Biomedical subjects

M Wasik

Publications and source records attributed to M Wasik.

At least 19 recordsLinked to original sources

PubMed2006

Humoral immune response against mycobacterial antigens in children with tuberculosis.

Different clinical outcomes of tuberculosis (TB) are related to the balance between cell-mediated and humoral immunity and may depend on environmental and individual factors including age and sex. The purpose of this study was to analyze the humoral immune response to recombinant and native mycobacterial antigens in relation to clinical presentations of pulmonary TB in children. We examined 224 serum samples including 81 primary and 31 postprimary TB cases, 30 cases of latent TB infection, and 82 nontuberculosis controls. Commercially available ELISA assays detecting IgG, IgA, and IgM against antigens: 38 kDa, 16 kDa, 38 kDa, lipoarabinomannan (LAM), and A-60 were used. The results indicate that IgG production was very low in primary compared with postprimary TB (P<0.0001). IgM levels did not differ between the examined groups. Antibody levels strongly depended on the child's age. In infants aged below 1 there was no difference in the antibody level between the TB and control cases. Most positive cases were observed in children aged above 10. The influence of BCG vaccination on the antibody level was not seen. In all subgroups, person-to-person heterogeneity of antigen recognition was observed. We conclude that humoral immune response is associated with the phase of TB and is stronger in more advanced TB forms. IgG and IgA production against mycobacterial antigens is very low in young children.

Adolescent↗

PubMed2006

Kinetics of calcium ion concentration accompanying signal transduction in neutrophils from children with increased susceptibility to infections.

Increased susceptibility to infections can be a consequence of altered function of immune cells including neutrophils. The goal of the study was to evaluate the process of neutrophil activation via Ca(2+)-mediated signal. The study was performed on isolated peripheral blood neutrophils obtained from 41 children with recurrent infections (21 girls, 20 boys) 3-10 years old with more than five episodes of respiratory tract infection (RI) per year and from a control group of 30 healthy children age and sex matched, free from allergic, immune and hematological disorders. Neutrophils were activated by bacterial peptide fMLP, opsonized zymosan (OZ), and phorbol myristat acetate (PMA). The kinetics of the intracellular Ca(2+) concentration i[Ca(2+) ] was assessed by flow cytometry (Coulter Epics XL) with the use of Fluo3 and Fura Red fluorescent dyes. Data were collected in histograms displaying Fluo3 fluorescence vs. time and Fura Red fluorescence vs. time and the mean channels of fluorescence intensity were used for calculations. fMLP and OZ-induced Ca(2+) mobilization lasted shorter in the RI group (P<0.05). The peak influx of free Ca(2+) and i[Ca(2+) ] in the resting state after stimulation with fMLP were lower in the patients (P<0.05). In the RI group stimulation with OZ was delayed compared with that in the control group (P<0.01). In response to PMA, i[Ca(2+) ] decreased faster. The kinetic slopes of i[Ca(2+) ] in both groups examined differed statistically at all points measured. A decrease in i[Ca(2+) ] after PMA stimulation was greater (P<0.01) and lasted longer in the RI group. We conclude that increased sensitivity to infections in RI children may be related to the disturbance in neutrophil activation that is mediated by changes in i[Ca(2+) ] with the subsequent production of free oxygen radicals. Such a disturbance may be inheritable or secondary to infection and antibiotic therapy.

Adolescent↗

PubMed2006

The Gln223Arg polymorphism of the leptin receptor gene and peripheral blood/bone marrow leptin level in leukemic children.

