The American Society of Hematology (ASH) Medical Educators Institute: a Pilot Faculty Development Project for Hematology Educators

Clinician educators at academic medical centers often lack the community, mentorship, and faculty development to support their missions around education scholarship and teaching. Inadequate support for clinician educators can lead to professional dissatisfaction and slowed academic advancement. In 2014, ASH conducted a needs assessment of medical school hematology course directors, hematology-oncology fellowship program directors, and other ASH members identified as educators to determine this community's desire for faculty development in medical education. These data furthered the development of an annual faculty development program for hematology educators offering an interactive curriculum and support for an educational scholarly project. The needs assessment indicated that over 70% of respondents would be personally interested in a faculty development opportunity for hematology educators and only 11% had previously participated in such a program. A steering committee designed an intervention blending didactics, interactive small group exercises, webinars, mentorship for a scholarly project, 360-degree feedback for each participant, and a forum to discuss common career development goals. Of 42 applicants, 20 participants were chosen for the inaugural workshop. Following successful execution of the workshop, participants reported significant increase in confidence in the knowledge, skills, and attitudes targeted by the curriculum. A series of follow-up webinars have been developed to deliver additional content not covered during the workshop and to continue mentorship relationships. The curriculum will be further refined based on feedback from faculty and participants. Long-term outcome measurement will include tracking all participants' publications and presentations, time to promotion, and involvement in national medical education initiatives.

Between a rux and a hard place: evaluating salvage treatment and outcomes in myelofibrosis after ruxolitinib discontinuation

Ruxolitinib is a JAK1/2 inhibitor that is effective in managing symptoms and splenomegaly related to myelofibrosis (MF). Unfortunately, many patients must discontinue ruxolitinib, at which time treatment options are not well defined. In this study, we investigated salvage treatment options and clinical outcomes among MF patients who received and discontinued ruxolitinib outside the context of a clinical trial. Among 145 patients who received ruxolitinib, 23 died while on treatment, 58 remained on treatment at time of analysis, leaving 64 people available for analysis. Development of cytopenias was the most common reason for discontinuation (38%) after median treatment time of 3.8 months (mo). The majority of patients received some form of salvage therapy after ruxolitinib discontinuation (n = 42; 66%), with allogeneic hematopoietic stem cell transplant (alloHSCT) (n = 17), being most commonly employed. Lenalidomide, thalidomide, hydroxyurea, interferon, and danazol were used with similar frequency. The response rate to salvage treatment was 26% (8 responses) and responses were most often seen with lenalidomide or thalidomide. Improved outcomes were observed in patients who underwent alloHSCT or received salvage therapy compared to those who did not receive additional therapy. Median overall survival (OS) after ruxolitinib discontinuation was 13 months. These findings show that salvage therapy can provide clinical responses after ruxolitinib discontinuation; however, these responses are rare and outcomes in this patient population are poor. This represents an area of unmet clinical need in MF.

The Treatment Landscape of Myelofibrosis Before and After Ruxolitinib Approval

INTRODUCTION/BACKGROUND

Myelofibrosis (MF) is a chronic myeloproliferative neoplasm that presents with a heterogeneous clinical phenotype and prognosis. Before the US Food and Drug Administration approval of ruxolitinib, treatment options were varied and had limited effect. The increased use of ruxolitinib has drastically altered the MF treatment landscape. In this study, we aimed to clarify the clinical situations in which ruxolitinib is being used and analyze its effect on this landscape.

PATIENTS AND METHODS

We retrospectively assessed treatment choices for MF patients treated at our institution (n = 309). This population was divided into 2 cohorts on the basis of a diagnosis before (cohort BR: n = 174) or after (cohort AR: n = 135) ruxolitinib approval. Cohorts were further stratified for comparison according to presenting clinical factors.

RESULTS

Expectedly, the first-line use of ruxolitinib markedly increased after its approval. AR patients were less likely to receive erythropoiesis-stimulating agents (ESAs; P = .0003) and thalidomide (P = .003) than BR patients. In patients with MF-related symptoms and/or splenomegaly, increased use of ruxolitinib was associated with decreased use of first-line ESA (P = .03) or thalidomide (P = .03). In anemic patients, increased use of first-line ruxolitinib was associated with a decreased use of thalidomide (P = .007). In patients with severe leukocytosis, ruxolitinib use did not significantly increase and hydroxyurea was the preferred first-line agent.

CONCLUSION

Overall, the increased use of ruxolitinib appears to have come predominantly at the expense of thalidomide and ESAs, while not having a large effect on the first-line use of hydroxyurea.

