levels of two mediators of HR, RPA and RAD51, and consistent with this, we observe increased ALT-associated promyelocytic leukemia body formation and telomere sister chromatid exchange. ORCA binds to RPA and modulates the association of RPA to telomeres. Finally, the loss of ORCA causes global chromatin decondensation, including at the telomeres. Our results demonstrate that ORCA acts as an inhibitor of HR by modulating RPA binding to ssDNA and inducing chromatin compaction.

Clinical efficacy of adjuvant therapy with hyperbaric oxygen in diabetic nephropathy

Background and objective: Diabetic kidney disease (DKD) is the most common microvascular chronic complication of diabetes mellitus. Hyperbaric oxygen (HBO2) therapy will increase the partial pressure of oxygen (PaO2) and may improve cell repair processes, which can lead to better renal function. The objective of this study was to quantify the efficacy of adjuvant HBO2 to increase the glomerular filtration rate and urinary albumin excretion in diabetic patients, as well as determine its effectiveness to modify the clinical course of DKD. Materials and methods: An experimental study was performed on patients with stage 3 and 4 DKD. Twenty sessions of HBO2 or ambient air in a hyperbaric chamber were administered. Estimated glomerular filtration rate, urine albumin:creatinine ratio calculation and clinical stage stratification were made prior to and after HBO2 administration. A descriptive, inferential and clinical efficacy analysis was performed. Results: Urinary albumin/creatinine (UACR) mean values prior to HBO2 were 1452.9 ± 644.3 mg/g and decreased to 876.1 ± 504.0 mg/g at the end of the study (p=0.06). The patients in the control group showed a UACR mean of 2784.5 ± 2128.6 mg/g and 2861.4 ± 2424.2 mg/g at baseline and at the end of the study, respectively (p=0.82). Patients in the experimental/HBO2 group showed an estimated GFR of 27.3 ± 9.5 mL/min /1.73m2 before HBO2, with a 34.4 ± 6.9 mL/min/1.73m2 after treatment (p=0.017); control group eGFR was 30.1 ± 9.2 mL/min/1.73m2, decreasing to 22.2 ± 6.8 mL/min/1.73m2 (p=0.004). Relative risk 0.00, relative risk reduction -100%, absolute risk reduction -71.4%, 95% CI (-104.9% to -38.0%), NNT 1, 95% CI (1 to 3). Conclusions: Management with HBO2 for DKD was associated with decreased excretion urinary albumin, improved GFR and clinical stage of patients in stages 3 and 4 of kidney damage unlike those receiving ambient air.

Metformin promotes mitophagy in mononuclear cells: a potential in vitro model for unraveling metformin's mechanism of action.

Increased oxidative stress in patients with type 2 diabetes mellitus (T2DM) results in abnormalities in cell repair processes, such as mitophagy, which compromises mitochondrial function and contributes to insulin resistance and β cell failure. Metformin, widely recommended in the management of T2DM, exerts its pleiotropic effects via 5'-AMP-activated protein kinase (AMPK); however, its effect on mitophagy remains elusive. Recent evidence demonstrates that peripheral blood mononuclear cells (PBMCs) express insulin receptors and the human organic cation transporter protein, and they are extensively being used as a surrogate for examining mitochondrial function in T2DM. Metformin treatment increased the formation of acidic vesicles and mitophagosomes, upregulated mitophagy markers, and enhanced mitophagic flux, as indicated by increased LC3-II expression and reduced p62 protein levels. In addition, pretreatment with compound C (an AMPK inhibitor) significantly decreased the expression of mitophagy markers in metformin-treated cells, indicating that metformin induces mitophagy via the AMPK pathway. In conclusion, metformin-induced mitophagy may improve cellular function, including in β cells, by restoring normal mitochondrial phenotype, which may prove beneficial in patients with T2DM and other mitochondrial-related diseases. Moreover, PBMCs may be used as a novel diagnostic biomarker for identifying mitochondrial disorders.

Temporal and spatial immunolocalization of osteopontin in the repair of orthopaedic bone defects treated with demineralized bone matrix

