The chronic wound milieu changes essential oils' antibiofilm activity-an in vitro and larval model study.

Essential Oils (EOs) are currently being researched as potential antibiofilm agents to combat infections related to chronic wound biofilms. As documented in the literature, EOs' in vitro antibacterial properties are often assessed using standard microbiological media and conditions that do not accurately reflect the actual environment of a chronic wound. To address this issue, In vitro Wound Milieu (IVWM) medium, which closely resembles the environment of a chronic wound, was applied for culturing S. aureus biofilms (n = 12) in this research. Biofilms cultivated in the standard Tryptic Soy Broth (TSB) medium served as a control for the experiment. Key biofilm features were analyzed and compared. Subsequently, staphylococci were exposed to the activity of thyme or rosemary EOs (T-EO and R-EO, respectively). As proof of concept, the cytotoxicity of T-EO and its antimicrobial in vivo activity were assessed using a G. mellonella larvae model. Key features of biofilm-forming cells were lower in the IVWM than in the TSB medium: biomass (up to 8 times), metabolic activity (up to 9 times), cell number (up to 100 times), and the live/dead cells ratio. Conversely, biofilm thickness was higher (up to 25%) in IVWM. These differences translated into varied responses of the biofilms to EOs exposure. The application of T-EO led to a greater reduction (up to 2 times) in 67% of biofilm-forming strains in IVWM compared to the TSB medium. Conversely, exposure to R-EO resulted in a higher reduction (up to 2.6 times) of 83% of biofilm-forming strains in TSB than in IVWM. The application of T-EO was not only non-toxic to G. mellonella larvae but also increased the survival of larvae infected with staphylococci (from 48 to 85%). Our findings suggest that EOs not only show promise as agents for treating biofilm-related wound infections but also that providing conditions reflecting the specific niche of the human body is of paramount importance in influencing the results obtained. However, before clinical application, challenges related to the methods of assessing their activity, microbial intra-species variability, and different levels of activity of various EOs should be analyzed and standardized.

Lunasin and Its Epigenetic Impact in Cancer Chemoprevention.

Cancer diseases are a leading cause of death worldwide. Therefore, it is pivotal to search for bioactive dietary compounds that can avert tumor development. A diet rich in vegetables, including legumes, provides chemopreventive substances, which have the potential to prevent many diseases, including cancer. Lunasin is a soy-derived peptide whose anti-cancer activity has been studied for over 20 years. The results of the previous research have shown that lunasin inhibits histone acetylation, regulates the cell cycle, suppresses proliferation and induces apoptosis of cancer cells. Thus, lunasin seems to be a promising bioactive anti-cancer agent and a potent epigenetic modulator. The present review discusses studies of the underlying molecular mechanisms and new perspectives on lunasin application in epigenetic prevention and anti-cancer therapy.

Curcumin from Turmeric Rhizome: A Potential Modulator of DNA Methylation Machinery in Breast Cancer Inhibition.

One of the most systematically studied bioactive nutraceuticals for its benefits in the management of various diseases is the turmeric-derived compounds: curcumin. Turmeric obtained from the rhizome of a perennial herb Curcuma longa L. is a condiment commonly used in our diet. Curcumin is well known for its potential role in inhibiting cancer by targeting epigenetic machinery, with DNA methylation at the forefront. The dynamic DNA methylation processes serve as an adaptive mechanism to a wide variety of environmental factors, including diet. Every healthy tissue has a precise DNA methylation pattern that changes during cancer development, forming a cancer-specific design. Hypermethylation of tumor suppressor genes, global DNA demethylation, and promoter hypomethylation of oncogenes and prometastatic genes are hallmarks of nearly all types of cancer, including breast cancer. Curcumin has been shown to modulate epigenetic events that are dysregulated in cancer cells and possess the potential to prevent cancer or enhance the effects of conventional anti-cancer therapy. Although mechanisms underlying curcumin-mediated changes in the epigenome remain to be fully elucidated, the mode of action targeting both hypermethylated and hypomethylated genes in cancer is promising for cancer chemoprevention. This review provides a comprehensive discussion of potential epigenetic mechanisms of curcumin in reversing altered patterns of DNA methylation in breast cancer that is the most commonly diagnosed cancer and the leading cause of cancer death among females worldwide. Insight into the other bioactive components of turmeric rhizome as potential epigenetic modifiers has been indicated as well.

