Role of base-excision repair in the treatment of childhood acute lymphoblastic leukaemia with 6-mercaptopurine and high doses of methotrexate.

Methotrexate (MTX) and 6-mercaptopurine (6MP) are the most commonly used drugs in the therapy of childhood acute lymphoblastic leukaemia (ALL). The main genotoxic effect of MTX resulting from inhibition of thymidylate synthase is mis-incorporation of uracil into DNA, which is considered essential for the effectiveness of the Protocol M in ALL IC BFM 2002/EURO LB 2002 regimens. In this study, we investigated the level of basal and induced DNA damage as well as the effectiveness of DNA repair in lymphocytes of children with ALL at four time-points during therapy with MTX and 6MP. To assess DNA damage and the efficacy of DNA repair we used the modified alkaline comet assay with uracil DNA glycosylase (Udg) and endonuclease III (EndoIII). In addition, we examined the induction of apoptosis in the lymphocytes of the patients during treatment. Finally, we compared the activity of base-excision repair (BER), involved in removal of both uracil and oxidized bases from DNA in lymphocytes of children with ALL and lymphocytes of healthy children. BER efficiency was estimated in an in vitro assay with cellular extracts and plasmid substrates of heteroduplex DNA with an AP-site. Our results indicate that there is a significant decrease in the efficacy of DNA repair associated with an increased level of uracil in DNA and induction of apoptosis during therapy. Moreover, it was found that the BER capacity was decreased in the lymphocytes of ALL patients in contrast to that in lymphocytes of healthy children. Thus, we suggest that an impairment of the BER pathway may play a role in the pathogenesis and therapy of childhood ALL.

Apoptosis-, proliferation, immune function-, and drug resistance- related genes in ER positive, HER2 positive and triple negative breast cancer.

The aim of our study was to examine an association between gene expression assessed using a 23-gene microarray and receptor status of breast cancer samples categorized as ER positive, HER2 positive and triple negative subtypes. The ER positive cohort was subsequently divided into Luminal A, Luminal B HER2 negative and Luminal B HER2 positive subtypes. Core- needle biopsies were collected from 78 female patients with inoperable locally advanced breast cancer or resectable tumors suitable for downstaging, before any treatment. Expressions of 23 genes were determined by means of TagMan Low Density Arrays. Analysis of variance was used to select genes with discriminatory potential between receptor subtypes. We introduced a correction for false discovery rates (presented as q values) due to testing multiple hypothesis. Pairwise post-hoc comparisons of receptor subtypes were performed using Tukey 's HSD test. Five genes out of a 23-gene microarray differed significantly in relation to breast cancer receptor-based subtypes. Among these five genes, we identified: BCL2 (p=0.0002, q=0.0009), MKI67 (p=0.0037, q=0.0064), IGF1R (p=0.0040, q=0.0064), FOXC1 (p=0.0113, q=0.0135) and IRF1 (p=0.0435, q=0.0416) as ones showing ER positive, HER2 positive and triple negative -subtype specific expression profiles. When incorporating Luminal A, Luminal B HER2 negative, Luminal B HER2 positive subtypes into analysis, four genes: BCL2 (p=0.0006, q=0.0034), MKI67 (p=0.0078, q=0.0198), FOXC1 (p=0.0102, q=0.0198) and IGF1R (p=0.0174, q=0.0254) were selected. Elevated levels of IGF1R and BCL2 were significantly linked with Luminal A subtype. Triple negative breast cancer subtype was associated with higher expression of IRF1, FOXC1 and MKI67. In HER2 positive cohort lower expression of all five analyzed genes was noted.

The influence of opioid peptides on matrix metalloproteinase-9 and urokinase plasminogen activator expression in three cancer cell lines.