Clinical prognostic factors and outcomes of essential thrombocythemia when transformed to myelodysplastic syndromes and acute myeloid leukemia

Transformation of essential thrombocythemia (ET) to myelodysplastic syndromes or acute myeloid leukemia is infrequent, comprising 1-5% of cases with dismal clinical outcome. Studies on prognosis in ET patients with leukemic transformation are limited. The large cohort included 40 patients (1990-2014) with ET transformation (median age of 59 years, M:F of 1:1). Median time from ET diagnosis to transformation was 76 months (26-481) with median follow-up time of 15 years. Advanced age, myelofibrosis (grade 2-3), and leukocytosis at the time of transformation were associated with inferior OS from transformation (p<0.05). Given rarity of the clinical scenario, multicenter efforts are encouraged.

Role of cell cycle regulatory molecules in retinoic acid- and vitamin D3-induced differentiation of acute myeloid leukaemia cells

The important role of cell cycle regulatory molecules in all trans-retinoic acid (ATRA)- and vitamin D3-induced growth inhibition and differentiation induction has been intensively studied in both acute myeloid leukaemia primary cells and a variety of leukaemia cell lines. Cyclin-dependent kinases (CDK)-activating kinase has been demonstrated to interact with retinoic acid receptor (RAR)α in acute promyelocytic leukaemia cells, and inhibition of CDK-activating kinase by ATRA causes hypophosphorylation of PML-RARα, leading to myeloid differentiation. In many cases, downregulation of CDK activity by ATRA and vitamin D3 is a result of elevated p21- and p27-bound CDKs. Activation of p21 is regulated at the transcriptional level, whereas elevated p27 results from both (indirectly) transcriptional activation and post-translational modifications. CDK inhibitors (CKIs) of the INK family, such as p15, p16 and p18, are mainly involved in inhibition of cell proliferation, whereas CIP/KIP members, such as p21, regulate both growth arrest and induction of differentiation. ATRA and vitamin D3 can also downregulate expression of G1 CDKs, especially CDK2 and CDK6. Inhibition of cyclin E expression has only been observed in ATRA- but not in vitamin D3-treated leukaemic cells. In vitro, not only dephosphorylation of pRb but also elevation of total pRb is required for ATRA and vitamin D3 to suppress growth and trigger their differentiation. Finally, sharp reduction in c-Myc has been observed in several leukaemia cell lines treated with ATRA, which may regulate expression of CDKs and CKIs.

TGFbeta inhibits GM-CSF-induced phosphorylation of ERK and MEK in human myeloid leukaemia cell lines via inhibition of phosphatidylinositol 3-kinase (PI3-k)

OBJECTIVES

Activation of SMAD-independent p44/42 MAPK (ERK1/2) signalling by TGFbeta has been recently reported in various cell types. However, the mechanisms for the linkage between the SMAD-dependent and -independent pathways are poorly understood. In this study, we investigated whether TGF-beta activates the ERK pathway and how TGFbeta communicates with the MAP kinase signals induced by a mitogen, in human myeloid leukaemia cells.

MATERIALS AND METHODS AND RESULTS

TGFbeta dramatically suppressed proliferation of MV4-11 and TF-1 cells without detectable phosphorylation of ERK1/2 and MEK1/2 for the duration of 48 h, as detected by MTT assay and Western blot analysis, respectively. In contrast, GM-CSF induced rapid and transient phosphorylation of MEK1/2 and ERK1/2 and up-regulated cell proliferation. Both GM-CSF-induced ERK1/2 activation and cell proliferation were significantly inhibited by TGFbeta. GM-CSF also induced transient phosphorylation of the p85 subunit of PI3-kinase. Corresponding to this change, phosphorylated p85 was found to bind to the GM-CSF receptor-alpha subunit, as detected by immunoprecipitation and Western blot analysis. PD98059, a selective inhibitor of MEK, blocked GM-CSF-induced phosphorylation of MEK and ERK but not p85. However, TGFbeta and LY294002, a potent inhibitor of PI3-kinase, significantly inhibited phosphorylation of both p85 and ERK1/2.

CONCLUSIONS

These studies thus indicate that TGFbeta does not activate the ERK pathway but turns off the GM-CSF-induced ERK signal via inhibition of the PI3-kinase-Akt pathway, in these human leukaemia cells.

Gap junction mediated transport of shRNA between human embryonic stem cells

Gap junction intracellular communication (GJIC) allows the direct transport of small molecules between adjacent cells. We hypothesized that siRNAs in one hESC could inhibit target RNA expression in another hESC via GJIC. We co-cultured green fluorescent protein (GFP)-expressing ENVY hESC with non-GFP-expressing hESC, which had been transduced to stably express shRNA directed against GFP. We discovered that the GFP shRNA expressing hESC inhibited GFP expression in the adjacent GFP-expressing hESC in a dose-dependent manner. This downregulation of GFP expression in ENVY cells was not observed when the co-cultured cells had been transduced with a non-functional GFP shRNA that was mutated at two nucleotides or when the cells were incubated with the GJIC inhibitor, alpha-glycyrrhetinic acid (alpha-GA). We conclude that 21-23 bp double-stranded shRNA/siRNA oligonucleotides are able to move through gap junctions between hESCs and thus can affect gene expression in neighbouring hESC. This novel intercellular gene expression regulatory mechanism may offer new approaches to manipulation of hESC.