Clofarabine­phytochemical combination exposures in CML cells inhibit DNA methylation machinery, upregulate tumor suppressor genes and promote caspase­dependent apoptosis.

Clofarabine (2­chloro­2'­fluoro­2'­deoxyarabinosyladenine, CIF), a second­generation 2'­deoxyadenosine analog, possesses a variety of anti­cancer activities, including the capacity to modulate DNA methylation marks. Bioactive nutrients, including resveratrol (RSV) and all­trans retinoic acid (ATRA) have been indicated to regulate epigenetic machinery in malignant cells. The purpose of the current study was to evaluate whether the tested phytochemicals, RSV or ATRA, can improve the therapeutic epigenetic effects of CIF in chronic myeloid leukemia (CML) cells. The present study investigates, to the best of our knowledge, for the first time, the influence of CIF in combination with RSV or ATRA on the expression of relevant modifiers of DNA methylation machinery, including DNA Methyltransferase 1 (DNMT1) and Cyclin dependent kinase inhibitor 1A (CDKN1A) in CML cells. Subsequently, the combinatorial effects on promoter methylation and transcript levels of methylation­silenced tumor suppressor genes (TSGs), including phosphatase and tensin homologue (PTEN) and retinoic acid receptor beta (RARB), were estimated using MSRA and qPCR, respectively. The tested TSGs were chosen according to bioinformatical analysis of publicly available clinical data of human DNA methylation and gene expression arrays in leukemia patients. The K562 cell line was used as an experimental CML in vitro model. Following a period of 72 h exposure of K562 cells, the tested combinations led to significant cell growth inhibition and induction of caspase­3­dependent apoptosis. These observations were accompanied by DNMT1 downregulation and CDKN1A upregulation, with a concomitant enhanced decrease in DNMT1 protein level, especially after ATRA treatment with CIF. Concurrent methylation­mediated RARB and PTEN reactivation was detected. The results of the current study demonstrated that CIF that was used in combination with the tested phytochemicals, RSV or ATRA, exhibited a greater ability to remodel DNA methylation marks and promote cell death in CML cells. These results may support the application of CIF combinations with natural bioactive agents in anti­leukemic epigenetic therapy.

Novel Clofarabine-Based Combinations with Polyphenols Epigenetically Reactivate Retinoic Acid Receptor Beta, Inhibit Cell Growth, and Induce Apoptosis of Breast Cancer Cells.

An epigenetic component, especially aberrant DNA methylation pattern, has been shown to be frequently involved in sporadic breast cancer development. A growing body of literature demonstrates that combination of agents, i.e. nucleoside analogues with dietary phytochemicals, may provide enhanced therapeutic effects in epigenetic reprogramming of cancer cells. Clofarabine (2-chloro-2'-fluoro-2'-deoxyarabinosyladenine, ClF), a second-generation 2'-deoxyadenosine analogue, has numerous anti-cancer effects, including potential capacity to regulate epigenetic processes. Our present study is the first to investigate the combinatorial effects of ClF (used at IC50 concentration) with epigallocatechin-3-gallate (EGCG, tea catechin) or genistein (soy phytoestrogen), at physiological concentrations, on breast cancer cell growth, apoptosis, and epigenetic regulation of retinoic acid receptor beta (RARB) transcriptional activity. In MCF7 and MDA-MB-231 cells, RARB promoter methylation and expression of RARB, modifiers of DNA methylation reaction (DNMT1, CDKN1A, TP53), and potential regulator of RARB transcription, PTEN, were estimated using methylation-sensitive restriction analysis (MSRA) and quantitative real-time polymerase chain reaction (qPCR), respectively. The combinatorial exposures synergistically or additively inhibited the growth and induced apoptosis of breast cancer cells, followed by RARB hypomethylation with concomitant multiple increase in RARB, PTEN, and CDKN1A transcript levels. Taken together, our results demonstrate the ability of ClF-based combinations with polyphenols to promote cancer cell death and reactivate DNA methylation-silenced tumor suppressor genes in breast cancer cells with different invasive potential.

