Biomedical subjects

T Skórski

Publications and source records attributed to T Skórski.

At least 19 recordsLinked to original sources

PubMed2004

ABL-fusion oncoproteins activate multi-pathway of DNA repair: role in drug resistance?

Chromosomal translocations of tyrosine kinase c-ABL gene from chromosome 9 may generate oncogenic kinases exhibiting constitutive tyrosine kinase activity. Recently, we have shown that ABL-fusion oncogenic tyrosine kinases, BCR/ABL and TEL/ABL, specific to hematopoietic malignances, induced resistance to DNA-damaging agents. To elucidate the role of DNA repair in this phenomenon we examined the capacity of murine BaF3 lymphoid cells and their TEL/ABL-transformed counterparts to repair DNA lesions caused by gamma- and UV-radiations and the anti-cancer drug, idarubicin. TEL/ABL-transformed cells displayed resistance to these DNA damaging agents as evaluated by MTT assay and the survival advantage was associated with an accelerated kinetics of DNA repair as measured by the alkaline comet assay. Deoxyribonucleosides (dNTPs) supplementation of the repair medium further stimulated DNA repair and the effect was specific to the DNA damage agent used in the experiment but only the transformed cells displayed this feature. A variety of damages induced imply the multi-pathway of DNA repair involved. We also examined the capability of BCR/ABL-fusion to modulate the repair of oxidative lesions, considered as a major side effect of various anti-cancer drugs including idarubicin and radiation. Employing the free radical scavenger alpha-phenyl-N-tert-butyl nitrone (PBN, a spin trap) and DNA repair enzymes: endonuclease III (EndoIII) that nicks DNA at sites of oxidized bases, we found that BCR/ABL-transformed cells repaired oxidative DNA lesions more effectively than control cells. Our results suggest, that oncogenic ABL-dependent stimulation of DNA repair may contribute to the cell resistance to genotoxic treatment.

Animals↗

PubMed2001

[Adverse effects of parenteral administration of antisense oligonucleotides].

To characterize the toxicity of phosphorothioate antisense oligodeoxynucleotides ([S]ODNs) in vivo, the mice received intravenously 26-mer bcr-abl antisense oligodeoxynucleotides (1 mg/mice/day) for 9 consecutive days. The organs and tissues were removed on the indicated days (+1, +7, +30) after the treatment. Our investigation revealed middle elevation of aminotransferases activity, lactate dehydrogenase level, total protein level and globulin level, decrease of glucose, albumin and blood urea nitrogen level in the peripheral blood. The mild anaemia and thrombocytopenia were observed too. The most significant treatment-related findings in the antisense treated mice were splenomegaly, reactive hepatitis and atrocytosis of kidney. These findings together with previous results demonstrate little and temporary toxicity effects mainly in organs known from cumulating of [S]ODNs.

Animals↗

PubMed1998

Apoptosis and some of its medical implications.

The following phases of apoptosis were proposed: decisive, executive and degradation. At least two checkpoints are recognized in the process of apoptosis: the p53 and Bcl-2/Bax protein family checkpoint and the protease-caspase and serine protease checkpoint. Signals to apoptosis from outside of the cell including Fas and Fas ligand interaction and sphingomyelin cycle were presented. Cellular morphological events in apoptosis: DNA chain breaks, changes in cell membrane and mitochondrial membranes were discussed. Some medical problems of cardiology in which apoptosis plays an important role were presented. The cancer treatment results depending on apoptosis of cancer cells were discussed as well.

Animals↗

PubMed1996

The influence of phosphorothioate oligodeoxynucleotides on various organs in vivo.

