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O Kovalchuk

Publications and source records attributed to O Kovalchuk.

At least 19 recordsLinked to original sources
PubMed2006

Irradiation induces DNA damage and modulates epigenetic effectors in distant bystander tissue in vivo.

Irradiated cells induce chromosomal instability in unirradiated bystander cells in vitro. Although bystander effects are thought to be linked to radiation-induced secondary cancers, almost no studies have evaluated bystander effects in vivo. Furthermore, it has been proposed that epigenetic changes mediate bystander effects, but few studies have evaluated epigenetic factors in bystander tissues in vivo. Here, we describe studies in which mice were unilaterally exposed to X-irradiation and the levels of DNA damage, DNA methylation and protein expression were evaluated in irradiated and bystander cutaneous tissue. The data show that X-ray exposure to one side of the animal body induces DNA strand breaks and causes an increase in the levels of Rad51 in unexposed bystander tissue. In terms of epigenetic changes, unilateral radiation suppresses global methylation in directly irradiated tissue, but not in bystander tissue at given time-points studied. Intriguingly, however, we observed a significant reduction in the levels of the de novo DNA methyltransferases DNMT3a and 3b and a concurrent increase in the levels of the maintenance DNA methyltransferase DNMT1 in bystander tissues. Furthermore, the levels of two methyl-binding proteins known to be involved in transcriptional silencing, MeCP2 and MBD2, were also increased in bystander tissue. Together, these results show that irradiation induces DNA damage in bystander tissue more than a centimeter away from directly irradiated tissues, and suggests that epigenetic transcriptional regulation may be involved in the etiology of radiation-induced bystander effects.

Animals↗
PubMed2006

Acute lymphoblastic leukaemia cells express CCR7 but not higher amounts of IL-10 after CD40 ligation.

OBJECTIVE: Production of cytokines that support T-cell activation and proliferation and migration to lymph nodes is one of the most important terms of cancer vaccine development. In previous studies we and others used CD40 ligation to obtain higher expression of co-stimulatory and adhesion molecules on leukaemic cells from children with acute lymphoblastic leukaemia (ALL). This time we assess the cytokine and chemokine gene expression profile in CD40-stimulated ALL cells. MATERIAL AND METHODS: Malignant cells from 25 children with BCP-ALL were stimulated (or not) with huCD40LT and rIL-4 for 96 h. Eleven different molecule, cytokine and chemokine mRNAs levels (CCR7, IL-23, TGF-beta-IP, IFN-gamma, IL-10, CD1a, CD40, CD54, CD80, CD83, CD86) were determined using the real-time PCR technique with TaqMan chemistry using ready-to-use low-density arrays for gene expression by Applied Biosystems. RESULTS: 1) Increases in mRNA levels for CD40, CD54 and CD80 after CD40L and IL-4 stimulation were observed, 2) CCR7 mRNA expression was higher after CD40 ligation than before the culture (p = 0.002), 3) IL-10 mRNA expression was higher after the culture with medium than before the culture (p = 0.01). CONCLUSIONS: The results show that leukaemia-derived dendritic cells obtained with CD40 ligation express CCR7 - chemokine is involved in migration to lymph nodes and does not produce higher amounts of IL-10, a potent immunosuppressive cytokine. Our preclinical findings could be used in the design of immunotherapy trials for the treatment of children with ALL.

CD40 Antigens↗
PubMed2006

The root-vole Microtus oeconomus (Pallas, 1776): a new potential reservoir of Anaplasma phagocytophilum.

Anaplasma phagocytophilum infection is a recently emerged tick-borne zoonosis. The bacterium's reservoirs likely comprise cervids, some ruminants, rodents, and perhaps other small and intermediate-size mammals; the main vector in Europe is the Ixodes ricinus tick. The Białowieza Primeval Forest is an ecosystem with a known prevalence of tick-borne pathogens. We studied the root-vole Microtus oeconomus to evaluate the natural infection of A. phagocytophilum. Intragranulocytic bacterial clusters (morulae) were not seen, but the A. phagocytophilum-specific nested polymerase chain reaction (PCR) product, targeting the rrs gene, was detected in two out of 30 rodent samples (GenBank accession nos. DQ361024 and DQ361025). Twenty-six root vole (86.6%) hosted ticks, mainly Dermacentor reticulatus larvae and nymphs. Only two rodents were parasitazed by I. ricinus single larvae. These data show the presence of natural infection of A. phagocytophilum among the root-vole M. oeconomus in the Białowieza Primeval Forest ecosystem.

Anaplasma phagocytophilum↗
PubMed2006

Low expression of costimulatory molecules and mRNA for cytokines are important mechanisms of immunosuppression in acute lymphoblastic leukemia in children?

