Der p, IL-4, and TGF-beta cooperatively induce EGFR-dependent TARC expression in airway epithelium

Thymus and Activation-Regulated Chemokine (TARC) may be critical in Th2 cell recruitment in allergic inflammation; however, the mechanisms of allergen-induced TARC release are unclear. Since airway epithelium is the first line of defense to inhaled allergens, we questioned whether house dust mite allergen (Der p) can induce TARC expression in bronchial epithelial cells, how this is regulated at the molecular level, and if micro-environmental cytokines augment this effect. We examined the effects of Der p and the cytokines IL-4 and TGF-beta on TARC expression in 16HBE cells and primary bronchial asthma epithelium. Real-time PCR and immunofluorescence demonstrated that Der p induces TARC expression in bronchial epithelium. Supernatants from Der p-stimulated 16HBE cells were able to induce TARC-dependent T cell trafficking. IL-4 and TGF-beta cooperatively enhanced Der p-induced TARC expression in 16HBE cells. Specific inhibitors, immunodetection, and gel-shifts revealed that these effects are mediated by phosphorylation of the epidermal growth factor receptor (EGFR), mitogen-activated protein kinase (MAPK) signaling and subsequent nuclear factor (NF)-kappaB activation. A Disintegrin And Metalloproteinase (ADAM), a family of proteins involved in shedding of various growth factors, was shown to be responsible for EGFR activation. The increase in TARC production by direct interaction of Der p with the bronchial epithelium may be an important initial step in the generation of allergic inflammation, which is further potentiated by micro-environmental cytokines. Interference with ADAM or EGFR activity may be a novel promising target to prevent TARC release and subsequent allergic inflammation.

18F-FLT PET in hematologic disorders: a novel technique to analyze the bone marrow compartment

Few diagnostic procedures are available to determine the degree of bone marrow cellularity and the numbers of cycling cells in patients with bone marrow disorders. Noninvasive imaging of the bone marrow compartment may be helpful. The PET tracer 3'-fluoro-3'-deoxy-L-thymidine (18F-FLT) has been developed recently. 18F-FLT uptake is related to the rate of DNA synthesis and increases with higher proliferation rates in many types of cancer. Background uptake of 18F-FLT in bone marrow is common. 18F-FLT PET might, therefore, visualize the high cycling activity of hematopoietic cells in the bone marrow compartment. Therefore, we investigated the feasibility of visualization and quantification of the activity of the bone marrow compartment with 18F-FLT PET to distinguish different hematologic disorders.

METHODS

Clinical and laboratory data of 18 patients with myelodysplasia (MDS), chronic myeloproliferative disorders, myelofibrosis, aplastic anemia, or multiple myeloma were correlated with the results of 18F-FLT PET using visual analysis and the standardized uptake value (SUV). Findings were compared with those of healthy control subjects (n = 14).

RESULTS

With SUV and visual analysis, a distinction could be made between MDS (n = 9), chronic myeloproliferative disorders (n = 3), and myelofibrosis (n = 3) compared with healthy control subjects. A significant increase in 18F-FLT uptake was observed in all of the studied patients with MDS and myeloproliferative disorders. In contrast, patients with myelofibrosis and aplastic anemia (n = 1) demonstrated a decline in bone marrow 18F-FLT uptake compared with healthy control subjects. Comparable results were observed in osteolytic lesions of patients with multiple myeloma (n = 2).

CONCLUSION

18F-FLT PET can be used to visualize the proliferative activity of the bone marrow compartment and may be helpful to distinguish separate hematologic disorders.

Early FDG-PET assessment in combination with clinical risk scores determines prognosis in recurring lymphoma

This study was set up to demonstrate whether prognostic classification based on the secondary age-adjusted International Prognostic Index (sAA-IPI) for recurring aggressive non-Hodgkin lymphoma (NHL) or the prognostic score for recurring Hodgkin lymphoma (HL) can be improved by including the midtreatment results of fluorine-18-fluorodeoxy-glucose-positron emission tomography (FDG-PET). Clinical data on patients with recurring lymphoma who were treated with second-line chemotherapy (DHAP-VIM-DHAP) followed by autologous stem cell transplantation (ASCT) were collected and combined with the results of FDG-PET performed before and after 2 cycles of reinduction chemotherapy. PET responses after 2 courses were scored as complete remission (CR), partial remission (PR), or no response (NR). A multivariate analysis was performed to design a predictive model. The number of patients (101 of 117) included those (78 patients with aggressive NHL and 23 patients with HL) that could be analyzed according to protocol. Of these, 80 patients were chemosensitive and 77 received transplants. Both secondary clinical risk score (P<.001) and FDG-PET response (P<.001) were independent predictive factors for the total evaluable group of patients with lymphoma and for patients with NHL alone. The combined use of the clinical risk score and FDG-PET response after 2 chemotherapy courses identified at least 4 categories of patients with a failure-free survival varying between 5% to 100% after transplantation (P<.001). These data indicate that the secondary clinical risk score in conjunction with FDG-PET response provides a more accurate prognostic instrument for the outcome of second-line treatment at least in patients with recurring NHL.