Leptin is an adipocyte-derived hormone regulating energy homeostasis and body weight. Leptin also plays a role in hematopoiesis, cell cycle regulation, and in oncogenesis. The leptin receptor is a single transmembrane protein belonging to the superfamily of cytokine receptors, structurally related to the hemopoietin receptor family. The aim of the study was to evaluate bone marrow and peripheral blood leptin level and frequency of distribution of leptin receptor gene polymorphism Gln223Arg in children with acute leukemia. The examined group included 92 children with acute leukemia (83 ALL and 9 AML) and 39 non-leukemic control children. Leptin level was measured by ELISA method at the day of leukemia diagnosis. Genomic DNA was isolated with the use of a column method and the genotyping of DNA sequence variation was carried out by the restriction enzyme analysis of PCR - amplified DNA. The samples were then electrophoresed on 2.5% agarose gel. Leptin level in leukemic children was lower than in healthy children. Bone marrow leptin level was significantly lower than that in the blood in leukemic children with ALL-T and AML. An analysis of frequency distribution of the Gln233Arg polymorphism in the leptin receptor gene in leukemic children showed lack of differences between the patients and controls. There was no difference in the genotype frequencies between the leukemic AML and ALL groups either. The results indicate a possible relation between the leptin level and leukemia development in children. The effectory effect of the hormone seems not related to Gln223Arg polymorphism of its receptor.

Adolescent↗

PubMed2005

Constitutive SOCS-3 expression protects T-cell lymphoma against growth inhibition by IFNalpha.

Signal transducer and activator of transcription (Stat)3 is constitutively activated in cutaneous T-cell lymphoma (CTCL), where it protects tumour cells against apoptosis. The constitutive activation of Stat3 leads to a constitutive expression of suppressor of cytokine signalling (SOCS)-3. In healthy cells, SOCS-3 is transiently expressed following cytokine stimulation and functions as a negative feedback inhibitor of the Stat3-activating kinases. Here, we attempt to resolve the apparent paradox of a simultaneous SOCS-3 expression and Stat3 activation in the same cells. We show that (i) SOCS-3 expression in tumour cells is equal to or higher than in cytokine-stimulated nonmalignant T cells, (ii) SOCS-3 is not mutated in CTCL, (iii) overexpression of SOCS-3 blocks IFNalpha-mediated growth inhibition without affecting Stat3 activation, growth, and apoptosis, and (iv) inhibition of SOCS-3 by a dominant negative Stat3 (Stat3D) increases the IFNalpha-mediated growth inhibition. Taken together, these data show that SOCS-3 does not inhibit Stat3 activation, growth, and survival in CTCL. In contrast, SOCS3 protects tumour cells against growth inhibition by IFNalpha. Unlike SOCS-1, SOCS-3 is therefore not a tumour suppressor but rather a protector of tumour cells.

Amino Acid Substitution↗

PubMed2005

Humoral immune response against mycobacterial antigens in bronchoalveolar fluid from tuberculosis patients.

Resistance to tuberculosis (TB) is cell-mediated but a humoral response is common and may be correlated with the lack of effective local cellular defense mechanisms. The goal of the study was to evaluate IgG, IgA, and IgM-mediated humoral immune response against 38-kDa+16-kDa and 38-kDa+lipoarabinomannan (LAM) mycobacterial antigens in bronchoalveolar fluid (BALF) from patients with pulmonary TB. Non-tuberculosis (NTB) patients were used as control. 179 BALF samples (56 TB and 123 NTB) were examined. Commercially available ELISA-based assays against proteins 38-kDa and 16-kDa or 38-kDa plus LAM were used. Three different dilutions of BALF: 1:1; 1:10, and 1:50 (100) were tested. Only the results obtained with the 1:10 dilution allowed distinguishing TB and NTB groups. The mean IgG level for 38-Da+LAM was significantly higher in the TB than that in the NTB group (P<0.0001). The mean IgA level for 38-kDa+LAM also was higher in the TB group (P<0.05). No difference was observed between TB and NTB groups in the titer of IgM antibodies. These findings indicate that TB is associated with the presence of detectable levels of antibodies in BALF. The antibody response is highly heterogeneous. This phenomenon results from the balance between pathogen and host immune system. The tests examined for detection of IgG in BALF can be used in combination with other diagnostic methods to increase diagnostic accuracy of pulmonary TB.

Antibodies, Bacterial↗

PubMed2005

Altered expression of immune surface markers in children with recurrent infections of respiratory tract.