UNLABELLED: Mechanisms leading blasts of acute lymphoblastic leukemia to escape from immune surveillance are still unknown. Only few reports showed that ALL cells are inefficient antigen presenting cells. The aim of the study was to assess expression of critical costimulatory/adhesion molecules and mRNA for main pro- and anti-inflammatory cytokines in ALL cells. Children with B-cell precursor ALL (n=20) were prospectively enrolled into the study. Expression of costimulatory/adhesion molecules (CD1a, CD11c, CD40, CD54, CD80, CD83, CD86, CD123, HLA class I and II) was assessed by flow cytometry and mRNA for cytokines (IFN-gamma, IL-10, IL-4, TGF-beta) - with real-time PCR. RESULTS: 1) high expression was observed for HLA I and II class, moderate for CD40, CD83, CD86 and low or no expression for CD80, CD54, CD1a, CD11c and CD123; 2) we found expression of mRNA for IFN-gamma, IL-10, IL-4 and TGF-beta in blasts cells (but not in all specimens). We noted relatively lower expression of all assessed cytokines comparing to T-cells obtained from healthy donors but interestingly expression for IL-10 was higher in normal B-cells than in blast cells, and IFN-gamma and IL-4 were not found in normal B-cells. In summary we suggest that ALL-blasts present low expression of costimulatory/adhesion molecules and mRNA for cytokines and this probably contribute to the absence of host T- cells stimulation to immune response.

Antigens, CD↗
PubMed2004

Serum levels of interleukin-18 (IL-18) and soluble interleukin-2 receptor (sIL-2R) in lung cancer.

PURPOSE: We evaluated the clinical usefulness of interleukin-18 (IL-18) and soluble interleukin-2 receptor (sIL-2R) during chemotherapy of lung cancer in relation to the histological type of the tumor, clinical stage, response to therapy and time survival. MATERIAL AND METHODS: Serum levels of IL-18 and sIL-2R were determined in 73 patients (62 males; mean age 64 years; 41 with non-small cell lung cancer-NSCLC, 32 with small cell lung cancer-SCLC); 12 healthy subjects served as controls. To determine IL-18 serum concentrations (Elisa), venous blood samples were collected from each patient before and after chemotherapy. RESULTS: The mean serum IL-18 level in all patients with lung cancer was significantly higher compared with healthy volunteers (p = 0.0001; NSCLC vs control p = 0.0001; SCLC vs control p = 0.004). In NSCLC group with stage IV the mean IL-18 level was significantly higher than those with stage IIIB (p = 0.04). Regarding tumor stage and response to therapy, no significant differences in IL-18 were observed. Using cut-off serum IL-18 concentration of 319.6 pg/ml, the prognoses of the two groups were different, but it was not statistically significant. The serum levels of sIL-2R in NSCLC patients were significantly higher than in controls (p = 0.018). There were no significant differences in serum sIL-2R levels in relation to clinical stage of lung cancer and response to therapy. The cut-off value between high and low serum sIL-2R concentration was defined as 582.27 U/ml. The difference in survival rate between the high and low sIL-2R groups was not significant. CONCLUSIONS: Serum IL-18 and sIL-2R levels can be useful in clinical practice, but their practical significance needs further studies.

Antineoplastic Agents↗
PubMed2004

Clinical usefulness of K-RAS mutation detection in colorectal cancer and in surgical margins of the colon.

The incidence of K-RAS gene mutations in tumour and surgical margins was investigated in 63 patients with adenocarcinomas of varied clinical stage and histological grade. Point mutations of codon 12 K-RAS gene were detected, using the PCR-RFPL technique in cancer tissue in 23 patients (36.5%) and in colon margin mucosa in 1 patient (3.7%), out of 27 examined subjects. No significant correlations were found between the mutations and clinical features. Tumours, located in the left colon, and mucinous neoplasms displayed a higher incidence of mutations. No correlation was observed with either Dukes or TMN clinical advancement.

Colon↗
PubMed2004

mRNA for chosen pro- and anti-inflammatory cytokines in T-lymphocytes in paediatric leukemias and lymphomas--a preliminary report.

We assessed mRNA for chosen pro- and anti-inflammatory cytokines in T-lymphocytes of peripheral blood in paediatric patients with leukemias and lymphomas. Levels of four different cytokine mRNAs (IFN-gamma, IL-10, IL-4, TGF-beta) were determined by the real-time PCR technique. In the whole examined group, at the time of diagnosis, we noted lower amounts of mRNA for TGF-beta1, comparing to respective values in the control patients. In the ALL group, we observed the following: 1) at the time of diagnosis: lower amounts of mRNA for IL-4 and for TGF-beta1, comparing to respective values in the control group; 2) lower amounts of mRNA for IL-10 after remission induction, comparing to the time of diagnosis. In our opinion, "immunedysregulation" in lymphoproliferative diseases in children is not caused by IFN-gamma deficiency. The deficit of anti-inflammatory cytokines, i.e., IL-4, TGF-beta, with higher amounts of IL-10, suggests their role in cancer development.