Megakaryocytic dysfunction in myelodysplastic syndromes and idiopathic thrombocytopenic purpura is in part due to different forms of cell death

Platelet production requires compartmentalized caspase activation within megakaryocytes. This eventually results in platelet release in conjunction with apoptosis of the remaining megakaryocyte. Recent studies have indicated that in low-risk myelodysplastic syndromes (MDS) and idiopathic thrombocytopenic purpura (ITP), premature cell death of megakaryocytes may contribute to thrombocytopenia. Different cell death patterns have been identified in megakaryocytes in these disorders. Growing evidence suggests that, besides apoptosis, necrosis and autophagic cell death, may also be programmed. Therefore, programmed cell death (PCD) can be classified in apoptosis, a caspase-dependent process, apoptosis-like, autophagic and necrosis-like PCD, which are predominantly caspase-independent processes. In MDS, megakaryocytes show features of necrosis-like PCD, whereas ITP megakaryocytes demonstrate predominantly characteristics of apoptosis-like PCD (para-apoptosis). Triggers for these death pathways are largely unknown. In MDS, the interaction of Fas/Fas-ligand might be of importance, whereas in ITP antiplatelet autoantibodies recognizing common antigens on megakaryocytes and platelets might be involved. These findings illustrate that cellular death pathways in megakaryocytes are recruited in both physiological and pathological settings, and that different forms of cell death can occur in the same cell depending on the stimulus and the cellular context. Elucidation of the underlying mechanisms might lead to novel therapeutic interventions.

Selective expression of cholesterol metabolism genes in normal CD34+CD38- cells with a heterogeneous expression pattern in AML cells

OBJECTIVE

To identify adenosine triphosphate-binding-cassette (ABC) transporters that are selectively expressed in normal and/or leukemic CD34+CD38- stem cells.

METHODS

Microarray experiments on murine stem cells identified 13 ABC transporters with a high expression level. Corresponding human transporters were analyzed in normal CD34+CD38- and CD34+CD38+ bone marrow cells by quantitative reverse transcriptase polymerase chain reaction.

RESULTS

Five ABC transporters, including ABCG1, were differentially expressed with a higher expression in CD34+CD38- cells. Besides ABCG1, known to be involved in cholesterol metabolism, expression of another major cholesterol transporter (ABCA1), some cholesterol metabolism genes (3-hydroxy-3-methyl-glutaryl-CoA reductase, low-density lipoprotein receptor), and the transcription factor controlling ABCA1 and ABCG1 expression, liver-X-receptor-alpha (LXR-alpha), were assessed. All these genes were predominantly expressed in the more primitive subpopulation, indicating a high rate of cholesterol metabolism and transport. Conversely in acute myeloid leukemia (AML), a heterogeneous expression pattern was found consisting of a considerably higher expression of particularly LXR-alpha in CD34+ cells and a reverse expression pattern in a subset of AML CD34+CD38+ cells.

CONCLUSION

These data suggest an active cholesterol metabolism and efflux in normal CD34+CD38- cells, although a subgroup of AMLs potentially demonstrate a hyperactive cholesterol metabolism.

STAT5-induced self-renewal and impaired myelopoiesis of human hematopoietic stem/progenitor cells involves down-modulation of C/EBPα