Infections of the respiratory tract are very common in young children. They may affect the quality of life and have a great economic impact. On the other hand, respiratory tract infections through MALT system play a positive role in the maturation and development of the immune system. The aim of the study was to examine quantitative and qualitative changes of T and B cells and granulocytes surface molecules in 24 children with recurrent (more than 8 episodes per year) infections of the respiratory tract and in 18 healthy children. The expression of CD2, CD3, CD4, CD8 on T cells; HLA-DR, CD19, CD5/CD20 on B cells, and CD11a/CD18, CD11b/CD18, CD62L, CD16 on granulocytes from peripheral blood was evaluated by a flow cytometry method. We observed a significant increase in the CD5+/CD20+ positive cells on B cells. We also observed a decreased expression of CD11c+/CD18+ cells, CD11a, and CD62L on granulocytes. The expression of other structures on lymphocytes and the CD11b/CD18+ on granulocytes remained unchanged. CD5+/CD20+ cells constitute a filogenetically old population responsible for the production of IgM of low specificity and affinity for specific antigens. The prevalence of this fetal phenotype population may be explained as a delayed maturation of the humoral immune system leading to increased susceptibility to infections. A lower percentage of CD11a may be related to the blockade of that molecule by rhinoviruses.

Antibody Formation↗

PubMed2004

In vivo activation of STAT3 in cutaneous T-cell lymphoma. Evidence for an antiapoptotic function of STAT3.

A characteristic feature of neoplastic transformation is a perpetual activation of oncogenic proteins. Here, we studied signal transducers and activators of transcription (STAT) in patients with mycosis fungoides (MF)/cutaneous T-cell lymphoma (CTCL). Malignant lymphocytes in dermal infiltrates of CTCL tumors showed frequent and intense nuclear staining with anti-PY-STAT3 antibody, indicating a constitutive activation of STAT3 in vivo in tumor stages. In contrast, only sporadic and faint staining was observed in indolent lesions of patch and plaque stages of MF. Moreover, neoplastic lymphocytes in the epidermal Pautrier abscesses associated with early stages of MF did not express activated STAT3. To address the role of STAT3 in survival/apoptosis, CTCL tumor cells from an advanced skin tumor were transfected with either wild-type STAT3 (STAT3wt) or dominant-negative STAT3 (STAT3D). Forced inducible expression of STAT3D triggered a significant increase in tumor cells undergoing apoptosis, whereas forced expression of STAT3wt or empty vector had no effect. In conclusion, a profound in vivo activation of STAT3 is observed in MF tumors but not in the early stages of MF. Moreover, STAT3 protects tumor cells from apoptosis in vitro. Taken together, these findings suggest that STAT3 is a malignancy factor in CTCL.

Adult↗

PubMed2001

STAT3-mediated constitutive expression of SOCS-3 in cutaneous T-cell lymphoma.

A characteristic feature of neoplastic transformation is the loss of external control by cytokines and extracellular matrix of cellular differentiation, migration, and mitogenesis. Because suppressors of cytokine signaling (SOCS) proteins are negative regulators of cytokine-induced signaling, it has been hypothesized that an aberrant SOCS expression plays a role in neoplastic transformation. This study reports on a constitutive SOCS-3 expression in cutaneous T-cell lymphoma (CTCL) cell lines. SOCS-3 protein is constitutively expressed in tumor cell lines (but not in nonmalignant T cells) obtained from affected skin from a patient with mycosis fungoides (MF) and from peripheral blood from a patient with Sezary syndrome (SS). In contrast, constitutive SOCS-3 expression is not found in the leukemic Jurkat T-cell line, the MOLT-4 acute lymphoblastic leukemia cell line, and the monocytic leukemic cell line U937. Expression of SOCS-3 coincides with a constitutive activation of STAT3 in CTCL tumor cells, and stable transfection of CTCL tumor cells with a dominant negative STAT3 strongly inhibits SOCS-3 expression, whereas transfection with wild-type STAT3 does not. Moreover, the reduced SOCS-3 expression in cells transfected with the dominant negative STAT3 is associated with an increased sensitivity to interferon-alpha (IFN-alpha). In conclusion, evidence is provided for a constitutive SOCS-3 expression in cancer cells obtained from patients with CTCL. Moreover, the findings indicate that the aberrant expression of SOCS-3 is mediated by a constitutive activation of STAT3 in CTCL cells and affects the IFN-alpha sensitivity of these cells. (Blood. 2001;97:1056-1062)

Cell Transformation, Neoplastic↗

PubMed2001

Release of cytokines and soluble cytokine receptors after intravenous anti-D treatment in children with chronic thrombocytopenic purpura.

