Protection and induction of chromosomal damage by vitamin C in human lymphocyte cultures

Mitochondrial targeted antioxidants, mitoquinone and SKQ1, not vitamin C, mitigate doxorubicin-induced damage in H9c2 myoblast: pretreatment vs. co-treatment

BACKGROUND

Preconditioning of the heart ameliorates doxorubicin (Dox)-induced cardiotoxicity. We tested whether pretreating cardiomyocytes by mitochondrial-targeted antioxidants, mitoquinone (MitoQ) or SKQ1, would provide better protection against Dox than co-treatment.

METHODS

We investigated the dose-response relationship of MitoQ, SKQ1, and vitamin C on Dox-induced damage on H9c2 cardiomyoblasts when drugs were given concurrently with Dox (e.g., co-treatment) or 24 h prior to Dox (e.g., pretreatment). Moreover, their effects on intracellular and mitochondrial oxidative stress were evaluated by 2,7-dichlorofluorescin diacetate and MitoSOX, respectively.

RESULTS

Dox (0.5-50 μM, n = 6) dose-dependently reduced cell viability. By contrast, co-treatment of MitoQ (0.05-10 μM, n = 6) and SKQ1 (0.05-10 μM, n = 6), but not vitamin C (1-2000 μM, n = 3), significantly improved cell viability only at intermediate doses (0.5-1 μM). MitoQ (1 μM) and SKQ1 (1 μM) significantly increased cell viability to 1.79 ± 0.12 and 1.59 ± 0.08 relative to Dox alone, respectively (both p < 0.05). Interestingly, when given as pretreatment, only higher doses of MitoQ (2.5 μM, n = 9) and SKQ1 (5 μM, n = 7) showed maximal protection and improved cell viability to 2.19 ± 0.13 and 1.65 ± 0.07 relative to Dox alone, respectively (both p < 0.01), which was better than that of co-treatment. Moreover, the protective effects were attributed to the significant reduction in Dox-induced intracellular and mitochondrial oxidative stress.

CONCLUSION

The data suggest that MitoQ and SKQ1, but not vitamin C, mitigated DOX-induced damage. Moreover, MitoQ pretreatment showed significantly higher cardioprotection than its co-treatment and SKQ1, which may be due to its better antioxidant effects.

An update on the mechanisms related to cell death and toxicity of doxorubicin and the protective role of nutrients

Doxorubicin (DOX), is a very effective chemotherapeutic agent against cancer whose clinical use is limited by toxicity. Different strategies have been proposed to attenuate toxicity, including combined therapy with bioactive compounds. This review update mechanisms of action and toxicity of doxorubicin and the role of nutrients like vitamins (A, C, E), minerals (selenium) and n-3 polyunsaturated fatty acids. Protective activities against DOX toxicity in liver, kidney, skin, bone marrow, testicles or brain have been reported, but these have not been evaluated for all of the reviewed nutrients. In most cases oxidation-related effects were present either, by reducing ROS levels and/or increasing antioxidant defenses. Antiapoptotic and anti-inflammatory mechanisms are also commonly reported. In some cases, interferences with autophagy and calcium homeostasis also have shown to be affected. Notwithstanding, there is a wide variety in duration and doses of treatment tested for both, compounds and DOX, which make difficult to compare the results of the studies. In spite of the reduction of DOX cardiotoxicity in health models, DOX anti-cancer activity in cancer cell lines or xenograft models usually did not result compromised when this has been evaluated. Importantly, clinical studies are needed to confirm all the observed effects.