Previously, we demonstrated that enforced activation of signal transducer and activator of transcription 5 (STAT5A) in human cord blood (CB)–derived stem/progenitor cells results in enhanced self-renewal and impaired myelopoiesis. The present study identifies C/EBPα as a critical component that is down-regulated by STAT5. Microarray and reverse transcriptase–polymerase chain reaction (RT-PCR) analysis on STAT5A1*6-transduced CD34+ cells identified C/EBPα as the most prominently down-regulated gene. To determine the cell-biological relevance of these observations, a 4-OHT-inducible C/EBPα-ER protein was co-expressed with the STAT5A1*6 mutant in CB CD34+ cells using a retroviral approach. Re-expression of C/EBPα in STAT5A1*6 cells resulted in a marked restoration of myelopoiesis. The proliferative advantage imposed on CD34+ cells by STAT5A1*6 depended on the down-modulation of C/EBPα, as reintroduction of C/EBPα induced a quick cell-cycle arrest and the onset of myeloid differentiation. Long-term culture–initiating cell (LTC-IC) frequencies were elevated from 0.8% ± 0.6% to 7.8% ± 1.9% by STAT5A1*6 as compared with controls, but these elevated LTC-IC frequencies were strongly reduced upon re-introduction of C/EBPα in STAT5A1*6 cells, and no second cobble-stone area–forming cells (CAFCs) could be generated from double-transduced cells. Enumeration of progenitors revealed that the number of colony-forming cells (CFCs) was reduced more than 20-fold when C/EBPα was co-expressed in STAT5A1*6 cells. Our data indicate that down-modulation of C/EBPα is a prerequisite for STAT5-induced effects on self-renewal and myelopoiesis.

The role of serial pre-transplantation positron emission tomography in predicting progressive disease in relapsed lymphoma

BACKGROUND AND OBJECTIVES

18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) appears to be an excellent tool for evaluating early response to chemotherapy in lymphoma patients. As only chemosensitive patients with relapsed lymphoma may benefit from ablative therapy and autologous stem cell transplantation (ASCT), PET may be used to select patients for ASCT. A prospective study was performed to investigate the optimal time point of pre-transplantation PET, using different PET-parameters.

DESIGN AND METHODS

Three serial whole-body attenuation-corrected FDG-PET scans were performed in 39 consecutive patients with relapsed lymphoma (28 with aggressive non-Hodgkin's lymphoma and 11 with Hodgkin's disease) eligible for second-line chemotherapy followed by ASCT: PET1 before treatment, PET2 after two cycles of induction chemotherapy and PET3 after a third cycle of chemotherapy just before ASCT in cases with an abnormal PET2. Visual analysis and standardized uptake value (SUV) parameters were obtained for each scan. The follow-up lasted a minimum of 6 months after ASCT.

RESULTS

PET2 normalized in 43% (17/39) of the patients, and PET3 normalized in 27% (6/22). Persistent abnormal FDG-uptake was observed in 41% of the patients: 15% showed partial remission and 26% stable or even progressive abnormalities. With a median follow-up of 22 months (range 6-55) 54% of all patients relapsed after ASCT. The results demonstrated that those patients who showed a complete response after the second and third cycles of chemotherapy had a 2-year progression-free survival of 71% and 58%, respectively, while those who showed no response, all relapsed shortly after ASCT. Analysis of the SUV parameters did not reveal additional information compared to that yielded by the visual assessment.

INTERPRETATION AND CONCLUSIONS

Two serial PET scans predict outcome after ASCT more precisely than one interim PET in patients with relapsed lymphoma.

Diagnostic performance of 123I-labeled serum amyloid P component scintigraphy in patients with amyloidosis

PURPOSE

To assess the diagnostic accuracy and additional information provided by 123I-labeled serum amyloid P component (SAP) scintigraphy in patients with systemic and localized amyloidosis.

SUBJECTS AND METHODS

123I-labeled human SAP was injected intravenously into 20 controls and 189 consecutive patients with histologically proven amyloidosis: of AA type in 60 cases, AL type in 80, hereditary ATTR type in 27, and localized amyloidosis in 22 cases. SAP scintigrams were obtained 24 hours after tracer injection and were analyzed for abnormal patterns of uptake. Sensitivity and specificity were determined, and scintigraphic findings were compared with clinical data.

RESULTS

Diagnostic sensitivity of SAP scintigraphy for systemic AA, AL, and ATTR amyloidosis was 90%, 90%, and 48% respectively, and specificity was 93%. The distribution of amyloid was less diverse in AA than in AL type. Myocardial uptake was not visualized in any patient. Splenic amyloid was very frequent (80%) in AA and AL type but rarely detected clinically (14%). Abnormal tracer uptake in the liver and kidneys correlated with disturbed liver function and proteinuria, respectively. Bone marrow uptake was specific for AL (21%) and was more frequent in AL kappa than AL lambda. Localized amyloid deposits were not imaged.

CONCLUSION

SAP scintigraphy is diagnostic of amyloid in most patients with AA and AL type but fewer with hereditary ATTR type, relating to differing distributions and burdens of amyloid in these disorders. It usually reveals more widespread organ involvement than is identified clinically, and certain distributions of amyloid are characteristic of particular fibril types.