Matrix metalloproteinases (MMPs) and urokinase plasminogen activator (uPA) regulate proteolysis of the extracellular matrix (ECM) and as a consequence are involved in a number of physiological and pathological states, including cancer. A crucial feature of cancer progression and metastasis is the disruption of the ECM and spreading of proliferating cancer cells. Over-expression of MMPs and uPA is common for most types of cancers and correlates well with the adverse prognosis. Compounds able to modulate the activity of these proteolytic enzymes may become important agents in cancer therapy. In the present study, we examined the effect of the mu-opioid receptor selective peptide, morphiceptin, and its two synthetic analogs on mRNA and protein levels of MMP-9 and uPA in three human cancer cell lines: MCF-7, HT-29, and SH-SY5Y. Our findings indicate that in all three cell lines morphiceptin and its analogs attenuated MMP-9 expression and secretion and that this effect is not mediated by opioid receptors but is under control of the nitric oxide system. On the other hand, tested opioids up-regulated uPA levels through a mechanism that involved opioid-receptors. Different pathways by which opioid peptides exert their actionin cancer cells can explain their contradictory influence on the level of cancer markers.

The association of polymorphisms in DNA base excision repair genes XRCC1, OGG1 and MUTYH with the risk of childhood acute lymphoblastic leukemia.

The aim of this study was to evaluate the association of polymorphisms in genes encoding three key proteins of DNA base excision repair (BER): the OGG1 Ser326Cys, the MUTYH Tyr165Cys and the XRCC1 Arg399Gln with the risk of childhood acute lymphoblastic leukemia (ALL). Our study included 97 children patients with ALL (mean age 5.4±2.5) and 131 healthy children (mean age 6.2±2.8) used as controls. Genetic polymorphisms in BER pathway genes were examined using PCR and restriction fragment length polymorphism (RFLP). We have demonstrated that the OGG1 Cys/Cys genotype increases the risk of ALL (OR 5.36) whereas the Ser/Ser genotype variant strongly reduces the risk of this cancer among Polish children (OR 0.45). Although we did not observe the differences in single nucleotide polymorphisms (SNPs) in MUTYH and XRCC1 genes between control group and children with ALL, we have shown that the combined genotypes of examined genes can modulate the risk of childhood ALL in Polish population. We found that the combined genotype Arg/Gln-Cys/Cys of XRCC1/OGG1 (OR 3.83) as well as the Cys/Cys-Tyr/Tyr of OGG1/MUTYH (OR 6.75) increases the risk of ALL. In contrast, the combined genotype Arg/Arg-Ser/Ser of XRCC1/OGG1 (OR 0.40) as well as the Ser/Ser-Tyr/Tyr of OGG1/MUTYH (OR 0.43) played a protective role against this malignant disease. In conclusion, we suggest that polymorphisms of BER genes may be used as an important predictive factor for acute lymphoblastic leukemia in children.

Impaired nucleotide excision repair pathway as a possible factor in pathogenesis of head and neck cancer.

Tobacco smoking is one of the major risk factors in pathogenesis of head and neck squamous cell carcinomas (HNSCC). Many of the chemical compounds present in tobacco are well-known carcinogens which form adducts with DNA. Cells remove these adducts mainly by the nucleotide excision repair pathway (NER). NER also eliminates a broad spectrum of pyrimidine dimers (CPD) and photo-products (6-4PP) induced by UV-radiation or DNA cross-links after cisplatin anti-cancer treatment. In this study DNA damage and repair was examined in peripheral blood lymphocytes obtained from 20 HNSCC patients and 20 healthy controls as well as HTB-43 larynx and SSC-25 tongue cancer cell lines. DNA repair kinetics in the examined cells after cisplatin or UV-radiation treatment were investigated using alkaline comet assay during 240min of post-treatment incubation. MTT assay was used to analyse cell viability and the Annexin V-FITC kit specific for kinase-3 was employed to determine apoptosis after treating the cells with UV-radiation at dose range from 0.5 to 60J/m(2). NER capability was assessed in vitro with cell extracts by the use of a bacterial plasmid irradiated with UV-light as a substrate for the repair. The results show that lymphocytes from HNSCC patients and HTB-43 or SSC-25 cancer cells were more sensitive to genotoxic treatment with UV-radiation and displayed impaired DNA repair. Also evidenced was a higher rate of apoptosis induction after UV-radiation treatment of lymphocytes from the HNSCC patients and the HTB-43 cancer cells than after treatment of those from healthy donors. Finally, our results showed that there was a significant decrease in NER capacity in HTB-43 or SSC-25 cancer cells as well as in peripheral blood lymphocytes of HNSCC patients compared to controls. In conclusion, we suggest that the impaired NER pathway might be a critical factor in pathogenesis of head and neck cancer.

