Rosemary (Rosmarinus officinalis L.) essential oil alleviates testis failure induced by Etoposide in male rats.

Rosemary (Rosmarinus officinalis L.) is a shrub used to treat hepatic, intestinal, renal, respiratory, and reproductive failures. Etoposide a plant-based compound derived from Podophyllum pelltatum, has been used for human malignancies treatment. However, it induces testis, and hepatic failures. In the present study, impact of rosemary essential oil against testis failure, lipid parameters, and hepatic enzymes in male rats has been studied. Forty male Wistar albino rats were grouped in a completely randomized design with Etoposide injection (ETO), rosemary supplementation (ROS), with Etoposide injection and rosemary supplement (ETO+ROS), and control rats with no Etoposide injection and no rosemary (CON). The experiment lasted for seven consecutive weeks including one week as acclimatization time. At the end of the experiment, rats were sacrificed by cervical dislocation, and blood samples were analyzed for serum alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), low-density lipoprotein-Cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), total cholesterol (TC), total Protein (TP), glucose (GLU) and testosterone. The left testis was harvested for histological examination. Results showed that rats with Etoposide injection had higher ALT, AST, and ALP the control rats. No significant difference was found among treatments in terms of glucose concentration in blood. Rosemary supplemntaion decreased cholesterol and TG concentration and increased HDL concentration in male rats. Furthermore, administration of rosemary essential oil increased blood testosterone but decreased ALT and AST. The epithelial height of seminiferous tubules was decreased significantly in ET as compared with CON. Rosemary essential oil lessened the adverse effect of Etopside on epithelial height in rat testis as it is shown in ET+ROS. In conclusion, dietary supplementation of rosemary essential oil alleviated liver toxicity and functional testis damage induced by Etopside.

Dexamethasone as an anti-cancer or hepatotoxic.

The linkage between inflammation and oxidative stress in liver damage has been proven and is undeniable; dexamethasone with some antioxidants can reduce the toxicity of liver tissue. Due to the importance of cancer treatment, glucocorticoids' synergistic effect in inhibiting cancer cell growth is also investigated. Dexamethasone alone and combined with etoposide were tested at concentrations of 1, 5, and 10 µM to evaluate the potency of dexamethasone in inhibiting the growth of A549 cells using oxidative stress factors and DNA damage. Also, intraperitoneal injection of dexamethasone in rats was used to induce liver toxicity. Coenzyme Q10 at different concentrations (1, 10, and 50 mg/kg) was used as an antioxidant to assess the oxidative stress factors and measure Caspase-3 activity. The results showed that dexamethasone combined with etoposide could significantly inhibit the growth of cancer cells and induce apoptosis. Treatment of A549 cells using dexamethasone also inhibits cancer cells' growth by inducing oxidative stress and DNA damage. Dexamethasone also, by inducing oxidative stress and activation of caspase 3, ultimately causes hepatotoxicity. Treatment with different concentrations of CoQ10 showed improved mitochondrial function, antioxidant defense, and liver enzyme. The best effect of coenzyme Q10 on dexamethasone-induced hepatotoxicity is 50 mg/kg. As a result, dexamethasone (alone and combined with etoposide) has an anti-cancer effect by damaging DNA and inducing oxidative stress. Also, CoQ10 has antioxidant effects against dexamethasone-induced hepatotoxicity by improving mitochondrial function and reducing caspase-3 activity.

Lycopene modulates hepatic toxicity and testicular injury induced by etoposide in male rats.

OBJECTIVE: Lycopene (C40H56), a carotenoid found in red colour fruits, is known as a powerful antioxidant that protects cells from damage caused by reactive oxygen species (ROS). Etoposide inhibits topoisomerase II activity and restricts the development of cancer cells, though it establishes oxidative stress. To study the effect of lycopene (Ly) against hepatotoxicity and testis injury induced by etoposide in male rats. ANIMALS: Forty male Wister albino rats. SETTINGS: The experiment lasted for seven consecutive weeks including one week as acclimatization time. DESIGN: The experiment was in a completely randomized design with a 2×2 factorial arrangement. INTERVENTION(S): The animals were grouped as follow: No etoposide injection and no lycopene (control), lycopene supplementation (LY), etoposide injection (ET), and rats with etoposide injection and lycopene supplement (ET+LY). MAIN OUTCOME MEASURE(S): At the end of the experiment, rats were sacrificed by cervical dislocation. Blood samples were harvested and analyzed for serum alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), low-density lipoprotein-Cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), total cholesterol (TC), Total Protein (TP), glucose (GLU) and testosterone. The left testis was manipulated for histological examination. RESULT(S): The result of experiment showed that rats with etoposide injection had higher ALT, AST, and ALP than the control rats. In contrast co-treated rats (ET+LY) significantly modulated the levels of the hepatic parameters. Administration of lycopene increased testosterone concentration and germinal epithelium of seminiferous tubules in testes rats. CONCLUSION(S): Lycopene might be a promising agent with hepatoprotective effect in restoring testis injury induced by etoposide in rats.