To characterize the distribution and toxicity of phosphorothioate antisense oligodeoxynucleotides ([S]ODNs) in vivo, the mice, previously injected with BV173 leukemic cells (Philadelphia chromosome-positive chronic myeloid leukemia blast-crisis), received intravenously 26-mer BCR-ABL antisense oligodeoxynucleotides (1 mg/mouse/day) for 9 consecutive days. Our investigation revealed that [S]ODNs were distributed to almost all organs except the brain with the highest level in the liver, spleen and kidneys. They were also detected in CD10+ leukemic cells isolated from spleen and bone marrow. Intracellular distribution assay showed the presence of [S]ODNs most prominently in nuclear and cytoplasmic fractions. Our data demonstrated no significant toxicity of [S]ODNs except the increase in spleen weight.

Animals↗

PubMed1996

Inhibition of in vitro proliferation of chronic myelogenous leukemia progenitor cells by c-myb antisense oligodeoxynucleotides.

Normal hematopoietic progenitors and acute myelogenous leukemia cells show a differential requirement for the encoded product of c-myb proto-oncogene for proliferation. To determine whether c-myb is also differentially required for the proliferation of hematopoietic progenitors of chronic myelogenous leukemia (CML), mononuclear cells derived from both chronic phase and blast crisis were exposed to c-myb antisense oligodeoxynucleotides and assayed for colony-forming ability. Exposure of CML-BC cells from 12 patients to c-myb antisense oligodeoxynucleotides resulted in significant (p<001) inhibition of leukemia colony formation (average inhibition 63%) and was accompanied by down-regulation of c-myb expression. Colonies derived from CML chronic phase progenitors were virtually unaffected in 10 cases, but down-regulation of c-myb expression was not detected. However, in studies conducted with CD34+ leukemia cells, a subset highly enriched for hematopoietic progenitors, colony formation was inhibited at both disease stages, whereas CFU-GM colony formation derived from normal CD34+ cells was not affected by exposure to c-myb antisense oligodeoxynucleotides. These data suggest that CML chronic phase and blast crisis progenitors are both sensitive to the inhibitory effects of c-myb antisense oligomers, and that the lack of inhibition in partially purified CML-chronic phase progenitors is probably due to inefficient penetration of oligodeoxynucleotides into the clonogenic cells. The preferential effect of c-myb antisense oligodeoxynucleotides on colonies arising from the compartment that includes CML-CD34+ progenitors likely reflects the expansion of a cell population with high proliferative potential and elevated c-myb mRNA levels.

Antigens, CD34↗

PubMed1995

[Progress in molecular biology of leukemias--clinical implications].

The origin of leukemias like other forms of cancer, lies in gene defects that alter the normal programs of cellular differentiation, proliferation, or apoptosis. Many leukemia genes have been identified and molecularly characterized during the last decade. These studies have revealed some common genetic mechanisms for leukemogenesis, provided molecular tools for leukemia diagnosis and monitoring, and identified potential targets for a new generation of leukemia therapies.

Chromosome Aberrations↗

PubMed1995

The diverse effect of topoisomerase I specific inhibitor (camptothecin) on normal and BCR/ABL-dependent hematopoietic cells proliferation: therapeutic implications.

Camptothecin (CPT), a specific topoisomerase I inhibitor, in the presence of hematopoietic growth factors exerted an antiproliferative effect against normal bone marrow cells (NBMC) as well as chronic myelogenous leukemia-chronic phase (CML-CP) and blast crisis (CML-BC) cells. In the absence of growth factors, however, only the colony formation by CML-BC cells was inhibited by CPT, leaving NBMC and CML-CP cells intact or much less affected. Analysis of the cellular DNA content revealed that CPT induced specific changes in cell cycle distribution: decrease in S and G2/M fraction with simultaneous accumulation of the cells in G1 phase and the appearance of "sub-diploid" (apoptotic) peak. To determine if CPT is able to exert selective antileukemic effect, 1:1 mixture of NBMC and CML-BC cells was exposed to CPT in the absence of growth factors and assayed for growth ability in clonogenic assay and for expression of BCR/ABL transcript in single colonies. BCR/ABL transcript was not detected in colonies incubated with CTP, in contrast, most of colonies arising from untreated cells possessed leukemic origin (BCR/ABL expression). Our results indicate that CPT is selectively effective in vitro against the leukemia cells. This offers the prospect of a novel and more selective treatment of CML.