CD4-Positive T-Lymphocytes↗
PubMed2004

Attempts to detect Helicobacter pylori in atherosclerotic plaques.

Cardiovascular and cerebrovascular diseases are regarded to be the main causes of mortality in developed countries, atherosclerosis being at their pathological base. During the recent years, attention was paid to the role of bacterial infections, including Helicobacter pylori, in the process of atherogenesis and coronary heart disease development. The aim of the study was an evaluation of H. pylori presence--by means of PCR technique--in atherosclerotic changes, obtained by endarterectomy, performed during coronary artery bypass grafting (CABG). In the analysed group of patients, the following risk factors were found: hyperlipidaemia, smoking, hypertension, obesity, diabetes mellitus, cardiac infarction. No DNA of the bacteria was traced in any of the patients.

Adult↗
PubMed2001

Biomonitoring the genotoxicity of environmental factors with transgenic plants.

All organisms must react to constantly changing surroundings. Environmental factors are thus powerful forces continuously shaping the genomes of all species. Induced genetic changes can be followed using a biomonitor - a living organism that reacts to a given compound in the environment. A vital but challenging task is identifying organisms with which to study the influence of changing environmental conditions. Plants are especially valuable biomonitors. Here, we describe the use of transgenic plant systems to evaluate the genotoxicity of chemical and radiological compounds. We evaluate the potential of further transgene-based systems for studying somatic and germ-line mutations.

Chromosome Aberrations↗
PubMed2001

A sensitive transgenic plant system to detect toxic inorganic compounds in the environment.

We describe a transgenic plant-based assay to study the genetic effects of heavy metals. Arabidopsis thaliana plants carrying a beta-glucuronidase (GUS) marker gene either with a point mutation or as a recombination substrate were used to analyze the frequency of somatic point mutations and homologous recombination in whole plants. Transgenic test plants sown on media contaminated by the salts of the heavy metals Cd2+, Pb2+, Ni2+, Zn2+, Cu2+, and As2O3 exhibited a pronounced uptake-dependent increase in the frequencies of both somatic intrachromosomal recombination and point mutation. The test was applied to monitor the genotoxicity of soils sampled in sites contaminated with several heavy metals. Our results indicate that this is a highly sensitive system for monitoring metal contamination in soils and water.

Animals↗
PubMed2001

Morphological and molecular aspects of cancerogenesis in the lung.

Morphology and some molecular aspects of hyperplastic (bronchial basal cell hyperplasia and alveolar cell hyperplasia), metaplastic (squamous metaplasia), preneoplastic and early neoplastic (dysplasia in squamous metaplasia, cancer in situ and atypical alveolar cell hyperplasia) changes were studied in 180 lungs resected due to non-small cell lung cancer: 106 cases (58.9%) of squamous cell carcinoma, 42 (23.3%) of adenocarcinoma and 32 (17.8%) of large cell carcinoma. P53 protein and PCNA expressions were detected immunohistochemically (using formalin-fixed, paraffin-embedded sections). DNA extracted from the microdissected P53-positive cells was analysed for point mutations in the P53 gene. No P53 immunostaining was observed in normal mucosa, hyperplasia of basal cells, squamous metaplasia without and with minor and moderate dysplasia of bronchial mucosa as well as alveolar cell hyperplasia. Overexpression of P53 protein occurred in 3 out of 12 (25%) cases of severe bronchial dysplasia, 5 out of 11 (45.5%) cases of intraepithelial carcinoma and 6 out of 45 (13.3%) cases of alveolar cell hyperplasia. Using direct sequencing, mutations in the P53 gene were detected in 11 out of 14 (87%) P53-immunopositive samples, including all severe dysplasias, all carcinomas in situ and 3 of 6 alveolar cell hyperplasias. A significant association was observed between PCNA expression and preinvasive as well as invasive lesions. The data clearly show that lung resected due to primary cancer ought to be treated as "field cancerization" in which one can find early morphologic events of multi-step cancerogenesis. P53 protein alterations and P53 gene mutations can occur before invasion and its frequency depends on the degree of dysplasia.

Carcinoma, Non-Small-Cell Lung↗
PubMed2001

Endothelial cells and angiogenesis intensity in lung cancer.

