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Colorectal cancer is a global killer that causes approximately 940 thousand deaths annually. Terminalia ivorensis (TI) is a tropical tree, the bark of which is used in African traditional medicine for the treatment of diabetes, malaria and ulcer. This study investigated TI as a potential anticancer agent in human colon cells in vitro. TI was extracted sequentially with petroleum ether, chloroform, ethyl acetate and ethanol. Antioxidant activity was assessed by DPPH and FRAP, and differential effects on cell viability, growth, DNA damage, DNA repair, and migration were measured in human colon cancer cells (CaCo-2) and/or non-cancerous human colonocytes (NCM460). The TI phytochemicals most strongly associated with these effects were identified by partial least-squares discriminant analysis. DPPH and FRAP activity were highest in TI ethyl acetate and ethanol extracts (p=0.001). All TI extracts significantly inhibited cell viability and growth and induced DNA damage and inhibited DNA repair in both cell models. The majority of TI extracts were significantly (p=0.01) more toxic to cancer cells than non-cancerous colonocytes. DNA repair was significantly (p=0.001) inhibited in CaCo-2 cells by ethyl acetate extract compared with NCM460 cells. Migration was also significantly inhibited (p<0.001) in CaCo-2 by ethyl acetate (80%) and ethanol extracts (75%). Specific benzoic acids, flavonoids and phenols were identified to be strongly associated with these effects. TI displayed strong antioxidant activity and specific anticancer effects by inducing cell death and DNA damage, and by inhibiting DNA repair, cell proliferation and migration., (© The Author(s) 2024. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society.)

How DNA damage and repair processes affect the biomechanical properties of the nucleus interior remains unknown. Here, an opto-acoustic microscope based on time-domain Brillouin spectroscopy (TDBS) was used to investigate the induced regulation of intra-nuclear mechanics. With this ultrafast pump-probe technique, coherent acoustic phonons were tracked along their propagation in the intra-nucleus nanostructure and the complex stiffness moduli and thicknesses were measured with an optical resolution. Osteosarcoma cells were exposed to methyl methanesulfonate (MMS) and the presence of DNA damage was tested using immunodetection targeted against damage signaling proteins. TDBS revealed that the intra-nuclear storage modulus decreased significantly upon exposure to MMS, as a result of the chromatin decondensation and reorganization that favors molecular diffusion within the organelle. When the damaging agent was removed and cells incubated for 2 h in the buffer solution before fixation the intra-nuclear reorganization led to an inverse evolution of the storage modulus, the nucleus stiffened. The same tendency was measured when DNA double-strand breaks were caused by cell exposure to ionizing radiation. TDBS microscopy also revealed changes in acoustic dissipation, another mechanical probe of the intra-nucleus organization at the nano-scale, and changes in nucleus thickness during exposure to MMS and after recovery.

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder that is marked by impaired social interactions, and increased repetitive behaviors. There is evidence of genetic changes in ASD, and several of these altered genes are linked to the process of DNA repair. Therefore, individuals with ASD must have improved DNA repair efficiency to mitigate risks associated with ASD. Despite numerous milestones in ASD research, the disease remains incurable, with a high occurrence rate and substantial financial burdens. This motivates scientists to search for new drugs to manage the disease. Disruption of glucagon-like peptide-1 (GLP-1) signaling, a regulator in neuronal development and maintains homeostasis, has been associated with the pathogenesis and progression of several neurological disorders, such as ASD. Our study aimed to assess the impact of semaglutide, a new GLP-1 analog antidiabetic medication, on behavioral phenotypes and DNA repair efficiency in the BTBR autistic mouse model. Furthermore, we elucidated the underlying mechanism(s) responsible for the ameliorative effects of semaglutide against behavioral problems and DNA repair deficiency in BTBR mice. The current results demonstrate that repeated treatment with semaglutide efficiently decreased autism-like behaviors in BTBR mice without affecting motor performance. Semaglutide also mitigated spontaneous DNA damage and enhanced DNA repair efficiency in the BTBR mice as determined by comet assay. Moreover, administering semaglutide recovered oxidant-antioxidant balance in BTBR mice. Semaglutide restored the disrupted DNA damage/repair pathways in the BTBR mice by reducing Gadd45a expression and increasing Ogg1 and Xrcc1 expression at both the mRNA and protein levels. This suggests that semaglutide holds great potential as a novel therapeutic candidate for treating ASD traits. • BTBR mice showed a higher percentage of DNA damage than C57 control mice. • BTBR mice showed a slower repair rate than C57 control mice. • In BTBR mice, semaglutide treatment attenuates repetitive behaviors. • In BTBR mice, semaglutide treatment alleviates oxidative stress. • In BTBR mice, semaglutide treatment restored repair gene disturbances. [ABSTRACT FROM AUTHOR]