Nitric oxide as a modulator in platelet- and endothelium-dependent antithrombotic effect of eplerenone in diabetic rats.

We have recently demonstrated the antithrombotic effect of eplerenone on the arterial thrombotic process in diabetic rats associated with suppression of coagulation and enhancement of fibrinolysis. The aim of this study was to evaluate the role of platelets and endothelium in the mechanism of eplerenone antithrombotic action. Diabetes was induced in male Wistar rats with a single injection of streptozotocin (65 mg/kg). On the 25th day, treatment with eplerenone (100 mg/kg) was initiated for 10 days. Eplerenone did not change hemodynamic parameters (blood pressure, carotid blood flow, and heart rate), however, improved endothelium-dependent vasorelaxation in aortas and small mesenteric arteries, enhanced the aortic amounts of mRNA of endothelial nitric oxide synthase (eNOS), and reduced mRNA of nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase 2. A prolongation of bleeding time and decrease in platelet adhesion to collagen ex vivo was also observed. These changes were accompanied by prolonged time to occlusion and increased blood flow, and finally reduced thrombus mass in diabetic rats. The inhibition of NOS with L-NAME reduced the eplerenone antithrombotic effect. Our study provides evidence that the antithrombotic effect of eplerenone in diabetic rats is nitric oxide-dependent and associated with inhibiting the adhesion of platelets, as well as normalizing endothelial function. The mechanism of eplerenone antithrombotic action in diabetes is a result of improved endothelial nitric oxide bioavailability that leads to the improvement vascular and platelet function.

Beneficial effect of combined spironolactone and quinapril treatment on thrombosis and hemostasis in 2K1C hypertensive rats.

A strong correlation between raised aldosterone levels and increased risk of thrombotic disorders has been provided. Clinical studies have demonstrated the benefits of the addition of the aldosterone receptor antagonist to the standard therapy with angiotensin-converting enzyme inhibitor in the reduction of cardiovascular events in patients. We suggest that the benefits of this dual renin-angiotensin-aldosterone system (RAAS) blockade may be related to the drug's effects on the hemostatic and oxidative balance. Thus, we investigated the effect of combined spironolactone (SPIRO) and quinapril (QUIN) administration on thrombosis, hemostasis and oxidative stress in hypertensive rats. A two-kidney, one-clip model of renovascular hypertension in Wistar rats was used. QUIN, SPIRO, or QUIN + SPIRO were administered for 10 days. Venous thrombosis was induced by vena cava ligation. Thrombus weight and incidences of thrombosis were assessed. Bleeding time, platelet adhesion, tissue factor (TF), tissue plasminogen activator (t-PA), plasminogen activator inhibitor (PAI-1), thrombin activatable fibrynolysis inhibitor (TAFI), malonyl dialdehyde, and hydrogen peroxide plasma levels were assayed. Aortic expression of NADPH oxidase and superoxidase dismutase were measured. We observed significant RAAS activation associated with hypercoagulability and oxidative stress augmentation in renovascular hypertensive rats. Thrombosis was reduced only in rats treated with QUIN + SPIRO. In all groups, decreases in TF, PAI-1, and TAFI levels were observed, however in the QUIN + SPIRO group those changes were more pronounced. The inhibition of platelet adhesion was also stronger in rats treated with QUIN + SPIRO. The oxidative stress parameters were markedly reduced in rats treated with QUIN or SPIRO, although the most evident changes were observed in the QUIN + SPIRO group. Dual RAAS blockade with aldosterone receptor antagonist and angiotensin-converting enzyme inhibitor provides additional benefits for experimental thrombosis associated with the antiplatelet, anticoagulative, profibrinolytic, and antioxidative effects in renovascular hypertensive rats.

Various dietary fats differentially change the gene expression of neuropeptides involved in body weight regulation in rats.