TGFbeta regulates the expression and activities of G2 checkpoint kinases in human myeloid leukemia cells

Transforming Growth Factor-beta (TGFbeta) is known to be a negative regulator of G1 cyclin/cdk activity. It is not clear whether TGFbeta has any effect on G2 checkpoint kinases. We have found that TGFbeta downregulated the expression of several G2 checkpoint kinases including cdc2, cyclin B1, and cdc25c without causing cell accumulation in G2/M phases in two human leukemia cell lines. The inhibition was time-dependent with a maximal inhibition being observed by 24h for cyclin B1 and cdc2 and by 48h for cdc25c. The inhibition was not a result of G1 arrest but a direct effect of TGFbeta which downregulates their expression at mRNA level. In proliferating cells, there was a significant formation of cdc2-pRb complexes, which was decreased to 30% of control levels by 48h after initiating TGFbeta treatment. Cdc2 showed a marked kinase activity on GST-Rb protein in proliferating cells detected by in vitro kinase assay, which was downregulated in response to TGFbeta. In addition, TGFbeta caused a rapid and transient dephosphorylation of cdc2 (Tyr15) and cdc25c (Ser216) for about 2-3h before a dramatic decrease of both molecules by 48h. Taken together, our data suggest that TGFbeta has a direct inhibitory effect on G2 checkpoint kinases, which is regulated at mRNA level. The transient activation of cdc2 and cdc25c and subsequent inhibition of cdc2, cyclin B1, and cdc25c could amplify TGFbeta-induced G1 arrest and growth inhibition.

Ubiquitin/proteasome-dependent degradation of D-type cyclins is linked to tumor necrosis factor-induced cell cycle arrest

Tumor necrosis factor-alpha (TNF) is well known for its cytotoxic effect on malignant cells. Its role in cell cycle control is relatively less known. In this study, we found that TNF induced G(1) arrest of TF-1 and MV4-11 cells while simultaneously causing apoptosis. Treatment of the cells with TNF for 48 h caused cell cycle arrest, accompanied by dephosphorylation of pRb and reduction in D-type cyclin expression. The down-regulation of the D-type cyclins resulted in approximately 50-80% decrease of the cyclin-dependent kinase activities. Cells treated with calpain-dependent inhibitor ALLN and apoptosis inhibitor zVAD-FMK suppressed degradation of IkappaBalpha and activation of caspase 3, respectively. However, treatment of cells with these two inhibitors was not able to prevent TNF-induced down-regulation of the D-type cyclins. In contrast, proteasome inhibitor MG-132 and lactacystin blocked both TNF-induced degradation of IkappaBalpha and down-regulation of D-type cyclins. These data suggest that down-regulation of D-type cyclins by TNF may be proteasome-proteolysis dependent. Additional support for this conclusion was obtained from experiments showing an increase of proteasome activity in TNF-treated cells and in vitro degradation of cyclin D3 by 26 S proteasome.

Differential effects of transforming growth factor on cell cycle regulatory molecules in human myeloid leukemia cells

In this report we have studied the mechanism by which Transforming Growth Factor beta (TGF beta) inhibits growth of human myeloid leukemia cell lines. TGF beta 1 arrested cells in G1 phase and significantly downregulated the expression of cyclin D2, cyclin D3, cdk4, cyclin A, and cdk2. The downregulation of the molecules resulted in approximately 50-90% decrease of the molecule-dependent kinase activity, varying with each molecule. Although treatment of cells with TGF beta 1 up-regulated accumulation of p27(kip1) in both nucleus and cytoplasm, the association of the p27(kip1) with cdk2, cyclin A, cyclin D2, cyclin D3, and cdk4 was markedly down-regulated, suggesting that p27(kip1) is not responsible for the downregulation of the kinase activity. In contrast, TGF beta 1 upregulated cyclin E-associated p27(kip1) with no effect on the expression of cyclin E. p27(kip1)-immunodepletion upregulated cyclin E-dependent kinase activity by more than 10-fold in TGF beta 1-treated cells but not in proliferating cells; whereas immunodepletion of p27(kip1) from cdk2-immunoprecipitates markedly downregulated cdk2 kinase activity in the lysates extracted from both proliferating and TGF beta-treated cells. Consistent with this observation, TGF beta 1 and p27(kip1) antisense cDNA had a synergistic or additive inhibitory effect on cdk2 but not cyclin E-dependent kinase activity. Our data suggest that (1) TGF beta 1-mediated growth inhibition is accomplished through multiple pathways and (2) p27(kip1) has opposing effects on cdk2 and cyclin E activity in response to TGF beta 1.