Osteopontin (OPN) is the most abundant non-collagen protein in the bone matrix, where it fulfils the function of cellular adhesion and biomineralization. In the present work, the authors report the temporal and spatial localization of OPN during the repair of experimental orthopaedic bone defects treated with demineralized bone matrix (DBM) processed by the authors. 30 rabbits were used, which were given an orthopaedic bone defect of critical size in one of the radiuses, which was filled with DBM. The rabbits were euthanized in groups of 5 individuals at days 7, 15, 21, 30, 60 and 150. Histological cuts were immunomarked to establish the spatial and temporal immunomarcation of OPN. The histological cuts were observed with an optic microscope with which histological images were captured and analysed with the ImageJ software. The image analysis allowed the authors to establish the optic density (OD) and the integrated optic density (IOD). The data was analysed with the ANOVA and Fischer LSD tests. At day 7, the presence of OPN was observed only in the DBM particles, where the OD was 0.08 and the IOD was 1.64; at day 15, OPN marked different sites of collagen condensations and cells contained in the interior of the matrix. In this period the OD was 0.096 and the IOD, 9.26. At days 21 and 30, the OPN immunosignalled osteocytes, osteoblasts, osteoclasts and hypertrophic chondrocytes in the bone trabeculae adjacent to the ossification zones. At day 21 the OD was 0.17 and IOD 6.22. At day 30, the OD was 0.14 and the IOD 2.52. At days 60 and 150, OPN was evenly distributed in the new bone matrix with an OD: 0.10 and IOD: 0.48, and OD: 0.35 and IOD: 3.80, respectively. The OD and IOD showed significant differences (p<=0.05) between days 7, 15, 21 and 30; and there was no difference at days 60 and 150 (p=0.05). OPN was found in the DBM particles: it increased the optic densities at day 15 and it diminished at day 60, after which it increased the OD and IOD again until day 150. It was established that the OPN immunoexpressed during the repair process in indifferentiated cells, osteoprogenitor chondrocytes and osteoblasts. The variation of OD and IOD allowed the authors to establish that the greatest degree of immunoexpression of OPN was at day 15 after repair initiated. On the other hand, the increase registered between days 60 and 150 post treatment was due to the biomineralization of the bone matrix.

Interactions of an Emerging Fungal Pathogen Scedosporium aurantiacum with Human Lung Epithelial Cells

Scedosporium fungi are found in various natural and host-associated environments, including the lungs of cystic fibrosis patients. However, their role in infection development remains underexplored. Here the attachment of conidia of a virulent S. aurantiacum strain WM 06.482 onto the human lung epithelial A549 cells in vitro was visualized using microscopy to examine the initial steps of infection. We showed that 75–80% of fungal conidia were bound to the A549 cells within four hours of co-incubation, and started to produce germ tubes. The germinating conidia seemed to invade the cells through the intercellular space, no intracellular uptake of fungal conidia by the airway epithelial cells after conidial attachment. Transcriptomic analysis of the A549 cells revealed that the up-regulated genes were mainly associated with cell repair and inflammatory processes indicating a protective response against S. aurantiacum infection. Network analysis of the differentially expressed genes showed activation of the innate immune system (NF-kB pathway) leading to the release of pro-inflammatory cytokines. We believe this is the first report showing the transcriptomic response of human alveolar epithelial cells exposed to S. aurantiacum conidia paving a way for better understanding of the mechanism of the infection process.

Toxin-induced hormesis may restrain aging.

Mild environmental stress might have beneficial effects in aging by activating maintenance and repair processes in cells and organs. These beneficial stress effects fit to the concept of hormesis. Prominent stressors acting in a hormetic way are physical exercises, fasting, cold and heat. This review will introduce some toxins, which have been found to induce hormetic responses in animal models of aging research. To highlight the molecular signature of these hormetic effects we will depict signaling pathways affected by low doses of toxins on cellular and organismic level. As prominent examples for signaling pathways involved in both aging processes as well as toxin responses, PI3K/Akt/mTOR- and AMPK-signal transduction will be described in more detail. Due to the striking overlap of signaling pathways mediating toxin induced responses and aging processes we propose considering the ability of low doses of toxins to slow down the rate of aging.

Comparison of DNA damage level in irradiated blood cells of mouse, frog and human

Here, we present the comparative studies of DNA damage induced by X-ray irradiation in vitro in mouse, frog and human blood cells and assessed by the “comet test” (alkaline version). We showed that, in contrast to mouse and human cells, DNA repair processes in frog blood cells are not completed by 60 minutes of the post-radiation period. The results suggest that frogs can be used as indicators of environmental radiation pollution. In this regard, additional experiments are needed to assess the different types of external and internal exposure of animals.

Quantification of somatic mutation flow across individual cell division events by lineage sequencing.

Mutation data reveal the dynamic equilibrium between DNA damage and repair processes in cells and are indispensable to the understanding of age-related diseases, tumor evolution, and the acquisition of drug resistance. However, available genome-wide methods have a limited ability to resolve rare somatic variants and the relationships between these variants. Here, we present lineage sequencing, a new genome sequencing approach that enables somatic event reconstruction by providing quality somatic mutation call sets with resolution as high as the single-cell level in subject lineages. Lineage sequencing entails sampling single cells from a population and sequencing subclonal sample sets derived from these cells such that knowledge of relationships among the cells can be used to jointly call variants across the sample set. This approach integrates data from multiple sequence libraries to support each variant and precisely assigns mutations to lineage segments. We applied lineage sequencing to a human colon cancer cell line with a DNA polymerase epsilon (POLE) proofreading deficiency (HT115) and a human retinal epithelial cell line immortalized by constitutive telomerase expression (RPE1). Cells were cultured under continuous observation to link observed single-cell phenotypes with single-cell mutation data. The high sensitivity, specificity, and resolution of the data provide a unique opportunity for quantitative analysis of variation in mutation rate, spectrum, and correlations among variants. Our data show that mutations arrive with nonuniform probability across sublineages and that DNA lesion dynamics may cause strong correlations between certain mutations.