Ameliorative potential role of Rosmarinus officinalis extract on toxicity induced by etoposide in male albino rats.

The present work was showed to assess the effect of administration of rosemary extract on etoposide-induced toxicity, injury and proliferation in male rats were investigated. Forty male albino rats were arranged into four equal groups. 1st group, control; 2nd group, etoposide; 3rd group, co-treated rosemary & etoposide; 4th group, rosemary alone. In comparison to the control group, etoposide administration resulted in a significant increase in serum ALT, AST, ALP, total bilirubin, total protein, and gamma GT. In contrast; a significant decrease in albumin level in etoposide group as compared to G1. G3 revealed a significant decrease in AST, ALT, ALP, total protein and total bilirubin levels and a significant rise in albumin level when compared with G2. Serum levels of urea, creatinine, potassium ions, and chloride ions significantly increased; while sodium ions were significantly decreased in G2 when compared with G1. Also, there was an increase of MDA level for etoposide treated group with corresponding control rats. However, there was a remarkable significant decrease in SOD, GPX and CAT levels in G2 as compared to G1. There was a significant increase in serum hydrogen peroxide (H2O2) and Nitric oxide (NO) levels in group treated with etoposide when compared to control group. It was noticeable that administrated by rosemary alone either with etoposide had not any effect on the levels of H2O2 and Nitric oxide. Serum level of T3 and T4 was significantly increased in etoposide-administered rats in comparison with G1. The administration of rosemary, either alone or with etoposide, increased the serum levels of T3 and T4 significantly when compared to control rats. The gene expression analysis showed significant downregulation of hepatic SOD and GPx in (G2) when compared with (G1). The treatment with rosemary extract produced significant upregulation of the antioxidant enzymes mRNA SOD and GPx. MDA gene was increased in (G2) when contrasted with (G1). Treatment of the etoposide- induced rats with rosemary extract delivered significant decrease in MDA gene expression when compared with etoposide group. Rats treated with etoposide showed significant decline in hepatic Nrf2 protein expression, when compared with G1. While, supplementation of Etoposide- administered rats with the rosemary produced a significant elevation in hepatic Nrf2 protein levels. Additionally, the liver histological structure displayed noticeable degeneration and cellular infiltration in liver cells. It is possible to infer that rosemary has a potential role and that it should be researched as a natural component for etoposide-induced toxicity protection.

Three dimensional and microphysiological bone marrow models detect in vivo positive compounds.

Micronucleus (MN) assessment is a valuable tool in safety assessment. However, several compounds are positive in the in vivo bone marrow (BM) MN assay but negative in vitro, reflecting that BM complexity is not recapitulated in vitro. Importantly, these compounds are not genotoxic; rather, drug-driven pharmacological-effects on the BM increase MN, however, without mechanistic understanding, in vivo positives stop drug-progression. Thus, physiologically-relevant BM models are required to bridge the gap between in vitro and in vivo. The current study aimed to investigate the utility of two human 3D BM models (fluidic and static) for MN assessment. MN induction following treatment with etoposide and Poly-ADP Ribose Polymerase inhibitor (PARPi) and prednisolone (negative in vitro, positive in vivo) was determined in 2D L5178Y and human BM cells, and the 3D BM models. Etoposide (0-0.070 µM) and PARPi (0-150 µM) induced MN in both 3D BM models indicating their utility for genotoxicity testing. Interestingly, PARPi treatment induced a MN trend in 3D more comparable to in vivo. Importantly, prednisolone (0-1.7 mM) induced MN in both 3D BM models, suggesting recapitulation of the in vivo microenvironment. These models could provide a valuable tool to follow up, and eventually predict, suspected pharmacological mechanisms, thereby reducing animal studies.