Various high-fat diets are obesogenic but not to the same extent. The aim of the present study was to investigate the effects of saturated fat n-6 and n-3 polyunsaturated fatty acids (PUFAs) on the central neuropeptidergic system in adult rats. Using reverse transcriptase-polymerase chain reaction and in situ hybridisation, we evaluated the net effect of feeding in these fats, comparing the effects of a high- to low-fat diet, and the diversity of the effects of these fats in the same amount within the diet. We also determined plasma lipids, glucose, insulin and leptin concentrations. Six-week feeding with high-saturated fat evoked hyperpahagia and the largest weight gain compared to both high-PUFA diets. Rats fed high-saturated fat were found to have decreased neuropeptide Y (NPY) mRNA expression in the arcuate nucleus (ARC) and the compact zone of the dorsomedial nucleus (DMHc), unchanged pro-opiomelanocortin (POMC), galanin-like peptide (GALP) mRNA expression in the ARC, as well as melanin-concentrating hormone (MCH) and prepro-orexin (preORX) mRNA expression in the lateral hypothalamus, compared to low-saturated fed rats. By contrast, feeding with both high-PUFA diets increased POMC and GALP mRNA expression in the ARC compared to the corresponding low-fat diet and the high-saturated fat diet. Furthermore, feeding with both low-PUFA diets reduced NPY mRNA expression compared to the low-saturated fat diet exclusively in the DMHc. Uniquely, the high n-3 PUFA feeding halved MCH and preORX mRNA expression in the lateral hypothalamus compared to the other high-fat and low n-3 PUFA diets. In rats fed three high-fat diets, plasma insulin and leptin concentrations were significantly increased and the type of fat had no effect on these hormone levels. Rats fed high-saturated fat had both hyperglycaemia and hypertriacylglycerolemia and rats fed high n-3 PUFA only had hyperglycaemia. The present study demonstrates that various forms of dietary fat differentially change the expression of neuropeptide genes involved in energy homeostasis.

Oxidative stress reduction related to the efficacy of n-3 polyunsaturated fatty acids in first episode schizophrenia: Secondary outcome analysis of the OFFER randomized trial.

Intervention studies of n-3 polyunsaturated fatty acids (n-3 PUFA) as add-on therapy in patients with schizophrenia have not examined changes in oxidative stress. A randomized placebo-controlled trial of a 26-week intervention composed of 2.2g/day of n-3 PUFA was found to reduce symptom severity in first-episode schizophrenia patients. The present study is an extension of our previous report, whose secondary aim was to assess the association between the clinical effect of n-3 PUFA and changes in oxidative stress indices. Seventy-one patients aged 16-35 were enrolled in the study and randomly assigned to the study arms. Total plasma antioxidant capacity and 8-epi-isoprostane F2α content were assessed at baseline and at weeks 8 and 26 of the study as secondary outcome measures. Significant changes in oxidative stress indices favouring the intervention group were observed: decreases in 8-isoprostane F2α (p<0.001) and increases in total plasma antioxidant capacity (p<0.001). Significant correlations between changes in clinical scores relevant to symptom severity and changes in oxidative indices were observed. The results of the present study hence suggest that the efficacy of a six-month intervention with n-3 PUFA observed in first-episode schizophrenia may be related to improvement in oxidative stress indices.

A new family of dispersed, highly repetitive sequences in bovine genome.

A new family of highly repetitive sequences which are dispersed in bovine genome is described. The members of the family are visible on agarose or polyacrylamide gels as a diffused band about 510 bp in length arising after digestion with PstI restriction nuclease. This family of fragments comprises the 160 bp bovine Bsu family and is linked with bovine Alu-like sequences.

A new recombinant thrombolytic and antithrombotic agent with higher fibrin affinity--a staphylokinase variant. I. In vitro study.