We focused our studies on single endothelial cells (ECs) scattered in extracellular matrix in lung cancer tumors. Neovascularization was evaluated in 100 tumors obtained from patients operated for lung cancer, in relation to histological type, tumor differentiation and clinical stage of the disease. Angiogenic objects (single endothelial cells and microvessels) were identified by immunohistochemistry using monoclonal antibodies against von Willebrand factor. The count of angiogenic objects per 1 mm2 in each section was determined in a "hot spot" located at the margin of the tumor. We used an arbitrary scale of angiogenesis intensity: 1 - 0-200, 2 - 201-400, 3 - >400 angiogenic objects/mm2. A majority (57%) of the examined cases belonged to the group 2. The angiogenesis intensity measured by the single EC numbers/mm2 correlates with the histological type and the differentiation of the tumors. There was no such a correlation when the angiogenesis intensity was measured by counting total angiogenic objects (microvessels + EC) number/mm2. Single EC number/mm2 in different histological types of cancer were as follows: 162+/-121 in squamous cell (SqCC), 194+/-71 in adenocarcinoma (AdC), 225+/-145 in large cell (LCC), 264+/-52 in small cell (SCC), 279+/-173 in combined cancer. The differences between the EC counts in the different histological types of lung cancers were statistically significant in the following pairs: SqCC vs SCC (p=0.0233) and AdC vs SCC (p=0.0409). The correlation between EC count in the "hot spot" and the grade of tumor differentiation was statistically significant for G1 vs G4 (p=0.0007) and G1 vs G2 (p=0.0411). Our results suggest that higher numbers of EC/mm2 may confirm rapid development of angioneogenesis. These relations should be examined in larger series of cases.

Adenocarcinoma↗
PubMed2001

Circulating anti-p53 antibodies in esophageal cancer patients.

Circulating anti-p53 protein antibodies (p53-Abs) have been detected in some cancer patients. The aim of the study was to determine the presence of circulating anti-p53 protein antibodies and their clinical significance in patients with esophageal carcinoma. Serum specimens from 75 consecutive patients with squamous cell carcinomas and 10 healthy subjects were studied. Enzyme linked immunosorbent assay (ELISA--Pharma Cell) was used to detect p53-Abs. At the time of diagnosis 20 (26.6%) of 75 analyzed patients had positive result in the p53-Abs test, but not any of the healthy subjects. The positive rate was 25% (1/4) cases in stage I, 41% (10/24) cases in stage IIA, 0% (0/8) cases in stage IIB, 28% (8/28) cases in stage III and 9% (1/11) cases in stage IV. In respect of tumour differentiation, cases graded as G1, G2 and G3 were positive in 28.5% (4/14), 25.9% (7/27) and 26.4% (9/34), respectively. There was no correlation between presence of p53-Abs and stage, rumour differentiation, lymph nodes metastases, tumour size, patient age and sex. In conclusion, the results of the present study indicate that serum p53-Abs did not correlate with cliniocopathologic feature of esophageal carcinoma.

Adult↗
PubMed2001

K-ras codon 12 mutations detected with enriched PCR method in operable non-small cell lung cancer.

Activated point mutations of the K-ras gene are one of the most common genetic alterations found in human malignancies, including lung cancer, and are largely limited to adenocarcinomas. Using a highly sensitive assay for codon 12 K-ras mutation detection, called enriched PCR, we investigated 130 radically resected stage I-IIIa non-small cell lung cancer (NSCLC). There were statistically less positive results for squamous cell carcinoma (1.3%) than for adenocarcinoma (42.4%) and large cell carcinoma (27.8%). No statistically significant association between results of K-ras mutations and TNM stage of disease was found. In stage I of adenocarcinoma patients the incidence of K-ras mutations was similar to that in stage II or IIIa (40%, 42.9% and 42.9%, respectively). The results of our study showed that K-ras mutations might play an important role in pathogenesis of pulmonary adenocarcinoma due to its high prevalence in the operable tumours.

Adult↗
PubMed2001

K-ras codon 12 mutations may be detected in serum of patients suffering from adeno- and large cell lung carcinoma. A preliminary report.

We investigated the presence of K-ras mutations in the serum of 40 patients with respectable stages of adeno- and large cell lung carcinomas. Mutations in codon 12 of the K-ras gene were examined by enriched PCR method in DNA extracts from surgical specimens and serum samples. K-ras mutations were detected in 20 (51%) of 39 analyzed tumours, and in 7 (35%) of 20 patients with K-ras gene mutation positive tumours, a mutation was found in the serum DNA. We also found K-ras mutation in two (10.5%) of 19 serum samples obtained from patients whose tumours were not found to harbor mutation and in one serum sample from patient without tumour sample available for investigation. All of the 14 control healthy persons were negative for serum DNA K-ras mutation assay. Although our results are preliminary they show that K-ras mutation may be detected in serum of patients suffering from adeno- and large cell lung carcinomas and confirm the suggestion that at least a part of a free-cell extracellular blood DNA in cancer patients has neoplastic origin and may become a noninvasive target for genetic investigations of lung cancer patients.

Adenocarcinoma↗