Relationship of muscle function to circulating myostatin, follistatin and GDF11 in older women and men.

BACKGROUND: Myostatin, its inhibitor follistatin, and growth/differentiation factor 11 (GDF11) have been proposed as factors that could potentially modify biological aging. The study aimed to test whether there is a relationship between these plasma circulating proteins and muscle strength, power and optimal shortening velocity (υopt) of older adults. METHODS: The cross-sectional study included 56 women and 45 men aged 60 years and older. Every participant underwent examination which included anthropometric and bioimpedance analysis measurements, functional and cognitive performance tests, muscle strength of upper and lower extremities, muscle power testing with two different methods and blood analyses. RESULTS: Women had higher plasma levels of myostatin and GDF11 than men. Men had higher plasma level of follistatin than women. In women, plasma level of myostatin was negatively correlated with left handgrip strength and υopt. Follistatin was negatively correlated with maximum power output (Pmax), power relative to kg of body mass (Pmax∙kg- 1) (friction-loaded cycle ergometer) and power at 70% of the 1-repetition maximum (1RM) strength value (P70%) of leg press (Keiser pneumatic resistance training equipment), and positively correlated with the Timed Up & Go (TUG) test. GDF11 was negatively correlated with body mass, body mass index, waist circumference, fat mass and the percentage of body fat. In men, there were no significant correlations observed between circulating plasma proteins and muscle function measures. CONCLUSIONS: The circulating plasma myostatin and follistatin are negatively associated with muscle function in older women. There is stronger relationship between these proteins and muscle power than muscle strength. GDF11 has a higher association with the body mass and composition than muscle function in older women.

Inhibition of breast cancer cell growth by the combination of clofarabine and sulforaphane involves epigenetically mediated CDKN2A upregulation.

Many antineoplastic nucleoside analogue-based combinatorial strategies focused on remodelling aberrant DNA methylation patterns have been developed. The number of studies demonstrate high efficacy of bioactive phytochemicals in support of conventional chemotherapy. Our recent discoveries of the epigenetic effects of clofarabine (2'-deoxyadenosine analogue, antileukaemic drug) and clofarabine-based combinations with dietary bioactive compounds in breast cancer cells led us to look for more DNA methylation targets of these cancer-preventive agents. In the present study, using methylation-sensitive restriction analysis (MSRA) and qPCR, we showed that clofarabine in combination with sulforaphane, a phytochemical from cruciferous vegetables, significantly reactivates DNA methylation-silenced CDKN2A tumour suppressor and inhibits cancer cell growth at a non-invasive breast cancer stage.

The levels of 7,8-dihydrodeoxyguanosine (8-oxoG) and 8-oxoguanine DNA glycosylase 1 (OGG1) - A potential diagnostic biomarkers of Alzheimer's disease.

Evidence indicates that oxidative stress contributes to neuronal cell death in Alzheimer's disease (AD). Increased oxidative DNA damage l, as measured with 8-oxoguanine (8-oxoG), and reduced capacity of proteins responsible for removing of DNA damage, including 8-oxoguanine DNA glycosylase 1 (OGG1), were detected in brains of AD patients. In the present study we assessed peripheral blood biomarkers of oxidative DNA damage, i.e. 8- oxoG and OGG1, in AD diagnosis, by comparing their levels between the patients and the controls. Our study was performed on DNA and serum isolated from peripheral blood taken from 100 AD patients and 110 controls. For 8-oxoG ELISA was employed. The OGG1 level was determined using ELISA and Western blot technique. Levels of 8-oxoG were significantly higher in DNA of AD patients. Both ELISA and Western blot showed decreased levels of OGG1 in serum of AD patients. Our results show that oxidative DNA damage biomarkers detected in peripheral tissue could reflect the changes occurring in the brain of patients with AD. These results also suggest that peripheral blood samples may be useful to measure oxidative stress biomarkers in AD.

Epigenetic changes in cancer by Raman imaging, fluorescence imaging, AFM and scanning near-field optical microscopy (SNOM). Acetylation in normal and human cancer breast cells MCF10A, MCF7 and MDA-MB-231.