Effects of Anthocyanin and Flavanol Compounds on Lipid Metabolism and Adipose Tissue Associated Systemic Inflammation in Diet-Induced Obesity

Background. Naturally occurring substances from the flavanol and anthocyanin family of polyphenols have been proposed to exert beneficial effects in the course of obesity. We hypothesized that their effects on attenuating obesity-induced dyslipidemia as well as the associated inflammatory sequelae especially have health-promoting potential. Methods. Male C57BL/6J mice (n = 52) received a control low-fat diet (LFD; 10 kcal% fat) for 6 weeks followed by 24 weeks of either LFD (n = 13) or high-fat diet (HFD; 45 kcal% fat; n = 13) or HFD supplemented with 0.1% w/w of the flavanol compound epicatechin (HFD+E; n = 13) or an anthocyanin-rich bilberry extract (HFD+B; n = 13). Energy substrate utilization was determined by indirect calorimetry in a subset of mice following the dietary switch and at the end of the experiment. Blood samples were collected at baseline and at 3 days and 4, 12, and 20 weeks after dietary switch and analyzed for systemic lipids and proinflammatory cytokines. Adipose tissue (AT) histopathology and inflammatory gene expression as well as hepatic lipid content were analyzed after sacrifice. Results. The switch from a LFD to a HFD lowered the respiratory exchange ratio and increased plasma cholesterol and hepatic lipid content. These changes were not attenuated by HFD+E or HFD+B. Furthermore, the polyphenol compounds could not prevent HFD-induced systemic rise of TNF-α levels. Interestingly, a significant reduction in Tnf gene expression in HFD+B mice was observed in the AT. Furthermore, HFD+B, but not HFD+E, significantly prevented the early upregulation of circulating neutrophil chemoattractant mKC. However, no differences in AT histopathology were observed between the HFD types. Conclusion. Supplementation of HFD with an anthocyanin-rich bilberry extract but not with the flavanol epicatechin may exert beneficial effects on the systemic early inflammatory response associated with diet-induced obesity. These systemic effects were transient and not observed after prolongation of HFD-feeding (24 weeks). On the tissue level, long-term treatment with bilberry attenuated TNF-α expression in adipose tissue.

An expert opinion on pharmacologic approaches to reducing the cardiotoxicity of childhood acute lymphoblastic leukemia therapies

INTRODUCTION

Acute lymphoblastic leukemia (ALL) is the most common hematologic malignancy in children. Treatment-related cardiac damage is progressive and often difficult to reverse. Strategies to minimize cardiotoxicity during treatment are crucial to prevent severe lasting effects on health and quality of life.

AREAS COVERED

This comprehensive review covers the pathophysiology and various presentations, both clinical and subclinical, of treatment-induced cardiotoxicity and characteristics associated with increased risk of cardiac dysfunction in childhood ALL survivors. Additionally, contemporary prevention strategies such as limiting cumulative anthracycline dose, altering drug administration schedule, the use of anthracycline structural analogs, liposomal encapsulated anthracyclines, cardioprotective agents and nutritional supplements are critically analyzed. Finally, this review covers the management options of chemotherapy-induced damage and other treatment-related cardiotoxicity.

EXPERT OPINION

Higher lifetime cumulative doses of anthracyclines, younger age at diagnosis, longer follow-up, female sex, higher dose rates and cranial irradiation are associated with more severe cardiotoxic effects. Long-term adverse effects of both anthracycline and non-anthracycline chemotherapeutic agents are becoming an increasing focus during treatment of childhood malignancies. There must be a careful balance between achieving remission of childhood ALL while avoiding the development of another often-fatal illness, heart failure.

Antimutagenic effect of aqueous extract from Agaricus brasiliensis on culture of human lymphocytes

The mushroom Agaricus brasiliensis (sun mushroom), native from the southeast of Brazil, is well known by its medicinal properties that include effects on diabetes, cholesterol levels, and osteoporosis. The antimutagenic effects of A. brasiliensis has been investigated recently and revealed some controversial results depending on the temperature by which the A. brasiliensis tea is obtained. In the present study, we evaluated the effect of the A. brasiliensis extract prepared in two different temperatures, 4°C and 25°C, on the doxorubicin-induced DNA strand breaks and chromosomal aberrations (CAs) in human lymphocytes. The results demonstrated that A. brasiliensis was able to reduce the DXR-induced DNA damage in both temperatures; however, the CA test was more sensitive to demonstrate a better reduction when the cells were treated with an extract obtained at 25°C. A. brasiliensis extract obtained in different temperatures exhibited antigenotoxic and anticlastogenic effects in human lymphocytes.