Harmful cyanobacterial blooms (HCBs) pose a global ecological threat. Ultraviolet C (UVC) irradiation at 254 nm is a promising method for controlling cyanobacterial proliferation, but the growth suppression is temporary. Resuscitation remains a challenge with UVC application, necessitating alternative strategies for lethal effects. Here, we show synergistic inhibition of Microcystis aeruginosa using ultraviolet A (UVA) pre-irradiation before UVC. We find that low-dosage UVA pre-irradiation (1.5 J cm -2 ) combined with UVC (0.085 J cm -2 ) reduces 85% more cell densities compared to UVC alone (0.085 J cm -2 ) and triggers mazEF -mediated regulated cell death (RCD), which led to cell lysis, while high-dosage UVA pre-irradiations (7.5 and 14.7 J cm -2 ) increase cell densities by 75-155%. Our oxygen evolution tests and transcriptomic analysis indicate that UVA pre-irradiation damages photosystem I (PSI) and, when combined with UVC-induced PSII damage, synergistically inhibits photosynthesis. However, higher UVA dosages activate the SOS response, facilitating the repair of UVC-induced DNA damage. This study highlights the impact of UVA pre-irradiation on UVC suppression of cyanobacteria and proposes a practical strategy for improved HCBs control., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Colorectal cancer (CRC) is one of the most common malignant tumors. One of the factors increasing the risk of its occurrence may be the reduced efficiency of repairing DNA damage, both nuclear and mitochondrial. The main mechanism for repairing oxidative damage is the BER system (in mitochondria mtBER), whose key proteins NEIL1, NEIL2, OGG1, MUTYH, APE1 and LIG3 obtain full efficiency only at the appropriate level of acetylation. Sirtuin 3 is a key protein for mitochondrial homeostasis, regulating a number of metabolic processes related mainly to the control of the level of reactive oxygen species. Because Sirt3 possesses acetylase activity, it can modulate the level of activity of mtBER proteins by their deacetylation. The conducted study showed that the tested proteins NEIL1, NEIL2, OGG1, MUTYH, APE1 and LIG3 are the substrate for the enzymatic deacetylation activity of Sirt3, which may lead to modulation of the risk of CRC, and in cancer cells may be a potential therapeutic target enhancing the action of cytostatic drugs. [ABSTRACT FROM AUTHOR]

Cisplatin (CDDP) is a commonly used drug for gallbladder cancer (GBC) chemotherapy. However, resistance to CDDP treatment results in relapse. Therefore, there is a need for the development of more effective treatment strategies to overcome chemoresistance. Dual-specificity phosphatase 1 (DUSP1) was reported to be involved in the resistance of a number of chemotherapeutic agents and was revealed to be highly expressed in CDDP-resistant GBC cells and CDDP-treated tumor types compared with normal cells or tissues in the present study. DUSP1 was revealed to inhibit the cytotoxicity of CDDP in two GBC cell lines, SGC996 and GBC-SD. P38 mitogen-activated protein kinases may be involved in the mechanism of chemoresistance. Furthermore, the number of DNA double-strand breaks in SGC996 OE cells was reduced compared with SGC996 vector cells indicating DUSP1 may attenuate the chemotherapeutic efficiency. Due to its potency against CDDP treatment, DUSP1 may be a promising target to overcome chemoresistance in GBC therapy. [ABSTRACT FROM AUTHOR]

To determine the protective effects of Pellino-1 against H2O2-induced apoptosis in periodontal ligament stem cells (PDLSC). We demonstrated that H2O2 decreases PDLSC viability by 40 and 50% with the concentrations of 400 and 500 μM, respectively, with an observed downregulation of Pellino-1 mRNA and protein; we further concluded that overexpression of Pellino-1 significantly lowers 8-hydroxy-2′-deoxyguanosine levels by 10% and upregulates superoxide dismutase 1, glutathione peroxidase levels, and catalase mRNA levels by 200, 40, and 250%, respectively. More importantly, we found that overexpression of Pellino-1 inhibited H2O2-induced cellular apoptosis through the activation of the NF-κB signaling pathway. Pellino-1 may be critically important for cell survival in the presence of oxidative elements; activation of the NF-κB signaling cascade was required for the overexpression of Pellino-1 to protect the cells from H2O2-induced apoptosis. [ABSTRACT FROM AUTHOR]

Abstract: CRISPR‐Cas technology has revolutionized genome engineering. While Cas9 was not the first programmable endonuclease identified, its simplicity of use has driven widespread adoption in a short period of time. While CRISPR‐Cas genome editing holds enormous potential for clinical applications, its use in laboratory settings for genotype‐phenotype studies and genome‐wide screens has led to breakthroughs in the understanding of many molecular pathways. Numerous protocols have been described for introducing CRISPR‐Cas components into cells, and here we sought to simplify and optimize a protocol for genome editing using readily available and inexpensive tools. We compared plasmid, ribonucleoprotein (RNP), and RNA transfection to determine which was method was most optimal for editing cells in a laboratory setting. We limited our comparison to lipofection‐mediated introduction because the reagents are widely available. To facilitate optimization, we developed a novel reporter assay to measure gene disruption and the introduction of a variety of exogenous DNA tags. Each method efficiently disrupted endogenous genes and was able to stimulate the introduction of foreign DNA at specific sites, albeit to varying efficiencies. RNP transfection produced the highest level of gene disruption and was the most rapid and efficient method overall. Finally, we show that very short homology arms of 30 base pairs can mediate site‐specific editing. The methods described here should broaden the accessibility of RNP‐mediated lipofection for laboratory genome‐editing experiments. [ABSTRACT FROM AUTHOR]