Fibroblast growth factor-1 and -2 preserve long-term repopulating ability of hematopoietic stem cells in serum-free cultures

In this study, we demonstrate that extended culture of unfractionated mouse bone marrow (BM) cells, in serum-free medium, supplemented only with fibroblast growth factor (FGF)-1, FGF-2, or FGF-1 +2 preserves long-term repopulating hematopoietic stem cells (HSCs). Using competitive repopulation assays, high levels of stem cell activity were detectable at 1, 3, and 5 weeks after initiation of culture. FGFs as single growth factors failed to support cultures of highly purified Lin(-)Sca-1(+)c-Kit(+)(LSK) cells. However, cocultures of purified CD45.1 LSK cells with whole BM CD45.2 cells provided high levels of CD45.1 chimerism after transplant, showing that HSC activity originated from LSK cells. Subsequently, we tested the reconstituting potential of cells cultured in FGF-1 + 2 with the addition of early acting stimulatory molecules, stem cell factor +interleukin-11 + Flt3 ligand. The addition of these growth factors resulted in a strong mitogenic response, inducing rapid differentiation and thereby completely overriding FGF-dependent stem cell conservation. Importantly, although HSC activity is typically rapidly lost after short-term culture in vitro, our current protocol allows us to sustain stem cell repopulation potential for periods up to 5 weeks.

Mammalian Target of Rapamycin Is Required for Thrombopoietin-Induced Proliferation of Megakaryocyte Progenitors

Thrombopoietin (TPO) is a potent regulator of megakaryopoiesis and stimulates megakaryocyte (MK) progenitor expansion and MK differentiation. In this study, we show that TPO induces activation of the mammalian target of rapamycin (mTOR) signaling pathway, which plays a central role in translational regulation and is required for proliferation of MO7e cells and primary human MK progenitors. Treatment of MO7e cells, human CD34+, and primary MK cells with the mTOR inhibitor rapamycin inhibits TPO-induced cell cycling by reducing cells in S phase and blocking cells in G0/G1. Rapamycin markedly inhibits the clonogenic growth of MK progenitors with high proliferative capacity but does not reduce the formation of small MK colonies. Addition of rapamycin to MK suspension cultures reduces the number of MK cells, but inhibition of mTOR does not significantly affect expression of glycoproteins IIb/IIIa (CD41) and glycoprotein Ib (CD42), nuclear polyploidization levels, cell size, or cell survival. The downstream effectors of mTOR, p70 S6 kinase (S6K) and 4E-binding protein 1 (4E-BP1), are phosphorylated by TPO in a rapamycin- and LY294002-sensitive manner. Part of the effect of the phosphatidyl inositol 3-kinase pathway in regulating megakaryopoiesis may be mediated by the mTOR/S6K/4E-BP1 pathway. In conclusion, these data demonstrate that the mTOR pathway is activated by TPO and plays a critical role in regulating proliferation of MK progenitors, without affecting differentiation or cell survival.

Identification of quantitative trait loci regulating haematopoietic parameters in B6AKRF2 mice

The haematopoietic system is a complex organised tissue with a hierarchical structure. Identification of organisational pathways within the haematopoietic system is relevant for a better understanding of haematopoiesis in health and disease. We have analysed numerous haematopoietic parameters in two panels of a total of 157 genetically distinct B6AKRF2 mice, derived from an intercross between AKR and C57Bl/6 mice, strains known to differ in various stem cell traits. The major objective of our study was to assess the extent to which various haematopoietic parameters, such as stem cell numbers, progenitor cell cycling, progenitor cell mobilisation and neutrophil numbers in blood and bone marrow are coregulated. The genotypes of these mice were used to search for genetic loci that regulate these parameters. We found significant quantitative trait loci (QTL) associated with the number of stem cells (CAFC-35) in the bone marrow and the number of neutrophils in the blood. However, most haematopoietic parameters appeared to be controlled by non-heritable (epigenetic) factors, or by multiple QTLs. Our study reveals striking differences in structure of the haematopoietic hierarchy between individual mice. Surprisingly, stem and progenitor cell pool size and proliferation rate, as well as peripheral blood cell counts are all independently regulated.

Expression of Multidrug Resistance–Associated Proteins Predicts Prognosis in Childhood and Adult Acute Lymphoblastic Leukemia

PURPOSE

Patients with acute lymphoblastic leukemia (ALL) are treated with a variety of chemotherapeutic drugs, which can be transported by six multidrug resistance-associated proteins (MRP). These MRPs have strongly overlapping functional activities. The aim of this study was to investigate the expression levels of MRP1 to MRP6 and study their effect on prognosis.

EXPERIMENTAL DESIGN

The mRNA expression levels of MRP1 to MRP6 were analyzed by quantitative real-time PCR in leukemic blasts of 105 de novo ALL patients (adults, n=49; children, n=56) including 70% B-lineage and 30% T-lineage ALL patients.