This paper examines epigenetic changes in breast cancer by Raman imaging, fluorescence imaging, AFM and SNOM and discusses how they contribute to different aspects of tumourigenesis in malignant human breast epithelial cell lines MCF7 and MDA-MB-231 compared with non-malignant MCF10A cell lines. The paper focuses on information that can be extracted from Raman microscopy and Raman imaging for the biological material of nucleoli contained within the cell nucleus and lipid droplets within the cell cytoplasm. The biochemical composition of the nuclei and lipid droplets in the non-malignant and malignant human breast epithelial cell lines has been monitored. The potential of Raman microspectroscopy to monitor acetylation processes and a prognostic value of Raman biomarkers in breast cancer have been discussed.

The Role of Sulforaphane in Epigenetic Mechanisms, Including Interdependence between Histone Modification and DNA Methylation.

Carcinogenesis as well as cancer progression result from genetic and epigenetic changes of the genome that leads to dysregulation of transcriptional activity of genes. Epigenetic mechanisms in cancer cells comprise (i) post-translation histone modification (i.e., deacetylation and methylation); (ii) DNA global hypomethylation; (iii) promoter hypermethylation of tumour suppressor genes and genes important for cell cycle regulation, cell differentiation and apoptosis; and (iv) posttranscriptional regulation of gene expression by noncoding microRNA. These epigenetic aberrations can be readily reversible and responsive to both synthetic agents and natural components of diet. A source of one of such diet components are cruciferous vegetables, which contain high levels of a number of glucosinolates and deliver, after enzymatic hydrolysis, sulforaphane and other bioactive isothiocyanates, that are involved in effective up-regulation of transcriptional activity of certain genes and also in restoration of active chromatin structure. Thus a consumption of cruciferous vegetables, treated as a source of isothiocyanates, seems to be potentially useful as an effective cancer preventive factor or as a source of nutrients improving efficacy of standard chemotherapies. In this review an attempt is made to elucidate the role of sulforaphane in regulation of gene promoter activity through a direct down-regulation of histone deacetylase activity and alteration of gene promoter methylation in indirect ways, but the sulforaphane influence on non-coding micro-RNA will not be a subject of this review.

Sulforaphane Alone and in Combination with Clofarabine Epigenetically Regulates the Expression of DNA Methylation-Silenced Tumour Suppressor Genes in Human Breast Cancer Cells.

BACKGROUND/AIM: Sporadic breast cancer is frequently associated with aberrant DNA methylation patterns that are reversible and responsive to environmental factors, including diet. In the present study, we investigated the effects of sulforaphane (SFN), a phytochemical from cruciferous vegetables, on the methylation and expression of PTEN and RARbeta2 tumour suppressor genes as well as on the expression of regulators of DNA methylation reaction, DNMT1 , p53 , and p21 , in MCF-7 and MDA-MB-231 human breast cancer cells with different invasive potential. We also evaluate the role of SFN epigenetic effects in support of therapy with clofarabine (ClF) that was recently shown to modulate the epigenome as well. METHODS: Promoter methylation and gene expression were estimated using methylation-sensitive restriction analysis and real-time PCR, respectively. RESULTS: In both MCF-7 and MDA-MB-231 cells, SFN at IC 50 (22 and 46 µ M , respectively) and a physiologically relevant 10 µ M concentration lead to hypomethylation of PTEN and RARbeta2 promoters with concomitant gene upregulation. The combination of SFN and ClF enhances these effects, resulting in an increase in cell growth arrest and apoptosis at a non-invasive breast cancer stage. CONCLUSIONS: Our findings provide evidence that SFN activates DNA methylation-silenced tumour suppressor genes in breast cancer cells and may contribute to SFN-mediated support of therapy with an anti-cancer drug, ClF, increasing its applications in solid tumours.

The role of lipid droplets and adipocytes in cancer. Raman imaging of cell cultures: MCF10A, MCF7, and MDA-MB-231 compared to adipocytes in cancerous human breast tissue.