Antineoplastic Agents, Phytogenic↗

PubMed1994

Oncogene-targeted antisense oligodeoxynucleotides combined with chemotherapy or immunotherapy: a new approach for tumor treatment?

Synthetic oligodeoxynucleotides (antisenses) complementary to bcr/abl breakpoint junction transcript on Philadelphia chromosome, or c-myb protooncogene inhibit partially the proliferation of Philadelphia positive leukemic cells (antisenses against bcr/abl and c-myb) and other tumor cells (antisenses against c-myb). This phenomenon is accompanied by specific downregulation of mRNA level of the particular gene. To develop a more effective procedure of tumor treatment the combination of low dose of cytostatic and bcr/abl or c-myb antisenses against Philadelphia chromosome positive cell line BV173, and the combination of anti-tumor cytotoxic T lymphocytes (CTL) and c-myb antisenses against melanoma cell line MM-28, were tested in vitro. Our results indicate that the combinations of conventional chemotherapeutic agent and antisense against bcr/abl or c-myb or tumor specific CTL and antisense against c-myb, are highly effective in killing of tumor cells and sparing normal cells. This creates the possibility to develop a more selective and effective treatment of neoplasia.

Bone Marrow Cells↗

PubMed1994

Cytokine stimulation of CD34+ bone marrow cells prior to cryopreservation enhances their post-thawing proliferative potential.

Marrow aplasia remains a significant cause of morbidity and mortality in the peri-transplant period. Administration of recombinant human hematopoietic growth factors along with the marrow graft is a widely used strategy to ameliorate this problem. Though arguably effective, this approach is extremely expensive. To develop alternative strategies for stimulating marrow engraftment, we investigated the utility of stimulating CD34+ enriched bone marrow cells with cytokines prior to cryopreservation. We found that culturing these cells for 1 to 3 days in Iscove's medium supplemented with kit ligand (KL), interleukin-3 (IL-3), interleukin-1 beta (IL-1 beta) and 20% bovine calf serum before freezing doubled the proliferative capacity of both myeloid and erythroid progenitor cells after thawing. Confirmation of increased proliferative activity in vivo would suggest that this approach might significantly shorten the period of marrow aplasia post transplant at far less expensive means.

Animals↗

PubMed1994

The role of c-Myc protooncogene in chronic myelogenous leukemia.

c-Myc transcriptional factor encoded by c-myc protooncogene plays an important role in the regulation of cell cycle. It was also established that c-Myc is important for the transformation of fibroblasts and murine bone marrow cells induced by BCR/ABL tyrosine kinase encoded by bcr/abl oncogene localized on Philadelphia-chromosome (Ph1). The role of c-Myc in the proliferation of the leukemic cells was not known. Therefore, we examined the effect of c-Myc protein downregulation, using antisense oligodeoxynucleotides, on the growth of the BCR/ABL- dependent cell line and chronic myelogenous leukemia (CML) patients cells. Downregulation of c-Myc expression caused complete inhibition of the proliferation of BCR/ABL-dependent BV173 cell line and 50-70% inhibition of the colony formation of CML cells. These results suggests that c-Myc cooperates with BCR/ABL and is necessary for the growth of Ph1-positive leukemias.

Base Sequence↗

PubMed1994

[In-vitro study of anemia in chronic inflammatory conditions. Effect of recombined interleukin-1 beta on human erythropoiesis].

Study was inspired by the suggestion that interleukin 1-beta (IL-1 beta), one of the major inflammatory mediators, is directly responsible for anaemia of chronic inflammatory conditions. Effect of IL-beta was studied in vitro on methyl cellulose cultures of normal human bone marrow cells, the inoculate having been previously highly enriched in progenitor and stem cells. Our data did not support results reported by others that IL-1 beta is a strong inhibitor of early stages of erythropoiesis in vitro measured by early and late BFU-E formation. About 30% statistically not significant CFU-E inhibition was observed. Above studies show that IL-1 beta role in the development of anaemia associated with chronic inflammatory diseases requires further studies.

