Biomedical subjects

Oystein Bruserud

Publications and source records attributed to Oystein Bruserud.

10 recordsLinked to original sources

PubMed2006

Microvascular endothelial cells increase proliferation and inhibit apoptosis of native human acute myelogenous leukemia blasts.

Interactions between acute myelogenous leukemia (AML) blasts and neighbouring endothelial cells in the bone marrow seem important both for disease development and susceptibility to chemotherapy. We investigated the effects of soluble mediators released by microvascular endothelial cells on native human AML cells. AML cells derived from 33 patients were cocultured with microvascular endothelial cells, separated by a semipermeable membrane. We investigated the effect of coculture on AML cell proliferation, viability/apoptosis and cytokine release. Coculture increased AML cell proliferation, and this growth enhancement included the clonogenic leukemia cell subset. Increased release of several soluble mediators was also detected (interleukin 3, interleukin 6, granulocyte-macrophage and granulocyte colony-stimulating factors) in cocultures. Our cytokine neutralization experiments suggest that an intercellular crosstalk involving several soluble mediators contribute to the increased leukemia cell proliferation. The presence of endothelial cells had an additional antiapoptotic effect on the AML cells. The endothelial cells did not have any growth-enhancing effect on native human acute lymphoblastic leukemia cells. Our in vitro results suggest that the release of soluble mediators by microvascular endothelial cells supports leukemic hematopoiesis through paracrine mechanisms by direct enhancement of AML blast proliferation and by inhibition of leukemic cell apoptosis.

Apoptosis↗

PubMed2006

Flt3 Y591 duplication and Bcl-2 overexpression are detected in acute myeloid leukemia cells with high levels of phosphorylated wild-type p53.

Loss or mutation of the TP53 tumor suppressor gene is not commonly observed in acute myeloid leukemia (AML), suggesting that there is an alternate route for cell transformation. We investigated the hypothesis that previously observed Bcl-2 family member overexpression suppresses wild-type p53 activity in AML. We demonstrate that wild-type p53 protein is expressed in primary leukemic blasts from patients with de novo AML using 2-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and phospho-specific flow cytometry. We found that p53 was heterogeneously expressed and phosphorylated in AML patient samples and could accumulate following DNA damage. Overexpression of antiapoptosis protein Bcl-2 in AML cells was directly correlated with p53 expression and phosphorylation on serine residues 15, 46, and 392. Within those patients with the highest levels of Bcl-2 expression, we identified a mutation in FLT3 that duplicated phosphorylation site Y591. The presence of this mutation correlated with greater than normal Bcl-2 expression and with previously observed profiles of potentiated STAT and MAPK signaling. These results support the hypothesis that Flt3-mediated signaling in AML enables accumulation of Bcl-2 and maintains a downstream block to p53 pathway apoptosis. Bcl-2 inhibition might therefore improve the efficacy of existing AML therapies by inactivating this suppression of wild-type p53 activity.

Cells, Cultured↗

PubMed2006

A distinct p53 protein isoform signature reflects the onset of induction chemotherapy for acute myeloid leukemia.

PURPOSE: The antioncogene protein product p53 has not been studied previously in cancer patients during in vivo chemotherapy. This study examined the early p53 protein and gene expression during induction chemotherapy in acute myeloid leukemia (AML). EXPERIMENTAL DESIGN: Leukemic cells were collected from five AML patients during their first 18 hours of induction chemotherapy and examined for p53 protein and gene expression by one- and two-dimensional gel immunoblot and high-density gene expression arrays. RESULTS: Up-regulation of p53 protein expression was detected in AML patients posttreatment in vivo. One- and two-dimensional gel immunoblots showed two main forms of p53, denominated alpha p53 and delta p53, both recognized by various NH2-terminal directed antibodies. As a response to treatment, we detected rapid accumulation of alpha p53, with significantly altered protein expression levels already after 2 hours. The accumulation of alpha p53 was accompanied by increased transcription of putative p53 target genes and subsequent cytopenia in the patients. CONCLUSION: Up-regulation of the p53 protein and target genes seems to be a prominent feature in induction chemotherapy of AML. The rapid shift from a shorter p53 protein form (delta) toward the full-length protein (alpha) underscores the complexity of p53 protein modulation in patients undergoing chemotherapy.