An IkappaBalpha inhibitor causes leukemia cell death through a p38 MAP kinase-dependent, NF-kappaB-independent mechanism

Treatment of U937 cells with an IkappaBalpha phosphorylation inhibitor, Bay 11-7085, induced a rapid phosphorylation of p38 mitogen-activated protein (MAP) kinase, significant apoptosis, extensive necrosis, and a weak phosphorylation of MAP kinase kinase. Bay 11-7085 had no effect on the basal levels of phosphorylated IkappaBalpha but completely inhibited phorbol 12-myristate 13-acetate-induced phosphorylation of IkappaBalpha. Although Bay 11-7085 prevented phorbol 12-myristate 13-acetate-induced NF-kappaB nuclear translocation, SN50, a specific inhibitor of nuclear translocation and function of NF-kappaB, did not induce any significant nuclear/DNA fragmentation, caspase 3 activation, or cell death. The p38 MAP kinase-specific inhibitor, SB203580, completely inhibited the phosphorylation of p38 MAP kinase and significantly decreased Bay 11-7085-induced apoptosis. In contrast, the MAP kinase kinase-specific inhibitor PD98059 had no effect on Bay 11-7085-induced apoptosis. Caspase-specific inhibitor, z-Val-Ala-Asp-fluoromethyl ketone prevented Bay 11-7085-induced activation of caspase 3 but was not able to block Bay 11-7085-induced phosphorylation of p38 MAP kinase. These data suggest that Bay 11-7085 induces apoptosis through a p38 MAP kinase-dependent, NF-kappaB-independent mechanism.

Transforming growth factor: signal transduction pathways, cell cycle mediation, and effects on hematopoiesis

Transforming growth factor-beta (TGF-beta) is a potent growth inhibitor of various cell types including hematopoietic cells. Two receptors, TGFbetaRI and TGFbetaRII, govern the interaction between the cell and the TGF-beta ligand. Primary binding of the ligand occurs with the RII receptor, promoting formation of a heterodimer with RI and activation of signaling. This induces transient association of Smad proteins with the receptors. Smad 3 and 4 may be involved in the TGF-beta-induced G(1) arrest. TGF-beta(1) down-regulates G(1) and G(2) cyclin-dependent kinases (cdks) and cyclins in terms of both kinase activity and protein amount. TGF- beta (1) also inhibits phosphorylation of the product of the retinoblastoma tumor suppressor gene (pRb) at multiple serine and threonine residues in human myeloid leukemia cells. The underphosphorylated pRb associates with transcription factor E2F-4 in G(1) phase, whereas the phosphorylated pRb mainly binds to E2F-1 and E2F-3. Because TGF-beta(1) up-regulates p130(pRb family member)/E2F-4 complex formation and down-regulates p107(pRb family member)/E2F-4 complex formation, with E2F-4 levels remaining constant, these results suggest that E2F-4 is switched from p107 to pRb and p130 when cells exit from the cell cycle and arrest in G(1) by the action of TGF-beta(1). The "cdk inhibitor" p27 is both a positive and a negative regulator of TGF-beta(1)-mediated cell cycle control. Although TGF-beta(1) has been reported to be a selected inhibitor of normal primitive hematopoietic stem cells, TGF-beta inhibits both primitive and more differentiated myeloid leukemia cell lines.

Transforming growth factor beta inhibits the phosphorylation of pRB at multiple serine/threonine sites and differentially regulates the formation of pRB family-E2F complexes in human myeloid leukemia cells

Transforming growth factor beta (TGFbeta)1 induced dephosphorylation of pRb at multiple serine and threonine residues including Ser249/Thr252, Thr373, Ser780, and Ser807/811 in MV4-11 cells. Likewise, TGFbeta1 caused the dephosphorylation of p130, while inhibiting accumulation of p107 protein. Phosphorylated pRb was detected to bind E2F-1 and E2F-3, which appears to be a major form of pRb complexes in actively cycling cells. TGFbeta1 significantly downregulated pRb-E2F-1 and pRb-E2F-3 complexes as a result of inhibition of E2F-1 and E2F-3. In contrast, complexes of E2F-4 with pRb and with p130 were increased markedly upon TGFbeta1 treatment, whereas p107 associated E2F-4 was dramatically decreased. In agreement with these results, p130-E2F-4 DNA binding activity was dominant in TGFbeta1 treated cells, whereas p107-E2F-4 DNA binding activity was only found in proliferating cells. Our data strongly suggest that inhibition of E2Fs and differential regulation of pRb family-E2F-4 complexes are linked to TGFbeta1-induced growth inhibition. E2F-4 is switched from p107 to p130 and pRb when cells are arrested in G1 phase by TGFbeta1.