INTRODUCTION: Immunoglobulin anti-D administration is one of several methods used in treating children with chronic immune thrombocytopenic purpura. Fc receptor blockade of the reticuloendothelial cell system and of mononuclear phagocytes is an important mechanism of the action of anti-D in ITP. Recently other possible mechanisms by which anti-D works in ITP have been considered. METHODS: The aim of this study was to obtain a better understanding of the effect of anti-D administration on cytokine, soluble cytokine receptors and platelet count in children with chronic ITP and to determine the pre-treatment plasma cytokine profile in this group of patients. Eighteen children with chronic ITP were examined. In our study the impact of anti-D on the cytokine network was evaluated by analysing serum levels of IL-6, IL-8, tumor necrosis alpha and soluble TNF receptors I and II by the EASIA method before and 1, 3, 20 and 40 h then seven days and one month after anti-D infusion. RESULTS: Anti-D caused a significant increase in platelet count 20 h postinfusion in 10 out of 18 children, 96 h postinfusion in three children and 168 h postinfusion in one child. The mean duration of the response was four weeks. A significant and rapid increase in plasma levels of IL-6, IL-8 and TNF-alpha was seen within 1 to 20 h after anti-D infusion. This increase was accompanied by a prolonged elevation of soluble TNF receptors. There was a significant correlation between TNF-alpha and IL-8, IL-8 and IL-6, TNF-alpha and sTNFRI, and sTNF receptors I and II. CONCLUSION: These data demonstrate that anti-D infusion caused changes in the cytokine network and raises the question of whether the therapeutic effectiveness of anti-D is related to its immunomodulating properties.

Adjuvants, Immunologic↗

PubMed2001

Expression of CD20 on acute lymphoblastic leukemia cells in children.

CD20 determinant expressed on B precursors is associated with regulation of proliferation, apoptosis and maturation of these cells. The acute lymphoblastic leukemia "common" type (cALL) based on expression of CD20 is subdivided in type I and II. However, the clinical significance of CD20 expression on cALL and significance of cALL type I and II discernment are not fully elucidated. The association of CD20 expression with the expression of multidrug resistance molecule (MDR), CD34, atypical immunophenotypes of leukemia cells and response to induction therapy were determined in the group of 147 patients with acute lymphoblastic leukemia (ALL) B progenitor type (ALL-proB -14 patients) and common type (cALL-133 patients). The expression of CD20 on leukemia cells was studied routinely at diagnosis before the therapy. This expression was noted on leukemia cells of 6 ALL-proB patients (42.8%) and 66 cALL patients (49.6%). The expression of CD20 showed no association with the expression of CD34, CD22 and MDR. The reverse association was observed between CD20 expression and the presence of co-expression of myeloid (CD13, CD33, CD65, CD15) and T lymphoid determinants (CD2, CD5, CD7) on leukemia cells. The effect of induction therapy analyzed as time of blast cells cytoreduction in peripheral blood and time of reaching the complete remission showed the slower clearance of peripheral blood from blast cells associated with expression of CD20. There was no association of CD20 expression with the time of reaching the hematological remission. The above results suggested a "protective" role of CD20 against co-expression of other determinants (myeloid and lymphoid) and no association with the results of induction therapy.

Adolescent↗

PubMed2001

[Assesment of the selected T and B lymphocyte subsets in children with newly diagnosed insulin-dependent diabetes mellitus].

The study was performed in 39 children with newly diagnosed insulin-dependent diabetes mellitus. The %age number of CD19+, CD5+/CD20+ B lymphocytes and CD3+, CD4+, CD8+, CD4+/DR+, CD8+/DR+ T lymphocytes subpopulations were investigated in the peripheral blood. Marked, statistically significant increase (p<0.0001) in CD5+ B lymphocytes was revealed in 77% of patients as compared to the healthy control. The elevated number of CD5+ B lymphocytes correlated with presence of activated lymphocytes T (CD4+/DR+ and CD8+/DR+). The total number of CD19+, CCD3+, CD4+, CD8+ lymphocytes was on comparable level in both groups.