Cell survival after DNA damage in the comet assay.

The comet assay is widely used in basic research, genotoxicity testing, and human biomonitoring. However, interpretation of the comet assay data might benefit from a better understanding of the future fate of a cell with DNA damage. DNA damage is in principle repairable, or if extensive, can lead to cell death. Here, we have correlated the maximally induced DNA damage with three test substances in TK6 cells with the survival of the cells. For this, we selected hydrogen peroxide (H2O2) as an oxidizing agent, methyl methanesulfonate (MMS) as an alkylating agent and etoposide as a topoisomerase II inhibitor. We measured cell viability, cell proliferation, apoptosis, and micronucleus frequency on the following day, in the same cell culture, which had been analyzed in the comet assay. After treatment, a concentration dependent increase in DNA damage and in the percentage of non-vital and apoptotic cells was found for each substance. Values greater than 20-30% DNA in tail caused the death of more than 50% of the cells, with etoposide causing slightly more cell death than H2O2 or MMS. Despite that, cells seemed to repair of at least some DNA damage within few hours after substance removal. Overall, the reduction of DNA damage over time is due to both DNA repair and death of heavily damaged cells. We recommend that in experiments with induction of DNA damage of more than 20% DNA in tail, survival data for the cells are provided.

Kaempferol and Its Glycoside Derivatives as Modulators of Etoposide Activity in HL-60 Cells.

Kaempferol is a polyphenol found in a variety of plants. Kaempferol exerts antitumor properties by affecting proliferation and apoptosis of cancer cells. We investigated whether kaempferol and its glycoside derivatives-kaempferol 3-O-[(6-O-E-caffeoyl)-ß-D-glucopyranosyl-(1→2)]-ß-D-galactopyranoside-7-O-ß-D-glucuropyranoside (P2), kaempferol 3-O-[(6-O-E-p-coumaroyl)-ß-D-glucopyranosyl-(1→2)]-ß-D-galactopyranoside-7-O-ß-D-glucuropyranoside (P5) and kaempferol 3-O-[(6-O-E-feruloyl)-ß-D-glucopyranosyl-(1→2)]-ß-D-galactopyranoside-7-O-ß-D-glucuropyranoside (P7), isolated from aerial parts of Lens culinaris Medik.-affect the antitumor activity of etoposide in human promyelocytic leukemia (HL-60) cells. We analyzed the effect of kaempferol and its derivatives on cytotoxicity, DNA damage, apoptosis, cell cycle progression and free radicals induced by etoposide. We demonstrated that kaempferol increases the sensitivity of HL-60 cells to etoposide but does not affect apoptosis induced by this drug. Kaempferol also reduces the level of free radicals generated by etoposide. Unlike kaempferol, some of its derivatives reduce the apoptosis of HL-60 cells (P2 and P7) and increase the level of free radicals (P2 and P5) induced by etoposide. Our results indicate that kaempferol and its glycoside derivatives can modulate the activity of etoposide in HL-60 cells and affect its antitumor efficacy in this way. Kaempferol derivatives may have the opposite effect on the action of etoposide in HL-60 cells compared to kaempferol.

Inhibition of Aedes aegypti DNA topoisomerase II by etoposide: Impact on survival and morphology of larvae and pupae.

DNA topoisomerase II enzymes maintain DNA stability during vital processes, such as genome replication, transcription and chromosomal segregation during mitosis and meiosis. In the present work, we analyzed functional aspects of the DNA topoisomerase II (AeTopII) enzyme of the mosquito Aedes aegypti. Here, we show that AeTopII mRNA is expressed at all stages of mosquito development. By in situ hybridization, we found that the AeTopII mRNA is concentrated along the ovarian follicular cells as well as in the region of the follicles. The observed expression profiles likely reflect increased topoisomerase II cellular requirements due to the intense ovarian growth and egg production following blood feeding in Ae. aegypti females. The drug etoposide, a classic inhibitor of topoisomerase II, was used for in vivo testing with 2nd stage larvae, in order to investigate the functional importance of this enzyme in Ae. aegypti survival and development. Inhibition of topoisomerase II activity with etoposide concentrations ranging from 10 to 200 µM did not leads to the immediate death of larvae. However, after 10 days of observation, etoposide treatments resulted in 30-40% decrease in survival, in a dose dependent manner, with persisting larvae and pupae presenting incomplete development, as well as morphological abnormalities. Also, approximately 50% of the treated larvae did not reach the pupal stage. Thus, we conclude that AeTopII is a vital enzyme in the development of Ae. aegypti and its sensitivity to inhibitors should be explored for potential chemical agents to be used in vector control.