RESULTS

Adults showed a higher expressions of MRP1 (P=0.008), MRP2 (P=0.026), and MRP3 (P=0.039) than children. Interestingly, this difference disappeared when patients were categorized based on clinical outcome. Relapsed patients showed a higher expression of all MRP genes, except MRP4. For the total group of ALL patients, the expressions of MRP1, MRP2, MRP3, MRP5, and MRP6 predicted relapse. Moreover, high expression of all MRP genes, except MRP4, was associated with a reduced relapse-free survival in children and adults (MRP1, P=0.005; MRP2, P=0.008; MRP3, P=0.001; MRP5, P=0.016; MRP6, P=0.037).

CONCLUSIONS

The present study shows that a subset of ALL patients with high MRP expression has an unfavorable prognosis independently of age.

Feasibility of withholding antibiotics in selected febrile neutropenic cancer patients

PURPOSE

To investigate the feasibility of withholding antibiotics and early discharge for patients with chemotherapy-induced neutropenia and fever at low risk of bacterial infection by a new risk assessment model.

PATIENTS AND METHODS

Outpatients with febrile neutropenia were allocated to one of three groups by a risk assessment model combining objective clinical parameters and plasma interleukin 8 level. Patients with signs of a bacterial infection and/or abnormal vital signs indicating sepsis were considered high risk. Based on their interleukin-8 level, remaining patients were allocated to low or medium risk for bacterial infection. Medium-risk and high-risk patients received standard antibiotic therapy, whereas low-risk patients did not receive antibiotics and were discharged from hospital after 12 hours of a febrile observation. End points were the feasibility of the treatment protocol.

RESULTS

Of 196 assessable episodes, 76 (39%) were classified as high risk, 84 (43%) as medium risk, and 36 (18%) as low risk. There were no treatment failures in the low-risk group (95% CI, 0% to 10%). Therefore, sensitivity of our risk assessment model was 100% (95% CI, 90% to 100%), the specificity, positive, and negative predictive values were 21%, 13%, and 100%, respectively. Median duration of hospitalization was 3 days in the low-risk group versus 7 days in the medium- and high-risk groups (P < .0001). The incremental costs of the experimental treatment protocol amounted to a saving of 471 (US $572) for every potentially low-risk patient.

CONCLUSION

This risk assessment model appears to identify febrile neutropenic patients at low risk for bacterial infection. Antibiotics can be withheld in well-defined neutropenic patients with fever.

Stem cell factor synergistically enhances thrombopoietin-induced STAT5 signaling in megakaryocyte progenitors through JAK2 and Src kinase

Stem cell factor (SCF) has a potent synergistic effect during megakaryopoiesis when administered in combination with the major megakaryocytic cytokine, thrombopoietin (TPO). In this study we analyzed the underlying mechanisms with regard to STAT5 activity. TPO stimulation of MO7e cells resulted in STAT5 transactivation, which could be enhanced 1.6-fold by costimulation with SCF, whereas SCF alone did not induce STAT5 transcriptional activity. This costimulatory effect of SCF was reflected in an increase in TPO-induced STAT5 DNA binding and increased and prolonged STAT5 tyrosine phosphorylation in both MO7e cells and primary human megakaryocyte progenitors. In contrast, serine phosphorylation of STAT5 was constitutive and associated with an inhibitory effect on STAT5 transactivation. Signal transduction pathways that might synergize in TPO-mediated STAT5 transactivation were analyzed using specific pharmacological inhibitors and indicated an essential role for Janus-activated kinase 2 (JAK2) and a partial role for Src-family kinases. Costimulation with SCF was found to increase and prolong tyrosine phosphorylation of JAK2 and the TPO receptor c-mpl. In addition, the Src kinase inhibitor SU6656 partially downregulated the additional effect of SCF costimulation on STAT5 tyrosine phosphorylation. SCF-induced enhancement of JAK2 phosphorylation was not affected by inhibition of Src kinase, suggesting that both JAK2 and Src kinase mediate STAT5 tyrosine phosphorylation. Synergistic activation of JAK2 and Src kinase may thus contribute to the enhanced STAT5 signaling in the presence of TPO and SCF.

Levels of Hematopoiesis InhibitorN-Acetyl-Seryl-Aspartyl-Lysyl-Proline Partially Explain the Occurrence of Anemia in Heart Failure

BACKGROUND

Anemia is common in patients with chronic heart failure (CHF) and is associated with a poor prognosis. However, only a minority of patients with CHF have impaired renal function or underlying hematinic deficiencies. It has been shown that inhibition of the renin-angiotensin system is associated with the development of anemia. The aim of the present study was to determine possible mechanisms linking anemia to renin-angiotensin system activity in CHF patients.