We attempted to construct a new recombinant protein characterized by fibrin-specific properties of plasminogen activation combined with antithrombin and antiplatelet activities. To the C-terminal part of recombinant staphylokinase (r-SAK), which is a promising profibrinolytic agent, we assembled: (i) the Kringle 2 domain (K2) of tissue-type plasminogen activator (t-PA), containing a fibrin-specific binding site, (ii) the RGD sequence (Arg-Gly-Asp) for the prevention of platelet aggregation and (iii) the antithrombotic agent - hirudin. The cDNA for hybrid protein SAK-RGD-K2-Hir was cloned into pESP-3 yeast protein expression vector. The introduction of K2 t-PA, RGD sequence and hirudin into r-SAK molecule did not alter the SAK activity. The plasminogen activation rate (determined by K(M) and K(cat)) of SAK-RGD-K2-Hir was not significantly different from that of r-SAK. Affinity and binding strength of the recombinant protein to fibrin immobilized on the biosensor were higher than to r-SAK. We observed a higher clot lysis potency of SAK-RGD-K2-Hir as evidenced by a faster and more profound lysis of 125I-labeled human fibrin clots. The potency of thrombin inhibition by the hirudin part of the recombinant fusion protein SAK-RGD-K2-Hir was the same as that of r-Hir alone. In conclusion, the results of the in vitro study suggest that the SAK-RGD-K2-Hir construct can be a more potent and faster-acting thrombolytic agent with antithrombin and antiplatelet properties compared with standard r-SAK.

Transcriptional upregulation of the human MRP2 gene expression by serine/threonine protein kinase inhibitors.

Transcriptional regulation by cellular signalling pathways of multidrug resistance proteins that pump anticancer drugs out of cells is one of key issues in the development of the multidrug resistance phenotype. In our study, we have used the reporter gene approach as well as determination of mRNA levels in two cancer cell lines of human origin, MCF-7 and A549, to study the regulation of multidrug resistance proteins 2 and 3 (MRP2 AND MRP3) by serine/threonine protein kinases. Since a prototypic PKC inducer, PMA, caused a marked upregulation of transcription from both human MRP2 and MRP3 promoters, a role for PKC isoforms in positive control of expression of these proteins could be postulated. Interestingly, broad-spectrum serine-threonine protein kinase inhibitors which also inhibit PKC, staurosporine and H-7, stimulated expression from the MRP2 promoter instead of inhibiting it. This effect was not seen for MRP3. MRP2 induction by staurosporine and H-7 was shown to have phenotypic consequences in whole cells, rendering them more resistant to etoposide and increasing their ability to export calcein through the plasma membrane. These results point to the involvement of serine/threonine protein kinases in negative regulation of the human MRP2 gene and to the necessity of testing novel anti-cancer drugs acting as protein kinase inhibitors with regard to their potential ability to induce multidrug resistance.

Bovine Alu-like sequences mediate transposition of a new site-specific retroelement.

We describe a new family of 3.1-kb repetitive sequences which is present in the bovine genome. The 5' and 3' ends of the unit are flanked with sequences homologous to the 5' and 3' halves of the bovine Alu-like monomer (BM), respectively. Distribution of the 5' ends of the family members in the genome is not random. They are close to the truncated bovine Alu-like dimer (BD) which, in some cases, is followed by 40-bp repeated sequences containing block A of the RNA polymerase III promoter. The ORFs found within the unit code for peptides homologous to amino-acid sequences characteristic for reverse transcriptases (RT). The family members may be considered as mutant mobile elements whose propagation in the genomes was accomplished by means of a process including site-specific recognition with BD. Because of this, we call this family the bovine dimer-driven family (BDDF).

Inhibition of azoxymethane-induced rat colon carcinogenesis by potassium hydrogen D-glucarate.

While calcium D-glucarate was shown to inhibit chemical carcinogenesis in various animal models, the effect of potassium hydrogen D-glucarate has not been extensively investigated. In the present study, potassium hydrogen D-glucarate markedly inhibited azoxymethane (AOM)-induced colon carcinogenesis in male F344 rats. Potassium hydrogen D-glucarate (PHG) or potassium hydrogen carbonate (PHC) were administered to rats in a diet (140 mmol/kg). Continual post-initiation treatment with potassium hydrogen D-glucarate reduced both tumor incidence and multiplicity at sacrifice by ca. 60%, while PHC had no effect. amelioration of overexpression of the betaG gene in rat colon carcinomas was observed using RT-PCR and Northern blot analysis. We hypothesize that previously demonstrated conversion of PHG to D-glucaro-1,4-lactone, a potent inhibitor of beta-glucuronidase (betaG), may be responsible for this effect. The mechanism of PHG inhibition of colon carcinogenesis may also involve suppression of cell proliferation and possibly alterations in cholesterol synthesis or cholesterol metabolism to bile acids. In conclusion, PHG possesses excellent potential as a natural, apparently non-toxic inhibitor to prevent colon cancer.