Melatonin protects rats testes against bleomycin, etoposide, and cisplatin-induced toxicity via mitigating nitro-oxidative stress and apoptosis.

There is growing concern that some cytotoxic regimens for cancer adversely affect spermatogenesis and male fertility. Increasing evidence demonstrated that melatonin has beneficial impacts on reproductive processes; however, whether melatonin can protect against bleomycin, etoposide, and cisplatin (BEP) chemotherapy regimen-induced testicular toxicity, remains obscure. The present study aimed to explore the effect of melatonin on BEP-evoked testicular injury in rats. Adult male Wistar rats (n = 10/group) were intraperitoneally (i.p.) injected with one cycle of 21 days of 0.33 therapeutically relevant dose levels of BEP (.5 mg/kg bleomycin, 5 mg/kg etoposide, and 1 mg/kg cisplatin) with or without melatonin. At the end of the study, sperm parameters, testosterone level, stereology of testes, testicular levels of malondialdehyde (MDA), nitric oxide (NO), and total antioxidant capacity (TAC), the expression of apoptosis-associated genes such as Bcl2, Bax, Caspase-3, p53, and TNF-α (Real-time PCR and Immunohistochemistry) were evaluated. Our findings showed that melatonin restored spermatogenesis by improving sperm count, motility, viability, and morphology. Testosterone level, histopathology, and stereology of testes were significantly improved in melatonin-administrated groups. Furthermore, melatonin recovered the oxidative status of the testes through elevating TAC and ameliorating MDA and NO levels. More importantly, melatonin therapy suppressed BEP-evoked apoptosis by modulating Bcl-2, Bax, Caspase-3, p53, and TNF-α expression in testes. In conclusion, melatonin protects the testes against BEP-induced testicular damage by attenuating nitro-oxidative stress, apoptosis, and inflammation, which provides evidence for melatonin as a possible clinical therapy against BEP-associated gonadotoxicity and male sub/infertility.

Clinical feasibility of oral low-dose etoposide and sobuzoxane for conventional chemotherapy-intolerant lymphoma patients.

Introduction: In Japan, etoposide or sobuzoxane, a type of topoisomerase II inhibitor, is orally administered in patients with lymphoma who cannot tolerate conventional combination chemotherapy. However, the related clinical data remain to be fully summarized.Areas covered: We evaluate the efficacy and toxicity of etoposide and sobuzoxane.Expert opinion: Previous studies on etoposide or sobuzoxane monotherapy, including those among patients who could not tolerate conventional chemotherapy, suggested a favorable overall response rate (ORR) with moderate gastrointestinal or liver/renal toxicity. As for adult T-cell leukemia/lymphoma, a clinical trial with a limited sample size exhibited an ORR of >70%. Remarkably, the percentage of patients with a poor performance status was high among those receiving etoposide/sobuzoxane. Given a lack of randomized studies, etoposide/sobuzoxane might be a therapeutic option for lymphoma in a palliative setting. In the future, prospective trials with a homologous treatment schedule are warranted, in which the association between clinical efficacy and characteristics of lymphomas, such as specific gene alterations, should be elucidated.

Berberine inhibits chemotherapy-exacerbated ovarian cancer stem cell-like characteristics and metastasis through GLI1.