Acute Disease↗

PubMed2006

A phase II trial of pegylated interferon alpha-2b therapy for polycythemia vera and essential thrombocythemia: feasibility, clinical and biologic effects, and impact on quality of life.

BACKGROUND: Conventional interferon-alpha (IFN) is an effective treatment for patients with myeloproliferative disorders. However, many patients discontinue therapy because of side effects. METHODS: In this 24-month, Phase II feasibility study of pegylated interferon alpha-2b (PEG-IFN) treatment, a starting dose of 0.5 microg/kg per week was received by 21 patients with polycythemia vera (PV) and 21 patients with essential thrombocythemia (ET). The treatment objective, a complete platelet response (CR), was a platelet count<400x10(9)/L in symptomatic patients and <600 in asymptomatic patients. Neutrophil polycythemia rubra vera-1 (PRV-1) messenger RNA expression was analyzed prior to and during therapy. Quality of life (QoL) was investigated by using the European Organization for Research and Treatment of Cancer QLQ-C30 questionnaire. RESULTS: At 6 months, 29 of 42 patients (69%) had achieved a CR after a median of 83 days. The CR rate was not related to diagnosis, gender, or previous therapy. Nineteen patients completed the planned 2-year treatment in CR. No thromboembolic or bleeding complications were observed. Phlebotomy requirements were reduced in the majority of patients with PV. Five of 14 patients (36%) who initially were positive for PRV-1 achieved normalized PRV-1 expression under PEG-IFN treatment. Side effects were the cause of therapy failure in 16 of 23 patients. However, only 8 of 19 patients reported any side effects at 2 years. The QLQ-C30 revealed clinically significant impairments in several aspects of QoL at 6 months; however, at 2 years, QoL measurements were not different from baseline. CONCLUSIONS: PEG-IFN effectively reduced platelet counts in 29 of 42 patients, but only 19 patients maintained a CR at 2 years. The reversal of PRV-1 positivity noted in a subset of patients suggested that PEG-IFN may have an effect on the malignant clone. PEG-IFN is a valuable therapeutic alternative for patients who tolerate its initial side effects.

Adult↗

PubMed2006

Cytokine accumulation in photochemically treated and gamma-irradiated platelet concentrates during storage.

BACKGROUND: Photochemical treatment (PCT) for pathogen reduction of platelet concentrates (PCs) affects all cells containing DNA and/or RNA. Soluble mediators, which may cause transfusion reactions, are determined by the balance between secretion and/or cell destruction and binding and/or degradation. STUDY DESIGN AND METHODS: Ten double-dose single-donor leukoreduced PCs were split in two identical units. Two study arms were created: Study Arm A consisting of five PCT PCs with corresponding untreated control PCs and Study Arm B consisting of five PCT PCs with corresponding gamma-irradiated control PCs. PCs that had added PAS-III (Intersol) were treated with amotosalen and ultraviolet A light. Corresponding controls PCs, to which PAS-II (T-sol) were added, received no treatment or were gamma-irradiated before storage. Platelet (PLT)-derived (CCL5/RANTES, CXCL4/PF4, CCL3/MIP-1alpha, transforming growth factor [TGF]-beta, CXCL8/interleukin [IL]-8, IL-1beta) as well as white blood cell (WBC)-associated (IL-6, IL-10, IL-11, IL-12, tumor necrosis factor, interferon-gamma) cytokines were investigated by enzyme-linked immunosorbent assay and cytometric bead array during storage for up to 12 days. RESULTS: Independent of previous treatment we observed that all concentrates showed low levels of WBC-associated cytokines. PLT-derived cytokines were detected at higher levels and showed significant increase during storage. Statistical analysis showed lower PLT content per unit in PCT PCs, higher levels of activation variables in PCT PCs, and higher levels and accumulation rate of CCL5, CXCL4, TGF-beta, and CXCL8 in PCT PCs. CONCLUSION: PLTs are the main source of released cytokines during storage of untreated, gamma-irradiated, and PCT PCs. PCT may affect the level of PLT-derived cytokines in PCs. No additional reduction of WBC-associated cytokines were observed after PCT in prestorage leukoreduced PCs.