Inhibition of RNA synthesis in vitro by acridines--relation between structure and activity.

The effects of acridine derivatives (proflavine and 2,7-dialkyl derivatives, diacridines and triacridines, 9-aminoacridine carboxamides, and 9-anilinoacridine, amsacrine and its congeners) on overall RNA synthesis in vitro, on synthesis of initiating oligonucleotides and the binding of the enzyme to DNA were studied. The primary mechanism of action is related to inhibition of the enzyme binding to DNA. The acridines (intercalating or non-intercalating and bis-intercalating ligands) assayed here differ in the properties of their complexes with DNA. Correlation is generally observed between inhibition of RNA synthesis in vitro and cytotoxicity in cell cultures for di- and triacridines and 9-aminoacridine carboxamide derivatives. No relationship was found between the effect on RNA polymerase system and biological effects for amsacrine and its derivatives in contrast to the other series of acridines studied here. The aniline ring seems to decrease the inhibitory potency of a ligand. The discrepancy between the biological effect and RNA synthesis inhibition may be due to a different mechanism of cytotoxicity action of amsacrine which is a potent topoisomerase II poison.

Mannan-binding lectin (MBL) in women with tumours of the reproductive system.

Mannan-binding lectin (MBL) is an important factor of innate immunity contributing to the clearance of microorganisms. Recently, an antitumourigenic role of MBL has been suggested. We investigated mbl2 genotypes, MBL concentrations, and MBL-MASP-2 complex activity in patients with ovarian cancer. The expression of both mbl2 and masp-2 genes were investigated in ovarian tissue sections. Additionally, samples from patients with other malignant and benign tumours of the reproductive tract were tested. A significantly higher incidence of MBL deficiency/insufficiency-associated genotypes was found among patients with malignant disease compared to age-matched controls. Unexpectedly, no differences in median MBL level or MBL-MASP-2 complex activity were found between the groups. This was partly a reflection of higher MBL concentrations and MBL-MASP-2 activity in cancer patients compared with healthy women carrying corresponding genotypes. MBL-specific mRNA expression was detected in several normal and malignant ovarian tissues, as well as in ovarian epithelial cell lines. Intracellular staining with MBL-specific antibodies demonstrated the presence of MBL in ovarian cell lines, and in normal as well as malignant ovarian tissue sections. In contrast, MASP-2-specific mRNA expression was detected only in the ovary tissues of patients with malignant disease. No significant changes in MBL concentration during 3 months of chemotherapy were noticed. MBL was detected in ascites and in the fluid of benign ovarian cysts. Our findings may reflect anti-tumourigenic activity of MBL protein which might suggest potential therapeutic application. However, it cannot be excluded that mbl-2 mutant alleles may be in linkage disequilibrium with an unidentified tumour susceptibility gene(s).

Extremes of L-ficolin concentration in children with recurrent infections are associated with single nucleotide polymorphisms in the FCN2 gene.

L-ficolin (also called ficolin-2, P35 or hucolin) is a soluble pattern recognition molecule of suspected importance in anti-microbial immunity. It activates the lectin pathway of complement and acts as an opsonin. l-ficolin, encoded by the FCN2 gene, recognizes microbial polysaccharides and glycoconjugates rich in GlcNAc or GalNAc. We report here data concerning four single nucleotide polymorphisms (SNPs) of the FCN2 gene and their relationship to l-ficolin serum concentrations. There are two pairs of SNPs in linkage disequilibrium: ss32469536 (located in promoter) with rs7851696 (in exon 8) and ss32469537 (promoter) with ss32469544 (exon 8). We selected groups possessing low or high serum l-ficolin concentrations (or= 4.5 microg/ml, respectively) from Polish children suffering from recurrent respiratory infections (n = 146). Low l-ficolin levels were associated with variant alleles for ss32469536 and rs7851696 and normal alleles for ss32469537 and ss32469544. Conversely, high l-ficolin levels were associated with variant alleles of ss32469537 and ss32469544. FCN2 genotyping should be a valuable additional tool for disease association studies.