METHODS AND RESULTS

We initially evaluated 98 patients with advanced stable CHF who were treated with ACE inhibitors (left ventricular ejection fraction, 28+/-1%; age, 69+/-1 years; 80% male), 10 of whom had an unexplained anemia (normal hematinics and no renal failure). These 10 anemic patients were matched with 10 nonanemic patients in terms of age and left ventricular ejection fraction. Serum ACE activity was 73% lower in anemic CHF patients compared with nonanemic CHF patients (P=0.018). Moreover, serum of these patients inhibited in vitro the proliferation of bone marrow-derived erythropoietic progenitor cells of healthy donors by 17% (P=0.003). Levels of the hematopoiesis inhibitor N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), which is almost exclusively degraded by ACE, were significantly higher in anemic CHF patients and were clearly correlated to erythroid progenitor cell proliferation (r=-0.64, P=0.001).

CONCLUSIONS

Serum ACE activity is markedly lower in anemic CHF patients, and serum of these patients inhibits hematopoiesis. The clear correlation between Ac-SDKP and proliferation of erythroid progenitor cells suggests an inhibitory role of Ac-SDKP on hematopoiesis in CHF patients, which may explain the observed anemia in patients treated with ACE inhibitors.

Oncogenic Ras blocks transforming growth factor-beta-induced cell-cycle arrest by degradation of p27 through a MEK/Erk/SKP2-dependent pathway

OBJECTIVE

To examine whether oncogenic Ras affects transforming growth factor (TGF)-beta-mediated cell-cycle arrest in hematopoietic cells and the downstream signal transduction pathway involved in the interference with TGF-beta-induced cell-cycle arrest.

MATERIALS AND METHODS

Two leukemic cell lines bearing N-Ras(L61) mutations; HL-60 and TF-1, and the M1 cell line with wt Ras were investigated for their response to TGF-beta. Signal transduction inhibitors, overexpression and RNA interference studies were performed to investigate the involvement of the various proteins.

RESULTS

Although TGF-beta signal transduction was not affected, G0-G1 arrest was absent in HL-60 and TF-1 cells due to the absence of p27. Overexpression of p27 restored TGF-beta-induced cell-cycle arrest, as well as interfering in Ras-mediated signaling. The farnesyl transferase inhibitor L744832 and the MEK inhibitor U0126 both restored p27 levels and cell-cycle arrest in response to TGF-beta. The absence of p27 protein is due to elevated levels of the ubiquitin ligase SKP2, which complexes with and targets p27 for degradation. RNA interference for SKP2 and treatment of these cells with the proteasome inhibitor MG132 restored p27 levels, corresponding with decreasing SKP2 levels after interfering in N-Ras signal transduction. P27, phosphorylated at threonine 187, is nuclear localized in N-Ras-containing cells. Mutation of this residue to alanine rendered p27 insensitive to degradation.

CONCLUSION

N-Ras(L61) transformed cells lack a G0-G1 arrest upon TGF-beta treatment due to absence of p27. p27 is degraded through a MapK-, and SKP2-dependent pathway. Overexpression of p27 results in restoration of cell-cycle arrest upon TGF-beta treatment.

Analysis of the efficacy and toxicity of bortezomib for treatment of relapsed or refractory multiple myeloma in community practice

The clinical data on the efficacy and toxicity of bortezomib as treatment for multiple myeloma patients are restricted to prospective phase II studies in expert myeloma centers. Here we report a multi-institutional analysis of the efficacy and toxicity of bortezomib in patients with relapsed or refractory multiple myeloma who were treated in community centers in a compassionate need program.

The value of the MDR1 reversal agent PSC-833 in addition to daunorubicin and cytarabine in the treatment of elderly patients with previously untreated acute myeloid leukemia (AML), in relation to MDR1 status at diagnosis

To determine whether MDR1 reversal by the addition of the P-glycoprotein (P-gp) inhibitor PSC-833 to standard induction chemotherapy would improve event-free survival (EFS), 419 untreated patients with acute myeloid leukemia (AML) aged 60 years and older were randomized to receive 2 induction cycles of daunorubicin and cytarabine with or without PSC-833. Patients in complete remission were then given 1 consolidation cycle without PSC-833. Neither complete response (CR) rate (54% versus 48%; P = .22), 5-year EFS (7% versus 8%; P = .53), disease-free survival (DFS; 13% versus 17%; P = .06) nor overall survival (OS; 10% in both arms; P = .52) were significantly improved in the PSC-833 arm. An integrated P-gp score (IPS) was determined based on P-gp function and P-gp expression in AML cells obtained prior to treatment. A higher IPS was associated with a significantly lower CR rate and worse EFS and OS. There was no significant interaction between IPS and treatment arm with respect to CR rate and survival, indicating also a lack of benefit of PSC-833 in P-gp-positive patients. The role of strategies aimed at inhibitory P-gp and other drug-resistance mechanisms continues to be defined in the treatment of patients with AML.