Anemia↗

PubMed1994

[Molecular basis of chronic granulocytic leukemia: from test-tube to patient].

BCR/ABL tyrosine kinases are encoded by hybrid oncogene bcr/abl which is a result of t(9;22) reciprocal translocation. Bcr/abl oncogene is located on Philadelphia chromosome which is detectable in hematopoietic cells of more than 95% of patients with chronic myelogenous leukemia, and in some cases of acute lymphocytic leukemia (20-35%) and acute myeloblastic leukemia (5%). Because BCR/ABL tyrosine kinase is localized in the cytoplasm, cooperation with other cytoplasmic and nuclear molecules is necessary for the induction of leukemia. Identification of the molecular mechanisms involved in transduction of the oncogenic signal is likely to be useful in elucidating the molecular mechanisms of leukemogenesis and may eventually lead to the identification of novel targets for antileukemia therapy. One of the possible treatment--inhibition of bcr/abl oncogene expression by antisense strategy--is described below.

Animals↗

PubMed1993

The influence of 4 degrees C storage on proliferative potential of human bone marrow CD34+ cells. Transplantological implications.

The possibility of storage of human bone marrow CD34+ cells at 4 degrees C was investigated for bone marrow transplantational purposes. The cells were placed in Iscove medium supplemented with 20% serum (15% bovine calf serum 5% human AB serum) for three weeks at 4 degrees C. During the storage time, clonogenecity of granulocyto-monocytic (CFU-GM) erythropoietic (BFU-E) and megakaryocytic (CFU-Meg) progenitors was investigated. It was found that it is possible to keep human CD34+ cells at 4 degrees C, at least for a few days before transplantation. At day four of the storage, the number of CFU-GM and BFU-E cells still exceeded 50% of the cells present at day 0. However, we have found that CFU-Meg in comparison to other progenitors are much more sensitive to metabolic storage stress. This enhanced sensitivity of megakaryocytic progenitors could explain, at least partially, the well known phenomenon of retardation of the thrombopoietic recovery in patients undergoing bone marrow transplantations.

Antigens, CD↗

PubMed1993

Successful mafosfamide purging of bone marrow from chronic myelogenous leukemia (CML) cells.

The in vitro sensitivity of human chronic myeloid leukemia-blast crisis and chronic phase (CML-BC and CML-CP, respectively) cells as well as adherent cell-depleted, T lymphocyte-depleted normal bone marrow cells (A-T-NBMC) to various concentrations of mafosfamide (ASTA Z7654), was examined by colony formation assay in the presence of IL-3 and GM-CSF, to test the possibility of purging of BMC from CML cells. Colony formation by CML cells was inhibited more efficiently than by NBMC. After the incubation with 50 micrograms/ml or 100 micrograms/ml of mafosfamide, the growth of leukemic CFU-GM was totally abrogated in 2/11 or 9/11 cases of CML-BC and in 1/7 or 6/7 cases of CML-CP, respectively. At the same time the CFU-GM arising from normal BMC were not inhibited totally with 50 or 100 micrograms/ml of the drug in any of five experiments. CML cells were still unable to form secondary colonies, while normal BMC were capable of regrowth. The CD34+ cells isolated form CML-BC and CML-CP patients were also more susceptible to mafosfamide cytotoxicity in comparison to CD34+ cells derived from NBMC. To confirm the possibility of purging, CML-BC cells were mixed with NBMC (1:1) and incubated with mafosfamide. Finally, the growing colonies were examined for the presence of bcr/abl hybrid gene by reverse transcriptase-Taq polymerase chain reaction (RT-PCR) and specific hybridization. The bcr/abl gene was not detected in the colonies growing after 100 micrograms/ml, and the signal was diminished after incubation with 50 micrograms/ml of mafosfamide, as compared to control. These results strongly suggest that high concentrations of mafosfamide may be useful for the purging of autologous BMC from CML cells.