Despite the remarkable clinical response in ovarian cancer therapy, the distinctively high metastasis rate is still a barrier to achieve satisfying prognosis. Our study aimed to decipher the role of berberine in inhibiting chemotherapy-exacerbated ovarian cancer metastasis. We found that chemotherapy exacerbated the migration and cancer stem cell (CSC)-like characteristics through transcriptional factor GLI1, which regulated the pluripotency-associated gene BMI1 and the epithelial-mesenchymal transition (EMT) markers Vimentin and Snail. Berberine could not only down-regulate CSC-like characteristics but also reverse EMT and migration through inhibiting chemotherapy-activated GLI1/BMI1 signaling pathway. Together, our study revealed the pivotal role of berberine in overcoming chemotherapy-exacerbated ovarian cancer metastasis, thereby provided a potential adjuvant therapeutic agent in combination with chemotherapeutics to prevent metastasis during ovarian cancer chemotherapy.

Ancient Sturgeons Possess Effective DNA Repair Mechanisms: Influence of Model Genotoxicants on Embryo Development of Sterlet, Acipenser ruthenus.

DNA damage caused by exogenous or endogenous factors is a common challenge for developing fish embryos. DNA damage repair (DDR) pathways help organisms minimize adverse effects of DNA alterations. In terms of DNA repair mechanisms, sturgeons represent a particularly interesting model due to their exceptional genome plasticity. Sterlet (Acipenser ruthenus) is a relatively small species of sturgeon. The goal of this study was to assess the sensitivity of sterlet embryos to model genotoxicants (camptothecin, etoposide, and benzo[a]pyrene), and to assess DDR responses. We assessed the effects of genotoxicants on embryo survival, hatching rate, DNA fragmentation, gene expression, and phosphorylation of H2AX and ATM kinase. Exposure of sterlet embryos to 1 µM benzo[a]pyrene induced low levels of DNA damage accompanied by ATM phosphorylation and xpc gene expression. Conversely, 20 µM etoposide exposure induced DNA damage without activation of known DDR pathways. Effects of 10 nM camptothecin on embryo development were stage-specific, with early stages, before gastrulation, being most sensitive. Overall, this study provides foundational information for future investigation of sterlet DDR pathways.

Expression of miR-34a is a sensitive biomarker for exposure to genotoxic agents in human lymphoblastoid TK6 cells.

miR-34a has been identified as a tumor suppressor microRNA (miRNA) involved in the P53 network. Its expression levels correlate to carcinogenesis, which are generally lower in tumor tissue and higher in response to DNA damage. In this study, the response of miR-34a from exposure to genotoxic agents in human lymphoblastoid TK6 cells was evaluated to assess whether the expression of this miRNA could be used as an early indicator for genotoxic damage in mammalian cells. TK6 cells were treated with seven genotoxic agents with different mode-of-actions (cisplatin, N-ethyl-N-nitrosourea, etoposide, mitomycin C, methyl methanesulphonate, taxol, and X-ray radiation) and a non-genetic toxin (usnic acid) at different concentrations for four hours (except for X-rays) and the expression levels of miR-34a were measured 24 h after the beginning of the treatments. The expression levels of miR-34a were significantly increased by these genetic toxins in a dose-dependent manner, while no significant change in miRNA expression was found in the usnic acid-treated cells. These results suggest that miR-34a can respond to genotoxic insults sensitively; thus, miR-34a expression has the potential to be used to evaluate genotoxicity of agents.

Genomic profiling of the transcription factor Zfp148 and its impact on the p53 pathway.

Recent data suggest that the transcription factor Zfp148 represses activation of the tumor suppressor p53 in mice and that therapeutic targeting of the human orthologue ZNF148 could activate the p53 pathway without causing detrimental side effects. We have previously shown that Zfp148 deficiency promotes p53-dependent proliferation arrest of mouse embryonic fibroblasts (MEFs), but the underlying mechanism is not clear. Here, we showed that Zfp148 deficiency downregulated cell cycle genes in MEFs in a p53-dependent manner. Proliferation arrest of Zfp148-deficient cells required increased expression of ARF, a potent activator of the p53 pathway. Chromatin immunoprecipitation showed that Zfp148 bound to the ARF promoter, suggesting that Zfp148 represses ARF transcription. However, Zfp148 preferentially bound to promoters of other transcription factors, indicating that deletion of Zfp148 may have pleiotropic effects that activate ARF and p53 indirectly. In line with this, we found no evidence of genetic interaction between TP53 and ZNF148 in CRISPR and siRNA screen data from hundreds of human cancer cell lines. We conclude that Zfp148 deficiency, by increasing ARF transcription, downregulates cell cycle genes and cell proliferation in a p53-dependent manner. However, the lack of genetic interaction between ZNF148 and TP53 in human cancer cells suggests that therapeutic targeting of ZNF148 may not increase p53 activity in humans.