Activation of p38 mitogen-activated protein kinase is required for tumor necrosis factor-alpha -supported proliferation of leukemia and lymphoma cell lines

To elucidate mechanisms of tumor necrosis factor alpha (TNF-alpha)-induced proliferation of a number of human leukemia and lymphoma cell lines, we examined the role of p38 mitogen-activated protein kinase (MAPK) in TNF-alpha signaling in Mo7e and Hut-78 cells. TNF-alpha-dependent p38 MAPK activation was detected in both Mo7e and Hut-78 cells and was blocked by the p38 MAPK inhibitor, SB203580. Ablation of p38 MAPK activity by SB203580 abrogated TNF-alpha-induced Mo7e cell proliferation and TNF-alpha-dependent autocrine growth of Hut-78. As we have shown previously that activation of the nuclear factor kappaB (NF-kappaB) is also required for TNF-alpha-induced Mo7e cell proliferation, the involvement of p38 MAPK in NF-kappaB activation was assessed. SB203580 did not affect TNF-alpha-signaled nuclear translocation and DNA-binding activity of NF-kappaB, and inhibition of NF-kappaB function did not affect TNF-alpha-induced p38 MAPK activation, indicating that these events are not dependent on each other. However, SB203580 depressed the expression of NF-kappaB-dependent genes, as monitored by a kappaB-driven reporter gene. Our findings demonstrate that activation of both p38 MAPK and NF-kappaB plays a critical role in TNF-alpha-mediated survival and proliferation of human leukemia and lymphoma cells, and p38 MAPK acts at least in part by facilitating the transcriptional activation function of NF-kappaB.

Cell cycle and transcriptional control of human myeloid leukemic cells by transforming growth factor beta

TGFbeta1 is a potent growth inhibitor of both primitive and more differentiated human myeloid leukemic cells. The extent of the growth inhibitory response to TGFbeta varies with cell type, and is not linked to stages of differentiation of cell lines. Downregulation of multiple cell cycle-regulatory molecules is a dominant event in TGFbeta1-mediated growth inhibition of human MV4-11 myeloid leukemia cells. Both G1-phase and G2-phase cyclins and cdks participate in the regulation of TGFbeta1-mediated growth inhibition of MV4-11 cells. By both depressing cdk2 synthesis and up-regulating cyclin E-associated p27, TGFbeta1 may magnify its inhibitory efficiency. TGFbeta1 also rapidly inhibits phosphorylation of pRb at several serine and threonine residues. The underphosphorylated pRb associates with E2F-4 in G1 phase, whereas the phosphorylated pRb mainly binds to E2F-1 and E2F-3 in proliferating MV4-11 cells. Since TGFbeta1 upregulates p130/E2F-4 complex formation and downregulates p107/E2F-4 complex formation, with E2F-4 levels remaining constant, our results suggest that E2F-4 is switched from p107 to pRb and p130 when cells exit from the cell cycle and arrest in G1 by TGFbeta1. In summary, TGFbeta1 inhibits growth of human myeloid leukemic cells through multiple pathways, whereas the "cdk inhibitor" p27 is both a positive and negative regulator.

Adult Chediak-Higashi parkinsonian syndrome with dystonia

Chediak-Higashi syndrome (CHS) is a rare autosomal-recessive disorder characterized by immune deficiency, partial oculocutaneous albinism, and large eosinophilic, peroxidase-positive inclusion bodies in granule-containing cells. The adult form of CHS manifests during late childhood to early adulthood and is marked by various neurologic sequelae, including parkinsonism, dementia, spinocerebellar degeneration, and peripheral neuropathy. We report the case of a 29-year-old man with adult CHS who exhibited a progressive asymmetric parkinsonism, including rest tremor, and axial, cervical, and appendicular dystonia. The diagnosis was confirmed by the presence of characteristic large peroxidase-positive granules within leukocytes and markedly decreased natural killer cell function. Levodopa/carbidopa and amantadine provided benefit for tremor. CHS, although rare, should be considered in the differential diagnosis of young adult parkinsonism.