Background Information: Repair of damaged DNA is essential for maintaining genomic stability. TP53‐binding protein 1 (53BP1) plays an important role in repair of the DNA double‐strand breaks. Nuclear localisation of 53BP1 depends on importin β and nucleoporin 153, but the type and location of 53BP1 nuclear localisation signal (NLS) have yet to be determined. Results: Here, we show that nuclear import of 53BP1 depends on two basic regions, namely 1667‐KRK‐1669 and 1681‐KRGRK‐1685, which are both needed for importin binding. Lysine 1667 is essential for interaction with importin and its substitution to arginine reduced nuclear localisation of 53BP1. Furthermore, we have found that CDK1‐dependent phosphorylation of 53BP1 at S1678 impairs importin binding during mitosis. Phosphorylation‐mimicking mutant S1678D showed reduced nuclear localisation, suggesting that phosphorylation of the NLS interferes with nuclear import of the 53BP1 Conclusions: We show that 53BP1 contains a classical bipartite NLS 1666‐GKRKLITSEEERSPAKRGRKS‐1686, which enables the importin‐mediated nuclear transport of 53BP1. Additionally, we found that posttranslational modification within the NLS region can regulate 53BP1 nuclear import. Significance: Our results indicate that integrity of the NLS is important for 53BP1 nuclear localisation. Precise mapping of the NLS will facilitate further studies on the effect of posttranslational modifications and somatic mutations on the nuclear localisation 53BP1 and DNA repair. [ABSTRACT FROM AUTHOR]

Sirtuin-1 (SIRT1) is a class-III histone deacetylase (HDAC), an NAD+-dependent enzyme deeply involved in gene regulation, genome stability maintenance, apoptosis, autophagy, senescence, proliferation, aging, and tumorigenesis. It also has a key role in the epigenetic regulation of tissue homeostasis and many diseases by deacetylating both histone and non-histone targets. Different studies have shown ambiguous implications of SIRT1 as both a tumor suppressor and tumor promoter. However, this contradictory role seems to be determined by the cell type and SIRT1 localization. SIRT1 upregulation has already been demonstrated in some cancer cells, such as acute myeloid leukemia (AML) and primary colon, prostate, melanoma, and non-melanoma skin cancers, while SIRT1 downregulation was described in breast cancer and hepatic cell carcinomas. Even though new functions of SIRT1 have been characterized, the underlying mechanisms that define its precise role on DNA damage and repair and their contribution to cancer development remains underexplored. Here, we discuss the recent findings on the interplay among SIRT1, oxidative stress, and DNA repair machinery and its impact on normal and cancer cells.

Exchange of genetic information during meiosis occurs in all sexually reproducing species to produce haploid gametes from diploid cells. This process involves tight coordination of a meiotic specific cohesin complex, the synaptonemal complex, and DNA damage repair mechanisms. In this study, we describe a putative myosin heavy chain protein orthologous to human myosin 1, F28D1.2, which we named Abnormal Transition Zone ( atz-1). Deletion of atz-1 results in embryonic lethality and a depleted transition zone, accompanied by reduced expression of the meiotic cohesin protein, REC-8. atz-1 mutants display disorganized and aggregated chromosomal bodies in diakinetic oocytes. In addition to this, atz-1 mutants are hypersensitive to mild inhibition of DNA damage repair, suggesting that DNA replication in atz-1 mutants is impaired. Moreover, the atz-1 mutant phenotype is germline specific and resupplying somatically expressed atz-1 does not rescue the reproductive defects associated with atz-1 mutants. Overall, our data suggest that atz-1 contributes to meiosis and maintains germline chromosomal stability. [ABSTRACT FROM AUTHOR]

Numerous plant products have been used to prevent and manage a wide variety of diseases for centuries. These products are now considered as promising options for the development of more effective and less toxic alternatives to the systems of medicine developed primarily in developed countries in the modern era. Grape seed proanthocyanidins (GSPs) are of great interest due to their anti-carcinogenic effects that have been demonstrated using various tumor models including ultraviolet (UV) radiation-induced non-melanoma skin cancer. In a pre-clinical mouse model supplementation of a control diet (AIN76A) with GSPs at concentrations of 0.2% and 0.5% (w/w) significantly inhibits the growth and multiplicity of UVB radiation-induced skin tumors. In this review, we summarize the evidence that this inhibition of UVB-induced skin tumor development by dietary GSPs is mediated by a multiplicity of coordinated effects including: ( i ) Promotion of the repair of damaged DNA by nuclear excision repair mechanisms, and ( ii ) DNA repair-dependent stimulation of the immune system following the functional activation of dendritic cells and effector T cells. Dietary GSPs hold promise for the development of an effective alternative strategy for the prevention of excessive solar UVB radiation exposure-induced skin diseases including the risk of non-melanoma skin cancer in humans. [ABSTRACT FROM AUTHOR]