We have studied live non-malignant (MCF10A), mildly malignant (MCF7) and malignant (MDA-MB-231) breast cancer cells and human breast cancer tissue. We demonstrate the first application of Raman imaging and spectroscopy in diagnosing the role of lipid droplets in cell line cultures that closely mimic an in vivo environment of various stages in human breast cancer tissue. We have analyzed the composition of the lipid droplets in non-malignant and malignant human breast epithelial cell lines and discussed the potential of lipid droplets as a prognostic marker in breast cancer. To identify any difference in the lipid droplet-associated biochemistry and to correlate it with different stages of breast cancer, the PCA method was employed. The chemical composition of lipids and proteins, both in the cell line models and in human breast tissue has been analyzed. The paper shows the alterations in lipid metabolism that have been reported in cancer, at both the cellular and tissue levels, and discusses how they contribute to the different aspects of tumourigenesis.

Clofarabine, a novel adenosine analogue, reactivates DNA methylation-silenced tumour suppressor genes and inhibits cell growth in breast cancer cells.

Clofarabine (2-chloro-2'-fluoro-2'-deoxyarabinosyladenine, ClF) is a second-generation 2'-deoxyadenosine analogue that is structurally related to cladribine (2-chloro-2'-deoxyadenosine, 2CdA) and fludarabine (9-beta-d-arabinosyl-2-fluoroadenine, F-ara-A). It demonstrates potent antitumour activity at much lower doses than parent compounds with high therapeutic efficacy in paediatric blood cancers. Our previous studies in breast cancer cells indicate that 2CdA and F-ara-A are involved in epigenetic regulation of gene transcription. We therefore investigated whether ClF influences methylation and expression of selected tumour suppressor genes, such as adenomatous polyposis coli (APC), phosphatase and tensin homologue (PTEN), and retinoic acid receptor beta 2 (RARbeta2), as well as expression of p53, p21 and DNA methyltransferase 1 (DNMT1) in MCF-7 and MDA-MB-231 breast cancer cell lines with different invasive potential. Promoter methylation and gene expression were estimated using methylation-sensitive restriction analysis (MSRA) and real-time PCR, respectively. ClF demonstrated potent growth inhibitory activity in MCF-7 and MDA-MB-231 cells after 96h treatment with IC50 determined as equal to 640nM and 50nM, respectively. In both breast cancer cell lines, ClF led to hypomethylation and up-regulation of APC, PTEN and RARbeta2 as well as increase in p21 expression. Only in non-invasive MCF-7 cells, these changes were associated with down-regulation of DNMT1. Our results provide first evidence of ClF implications in epigenetic regulation of transcriptional activity of selected tumour suppressor genes in breast cancer. It seems to be a new important element of ClF anticancer activity and may indicate its potential efficacy in epigenetic therapy of solid tumours, especially at early stages of carcinogenesis.

Folic acid enforces DNA methylation-mediated transcriptional silencing of PTEN, APC and RARbeta2 tumour suppressor genes in breast cancer.

Folate, one of the most studied dietary compounds, has recently become the main topic of debates on food fortification. Although low folate levels may be associated with increased risk of cancer development, simultaneously several reports indicate a detrimental effects mediated by high folate concentrations. Using the methylation sensitive restriction analysis (MSRA) and real-time RT-PCR we tested the effect of folic acid on DNA promoter methylation and expression of PTEN, APC and RARbeta2 tumour suppressor genes in MCF-7 and MDA-MB-231 breast cancer cell lines with different invasive capacity. The tested genes encode proteins involved in regulation of oncogenic intracellular signaling pathways. The results show that the increasing concentrations of folic acid lead to a dose-dependent down-regulation of tumour suppressor genes which may be linked to the increased DNA methylation detected within their promoter regions. The effects were more remarkable in non-invasive MCF-7 cells where we also observed 30% up-regulation of DNMT1 expression at the highest folate concentration used. Our findings show that caution need to be used when introducing folic acid supplementation since it may lead to cancer progression.

Comparative effects of retinoic acid, vitamin D and resveratrol alone and in combination with adenosine analogues on methylation and expression of phosphatase and tensin homologue tumour suppressor gene in breast cancer cells.