Substituted 4,5'-Bithiazoles as Catalytic Inhibitors of Human DNA Topoisomerase IIα.

Human type II topoisomerases, molecular motors that alter the DNA topology, are a major target of modern chemotherapy. Groups of catalytic inhibitors represent a new approach to overcome the known limitations of topoisomerase II poisons such as cardiotoxicity and induction of secondary tumors. Here, we present a class of substituted 4,5'-bithiazoles as catalytic inhibitors targeting the human DNA topoisomerase IIα. Based on a structural comparison of the ATPase domains of human and bacterial type II topoisomerase, a focused chemical library of 4,5'-bithiazoles was assembled and screened to identify compounds that better fit the topology of the human topo IIα adenosine 5'-triphosphate (ATP) binding site. Selected compounds showed inhibition of human topo IIα comparable to that of the etoposide topo II drug, revealing a new class of inhibitors targeting this molecular motor. Further investigations showed that compounds act as catalytic inhibitors via competitive ATP inhibition. We also confirmed binding to the truncated ATPase domain of topo IIα and modeled the inhibitor molecular recognition with molecular simulations and dynophore models. The compounds also displayed promising cytotoxicity against HepG2 and MCF-7 cell lines comparable to that of etoposide. In a more detailed study with the HepG2 cell line, there was no induction of DNA double-strand breaks (DSBs), and the compounds were able to reduce cell proliferation and stop the cell cycle mainly in the G1 phase. This confirms the mechanism of action of these compounds, which differs from topo II poisons also at the cellular level. Substituted 4,5'-bithiazoles appear to be a promising class for further development toward efficient and potentially safer cancer therapies exploiting the alternative topo II inhibition paradigm.

Interaction of Deubiquitinase 2A-DUB/MYSM1 with DNA Repair and Replication Factors.

The deubiquitination of histone H2A on lysine 119 by 2A-DUB/MYSM1, BAP1, USP16, and other enzymes is required for key cellular processes, including transcriptional activation, apoptosis, and cell cycle control, during normal hematopoiesis and tissue development, and in tumor cells. Based on our finding that MYSM1 colocalizes with γH2AX foci in human peripheral blood mononuclear cells, leukemia cells, and melanoma cells upon induction of DNA double-strand breaks with topoisomerase inhibitor etoposide, we applied a mass spectrometry-based proteomics approach to identify novel 2A-DUB/MYSM1 interaction partners in DNA-damage responses. Differential display of MYSM1 binding proteins significantly enriched after exposure of 293T cells to etoposide revealed an interacting network of proteins involved in DNA damage and replication, including factors associated with poor melanoma outcome. In the context of increased DNA-damage in a variety of cell types in Mysm1-deficient mice, in bone marrow cells upon aging and in UV-exposed Mysm1-deficient skin, our current mass spectrometry data provide additional evidence for an interaction between MYSM1 and key DNA replication and repair factors, and indicate a potential function of 2A-DUB/MYSM1 in DNA repair processes.

Human oocytes harboring damaged DNA can complete meiosis I.

OBJECTIVE: To determine whether human oocytes possess a checkpoint to prevent completion of meiosis I when DNA is damaged. DESIGN: DNA damage is considered a major threat to the establishment of healthy eggs and embryos. Recent studies found that mouse oocytes with damaged DNA can resume meiosis and undergo germinal vesicle breakdown (GVBD), but then arrest in metaphase of meiosis I in a process involving spindle assembly checkpoint (SAC) signaling. Such a mechanism could help prevent the generation of metaphase II (MII) eggs with damaged DNA. Here, we compared the impact of DNA-damaging agents with nondamaged control samples in mouse and human oocytes. SETTING: University-affiliated clinic and research center. PATIENT(S): Patients undergoing ICSI cycles donated GV-stage oocytes after informed consent; 149 human oocytes were collected over 2 years (from 50 patients aged 27-44 years). INTERVENTIONS(S): Mice and human oocytes were treated with DNA-damaging drugs. MAIN OUTCOME MEASURE(S): Oocytes were monitored to evaluate GVBD and polar body extrusion (PBE), in addition to DNA damage assessment with the use of γH2AX antibodies and confocal microscopy. RESULT(S): Whereas DNA damage in mouse oocytes delays or prevents oocyte maturation, most human oocytes harboring experimentally induced DNA damage progress through meiosis I and subsequently form an MII egg, revealing the absence of a DNA damage-induced SAC response. Analysis of the resulting MII eggs revealed damaged DNA and chaotic spindle apparatus, despite the oocyte appearing morphologically normal. CONCLUSION(S): Our data indicate that experimentally induced DNA damage does not prevent PBE in human oocytes and can persist in morphologically normal looking MII eggs.