Prolonged activation of the mitogen-activated protein kinase pathway is required for macrophage-like differentiation of a human myeloid leukemic cell line

The role of the mitogen-activated protein kinase (MAPK) signal transduction pathway in the proliferation of mammalian cells has been well established. However, there are relatively few reports concerning cell differentiation being mediated by MAPK. The effect of phorbol 12-myristate 13-acetate (PMA) on cell differentiation and signal transduction in a human myeloid leukemia cell line, TF-1a, was investigated. When TF-1a cells were treated with 10(-6), 10(-7), 10(-8), and 10(-9) M PMA for 24 h, they underwent 98, 93, 91, and 51% macrophage-like differentiation, respectively. PMA treatment rapidly (10 min) induced phosphorylation of MAPK kinase (MEK and p44/42 MAPK), which persisted for at least 24 h. p44/42 MAPK immunoprecipitates from lysates of PMA-treated cells had increased ability to phosphorylate the transcription factor Elk-1. This is important because phosphorylated Elk-1 can be considered an "end-product" of the MAPK pathway. In contrast, treatment of TF-1a cells with granulocyte/macrophage-colony stimulating factor induced only transient activation of MEK and p44/42 MAPK (10-20 min) and an increase (approximately 50%) in cell proliferation, without any change in cellular differentiation. These results suggest that macrophage-like differentiation may be dependent on prolonged activation of the MAPK pathway. Additional support for this conclusion was obtained from experiments showing that treatment of TF-1a cells with antisense oligonucleotides for MEK1 coding sequences prior to adding PMA inhibited macrophage-like differentiation. Furthermore, transient transfection with an inactive, dominant-negative MEK mutant also inhibited PMA-induced differentiation, whereas transient transfection with a plasmid coding for constitutively activated MEK led to macrophage-like differentiation in the absence of PMA.

TNF-alpha-induced growth suppression of CD34+ myeloid leukemic cell lines signals through TNF receptor type I and is associated with NF-kappa B activation

Conflicting results have been reported regarding the effect of TNF-alpha on the growth of human primitive hemopoietic cells. In this study, we have examined the effect of TNF-alpha on the proliferation of several CD34+/CD38+ (KG-1, TF-1) and CD34+/CD38- (KG-1a, TF-1a) myeloid leukemic progenitor cell lines. Our data show that TNF-alpha markedly inhibits the growth of these cells in both liquid and soft agar cultures. Addition of GM-CSF or IL-3 does not prevent TNF-alpha-induced growth inhibition. Flow cytometry analyses of propidium iodide-stained cells demonstrated cell death of all four cell lines, as judged by the presence of cells with hypodiploid DNA content after exposure of cells to TNF-alpha for 4 days. Annexin V assays detected apoptosis in TF-1, but not in TF-1a, KG-1, and KG-1a cells in terms of translocation of phosphatidylserine shortly after TNF-alpha treatment. Neutralizing anti-TNF receptor type I (TNFR-I; p55) Ab almost completely reversed TNF-alpha-induced growth inhibition in both liquid and soft agar cultures, whereas anti-TNFR-II (p75) Ab had only a marginal effect. TNF-alpha rapidly induced marked activation of nuclear transcription factor NF-kappa B in all 4 cell lines. The majority of this effect was abolished by the type I receptor Ab, whereas the type II receptor neutralizing Ab had no effect. Our data also show that TNF-alpha is incapable of inducing activation of the mitogen-activated protein kinase pathway in these leukemic cell lines.

TNF-α-Induced Growth Suppression of CD34+ Myeloid Leukemic Cell Lines Signals Through TNF Receptor Type I and Is Associated with NF-κB Activation

Conflicting results have been reported regarding the effect of TNF-α on the growth of human primitive hemopoietic cells. In this study, we have examined the effect of TNF-α on the proliferation of several CD34+/CD38+ (KG-1, TF-1) and CD34+/CD38− (KG-1a, TF-1a) myeloid leukemic progenitor cell lines. Our data show that TNF-α markedly inhibits the growth of these cells in both liquid and soft agar cultures. Addition of GM-CSF or IL-3 does not prevent TNF-α-induced growth inhibition. Flow cytometry analyses of propidium iodide-stained cells demonstrated cell death of all four cell lines, as judged by the presence of cells with hypodiploid DNA content after exposure of cells to TNF-α for 4 days. Annexin V assays detected apoptosis in TF-1, but not in TF-1a, KG-1, and KG-1a cells in terms of translocation of phosphatidylserine shortly after TNF-α treatment. Neutralizing anti-TNF receptor type I (TNFR-I; p55) Ab almost completely reversed TNF-α-induced growth inhibition in both liquid and soft agar cultures, whereas anti-TNFR-II (p75) Ab had only a marginal effect. TNF-α rapidly induced marked activation of nuclear transcription factor NF-κB in all 4 cell lines. The majority of this effect was abolished by the type I receptor Ab, whereas the type II receptor neutralizing Ab had no effect. Our data also show that TNF-α is incapable of inducing activation of the mitogen-activated protein kinase pathway in these leukemic cell lines.