Baicalein protects against doxorubicin-induced cardiotoxicity by attenuation of mitochondrial oxidant injury and JNK activation

The cardiotoxicity of doxorubicin limits its clinical use in the treatment of a variety of malignancies. Previous studies suggest that doxorubicin-associated cardiotoxicity is mediated by reactive oxygen species (ROS)-induced apoptosis. We therefore investigated if baicalein, a natural antioxidant component of Scutellaria baicalensis, could attenuate ROS generation and cell death induced by doxorubicin. Using an established chick cardiomyocyte model, doxorubicin (10 µM) increased cell death in a concentration- and time-dependent manner. ROS generation was increased in a dose-response fashion and associated with loss of mitochondrial membrane potential. Doxorubicin also augmented DNA fragmentation and increased the phosphorylation of ROS-sensitive pro-apoptotic kinase c-Jun N-terminal kinase (JNK). Adjunct treatment of baicalein (25 µM) and doxorubicin for 24 h significantly reduced both ROS generation (587 ± 89 a.u. vs. 932 a.u. ± 121 a.u., P < 0.01) and cell death (30.6 ± 5.1% vs. 46.8 ± 8.3%, P < 0.01). The dissipated mitochondrial potential and increased DNA fragmentation were also ameliorated. Along with the reduction of ROS and apoptosis, baicalein attenuated phosphorylation of JNK induced by doxorubicin (1.7 ± 0.3 vs. 3.0 ± 0.4-fold, P < 0.05). Co-treatment of cardiomyocytes with doxorubicin and JNK inhibitor SP600125 (10 µM; 24 h) reduced JNK phosphorylation and enhanced cell survival, suggesting that the baicalein protection against doxorubicin cardiotoxicity was mediated by JNK activation. Importantly, concurrent baicalein treatment did not interfere with the anti-proliferative effects of doxorubicin in human breast cancer MCF-7 cells. In conclusion, baicalein adjunct treatment confers anti-apoptotic protection against doxorubicin-induced cardiotoxicity without compromising its anti-cancer efficacy.

Antigenotoxic and anticytotoxic effect of camel milk in mice treated with cisplatin

Camel milk (CM) has good nutritive value, in addition to its antigenotoxic and anticytotoxic effects. Therefore the aim of this investigation was to evaluate the capacity of CM to inhibit the micronucleated polychromatic erythrocytes (MnPCEs) in the bone marrow and improve the mitotic activity produced by cisplatin. Cisplatin is one of the most widely used antineoplastic drugs in the treatment of cancer. The 70 adult male Swiss albino mice were divided into seven groups:Gr. I: treated with distilled water and considered as a control group.Gr. II: treated with camel milk (33 ml/kg, b.w).Gr. III: treated previously with cisplatin (0.5 mg/kg, b.w).Gr. IV: treated with camel milk and followed after 2 h. with cisplatin (33 ml/kg → 0.5 mg/kg, b.w).Gr. V: treated with camel milk and cisplatin at the same time (33 ml/kg + 0.5 mg/kg, b.w).Gr. VI: treated with an acute single dose of cisplatin (2.5 mg/kg, b.w).Gr. VII: treated with camel milk prior and followed with an acute single dose of cisplatin (33 ml/kg → 2.5 mg /kg, b.w). The animals were sacrificed 24 h after cisplatin injection. The pretreatment with CM dose caused a significant decrease (P < 0.001) in the frequency of MnPCEs and increase (P < 0.001) in the mitotic index (MI) induced by cisplatin when compared with the groups treated with cisplatin alone. The possible explanation for the antigenotoxic and anticytotoxic effects observed in the pretreatment with CM is ascribed to its contents. In conclusion, from the findings we suggest that this milk has some antioxidant effect, and the antigenotoxic mechanism of this milk needs to be explored further before their use during cisplatin chemotherapy.