Blood Platelets↗

PubMed2005

In vitro culture of human osteosarcoma cell lines: a comparison of functional characteristics for cell lines cultured in medium without and with fetal calf serum.

PURPOSE: Experimental in vitro models including well-characterised cell lines can be used to identify possible new therapeutic targets for the treatment of osteosarcoma. Culture media including inactivated serum is often recommended for in vitro culture of osteosarcoma cells, but the serum component then represents a nonstandardised parameter including a wide range of unidentified mediators. To improve the standardisation we have investigated whether serum-free culture media can be used in experimental in vitro studies of osteosarcoma cell lines. METHODS: The seven osteosarcoma cell lines Cal72, SJSA-1, Saos-2, SK-ES-1, U2OS, 143.98.2, and KHOS-32IH were cultured in vitro in various serum-free media and media supplemented with 10% heat-inactivated fetal calf serum (FCS). RESULTS: Although proliferation often was relatively low in serum-free media (X-vivo 10, X-vivo 15, X-vivo 20, Stem Span SFEM), some cell lines (Cal72, KHOS-32IH, Saos-2) showed proliferation comparable with the recommended FCS-containing media even when using serum-free conditions. The optimal serum-free medium then varied between cell lines. We also compared 6 different FCS-containing media (including Stem Span with 10% FCS) and the optimal FCS-containing medium varied between cell lines. However, all cell lines proliferated well in Stem Span with FCS, and this medium was regarded as optimal for four of the lines. FCS could not be replaced by fatty acids or low density lipoprotein when testing the Stem Span medium. The release of a wide range of soluble mediators showed only minor differences when using serum-free and FCS-containing media (including Stem Span with and without FCS), and serum-free Stem Span could also be used for in vitro studies of mitogen-stimulated T cell activation in the presence of accessory osteosarcoma cells. The use of Stem Span with 10% FCS allowed the release of a wide range of chemokines by osteosarcoma cell lines (Cal72, SJSA-1), and the chemokine release profile was very similar to the fibroblast lines Hs27 and HFL1. CONCLUSIONS: Serum-free culture media can be used for in vitro studies of several osteosarcoma cell lines, but the optimal medium varies between cell lines and thus depends on: (i) the cell lines to be investigated/compared; (ii) the functional characteristic that is evaluated (proliferation, cytokine release); and (iii) whether coculture experiments are included.

Acute Disease↗

PubMed2005

CD34 expression in native human acute myelogenous leukemia blasts: differences in CD34 membrane molecule expression are associated with different gene expression profiles.

BACKGROUND: The stem cell marker CD34 is expressed by leukemia blasts only for a subset of patients with acute myelogenous leukemia (AML). It is still controversial as to whether CD34 expression (defined as at least 10-20% positive cells) has any prognostic effect in patients with AML who receive intensive chemotherapy. The present study investigated whether gene expression profiling could be used to further subclassify CD34(+) AML cell populations. METHODS: AML blasts derived from 25 patients were examined; these patients were randomly selected from a larger consecutive group of patients. CD34 protein expression was determined by flow cytometry and expressed as the percentage of positive cells. Gene expression profiles were determined by complementary DNA microarrays. RESULTS: By unsupervised hierarchical clustering our patients could be grouped into two or three major subsets depending on the methodologic approach before clustering analysis (filtering or flooring of data, respectively). However, both approaches identified a cluster characterized by high gene expression and membrane molecule level of CD34. When using the floored expression profiles, the patient cluster characterized by increased CD34 gene expression was also characterized by a high percentage of CD34(+) cells (median 82%, range 56-100%) compared with the two other major clusters (median 19%, range <1-55%), but three of four outpatients also showed a high percentage of CD34(+) cells. CONCLUSION: A major proportion of patients with AML and high CD34 expression (usually >80% CD34(+) cells; nearly all patients had >50% positive cells) showed similarities in gene expression profile. In contrast, patients with lower CD34 expression often had a profile similar to those of patients regarded as CD34(-) according to conventional criteria. Our results suggest that the possible prognostic effect of CD34 expression should be reevaluated in clinical studies using additional or alternative cutoff values to describe CD34 expression.