Tumor necrosis factor-alpha-induced proliferation of human Mo7e leukemic cells occurs via activation of nuclear factor kappaB transcription factor

Tumor necrosis factor-alpha (TNF-alpha) stimulates proliferation of Mo7e, CMK, HU-3, and M-MOK human leukemic cell lines. We report here the signal transduction pathway involved in TNF-alpha-induced Mo7e cell proliferation. Mo7e cells spontaneously die in the absence of growth factors, but treating the cells with interleukin (IL)-3, IL-6, thrombopoietin, granulocyte/macrophage colony-stimulating factor, or TNF-alpha promotes their survival and proliferation. Although most of these factors activate MAP kinase and Jun NH2-terminal kinase/signal transducer and activators of transcription signaling pathways, TNF-alpha fails to activate either pathway. When Mo7e cells were treated with TNF-alpha, nuclear factor kappaB (NF-kappaB) was activated transiently. The activated NF-kappaB consisted of heterodimers of p65 and p50 subunits. The degradation of IkappaBalpha coincided with activation of NF-kappaB in TNF-alpha-treated cells. To investigate the role of activated NF-kappaB in TNF-alpha-induced Mo7e proliferation, a cell-permeable peptide (SN50) carrying the nuclear localization sequence of p50 NF-kappaB was used to block nuclear translocation of activated NF-kappaB. Pretreating Mo7e cells with SN50 blocked TNF-alpha-induced nuclear translocation of NF-kappaB and inhibited TNF-alpha-induced Mo7e cell survival and proliferation. A mutant SN50 peptide did not affect TNF-alpha-induced Mo7e cell growth. SN50 had no effects on IL-3- or granulocyte/macrophage colony-stimulating factor-induced Mo7e cell proliferation. The results indicate that activation of NF-kappaB is involved in TNF-alpha-induced Mo7e cell survival and proliferation.

Transforming growth factor beta inhibits growth of more differentiated myeloid leukemia cells and retinoblastoma protein phosphorylation at serine 795

Transforming growth factor beta (TGF-beta) has been shown to be a specific inhibitor of early human myeloid progenitors. We show here that TGF-beta1 potentially inhibited not only the growth of primitive but also more mature myeloid leukemic cells. Surprisingly, those apparently more mature progenitor cells, such as MV4-11 and Mo7e cells, are very sensitive to the action of TGF-beta. The addition of TGF-beta1 to liquid cultures of these cells significantly inhibited their proliferation, with as much as 72% inhibition of growth of MV4-11 cells. The suppressive effect by TGF-beta1 was not reversed or prevented by granulocyte-macrophage colony-stimulating factor or interleukin 3 used to promote cell growth in TF-1a and MV4-11 cells. TGF-beta1 completely abolished the clonal growth of MV4-11 cells in soft agar and inhibited Mo7e, KG-1, K562, TF-1, and TF-1a colony growth by 99%, 90%, 63%, 53%, and 43%, respectively. The cells treated with TGF-beta1 showed progressive accumulation in the G1 phase of cell cycle. Maximal G1 arrest (93%) was observed in MV4-11 cells. Using anti-retinoblastoma protein (pRb) and anti-specific phosphorylated-pRb antibodies, we demonstrated that TGF-beta1 greatly inhibited pRb phosphorylation at serine 795 in MV4-11 and Mo7e cells. Taken together, our data suggest that the sensitivity of myeloid leukemic progenitor cells to growth inhibition by TGF-beta may not be inversely correlated with their maturation stage, and the inhibition of the cells appeared to be linked to the suppression of pRb phosphorylation at serine 795.

Constitutive activation of the JAK2/STAT5 signal transduction pathway correlates with growth factor independence of megakaryocytic leukemic cell lines

The factor-independent Dami/HEL and Meg-01 and factor-dependent Mo7e leukemic cell lines were used as models to investigate JAK/STAT signal transduction pathways in leukemic cell proliferation. Although Dami/HEL and Meg-01 cell proliferation in vitro was independent of and unresponsive to exogenous cytokines including granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), IL-6, thrombopoietin (TPO), and tumor necrosis factor-alpha (TNF-alpha), the growth of Mo7e cells was dependent on hematopoietic growth factors. When these cell lines were cultured in medium without cytokines, a constitutively activated STAT-like DNA-binding factor was detected in nuclear extracts from both Dami/HEL and Meg-01 cells. However, the STAT-like factor was not detectable in untreated Mo7e cells, but was activated transiently in Mo7e cells in response to cytokine treatments. The constitutively activated and cytokine-induced STAT-like DNA-binding factor in these three cell lines was identified as STAT5 by oligonucleotide competition gel mobility assays and by specific anti-STAT antibody gel supershift assays. Constitutive activation of JAK2 also was detected in the factor-independent cell lines, but not in Mo7e cells without cytokine exposure. Meg-01 cells express a p185 BCR/ABL oncogene, which may be responsible for the constitutive activation of STAT5. Dami/HEL cells do not express the BCR/ABL oncogene, but increased constitutive phosphorylation of Raf-1 oncoprotein was detected. In cytokine bioassays using growth factor-dependent Mo7e and TF-1 cells as targets, conditioned media from Dami/HEL and Meg-01 cells did not show stimulatory effects on cell proliferation. Our results indicate that the constitutive activation of JAK2/STAT5 correlates with the factor-independent growth of Dami/HEL and Meg-01 cells. The constitutive activation of JAK2/STAT5 in Dami/HEL cells is triggered by a mechanism other than autocrine cytokines or the BCR/ABL oncoprotein.