Anticlastogenic and antigenotoxic effects of selenomethionine on doxorubicin-induced damage in vitro in human lymphocytes

The use of antioxidants during chemotherapy has been shown to reduce or prevent the undesirable effects experienced by healthy cells. Micronutrient selenium is well known for its antioxidant properties; however, selenium exhibits a bimodal nature in that both its beneficial and toxic properties lie within a limited and narrow dose range. The present study investigated the possible protective effects of selenomethionine (SM) on the cytotoxicity, genotoxicity and clastogenicity of the chemotherapic doxorubicin (DXR), a key chemotherapic used in cancer treatment. Human peripheral lymphocytes were treated in vitro with varying concentrations of SM (0.25 microM, 0.5 microM, 1.0 microM and 2.0 microM), tested in combination with DXR (0.15 microg/mL). SM alone was not cytotoxic and when combined with DXR treatment, reduced the DNA damage index significantly, the frequency of chromosomal aberrations, the number of aberrant metaphases and the frequency of apoptotic cells. The mechanism of chemoprotection of SM may be related to its antioxidant properties as well as its ability to interfere with DNA repair pathways. Therefore this study showed that SM is effective in reducing the genetic damage induced by the antitumoral agent DXR.

Evaluation of the clastogenicity and anticlastogenicity of vitamin B6 in human lymphocyte cultures

Insufficient intakes of many micronutrients found in fruits and vegetables, such as folic acid, vitamins C and B6 may lead to DNA damage, cancer, and degenerative disease. The investigation of dietary antioxidants is a field of great interest for elucidating mechanisms of mutagenesis/carcinogenesis. The present study was undertaken to investigate the effects of vitamin B6 on the induction of chromosomal aberrations in cultured human lymphocytes and to examine the possible anticlastogenic effect of this vitamin on chromosomal damage induced by the antitumor drug doxorubicin. The results showed that when the cultures treated with vitamin B6 were compared with the untreated control in terms of total chromosomal damage and abnormal metaphases, pre- and simultaneous treatment with this vitamin showed no significant differences. In the post-treatment, average and above average concentrations of vitamin B6 alone showed a clastogenic effect. In the simultaneous protocol, this vitamin (15, 90 and 120 microg/mL) was effective in inhibiting chromosomal aberrations induced by doxorubicin (p<0.05), with a reduction of 33.1% with the highest concentration tested. However, in the post-treatment, the associations of vitamin B6 and doxorubicin exerted a more evident clastogenic effect than that observed in the cultures exposed only to the antitumor drug. In the present investigation, the inability of vitamin B6 to decrease chromosomal damage induced by doxorubicin in the pre- and post-treatments could be justified by the instability of this vitamin as a free radical scavenger. In conclusion, the results from this study confirmed that vitamin B6 is protective against chromosomal damage induced by doxorubicin in cultured human lymphocytes, but that the effects depend on concentration and form of treatment.

Acetylsalicylic acid exhibits anticlastogenic effects on cultured human lymphocytes exposed to doxorubicin

Acetylsalicylic acid (ASA) is a non-steroidal anti-inflammatory drug (NSAID) with many pharmacological properties, such as anti-inflammatory, antipyretic and analgesic. Many studies have suggested the possible efficiency of ASA and other NSAIDs in preventing cancer. ASA could also have antimutagenic and antioxidant properties. The aim of this study was to investigate the possible clastogenic and anticlastogenic effects of different concentrations of ASA on doxorubicin-induced chromosomal aberrations in human lymphocytes. Human blood samples were obtained from six healthy, non-smoking volunteers; and the chromosomal aberration assay was carried out using conventional techniques. The parameters analyzed were mitotic index, total number of chromosomal aberrations and percentage of aberrant metaphases. The concentrations of ASA (25, 50 or 100 microg/mL) tested in combination with DXR (0.2 microg/mL) were established on the basis of the results of the mitotic index. The treatment with ASA alone was neither cytotoxic nor clastogenic (p>0.01). In lymphocyte cultures treated with different combinations of ASA and DXR, a significant decrease in the total number of chromosome aberrations was observed compared with DXR alone (p<0.01). This protective effect of ASA on DXR-induced chromosomal damage was obtained for all combinations, and it was most evident when ASA was at 25.0 microg/mL. In our experiments, ASA may have acted as an antioxidant and inhibited the chromosomal damage induced by the free radicals generated by DXR. The identification of compounds that could counteract the free radicals produced by doxorubicin could be of possible benefits against the potential harmful effects of anthracyclines. The results of this study show that there is a relevant need for more investigations in order to elucidate the mechanisms underlying the anticlastogenic effect of ASA.