Aberrations in DNA methylation patterns have been reported to be involved in driving changes in the expression of numerous genes during carcinogenesis and have become promising targets for chemopreventive action of natural compounds. In the present study, we investigated the effects of all-trans retinoic acid (ATRA), vitamin D3 and resveratrol alone and in combination with adenosine analogues, 2-chloro-2'-deoxyadenosine (2CdA) and 9-ß-d-arabinosyl-2-fluoroadenine (F-ara-A), on the methylation and expression of phosphatase and tensin homologue (PTEN) tumour suppressor gene in MCF-7 and MDA-MB-231 breast cancer cells. The present results showed that in non-invasive MCF-7 cells, ATRA, vitamin D3 and resveratrol possess high efficacy in the reduction of PTEN promoter methylation. It was associated with PTEN induction as well as DNA methyltransferase down-regulation and p21 up-regulation after treatments with vitamin D3 and resveratrol, suggesting a complex regulation of the DNA methylation machinery. Vitamin D3 and resveratrol improved the inhibitory effects of 2CdA and F-ara-A on PTEN methylation in MCF-7 cells; however, only the combined action of vitamin D3 and 2CdA boosted the induction of PTEN expression, suggesting a cooperation of these compounds in additional processes driving changes in PTEN expression. In contrast, in highly invasive MDA-MB-231 cells, only vitamin D3 reduced PTEN methylation and induced its expression without notable effects in combined treatments. The present results suggest that natural compounds can find application in epigenetic anticancer therapy aimed at inhibition of promoter methylation of tumour suppressor genes and induction of their expression at early stages of carcinogenesis.

Clofarabine (2-chloro-2'-fluoro-2'-deoxyarabinosyladenine)--biochemical aspects of anticancer activity.

Clofarabine (2-chloro-2'-fluoro-2'-deoxyarabinosyladenine) is a second generation analogue of 2'-deoxyadenosine connecting biochemical activities of its prototypes: cladribine (2-chloro-2'-deoxyadenosine) and fludarabine (2-fluoro-arabinosyladenine). This new anticancer drug is more effective (in low doses) and indicates higher oral bioavailability in comparison to its congeners. The studies indicated that the molecular mechanism of clofarabine cytotoxic action includes cell apoptosis, which results from inhibition (by the drug triphosphate nucleotides) of ribonucleotide reductase and DNA polymerases. The most recent research demonstrated also that action of the drug may cause up-expression of some genes on mRNA and protein levels. Clofarabine was synthesized in 1992 and in 2004 was approved for treatment of pediatric patients with refractory or relapsed acute lymphoblastic leukemia (ALL). Encouraging results of clinical trials with clofarabine in acute leukemias inclined to present background knowledge about multidirectional biomolecular mechanism of its cytotoxicity.

Influence of clofarabine on transcriptional activity of PTEN, APC, RARB2, ZAP70 genes in K562 cells.

BACKGROUND: In this study, the effect of clofarabine, a new generation 2'-deoxyadenosine analogue, on promoter methylation and transcriptional activity of selected genes (PTEN, APC, RARB2, ZAP70) in K562 cells was assessed. MATERIALS AND METHODS: Promoter methylation was estimated using methylation-sensitive restriction analysis. The mRNA level of the genes was measured with real-time PCR. RESULTS: The inhibitory cytostatic index (IG(50)) for clofarabine in K562 cells cultured for 72 (or 96) h was 8 nM. The drug (20 nM) caused: (i) potent diminution in methylation of PTEN promoter, moderate methylation reduction of APC and RARB2 promoters, and complete methylation of ZAP70 promoter; (ii) significant stimulation of PTEN, APC, RARB, and p21 mRNA expression and (iii) decline in mRNA level of ZAP70 and DNMT1 genes. CONCLUSION: The results indicated that clofarabine is involved in epigenetic regulation of transcriptional activity of the tested tumour suppressor genes and genes encoding proteins involved in DNA methylation process.

Hypomethylation and induction of retinoic acid receptor beta 2 by concurrent action of adenosine analogues and natural compounds in breast cancer cells.