Despite improvements in therapeutic strategies, glioblastoma (GB) remains one of the most lethal cancers. The presence of the blood-brain barrier, the infiltrative nature of the tumor and several resistance mechanisms account for the failure of current treatments. Distinct DNA repair pathways can neutralize the cytotoxicity of chemo- and radio-therapeutic agents, driving resistance and tumor relapse. It seems that a subpopulation of stem-like cells, indicated as glioma stem cells (GSCs), is responsible for tumor initiation, maintenance and recurrence and they appear to be more resistant owing to their enhanced DNA repair capacity. Recently, attention has been focused on the pivotal role of the DNA damage response (DDR) in tumorigenesis and in the modulation of therapeutic treatment effects. In this review, we try to summarize the knowledge concerning the main molecular mechanisms involved in the removal of genotoxic lesions caused by alkylating agents, emphasizing the role of GSCs. Beside their increased DNA repair capacity in comparison with non-stem tumor cells, GSCs show a constitutive checkpoint expression that enables them to survive to treatments in a quiescent, non-proliferative state. The targeted inhibition of checkpoint/repair factors of DDR can contribute to eradicate the GSC population and can have a great potential therapeutic impact aiming at sensitizing malignant gliomas to treatments, improving the overall survival of patients. [ABSTRACT FROM AUTHOR]

Worldwide, breast cancer is the most commonly diagnosed cancer among women and is the leading cause of female cancer deaths. Zinc (Zn) functions as an antioxidant and plays a role in maintaining genomic stability. Zn deficiency results in oxidative DNA damage and increased cancer risk. Studies suggest an inverse association between dietary and plasma Zn levels and the risk for developing breast cancer. In contrast, breast tumor biopsies display significantly higher Zn levels compared with normal tissue. Zn accumulation in tumor tissue also correlates with increased levels of Zn importing proteins. Further, aberrant expression of Zn transporters in tumors correlates with malignancy, suggesting that altered metal homeostasis in the breast could contribute to malignant transformation and the severity of cancer. However, studies have yet to link dysregulated Zn transport and abnormal Zn-dependent functions in breast cancer development. Herein, we summarize studies that address the multi-modal role of Zn dyshomeostasis in breast cancer with respect to the role of Zn in modulating oxidative stress, DNA damage response/repair pathways and cell proliferation/apoptosis, and the relationship to aberrant regulation of Zn transporters. We also compare Zn dysregulation in breast tissue to that of prostate, pancreatic and ovarian cancer where possible.

ABSTRACT In order to study the mechanisms underlying the alleviation of aflatoxin B1-induced genomic damage by proanthocyanidins (PAs), we examined the modulation of oxidative DNA damage induced by aflatoxin B1 in PAs-pretreated animals. The effects of PAs on changes in the expression of DNA damage and repair genes induced by aflatoxin B1 were also evaluated in rat marrow cells. Administration of PAs before aflatoxin B1 significantly mitigated aflatoxin B1-induced oxidative DNA damage in a dose-dependent manner. Aflatoxin B1 treatment induced significant alterations in the expression of specific DNA repair genes, and the pre-treatment of rats with PAs ameliorated the altered expression of these genes. Conclusively, PAs protect against aflatoxin B1-induced oxidative DNA damage in rats. These protective effects are attributed to the antioxidant effects of PA and enhanced DNA repair through modulation of DNA repair gene expression. Therefore, PAs are a promising chemoprotective agent for averting genotoxic risks associated with aflatoxin B1 exposure. [ABSTRACT FROM AUTHOR]

Purpose: Hyperthermia is used in combination with conventional anticancer agents to potentiate their cytotoxicity. One of its key events is the synthesis of heat shock proteins (HSPs), which are able to associate with components from DNA repair mechanisms. However, little is known about their relationship with the mismatch repair system (MMR). Our aim was to study the effects of hyperthermia on cisplatin (cPt) sensitivity and to determine whether MLH1 and MSH2 associate with Hsp27 and Hsp72 in MMR-deficient(−)/-proficient(+) cells. Materials and methods: HCT116+ch2 (MMR−) and HCT116+ch3 (MMR+) cell lines were exposed to cPt with or without previous hyperthermia (42 °C, 1 h). Clonogenic survival assays, MTT, confocal immunofluorescence, immunoprecipitation, immunoblotting and flow cytometry were performed. Results: Hyperthermia increased the cPt resistance in MMR− cells 1.42-fold. Immunofluorescence revealed that after cPt, Hsp27 and Hsp72 translocated to the nucleus and colocalisation coefficients between these proteins with MLH1 and MSH2 increased in MMR+ cells. Immunoprecipitation confirmed the interactions between HSPs and MMR proteins in control and treated cells. Hyperthermia pretreatment induced cell cycle arrest, increased p73 expression and potentiated cPt sensitivity in MMR+ cells. Conclusions: This is the first report showing in a MMR−/+ cellular model that MLH1 and MSH2 are client proteins of Hsp27 and Hsp72. Our study suggests that p73 might participate in the cellular response to hyperthermia and cPt in a MMR-dependent manner. Further functional studies will confirm whether HSPs cooperate with the MMR system in cPt-induced DNA damage response or whether these protein interactions are only the result of their chaperone functions. [ABSTRACT FROM PUBLISHER]