English Abstract↗

PubMed2000

Bcl-2 expression restores the leukemogenic potential of a BCR/ABL mutant defective in transformation.

Growth factor-dependent hematopoietic cell lines expressing the BCR/ABL oncoprotein of the Ph chromosome show growth factor-independent proliferation and resistance to apoptosis. Apoptosis resistance of BCR/ABL-expressing cells may depend on enhanced expression of anti-apoptotic proteins as well as reduced expression and/or inactivation of pro-apoptotic proteins. Compared to myeloid precursor 32Dcl3 cells expressing wild type BCR/ABL, cells expressing a BCR/ABL mutant lacking amino acids 176-426 in the BCR domain (p185 delta BCR) are susceptible to apoptosis induced by interleukin-3 (IL-3) deprivation. These cells exhibited the hypophosphorylated apoptotic BAD and markedly reduced levels of Bcl-2. Upon ectopic expression of Bcl-2, these cells showed no changes in BAD phosphorylation, but they became apoptosis-resistant and proliferated in the absence of IL-3, albeit more slowly than cells expressing wild type BCR/ABL. Moreover, the p185 delta BCR/Bcl-2 double transfectants were leukemogenic when injected into immunodeficient mice, but Bcl-2 expression did not restore the leukemia-inducing effects of p185 delta BCR to the levels of wild type BCR/ABL. Leukemic cells recovered from the spleen of mice injected with p185 delta BCR/Bcl-2 cells did not show rearrangements in the Bcl-2 genomic locus, but they exhibited enhanced proliferation in culture and induced a rapidly fatal disease process when inoculated in secondary recipient mice. Together, these data support the importance of anti-apoptotic pathways for BCR/ABL-dependent leukemogenesis and suggest that Bcl-2 expression promotes secondary changes leading to a more aggressive tumor phenotype. (Blood. 2000;96:3915-3921)

Animals↗

PubMed2000

Granulocyte chemiluminescence activity, antibody production and percentage of CD4(+) and CD8(+) lymphocytes in peripheral blood of offspring of salbutamol-treated pregnant C3H mice.

Preterm delivery is one of the most important problems in obstetric care. One of commonly used treatment of such high risk cases is salbutamol-beta(2) adrenoceptor agonist. The aim of present study was to determine if such treatment causes any changes in neonatal immune system and therefore should be considered in newborn care. The experiments were performed in 4-5- and 6-7-week-old female and male offspring of salbutamol treated C3H inbred mice. In the present study chemiluminescent activity of peripheral blood granulocytes, percentage of CD4(+) and CD8(+) lymphocytes and antibody production were evaluated. A lower number of peripheral blood granulocytes in 6-7-week-old offspring of salbutamol treated mothers was observed, while in the case of younger mice's lymphocytes count in both groups, the differences were not significant as compared to control group. In 4-5-week-old mice a lower percentage of CD4(+), CD3(+) and CD8(+) was evaluated, while in older offspring the percentage of CD4(+) and CD3(+) was higher in the case of the progeny of salbutamol treated mothers. As far as chemiluminescent activity was concerned no differences were found in any of experimental groups. We showed higher IgM production both in male and female offspring of the experimental group and no changes in IgG levels in mice sera. Alterations observed in progeny of salbutamol treated mice might have influence on their further immune system development and function.

Adrenergic beta-Agonists↗

PubMed2000

Thymus and lymph node cell CD4(+) and CD8(+) marker expression and their angiogenic activity of offspring of salbutamol-treated pregnant C3H mice.