Protecting against anthracycline-induced myocardial damage: a review of the most promising strategies

Over the last 40 years, great progress has been made in treating childhood and adult cancers. However, this progress has come at an unforeseen cost, in the form of emerging long-term effects of anthracycline treatment. A major complication of anthracycline therapy is its adverse cardiovascular effects. If these cardiac complications could be reduced or prevented, higher doses of anthracyclines could potentially be used, thereby further increasing cancer cure rates. Moreover, as the incidence of cardiac toxicity resulting in congestive heart failure or even heart transplantation dropped, the quality and extent of life for cancer survivors would improve. We review the proposed mechanisms of action of anthracyclines and the consequences associated with anthracycline treatment in children and adults. We summarise the most promising current strategies to limit or prevent anthracycline-induced cardiotoxicity, as well as possible strategies to prevent existing cardiomyopathy from worsening.

Ascorbic acid potentiates mitomycin C-induced micronuclei and sister chromatid exchanges in human peripheral blood lymphocytes in vitro

Vitamin C (l-ascorbic acid), an effective free radical scavenger present as ascorbate in most biological systems, is one of the most extensively studied antioxidant vitamins. Vitamin C acts as either a free radical scavenger or a pro-oxidant producing hydrogen peroxide and free radicals. The modulatory effect of L-ascorbic acid (AA) on Mitomycin C (MMC) induced chromosome damage has been evaluated in human peripheral blood lymphocytes in vitro. The effect of L-ascorbic acid, 200 microg/ml as 1- and 2-h pretreatment on the frequencies of the biomarkers micronuclei (MN), sister chromatid exchanges (SCEs), and chromosome aberrations (CA) induced by mitomycin C 0.1 and 0.2 microg/ml has been studied. AA pretreatment caused a statistically significant increase in MMC-induced MN and SCE frequencies for all treatment groups, but did not show an increase in induced chromosome aberrations compared to MMC treatment alone. Cell division delays caused by MMC was reversed in the presence of AA. Interindividual variability in MMC as well as AA plus MMC-induced MN, SCE, and CA frequencies were evident. Ascorbic acid potentiated MMC-induced chromosome damage in human lymphocytes in vitro. The potentiation observed has to be viewed in the light of metal ion catalysed autooxidation of AA in oxygenated media and the existence of an antioxidant system in vivo that inactivates oxyradicals before their interaction with DNA.

Inhibitory effects of ascorbic acid and folinic acid on chromosome aberrations induced by pyrimethamine in vitro

In this study, the anticlastogenic effects of ascorbic acid and the protective effect of folinic acid against the formation of chromosomal aberrations in humans by pyrimethamine were investigated. Pyrimethamine is a folic acid antagonist used for the treatment of malaria and toxoplasmosis. In this study, 18 different healthy people, who do not drink alcohol and are non-smokers, were chosen as an experimental group; 0.025 mg/ml pyrimethamine was given to the lymphocyte culture, which had been prepared with the peripheral blood taken from this group. After that each of the following doses were given to the same culture: 20, 40, and 80 mM of ascorbic acid and 25, 50, and 100 mM of folinic acid. The results of the cytogenetic evaluation showed that the aberrations due to pyrimethamine in the chromosomes were reduced by ascorbic acid and folinic acid significantly, depending on the given dose.

Genotoxicity is modulated by ascorbic acid

The ability of ascorbic acid (Vitamin C) to modulate the genotoxic action of several mutagens was investigated in the wing spot test of Drosophila melanogaster. In this assay, 3-day-old transheterozygous larvae for the multiple wing hairs (mwh, 3-0.3) and flare (flr, 3-38.8) genes were treated with three reference mutagenic compounds, namely cobalt chloride (CoCl2), 4-nitroquinoline 1-oxide (4-NQO) and potassium dichromate (K2Cr2O7). The results obtained show that the three reference mutagens tested were clearly genotoxic in the Drosophila wing somatic mutation and recombination test (SMART). None of the three concentrations tested of ascorbic acid (25, 75 and 250mM) induced significant increases in the frequency of the mutant clones recorded. When co-treatment experiments with ascorbic acid were carried out, different results were found. Thus, ascorbic acid was effective in reducing the genotoxicity of K2Cr2O7 virtually to the control level; on the contrary, it did not show any antigenotoxic effect on the genotoxicity of 4-NQO. Finally, co-treatments with CoCl2 and ascorbic acid show a significant increase in the frequency of mutant clones over the values obtained with CoCl2 alone.