Purpose: To determine whether mice exposed to radiofrequency fields (RF) and then injected with a radiomimetic drug, bleomycin (BLM), exhibit adaptive response and provide some mechanistic evidence for such response. Materials and methods: Adult mice were exposed to 900 MHz RF at 120 μW/cm2 power density for 4 hours/day for 7 days. Immediately after the last exposure, some mice were sacrificed while the others were injected with BLM 4 h later. In each animal: (i) The primary DNA damage and BLM-induced damage as well as its repair kinetics were determined in blood leukocytes; and (ii) the oxidative damage was determined from malondialdehyde (MDA) levels and the antioxidant status was assessed from superoxide dismutase (SOD) levels in plasma, liver and lung tissues. Results: There were no indications for increased DNA and oxidative damages in mice exposed to RF alone in contrast to those treated with BLM alone. Mice exposed to RF+ BLM showed significantly: (a) reduced BLM-induced DNA damage and that remained after each 30, 60, 90, 120 and 150 min repair time, and (b) decreased levels of MDA in plasma and liver, and increased SOD level in the lung. Conclusions: The overall data suggested that RF exposure was capable of inducing adaptive response and mitigated BLM- induced DNA and oxidative damages by activating certain cellular processes. [ABSTRACT FROM AUTHOR]

The SWI/SNF chromatin-remodeling complex plays an essential role in several cellular processes including cell proliferation, differentiation, and DNA repair. Loss of normal function of the SWI/SNF complex because of mutations in its subunits correlates with tumorigenesis in humans. For many of these cancers, cytotoxic chemotherapy is the primary, and sometimes the only, therapeutic alternative. Among the antineoplastic agents, anthracyclines are a common treatment option. Although effective, resistance to these agents usually develops and serious dose-related toxicity, namely, chronic cardiotoxicity, limits its use. Previous work from our laboratory showed that a deletion of the SWI/SNF factor SNF2 resulted in hypersensitivity to doxorubicin. We further investigated the contribution of other chromatin remodelling complex components in the response to cytotoxic chemotherapy. Our results indicate that, of the eight SWI/SNF strains tested, snf2, taf14, and swi3 were the most sensitive and displayed distinct sensitivity to different cytotoxic agents, while snf5 displayed resistance. Our experimental results indicate that the SWI/SNF complex plays a critical role in protecting cells from exposure to cytotoxic chemotherapy and other cytotoxic agents. Our findings may prove useful in the development of a strategy aimed at targeting these genes to provide an alternative by hypersensitizing cancer cells to chemotherapeutic agents. [ABSTRACT FROM AUTHOR]

The aim of this work was to answer the question whether the broad range of parameters which describe oxidative stress and oxidatively damaged DNA and repair are appropriate prognosis factors of colon cancer (CRC) patients survival? The following parameters were analyzed for 89 CRC patients: concentration of uric acid and vitamins A, E, C in plasma; levels of 8-oxodGuo (8-oxo-7,8-dihydro-2′-deoxyguanosine) in DNA of leukocyte and colon tissues; urinary excretion rates of 8-oxodGuo and 8-oxoGua (8-oxo-7,8-dihydroguanine); the activity and mRNA or protein level of repair enzymes OGG1, APE1, ANPG, TDG and PARP1. All DNA modifications and plasma antioxidants were analyzed using high performance liquid chromatography (HPLC) or HPLC/gas chromatography-mass spectrometry techniques. Expression of repair proteins was analyzed by QPCR, Western or immunohistochemistry methods. Longer survival coincided with low levels of 8-oxodGuo/8oxoGua in urine and 8-oxodGuo in DNA as well as with high concentration of uric acid plasma level. In contrast to expectations, longer survival coincided with lower mRNA level in normal colon tissue of the main 8-oxoGua DNA glycosylase, OGG1, but no association was found for PARP-1 expression. When analyzing simultaneously two parameters the discriminating power increased significantly. Combination of low level of urinary 8-oxoGua together with low level of 8-oxodGuo in leukocyte (both below median value) or high concentration of plasma uric acid (above median value) have the best prediction power. Since prediction value of these parameters seems to be comparable to conventional staging procedure, they could possibly be used as markers to predict clinical success in CRC treatment. [ABSTRACT FROM AUTHOR]

Highlights: [•] Wogonin was neither genotoxic nor apoptogenic in mice at doses tested. [•] Wogonin enhances the repair of etoposide-induced DNA damage and apoptosis. [•] Wogonin ameliorates the alterations of OGG1 repair gene and oxidative DNA stress. [•] Wogonin had no antagonizing effect on etoposide-induce topo-II inhibition. [ABSTRACT FROM AUTHOR]