Upregulation of thyroid hormone receptor interactor13 is associated with human hepatocellular carcinoma.

Hepatocellular carcinoma(HCC) is the second leading cause of cancer-related mortality worldwide. Thyroid hormone receptor interactor13(TRIP13) has been reported to promote nonhomologous end joining(NHEJ). However, the role of TRIP13 in the molecular pathogenesis of HCC remains to be elucidated. The aim of the present study was to investigate the role and potential mechanism of TRIP13 in HCC. Real-time PCR and western blotting were used to detect the expression of TRIP13 in 47paired HCC and adjacent liver tissues. The Cancer Genome Atlas (TCGA) database was used to collect TRIP13 expression data in HCC. Loss-of-function siRNA assays were performed to alter TRIP13 expression. Cell proliferation, migration and invasion capabilities were investigated using CCK-8, wound healing and Transwell assays, while cell cycle distribution and apoptosis were assessed using flow cytometry. The expression of TRIP13 was upregulated in HCC tissues and cell lines. We analyzed the association between TRIP13 expression and patient prognosis. Patients with higher TRIP13 expression had significantly shorter survival periods compared with patients with lower TRIP13 expression. CCK-8, wound healing and Transwell assays revealed that TRIP13 downregulation inhibited the proliferation, migration and invasion of HCC cells. TRIP13 downregulation resulted in increased apoptosis and cell cycle arrest at S-phase. Finally, we found that loss of TRIP13 reduced the expression of cellular NHEJ proteins such as KU70, KU80 and PRKDC, and these results suggest that loss of TRIP 13 impairs the NHEJ repair process in HCC cells. Collectively, these results provide evidence that TRIP13 may act as a tumor promoter during HCC development and could serve as a potential therapeutic target for this disease.

Increased Glutathione Reductase Expression and Activity in Colorectal Cancer Tissue Samples: An Investigational Study in Mashhad, Iran

Background: Glutathione reductase is an important enzyme in oxidative metabolism that provides reduced glutathione from its oxidized form in the cells. The role of oxidative stress in tumor tissues has led us to investigate the gene expression and activity of this enzyme in tumor and adjacent resected margins of colorectal cancer tissues, one of the most common malignancies in humans. Methods: We conducted this study on 15 Iranian colorectal cancer patients. RNA was extracted from fresh colon tissues that included tumor and anatomically normal margin tissue. Expression of the glutathione reductase gene was determined using realtime PCR by the ΔΔCt relative quantification method. The gene expression results were standardized with glyceraldehyde 3-phosphate dehydrogenase as the endogenous reference gene. In addition, we measured enzyme activity of glutathione reductase with a commercial kit based on a colorimetric assay. Results: The tumor tissue had higher expression of glutathione reductase compared to the margin tissue (P=0.005). There was significantly greater glutathione reductase enzyme activity in the tumor tissue (116.9±34.31 nmol/min/ml) compared to the noncancerous adjacent tissues (76.7±36.85 nmol/min/ml; P=0.003). Conclusion: These data showed increased glutathione reductase expression and enzyme activity in colorectal tumor tissue. Given the key role of glutathione in synthesis of dNTPs for DNA repair with the glutaredoxin system, the increased glutathione reductase expression and activity might be a reflection of hyperactivity of this enzyme in DNA synthesis and the repair process in colorectal cancer cells.

Effect of subchronic exposure to inorganic arsenic on the structure and function of the intestinal epithelium

Inorganic arsenic (As), the most toxic form of As found in water and food, is considered a human carcinogen. Numerous studies show its systemic toxicity, describing pathologies associated with chronic exposure. The main pathway of exposure to inorganic As is oral, but many of the events that occur during its passage through the gastrointestinal tract are unknown.This study evaluates the effect of subchronic exposure to inorganic As [As(III): 0.025–0.1 mg/L; As(V): 0.25–1 mg/L, up to 21 days] on the intestinal epithelium, using Caco-2 cells as in vitro model. Inorganic As produces a pro-inflammatory response throughout the exposure time, with an increase in IL-8 release (up to 488%). It also causes changes in the program of cell proliferation and differentiation, which leads to impairment of the cell repair process. In addition, subchronic exposure affects the epithelial structure, causing loss of microvilli, fundamental structures in the processes of intestinal absorption and digestion. Moreover, the exposure affects the epithelial barrier function, evidenced by an increase of Lucifer Yellow transport (103–199%). Therefore, it can be concluded that subchronic exposure to inorganic As can alter intestinal homeostasis, affecting the mucosal layer, which performs the most important functions of the intestinal wall.