Role of ascorbic acid on mercuric chloride-induced genotoxicity in human blood cultures

Efforts are made to find therapeutic agents capable of minimizing genotoxicity of various natural and man-made compounds. The genotoxicity induced by mercury compounds remains controversial. Therefore we have investigated the genotoxic effect of mercuric chloride (MC; HgCl(2)) at three concentrations (1.052, 5.262 and 10.524 microM) and role of L-ascorbic acid (vitamin C) at a concentration of 9.734 microM on MC-treated short-term human leucocyte cultures. We assessed the proliferative rate index (PRI), sister chromatid exchange (SCE) and chromosomal aberrations (CAS) in control and MC-treated cultures with and without vitamin C supplementation. The results showed that MC has no effect on cell-cycle kinetics, but the frequency of SCE/cell was significantly higher in a dose-dependent manner than control values. HgCl(2) also significantly induced C-anaphases (abnormal mitosis) in blood cultures. These effects were prevented by the addition of vitamin C to MC-treated cultures. The data indicate the mutagenic activity of MC and the protective role of vitamin C on mercury-induced genotoxicity in human blood cultures is probably due to its strong antioxidant and nucleophilic nature.

Anticlastogenic effect of Vitamin C on cisplatin induced chromosome aberrations in human lymphocyte cultures

Vitamin C (ascorbic acid) is an antioxidant that can scavenge free radicals and protect cellular macromolecules, including DNA, from oxidative damage induced by different agents. The protective effect of Vitamin C on cisplatin induced chromosome aberrations has been determined in the human peripheral lymphocyte chromosome aberration test in vitro. The results of treatments with Vitamin C indicated that it statistically significantly decreases the number of chromosome aberrations and number of metaphases with aberrations induced with cisplatin, but it can not completely protect cells from damage. The test concentrations of Vitamin C (10 and 100 microg/ml) had a limited antimutagen effect on cisplatin (0.5 microg/ml), which can cause genetic damage through free radical mechanisms. The antimutagen effect included the anticlastogenic effect of Vitamin C and its ability to decrease the number of aneuploid mitoses. Vitamin C showed the most efficient anticlastogenic effect during simultaneous treatment with cisplatin. Also, Vitamin C reduced cell toxicity of cisplatin during simultaneous treatment.

Anti-oxidants as modulators of immune function

In order to confirm the hypothesis of the immunomodulating action of anti-oxidants (bringing back altered immune function to more optimum values), the possibility that anti-oxidants may be useful in two experimental models of altered immune function has been studied. The first is a pathological model, that is, lethal murine endotoxic shock caused by an LPS injection of 100 mg/kg, in which the lymphocytes show increased adherence and depressed chemotaxis. The injection of N-acetylcysteine (150 mg/kg), which increased both functions in control animals, decreased adherence and increased chemotaxis in mice with endotoxic shock. The second is a physiological model; aged human subjects (70 +/- 5-year-old men) who, in their largest segment of population ('standard' group) showed an increased lymphocyte adherence and decreased lymphoproliferative response to mitogens compared with younger adults. The ingestion of vitamin E (200 mg daily for 3 months in this standard group) lowered adherence and stimulated lymphoproliferation. However, a smaller segment of the human population tested showed 'non-standard' values in these lymphocyte functions, that is, very low adherence and very high proliferation. In those subjects, vitamin E showed the opposite effects, namely adherence increase and depressed lymphoproliferation. In both age groups of men, these functions reached adult levels after vitamin E ingestion. These data suggest that anti-oxidants preserve adequate function of immune cells against homeostatic disturbances such as those caused by endotoxic shock and ageing.