Salbutamol, beta(2)-adrenoceptor agonist is a first choice drug in preterm delivery treatment. The aim of the present study was to determine whether salbutamol can cause any alterations in neonatal immune systems and therefore should be considered in newborn care. The experiments were performed on 4-5- and 6-7-week-old female and male offspring of salbutamol-treated C3H inbred mice. Thymus and lymph node weight, cellularity and lymphatic organs, lymphocytes phenotypes and their angiogenic activity were evaluated. We observed lower thymus weight in 6-7-week-old progeny of salbutamol-treated mothers and in the same time lower thymus cell number in both age groups. Lower lymph node weight was developed in older progeny while cellularity was diminished both in 4-5- and 6-7-week-old offspring of salbutamol-treated mothers. We have not detected any changes in percentage of CD4, CD8, CD3 and CD4CD8 positive lymphocytes in progeny of salbutamol-treated mothers. As far as lymph node lymphocytes phenotype is considered we showed in both age groups lowering of CD4 and CD3 positive cells in experimental groups. In the LIA test (lymphocyte-induced angiogenesis) we showed lower lymph node cell angiogenic activity of salbutamol-treated mothers' progeny in both age groups. In the case of thymus lymphocytes we have not observed any alterations in their angiogenic activity. The differences in histological examination of thymus and lymph nodes were not detected in experimental and control groups.

Adrenergic beta-Agonists↗

PubMed2000

Potentiation of the anti-tumour effects of Photofrin-based photodynamic therapy by localized treatment with G-CSF.

Photofrin-based photodynamic therapy (PDT) has recently been approved for palliative and curative purposes in cancer patients. It has been demonstrated that neutrophils are indispensable for its anti-tumour effectiveness. We decided to evaluate the extent of the anti-tumour effectiveness of PDT combined with administration of granulocyte colony-stimulating factor (G-CSF) as well as the influence of Photofrin and G-CSF on the myelopoiesis and functional activity of neutrophils in mice. An intensive treatment with G-CSF significantly potentiated anti-tumour effectiveness of Photofrin-based PDT resulting in a reduction of tumour growth and prolongation of the survival time of mice bearing two different tumours: colon-26 and Lewis lung carcinoma. Moreover, 33% of C-26-bearing mice were completely cured of their tumours after combined therapy and developed a specific and long-lasting immunity. The tumours treated with both agents contained more infiltrating neutrophils and apoptotic cells then tumours treated with either G-CSF or PDT only. Importantly, simultaneous administration of Photofrin and G-CSF stimulated bone marrow and spleen myelopoiesis that resulted in an increased number of neutrophils demonstrating functional characteristics of activation. Potentiated anti-tumour effects of Photofrin-based PDT combined with G-CSF observed in two murine tumour models suggest that clinical trials using this tumour therapy protocol would be worth pursuing.

Adenocarcinoma↗

PubMed1999

Relationship between concussion and neuropsychological performance in college football players.

CONTEXT: Despite the high prevalence and potentially serious outcomes associated with concussion in athletes, there is little systematic research examining risk factors and short- and long-term outcomes. OBJECTIVES: To assess the relationship between concussion history and learning disability (LD) and the association of these variables with neuropsychological performance and to evaluate postconcussion recovery in a sample of college football players. DESIGN, SETTING, AND PARTICIPANTS: A total of 393 athletes from 4 university football programs across the United States received preseason baseline evaluations between May 1997 and February 1999. Subjects who had subsequent football-related acute concussions (n = 16) underwent neuropsychological comparison with matched control athletes from within the sample (n = 10). MAIN OUTCOME MEASURES: Clinical interview, 8 neuropsychological measures, and concussion symptom scale ratings at baseline and after concussion. RESULTS: Of the 393 players, 129 (34%) had experienced 1 previous concussion and 79 (20%) had experienced 2 or more concussions. Multivariate analysis of variance yielded significant main effects for both LD (P<.001) and concussion history (P=.009), resulting in lowered baseline neuropsychological performance. A significant interaction was found between LD and history of multiple concussions and LD on 2 neuropsychological measures (Trail-Making Test, Form B [P=.007] and Symbol Digit Modalities Test [P=.009]), indicating poorer performance for the group with LD and multiple concussions compared with other groups. A discriminant function analysis using neuropsychological testing of athletes 24 hours after acute in-season concussion compared with controls resulted in an overall 89.5% correct classification rate. CONCLUSIONS: Our study suggests that neuropsychological assessment is a useful indicator of cognitive functioning in athletes and that both history of multiple concussions and LD are associated with reduced cognitive performance. These variables may be detrimentally synergistic and should receive further study.