Adult↗

PubMed2005

In vitro crosstalk between fibroblasts and native human acute myelogenous leukemia (AML) blasts via local cytokine networks results in increased proliferation and decreased apoptosis of AML cells as well as increased levels of proangiogenic Interleukin 8.

Interactions between native human acute myelogenous leukemia (AML) blasts and nonleukemic cells in the bone marrow microenvironment seem important both for disease development chemosensitivity. Native human AML blasts from consecutive patients were cultured with normal human bone marrow stromal cells and two fibroblast lines (HFL1 and Hs27) separated by a semipermeable membrane. This bidirectional crosstalk via the cytokine network between AML blasts and fibroblasts caused (i) increased proliferation, (ii) mediated antiapoptotic signalling and (iii) increased local levels of proangiogenic IL8.

Adult↗

PubMed2003

Human acute lymphoblastic leukemia (ALL) blasts as accessory cells during T-cell activation: differences between patients in costimulatory capacity affect proliferative responsiveness and cytokine release by activated T cells.

The ability of acute lymphoblastic leukemia (ALL) blasts to mediate costimulatory signals during T-lymphocyte activation was investigated in an experimental model in which monoclonal T-cell populations were stimulated with standardized activation signals (anti-CD3 and anti-CD28 monoclonal antibodies; phytohemagglutinin, PHA). Leukemia cells from 12 consecutive ALL patients with high peripheral blood blast counts were studied. Proliferative T-cell responses were detected for a majority of these patients when irradiated leukemia blasts were used as accessory cells during activation. T-cell cytokine release was also observed for most patients when using nonirradiated ALL accessory cells. Low or undetectable cytokine levels were usually observed for CD8+ clones, whereas the CD4+ clones often showed a broad cytokine response with release of interleukin-2 (IL-2), IL-4, IL-10, IL-13 and interferon gamma(IFN-gamma) in the presence of the ALL accessory cells. ALL blasts were also able to function as allostimulatory cells for normal peripheral blood mononuclear responder cells. However, both T-cell proliferation and cytokine release showed a wide variation between ALL patients. The accessory cell function of ALL blasts showed no correlation with the release of immunomodulatory mediators (IL-2, IL-10, IL-15) or the expression of any single adhesion/costimulatory membrane molecule (CD54, CD58, CD80, CD86) by the blasts. We conclude that for a majority of patients, native ALL blasts can mediate costimulatory signals needed for accessory cell-dependent T-cell activation, but differences in costimulatory capacity between ALL patients affects both the proliferative responsiveness and cytokine release by activated T cells.

Adolescent↗

PubMed2002

Acute myelogenous leukemia with internal tandem duplication of the Flt3 gene appearing or altering at the time of relapse: a report of two cases.

Detection of Flt3-internal tandem duplication (ITD) in acute myelogenous leukemia (AML) blasts at the time of diagnosis is associated with an increased risk of leukemia relapse after chemotherapy. In the present report, we describe two patients with Flt3-abnormalities that were only detectable at the time of relapse. One of the patients had an ITD at the time of diagnosis (duplicated region 41-133 numbered from the start of exon 14 plus CGG insertion), but at the time of relapse a new abnormality (duplicated region 70-230 plus insertion GGGGAGT) was detected as the only Flt3-abnormality. The second patient showed no Flt3-ITD at the time of diagnosis, but ITD was detected at the time of relapse (duplicated region 12-96, no insertion). Our observations of independent Flt3-ITD and the detection of new Flt3-abnormalities at the time of relapse suggest that (i) Flt3-gene abnormalities may be even more important in the pathogenesis of chemotherapy-resistant AML than suggested from previous studies of newly diagnosed AML, and (ii) monitoring of minimal residual disease by using patient-specific real-time polymerase chain reaction assays for Flt3-abnormalities may not be reliable.

Adult↗