How DNA damage and repair processes affect the biomechanical properties of the nucleus interior remains unknown. Here, an opto-acoustic microscope based on time-domain Brillouin spectroscopy (TDBS) was used to investigate the induced regulation of intra-nuclear mechanics. With this ultrafast pump-probe technique, coherent acoustic phonons were tracked along their propagation in the intra-nucleus nanostructure and the complex stiffness moduli and thicknesses were measured with an optical resolution. Osteosarcoma cells were exposed to methyl methanesulfonate (MMS) and the presence of DNA damage was tested using immunodetection targeted against damage signaling proteins. TDBS revealed that the intra-nuclear storage modulus decreased significantly upon exposure to MMS, as a result of the chromatin decondensation and reorganization that favors molecular diffusion within the organelle. When the damaging agent was removed and cells incubated for 2 h in the buffer solution before fixation the intra-nuclear reorganization led to an inverse evolution of the storage modulus, the nucleus stiffened. The same tendency was measured when DNA double-strand breaks were caused by cell exposure to ionizing radiation. TDBS microscopy also revealed changes in acoustic dissipation, another mechanical probe of the intra-nucleus organization at the nano-scale, and changes in nucleus thickness during exposure to MMS and after recovery., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors.)

Abstract: 8-Oxo-7,8-dihydroguanine (8-oxoG) accumulates in the genome over time and is believed to contribute to the development of aging characteristics of skeletal muscle and various aging-related diseases. Here, we show a significantly increased level of intrahelical 8-oxoG and 8-oxoguanine-DNA glycosylase (OGG1) expression in aged human skeletal muscle compared to that of young individuals. In response to exercise, the 8-oxoG level was lastingly elevated in sedentary young and old subjects, but returned rapidly to preexercise levels in the DNA of physically active individuals independent of age. 8-OxoG levels in DNA were inversely correlated with the abundance of acetylated OGG1 (Ac-OGG1), but not with total OGG1, apurinic/apyrimidinic endonuclease 1 (APE1), or Ac-APE1. The actual Ac-OGG1 level was linked to exercise-induced oxidative stress, as shown by changes in lipid peroxide levels and expression of Cu,Zn-SOD, Mn-SOD, and SIRT3, as well as the balance between acetyltransferase p300/CBP and deacetylase SIRT1, but not SIRT6 expression. Together these data suggest that that acetylated form of OGG1, and not OGG1 itself, correlates inversely with the 8-oxoG level in the DNA of human skeletal muscle, and the Ac-OGG1 level is dependent on adaptive cellular responses to physical activity, but is age independent. [Copyright &y& Elsevier]

DNA damage initiates damage response pathways, cell cycle arrest and apoptosis. These processes act in a concerted fashion and remain functionally linked through mechanisms not completely understood. Programmed cell death, referred to as apoptosis, is a tightly regulated phenomenon ensuring that cells that accumulate irreversible DNA damage do not replicate. Interestingly, hyperacetylation of histone proteins, which alters transcription patterns and appears linked to DNA repair, also induces apoptosis, suggesting that aspects of chromatin modification link these very distinct processes. Modulating chromatin structure in the absence of any DNA lesions also activates key DNA damage-signalling proteins, further supporting the role of higher-order chromatin structure in mediating stress responses. This review will present an overview of the epigenetic control of eukaryotic genomes by chromatin remodelling as it pertains to DNA damage and highlight the potential role of the ING PHD proteins in linking apoptosis and DNA repair to gene transcription. [ABSTRACT FROM AUTHOR]

The study summarizes some recent data from our and other groups underlining the contribution to neurodegeneration of two transcription factors known to be involved in DNA damage sensing and repairing: the tumour suppressor gene p53 and the component of the DNA repair system MSH2. Both proteins participate in the cancer prevention machinery for the body as well as in the neurodegenerative process, suggesting that cancer and neurodegenerative disease may share common genetic risk factors for the development and progression of the disease. Here we show that, in neuronal cells, divergent cellular insults, i.e. the exposure to glutamate, β-amyloid (Aβ) or H2O2, may converge to a common pathway that initiate with elevation of p53 protein levels. We also found that in SH-SY5Y neuronal cellsH2O2 induced the activation of DNA repair system with the nuclear translocation of MSH2, and PCNA. Differently no changes in MSH2 and PCNA cellular distribution were found in undifferentiating SH-SY5Y cells exposed to H2O2. This argues that defects in the repair of, or response to, DNA damage impact significantly on brain function. [Copyright &y& Elsevier]