Carnitine Diminishes Etoposide Toxic Action on Spermatogonial Self-renewal and Sperm Production in Adult Rats Treated in the Prepubertal Phase.

The aim of this study was to investigate carnitine action against negative effects of etoposide on stem/progenitor spermatogonia and on sperm production. Carnitine (250 mg/kg body weight/day) and etoposide (5 mg/kg body weight/day) were administered from 25-days postpartum to 32-days postpartum. Testes were collected at 32-days postpartum, 64-days postpartum, and 127-days postpartum, and submitted to the immuno-labeling of UTF1, SOX2, and PLZF proteins to identify undifferentiated spermatogonia populations. At 127-days postpartum, sperm were collected for analysis. Carnitine+etoposide group showed a higher numerical density of spermatogonia labeled for all studied proteins at 64-days postpartum (critical age) compared to the etoposide group. Moreover, there was an improvement of spermatic parameters and sperm DNA integrity in rats of the carnitine+etoposide group in comparison with rats of the etoposide group. The results suggest that carnitine improves the self-renewal of undifferentiated spermatogonia and promotes a partial protection on them, alleviating the etoposide harmful late effects and leading to an enhancement of the sperm parameters in adulthood.

Nuclear myosin 1 activates p21 gene transcription in response to DNA damage through a chromatin-based mechanism.

Nuclear myosin 1 (NM1) has been implicated in key nuclear functions. Together with actin, it has been shown to initiate and regulate transcription, it is part of the chromatin remodeling complex B-WICH, and is responsible for rearrangements of chromosomal territories in response to external stimuli. Here we show that deletion of NM1 in mouse embryonic fibroblasts leads to chromatin and transcription dysregulation affecting the expression of DNA damage and cell cycle genes. NM1 KO cells exhibit increased DNA damage and changes in cell cycle progression, proliferation, and apoptosis, compatible with a phenotype resulting from impaired p53 signaling. We show that upon DNA damage, NM1 forms a complex with p53 and activates the expression of checkpoint regulator p21 (Cdkn1A) by PCAF and Set1 recruitment to its promoter for histone H3 acetylation and methylation. We propose a role for NM1 in the transcriptional response to DNA damage response and maintenance of genome stability.

Quantitative phosphoproteomics to unravel the cellular response to chemical stressors with different modes of action.

Damage to cellular macromolecules and organelles by chemical exposure evokes activation of various stress response pathways. To what extent different chemical stressors activate common and stressor-specific pathways is largely unknown. Here, we used quantitative phosphoproteomics to compare the signaling events induced by four stressors with different modes of action: the DNA damaging agent: cisplatin (CDDP), the topoisomerase II inhibitor: etoposide (ETO), the pro-oxidant: diethyl maleate (DEM) and the immunosuppressant: cyclosporine A (CsA) administered at an equitoxic dose to mouse embryonic stem cells. We observed major differences between the stressors in the number and identity of responsive phosphosites and the amplitude of phosphorylation. Kinase motif and pathway analyses indicated that the DNA damage response (DDR) activation by CDDP occurs predominantly through the replication-stress-related Atr kinase, whereas ETO triggers the DDR through Atr as well as the DNA double-strand-break-associated Atm kinase. CsA shares with ETO activation of CK2 kinase. Congruent with their known modes of action, CsA-mediated signaling is related to down-regulation of pathways that control hematopoietic differentiation and immunity, whereas oxidative stress is the most prominent initiator of DEM-modulated stress signaling. This study shows that even at equitoxic doses, different stressors induce distinctive and complex phosphorylation signaling cascades.