Association with HLA class I in Epstein-Barr-virus-positive and with HLA class III in Epstein-Barr-virus-negative Hodgkin's lymphoma

BACKGROUND

Associations of Hodgkin's lymphoma with HLA have been reported for many years. In 20-40% of patients with this disorder, Epstein-Barr virus (EBV) is present in the neoplastic cells. Because presentation of EBV antigenic peptides can elicit vigorous immune responses, we investigated associations of the HLA region with EBV-positive and EBV-negative Hodgkin's lymphoma.

METHODS

In a retrospective, population-based study, patients with Hodgkin's lymphoma were reclassified according to the WHO classification, and EBV status was assessed by in-situ hybridisation of EBV-encoded small RNAs. Germline DNA was isolated from 200 patients diagnosed between 1987 and 2000 and from their first-degree relatives. Genotyping was done with 33 microsatellite markers spanning the entire HLA region and two single-nucleotide polymorphisms in the genes for tumour necrosis factor alpha and beta. Classic association analysis and the haplotype sharing statistic were used to compare patients with controls.

FINDINGS

Classic association analysis (but not the haplotype sharing statistic) showed an association of consecutive markers D6S265 and D6S510 (p=0.0002 and 0.0003), located in the HLA class I region, with EBV-positive lymphomas. The haplotype sharing statistic (but not classic association analysis) showed a significant difference in mean haplotype sharing between patients and controls surrounding marker D6S273 (p=0.00003), located in HLA class III.

INTERPRETATION

Areas within the HLA class I and class III regions are associated with susceptibility to Hodgkin's lymphoma, the association with class I being specific for EBV-positive disease. This finding strongly suggests that antigenic presentation of EBV-derived peptides is involved in the pathogenesis of EBV-involved Hodgkin's lymphoma.

RELEVANCE TO PRACTICE

Polymorphisms in the HLA region could explain ethnic variation in the incidence of Hodgkin's lymphoma. The association of EBV-positive Hodgkin's lymphoma with HLA class I suggests that this polymorphism might affect the proper presentation of EBV antigens to cytotoxic T lymphocytes.

Impaired hematopoietic stem cell functioning after serial transplantation and during normal aging

Adult somatic stem cells possess extensive self-renewal capacity, as their primary role is to replenish aged and functionally impaired tissues. We have previously shown that the stem cell pool in short-lived DBA/2 (D2) mice is reduced during aging, in contrast to long-lived C57BL/6 (B6) mice. This suggests the existence of a genetically determined mitotic clock operating in stem cells, which possibly limits organismal aging. In the study reported here, unfractionated bone marrow (BM) cells or highly purified Lin(-)Sca-1(+)c-kit(+) (LSK) cells were serially transplanted in lethally irradiated D2 and B6 mice. In both strains, serial transplantation resulted in a substantial loss of stem cell activity. However, as we estimate that in B6 mice, the maximum number of population doublings of primitive cells is approximately 30, in D2 mice this is only approximately 20, resulting in a 1,000-fold difference in expansion potential, irrespective of whether whole bone marrow or purified hematopoietic stem cells (HSCs) were transplanted. Interestingly, recipients reconstituted with serially transplanted BM cells were able to accept a freshly isolated graft without any further conditioning. Finally, we show that whereas transplantation of BM cells into healthy, nonconditioned, young B6 recipients does not lead to engraftment, young BM cells do engraft and provide multilineage reconstitution in nonirradiated aged mice. Our data clearly establish the relevance of an intrinsic, genetically controlled program associated with impaired stem cell functioning during aging.

HSP27 protects AML cells against VP-16-induced apoptosis through modulation of p38 and c-Jun

OBJECTIVE

To investigate 1) the signal transduction pathways affected by heat shock protein 27 (HSP27) expression; and 2) the expression and regulation of HSP27 in acute myeloid leukemia (AML).

MATERIALS AND METHODS

RNA interference studies for HSP27 in leukemic TF-1 cells were used to investigate the effects on downstream signal transduction and apoptosis after VP-16 and CD95/Fas treatment. HSP27 expression and activation was investigated in AML blasts through Western blot analysis.