Sirtuin-1 (SIRT1) is a class-III histone deacetylase (HDAC), an NAD+-dependent enzyme deeply involved in gene regulation, genome stability maintenance, apoptosis, autophagy, senescence, proliferation, aging, and tumorigenesis. It also has a key role in the epigenetic regulation of tissue homeostasis and many diseases by deacetylating both histone and non-histone targets. Different studies have shown ambiguous implications of SIRT1 as both a tumor suppressor and tumor promoter. However, this contradictory role seems to be determined by the cell type and SIRT1 localization. SIRT1 upregulation has already been demonstrated in some cancer cells, such as acute myeloid leukemia (AML) and primary colon, prostate, melanoma, and non-melanoma skin cancers, while SIRT1 downregulation was described in breast cancer and hepatic cell carcinomas. Even though new functions of SIRT1 have been characterized, the underlying mechanisms that define its precise role on DNA damage and repair and their contribution to cancer development remains underexplored. Here, we discuss the recent findings on the interplay among SIRT1, oxidative stress, and DNA repair machinery and its impact on normal and cancer cells. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) is one of the most common malignant tumors. One of the factors increasing the risk of its occurrence may be the reduced efficiency of repairing DNA damage, both nuclear and mitochondrial. The main mechanism for repairing oxidative damage is the BER system (in mitochondria mtBER), whose key proteins NEIL1, NEIL2, OGG1, MUTYH, APE1 and LIG3 obtain full efficiency only at the appropriate level of acetylation. Sirtuin 3 is a key protein for mitochondrial homeostasis, regulating a number of metabolic processes related mainly to the control of the level of reactive oxygen species. Because Sirt3 possesses acetylase activity, it can modulate the level of activity of mtBER proteins by their deacetylation. The conducted study showed that the tested proteins NEIL1, NEIL2, OGG1, MUTYH, APE1 and LIG3 are the substrate for the enzymatic deacetylation activity of Sirt3, which may lead to modulation of the risk of CRC, and in cancer cells may be a potential therapeutic target enhancing the action of cytostatic drugs.

Trypanosoma cruzi is under the attack of reactive species produced by its mammalian and insect hosts. To survive, it must repair its damaged DNA. We have shown that a base excision DNA repair (BER)-specific parasite TcAP1 endonuclease is involved in the resistance to H 2 O 2 . However, a putative TcAP1 negative dominant form impairing TcAP1 activity in vitro did not show any in vivo effect. Here, we show that a negative dominant form of the human APE1 apurinic/apyrimidinic (AP) endonuclease (hAPE1DN) induces a decrease in epimastigote and metacyclic trypomastigote viability when parasites were exposed to H 2 O 2 . Those results confirm that TcAP1 AP endonuclease activity plays an important role in epimastigote and in infective metacyclic trypomastigote oxidative DNA damage resistance leading to parasite persistence in the insect and mammalian hosts. All along its biological cycle and in its different cellular forms, T. cruzi, the etiological parasite agent of Chagas' disease, is under the attack of reactive species produced by its mammalian and insect hosts. To survive, T. cruzi must repair their oxidative damaged DNA. We have previously shown that a specific parasite TcAP1 AP endonuclease of the BER is involved in the T. cruzi resistance to oxidative DNA damage. We have also demonstrated that epimastigotes and cell-derived trypomastigotes parasite forms expressing a putative TcAP1 negative dominant form (that impairs the TcAP1 activity in vitro), did not show any in vivo effect in parasite viability when exposed to oxidative stress. In this work, we show the expression of a negative dominant form of the human APE1 AP endonuclease fused to a green fluorescent protein (GFP; hAPE1DN-GFP) in T. cruzi epimastigotes. The fusion protein is found both in the nucleus and cytoplasm of noninfective epimastigotes but only in the nucleus in metacyclic and cell-derived trypomastigote infective forms. Contrarily to the TcAP1 negative dominant form, the ectopic expression of hAPE1DN-GFP induces a decrease in epimastigote and metacyclic trypomastigote viability when parasites were exposed to increasing H 2 O 2 concentrations. No such effect was evident in expressing hAPE1DN-GFP cell-derived trypomastigotes. Although the viability of both wild-type infective trypomastigote forms diminishes when parasites are submitted to acute oxidative stress, the metacyclic forms are more resistant to H 2 O 2 exposure than cell-derived trypomastigotes.Those results confirm that the BER pathway and particularly the AP endonuclease activity play an important role in epimastigote and metacyclic trypomastigote oxidative DNA damage resistance leading to parasite survival and persistence inside the mammalian and insect host cells., (© 2019 Wiley Periodicals, Inc.)

Background: Estrogens are critical players in prostate growth and disease. Estrogen therapy has been the standard treatment for advanced prostate cancer for several decades; however, it has currently been replaced by alternative anti-androgenic therapies. Additionally, studies of its action on prostate biology, resulting from an association between carcinogens and estrogen, at different stages of life are scarce or inconclusive about its protective and beneficial role on induced-carcinogenesis. Thus, the aim of this study was to determine whether estradiol exerts a protective and/or stimulatory role on N-methyl-N-nitrosurea-induced prostate neoplasms., Methods: We adopted a rodent model that has been used to study induced-prostate carcinogenesis: the Mongolian gerbil. We investigated the occurrence of neoplasms, karyometric patterns, androgen and estrogen receptors, basal cells, and global methylation status in ventral and dorsolateral prostate tissues., Results: Histopathological analysis showed that estrogen was able to slow tumor growth in both lobes after prolonged treatment. However, a true neoplastic regression was observed only in the dorsolateral prostate. In addition to the protective effects against neoplastic progression, estrogen treatment resulted in an epithelium that exhibited features distinctive from a normal prostate, including increased androgen-insensitive basal cells, high androgens and estrogen receptor positivity, and changes in DNA methylation patterns., Conclusions: Estrogen was able to slow tumor growth, but the epithelium exhibited features distinct from a normal prostatic epithelium, and this unstable microenvironment could trigger lesion recurrence over time., (© 2017 Wiley Periodicals, Inc.)