Adolescent↗

PubMed1998

BCR/ABL-mediated leukemogenesis requires the activity of the small GTP-binding protein Rac.

The phenotype of hematopoietic cells transformed by the BCR/ABL oncoprotein of the Philadelphia chromosome is characterized by growth factor-independent proliferation, reduced susceptibility to apoptosis, and altered adhesion and motility. The mechanisms underlying this phenotype are not fully understood, but there is evidence that some of the properties of BCR/ABL-expressing cells are dependent on the activation of downstream effector molecules such as RAS, PI-3k, and bcl-2. We show here that the small GTP-binding protein Rac is activated by BCR/ABL in a tyrosine kinase-dependent manner. Upon transfection with a vector carrying the dominant-negative N17Rac, BCR/ABL-expressing myeloid precursor 32Dcl3 cells retained the resistance to growth factor deprivation-induced apoptosis but showed a decrease in proliferative potential in the absence of interleukin-3 (IL-3) and markedly reduced invasive properties. Moreover, compared with BCR/ABL-expressing cells, fewer BCR/ABL plus N17Rac double transfectants were capable of homing to bone marrow and spleen. Consistent with these findings, survival of SCID mice injected with the BCR/ABL plus N17Rac double transfectants was markedly prolonged as compared with that of mice injected with BCR/ABL-expressing cells. Together, these data support the important role of a Rac-dependent pathway(s) controlling motility in BCR/ABL-mediated leukemogenesis.

Animals↗

PubMed1998

Role of p53 in hematopoietic recovery after cytotoxic treatment.

Prompt reconstitution of hematopoiesis after cytoreductive therapy is essential for patient recovery and may have a positive impact on long-term prognosis. We examined the role of the p53 tumor suppressor gene in hematopoietic recovery in vivo after treatment with the cytotoxic drug 5-fluorouracil (5-FU). We used p53 knock-out (p53-/-) and wild-type (p53+/+) mice injected with 5-FU as the experimental model. Analysis of the repopulation ability and clonogenic activity of hematopoietic stem cells (HSCs) and their lineage-committed descendants showed a greater number of HSCs responsible for reconstitution of lethally irradiated recipients in p53-/- bone marrow cells (BMCs) recovering after 5-FU treatment than in the corresponding p53+/+ BMCs. In post-5-FU recovering BMCs, the percentage of HSC-enriched Lin- Sca-1(+) c-Kit+ cells was about threefold higher in p53-/- than in p53+/+ cells. Although the percentage of the most primitive HSCs (Lin- Sca-1(+) c-Kit+ CD34(low/-)) did not depend on p53, the percentage of multipotential HSCs and committed progenitors (Lin- Sca-1(+) c-Kit+ CD34(high/+)) was almost fourfold higher in post-5-FU recovering p53-/- BMCs than in their p53+/+ counterparts. The pool of HSCs from 5-FU-treated p53-/- BMCs was exhausted more slowly than that from the p53+/+ population as shown in vivo using pre-spleen colony-forming unit (CFU-S) assay and in vitro using long-term culture-initiating cells (LTC-ICs) and methylcellulose replating assays. Clonogenic activity of various lineage-specific descendants was significantly higher in post-5-FU regenerating p53-/- BMCs than in p53+/+ BMCs, probably because of their increased sensitivity to growth factors. Despite all these changes and the dramatic difference in sensitivity of p53-/- and p53+/+ BMCs to 5-FU-induced apoptosis, lineage commitment and differentiation of hematopoietic progenitors appeared to be independent of p53 status. These studies suggest that suppression of p53 function facilitates hematopoietic reconstitution after cytoreductive therapy by: (1) delaying the exhaustion of the most primitive HSC pool, (2) stimulating the production of multipotential HSCs, (3) increasing the sensitivity of hematopoietic cells to growth factors, and (4) decreasing the sensitivity to apoptosis.

Animals↗