RESULTS

RNA interference for HSP27 resulted in a twofold increase in VP-16-induced apoptosis, which was preceded by enhanced p38 and c-Jun phosphorylation and a twofold increased cytochrome c release into the cytoplasm. DAXX co-immunoprecipitated with HSP27, suggesting an inhibitory role of HSP27 in VP-16-mediated activation of the ASK1/p38/JNK pathway. CD95/Fas-induced apoptosis, however, was unaffected by HSP27 siRNA, due to upregulation of HSP27. Although HSP27 was highly expressed and phosphorylated in primitive monocytic AML blasts (M4-M5, 91%, n=11) and undetectable in myeloid blasts (M1-M2, n=5), VP-16-mediated apoptosis correlated moderately with HSP27 expression. This is likely due to the co-expression of p21Waf1/Cip1, which is in the majority of the monocytic AML M4-M5 blasts constitutively localized in the cytoplasm. Overexpression of cytoplasmic p21 inhibited the enhanced p38 phosphorylation after HSP27 RNAi, suggesting a predominant anti-apoptotic role of p21 over HSP27.

CONCLUSION

1) HSP27 inhibits VP-16-mediated phosphorylation of p38 and c-Jun, cytochrome c release, and subsequent apoptosis; 2) HSP27 is expressed and activated in monocytic AML blasts; 3) cytoplasmic expression of p21 compensates for the lack of HSP27.

Inhibition of the transforming growth factor beta (TGFbeta) pathway by interleukin-1beta is mediated through TGFbeta-activated kinase 1 phosphorylation of SMAD3

Transforming growth factor beta is the prototype of a large family of secreted factors that regulate multiple biological processes. In the immune system, TGFbeta acts as an anti-inflammatory and immunosuppressive molecule, whereas the cytokine interleukin (IL)-1beta is a crucial mediator of inflammatory responses and induces proinflammatory genes and acute phase proteins. Here, we present evidence for the existence of a direct inhibitory interaction between the IL-1beta and TGFbeta signaling cascades that is not dependent on IL-1beta-induced SMAD7 expression. IL-1beta and its downstream mediator TAK1 inhibit SMAD3-mediated TGFbeta target gene activation, whereas SMAD3 nuclear translocation and DNA binding in response to TGFbeta are not affected. IL-1beta transiently induces association between TAK1 and the MAD homology 2 domain of SMAD3, resulting in SMAD3 phosphorylation. Furthermore, IL-1beta alleviates the inhibitory effect of TGFbeta on in vitro hematopoietic myeloid colony formation. In conclusion, our data provide evidence for the existence of a direct inhibitory effect of the IL-1beta-TAK1 pathway on SMAD3-mediated TGFbeta signaling, resulting in reduced TGFbeta target gene activation and restored proliferation of hematopoietic progenitors.

Increased peripheral platelet destruction and caspase-3–independent programmed cell death of bone marrow megakaryocytes in myelodysplastic patients

To investigate underlying mechanisms of thrombocytopenia in myelodysplastic syndrome (MDS), radiolabeled platelet studies were performed in 30 MDS patients with platelet counts less than 100 × 109/L. Furthermore, plasma thrombopoietin and glycocalicin index (a parameter of platelet or megakaryocyte destruction) were determined. Mean platelet life (MPL), corrected for the degree of thrombocytopenia, was reduced in 15 of 30 patients (4.3 ± 0.9 days [mean ± SD] vs 6.0 ± 1.3, P = .0003). Platelet production rate (PPR) was reduced in 25 of 30 patients (68 ± 34 × 109/d vs 220 ± 65, P &lt; .0001). Thrombopoietin levels were not significantly correlated with the PPR. However, the glycocalicin index was significantly higher compared with controls (15 ± 16 vs 0.7 ± 0.2, P = .001) and significantly correlated with the PPR (P = .02, r = -0.5), but not with the MPL (P = 1.8). Ultrastructural studies demonstrated necrosis-like programmed cell death (PCD) in mature and immature megakaryocytes (n = 9). Immunohistochemistry of the bone marrow biopsies demonstrated no positive staining of MDS megakaryocytes for activated caspase-3 (n = 24) or cathepsin D (n = 21), while activated caspase-8 was demonstrated in a subgroup of patients (5/21) in less than 10% of megakaryocytes. These results indicate that the main cause of thrombocytopenia in MDS is caspase-3–independent necrosis-like PCD resulting in a decreased PPR in conjunction with an increased glycocalicin index.