The SWI/SNF chromatin-remodeling complex plays an essential role in several cellular processes including cell proliferation, differentiation, and DNA repair. Loss of normal function of the SWI/SNF complex because of mutations in its subunits correlates with tumorigenesis in humans. For many of these cancers, cytotoxic chemotherapy is the primary, and sometimes the only, therapeutic alternative. Among the antineoplastic agents, anthracyclines are a common treatment option. Although effective, resistance to these agents usually develops and serious dose-related toxicity, namely, chronic cardiotoxicity, limits its use. Previous work from our laboratory showed that a deletion of the SWI/SNF factor SNF2 resulted in hypersensitivity to doxorubicin. We further investigated the contribution of other chromatin remodeling complex components in the response to cytotoxic chemotherapy. Our results indicate that, of the eight SWI/SNF strains tested, snf2, taf14, and swi3 were the most sensitive and displayed distinct sensitivity to different cytotoxic agents, while snf5 displayed resistance. Our experimental results indicate that the SWI/SNF complex plays a critical role in protecting cells from exposure to cytotoxic chemotherapy and other cytotoxic agents. Our findings may prove useful in the development of a strategy aimed at targeting these genes to provide an alternative by hypersensitizing cancer cells to chemotherapeutic agents.

Trypanosoma cruzi is the etiological agent of Chagas disease. The parasite has to overcome oxidative damage by ROS/RNS all along its life cycle to survive and to establish a chronic infection. We propose that T. cruzi is able to survive, among other mechanisms of detoxification, by repair of its damaged DNA through activation of the DNA base excision repair (BER) pathway. BER is highly conserved in eukaryotes with apurinic/apirimidinic endonucleases (APEs) playing a fundamental role. Previous results showed that T. cruzi exposed to hydrogen peroxide and peroxinitrite significantly decreases its viability when co-incubated with methoxyamine, an AP endonuclease inhibitor. In this work the localization, expression and functionality of two T. cruzi APEs (TcAP1, Homo sapiens APE1 orthologous and TcAP2, orthologous to Homo sapiens APE2 and to Schizosaccaromyces pombe Apn2p) were determined. These enzymes are present and active in the two replicative parasite forms (epimastigotes and amastigotes) as well as in the non-replicative, infective trypomastigotes. TcAP1 and TcAP2 are located in the nucleus of epimastigotes and their expression is constitutive. Epimastigote AP endonucleases as well as recombinant TcAP1 and TcAP2 are inhibited by methoxyamine. Overexpression of TcAP1 increases epimastigotes viability when they are exposed to acute ROS/RNS attack. This protective effect is more evident when parasites are submitted to persistent ROS/RNS exposition, mimicking nature conditions. Our results confirm that the BER pathway is involved in T. cruzi resistance to DNA oxidative damage and points to the participation of DNA AP endonucleases in parasite survival., (© 2013 Wiley Periodicals, Inc.)

Worldwide, breast cancer is the most commonly diagnosed cancer among women and is the leading cause of female cancer deaths. Zinc (Zn) functions as an antioxidant and plays a role in maintaining genomic stability. Zn deficiency results in oxidative DNA damage and increased cancer risk. Studies suggest an inverse association between dietary and plasma Zn levels and the risk for developing breast cancer. In contrast, breast tumor biopsies display significantly higher Zn levels compared with normal tissue. Zn accumulation in tumor tissue also correlates with increased levels of Zn importing proteins. Further, aberrant expression of Zn transporters in tumors correlates with malignancy, suggesting that altered metal homeostasis in the breast could contribute to malignant transformation and the severity of cancer. However, studies have yet to link dysregulated Zn transport and abnormal Zn-dependent functions in breast cancer development. Herein, we summarize studies that address the multi-modal role of Zn dyshomeostasis in breast cancer with respect to the role of Zn in modulating oxidative stress, DNA damage response/repair pathways and cell proliferation/apoptosis, and the relationship to aberrant regulation of Zn transporters. We also compare Zn dysregulation in breast tissue to that of prostate, pancreatic and ovarian cancer where possible.

Fanconi anemia (FA) is an autosomal recessive disorder characterized by congenital abnormalities, bone marrow failure, chromosome fragility, and cancer susceptibility. At least eleven members of the FA gene family have been identified using complementation experiments. Ubiquitin-proteasome has been shown to be a key regulator of FA proteins and their involvement in the repair of DNA damage. Here, we identified a novel functional link between the FA/BRCA pathway and E2F-mediated cell cycle regulome. In silico mining of a transcriptome database and promoter analyses revealed that a significant number of FA gene members were regulated by E2F transcription factors, known to be pivotal regulators of cell cycle progression - as previously described for BRCA1. Our findings suggest that E2Fs partly determine cell fate through the FA/BRCA pathway.