Antineoplastic Agents↗

PubMed1993

Immunogenic and nondividing mafosfamide-treated L 1210 cells--comparison of lines resistant and nonresistant to cyclophosphamide.

Cyclophosphamide/mafosfamide-resistant L 1210 cell line [L 1210(Cy)R] was established from a sensitive parental line. The L 1210(Cy)R line was resistant to cyclophosphamide at the dose of 100 mg/kg. Cells of L 1210(Cy)R line were more immunogenic for semisyngeneic CD2F1, mice as compared with parental line. They grew slower in immunocompetent mice compared to immunosuppressed mice. It has been shown that L 1210(Cy)R cells treated with mafosfamide at high concentration not only retained immunogenicity but were even more immunogenic than parental L 1210 cells. In conclusion, it was possible to produce immunogenic, nondividing leukemia cells even when cells were resistant to the cytostatic used for cell modification.

Animals↗

PubMed1992

A model of Ph' positive chronic myeloid leukemia-blast crisis cell line growth in immunodeficient SCID mice.

A human Philadelphia-chromosome positive chronic myeloid leukemia-blast crisis (CML-BC) cell line BV173 proliferated in the hematopoietic tissues, infiltrated various organs and caused the death of immunodeficient SCID mice. Leukemia spreading was assessed with diminished number of bone marrow cells and caused splenomegaly. The leukemic colonies grew from single cell suspension of bone marrow, spleen and peripheral blood. Bcr-abl m-RNA was detectable in bone marrow, spleen, peripheral blood, liver, lungs and brain. Dying mice demonstrated severely hypoplastic bone marrow, splenomegaly and massive metastases in the liver and kidneys. The survival time of animals was dependent on the number of inoculated leukemia cells.

Animals↗

PubMed1991

Early induction of immune resistance against leukemia in mice after lethal irradiation followed by syngeneic bone marrow transplantation and injection of syngeneic leukocytes.

BALB/cxDBA/2Wf F1 (CD2F1) mice were lethally irradiated and reconstituted with syngeneic bone marrow cells untreated or treated with 75 micrograms/ml of mafosfamide. One day after bone marrow transplantation some groups of mice were injected with syngeneic splenocytes, peripheral blood leukocytes, or thymocytes. Seven days after marrow grafting the anti-L1210 leukemia immunization of mice, consisting of four i.p. injections of 10(6) L1210-Maf cells (L1210 cells treated in vitro with mafosfamide for inhibition of their growth in vivo), was started. Strong resistance against leukemia could be obtained only in mice receiving splenocytes or peripheral blood leukocytes, not in mice injected with thymocytes or in those not receiving any cells. In vitro elimination of various subpopulations from among the splenocytes before their injection into the mice made it possible to deduce which are necessary for early induction of antitumor resistance after bone marrow transplantation in mice. These cells are: Thy 1.2-, Ig-, AsGM 1-, Mac 1+, 1-Ad+/-, are adherent and nonsusceptible to carrageenan toxicity.

Animals↗

PubMed1991

Changes of thymocyte subpopulations induced by activities diffusing from leukemia L1210 cells.

Mice with intraperitoneally inoculated leukemia L1210 cells had a lower total number of thymocytes and a markedly reduced percentage of L3T4+ Lyt2+ (CD4+ 8+) thymocytes, but increased subpopulations of L3T4+ Lyt2-, L3T4- Lyt2+, L3T4-Lyt2-. The percentage of Thy 1.2+ thymocytes was unchanged as compared with control animals. A similar effect was observed is suggested that leukemia L1210 cells produce some activities which diffuse through 0.22 microns filters and influence the subpopulations of thymocytes.

Animals↗