DNA methylation is considered as a potential cause of aberrations in regulation of gene expression during carcinogenesis. Therefore, changes in DNA methylation patterns may be targets for chemoprevention. In the present study, we investigated effects of all-trans retinoic acid (ATRA), vitamin D(3), and resveratrol alone and in combination with adenosine analogues: 2-chloro-2'-deoxyadenosine (2CdA) and 9-beta-D-arabinosyl-2-fluoroadenine (F-ara-A), on methylation and expression of retinoic acid receptor beta 2 (RAR beta 2) in MCF-7 and MDA-MB-231 breast cancer cell lines. Alterations in methylation and expression levels after treatment of cells with the tested compounds were evaluated by methylation-sensitive restriction analysis (MSRA) and real-time PCR, respectively. RAR beta 2 promoter in the tested fragment was partially methylated in MCF-7 cells and non-methylated in MDA-MB-231 cells. In MCF-7 cells, all compounds, except for resveratrol, inhibited promoter methylation and increased expression of RAR beta 2. All natural compounds improved the action of 2CdA and F-ara-A on RAR beta 2 methylation and/or expression. Combination of ATRA or vitamin D(3) with 2CdA was the most effective. In MDA-MB-231 cells, only 2CdA, F-ara-A, and ATRA induced RAR beta 2 expression without any notable effects in combined treatment. Our results demonstrate that both natural compounds and adenosine analogues are able to reduce promoter methylation and/or induce expression of RAR beta 2 in non-invasive MCF-7 cells. Furthermore, the natural compounds improve effects of adenosine analogues, however only at early non-invasive stages of carcinogenesis.

The effects of cladribine and fludarabine on DNA methylation in K562 cells.

The effects of the antileukemic adenosine analogues, 2-chloro-2'-deoxyadenosine (cladribine) and 9-beta-D-arabinosyl-2-fluoroadenine (fludarabine), on DNA methylation were studied in a cell line K562. It was previously found that both drugs inactivated SAH hydrolase, an enzyme which participates in the "active methyl" cycle. The study examined the effects of these drugs on three aspects of DNA methylation: (i) activity of endogenous C-5 DNA methyltransferase; (ii) capacity of genomic DNA (gDNA) to accept methyl groups, transferred from S-adenosylmethionine by the bacterial methyltransferase, SssI; (iii) estimation of changes of methylated cytosine levels in gDNA, using methylation-dependent restriction analysis. Cladribine and fludarabine inhibited C-5 DNA methyltransferase, with ED(50) values of 3.5 and 47.0 microM, respectively, after 24hr cell growth in the presence of the drugs. After 48 hr growth of cells with cladribine (0.1 microM) or fludarabine (3 microM), the capacity of DNA to accept methyl groups, in the presence of exogenous bacterial SssI methylase, increased by approximately 1.8 and 1.6 times, respectively, compared to control DNA. Digestion of gDNA with endonucleases HpaII and BssHII followed by SssI DNA methylation, indicated that cladribine (0.1 microM) reduced the level of methylated cytosines in both CpG islands and CCGG sequences, sensitive to HpaII restriction enzyme. Inhibition of DNA methylation by fludarabine was observed mainly in CpG dinucleotide located within sequences sensitive to HpaII. The perturbation of DNA methylation was considered as a complex process. Our findings for cladribine and fludarabine should be regarded as an extra element of their antileukemic efficacy.

Purine metabolism in leukocytes and erythrocytes in Graves' or Hashimoto's disease.

INTRODUCTION: Adenosine deaminase (ADA), purine nucleoside phosphorylase (PNPase), S-adenosylhomocysteine hydrolase (SAHH), 5'-nucleotidase (5N), and deoxycytidine kinase (dCK) are involved in purine salvage metabolism. Changes of the activities of the above enzymes have been observed in blood cells in patients with immunological disorders. MATERIALS AND METHODS: The activities of ADA, PNPase, SAHH, 5'N, and dCK in lysates of leukocytes and erythrocytes, obtained from patients with Graves' or Hashimoto's disease, were measured, using chromatographic analysis. Serum concentrations of antithyroglobulin (Tg Ab) and antithyroperoxidase (TPO Ab) antibodies were measured by an immunoenzymatic method. RESULTS: (1) ADA activity in leukocytes, obtained from patients with Hashimoto's disease, was significantly higher than in control leukocytes, as well as in leukocytes from patients with Graves' disease; (2) dCK activities in leukocytes from patients with both Graves' and Hashimoto's diseases were approximately four and five times higher, respectively, than in leukocytes of control subjects; (3) a positive correlation was observed between dCK activity in leukocytes and serum Tg Ab concentration in patients with Graves' disease. In conclusion, the increased ADA and dCK activities in leukocytes from patients with Graves' and Hashimoto's diseases may be regarded as indicators of autoimmunological thyroid diseases.