Characterization of a unique factor-independent variant derived from human factor-dependent TF-1 cells: a transformed event

A factor-independent variant (TF-1a) has been isolated from the factor-dependent TF-1 cell line. The subline has been grown continuously in culture for > 1.5 years without added cytokines. The cells retain the ability to respond to multicytokines, with a different response pattern from its parental cell line. The TF-1 cells appeared singly in liquid culture. In contrast. TF-1a cells formed aggregates which increased markedly in size and in number upon TGFbeta1 treatment and showed a diminished TGFbeta-mediated growth inhibition. TF-1a, but not TF-1 cells, formed colonies in soft agar culture in the absence of any added growth factors, and developed the capacity to generate an invasive tumor(s) in nude mice. There was a constitutive activation of MAPK and MEK in TF-1a but not in TF-1 cells, which may be one of the mechanisms leading to factor-independent growth of TF-1a cells. Phenotypically, TF-1 cells were CD34+ /CD38+, whereas TF-1a cells were CD34+ /CD38-. This suggests that TF-1a may represent a less mature hematopoietic cell than TF-1. In conclusion, TF-1a is different from TF-1 in many important aspects which are associated with neoplastic transformation. The variant appears to be an excellent model for studying the process of progressive malignant transformation of myeloid cells and for studying signal pathways involved in the spontaneous and factor-induced growth of the cells.

Cloning and sequencing of an alternative splicing-derived cDNA variant of the GM-CSF receptor alpha subunit, which encodes a truncated protein

GM-CSF interacts with the low affinity GM-CSF receptor alpha-subunit, which leads to high affinity association with the alpha-subunit/common beta-subunit complex and transduction of intracellular signals leading to proliferation, differentiation, and/or activation of hemopoietic cells, predominantly in the neutrophil and monocyte/macrophage lineages. Several alternative splicing-derived variants of the GM-CSF receptor alpha-subunit have been described previously by this and other laboratories. A newly discovered alternative-splicing derived variant was isolated from the peripheral blood mononuclear cells of a patient with juvenile myelomonocytic leukemia. This variant lacks 397 base pairs corresponding to exons 8-11 of the wild type GM-CSF receptor alpha-subunit cDNA and potentially encodes a 233 amino acid protein lacking a membrane-anchoring domain and creating the fourth known potential soluble isoform of the alpha-subunit of the GM-CSF receptor.

The role of type I and type II tumor necrosis factor (TNF) receptors in the ability of TNF-alpha to transduce a proliferative signal in the human megakaryoblastic leukemic cell line Mo7e

We investigated the effects of tumor necrosis factor (TNF) alpha on the human megakaryocytic leukemic cell lines Mo7e, Meg-01, and Dami/HEL. Our data show that both type I and type II TNF receptors (TNF-RI and TNF-RII) are expressed on all of these cells, and TNF-alpha significantly stimulates the proliferation of growth factor-dependent Mo7e cells but not of Meg-01 or Dami/HEL cells, which grow in a factor-independent manner. TNF-alpha serves predominantly as a mitogen for Mo7e cell proliferation and does not induce Mo7e cell differentiation. Coincubation with both TNF-alpha and anti-TNF-alpha neutralizing antibody completely abolishes the TNF-alpha-induced proliferation of Mo7e cells. In bioassays, there is no detectable level of other stimulatory cytokines in conditioned medium from Mo7e cells previously stimulated by TNF-alpha, implying that the stimulatory effect of TNF-alpha on Mo7e cells is derived from the direct action of TNF-alpha rather than via the induction of secondary cytokines by TNF-alpha. Flow cytometric studies demonstrated that TNF-alpha binds to Mo7e cells that have been pretreated with either anti-TNF-RI or anti-TNF-RII neutralizing antibody, but TNF-alpha does not bind to cells pre-exposed to both receptor antibodies. However, the incubation of Mo7e cells with either TNF-RI or TNF-RII neutralizing antibodies or with either soluble TNF-RI or TNF-RII inhibits TNF-alpha-induced cell proliferation, indicating the requirement of interactions with both TNF receptors for the mitogenic activity of TNF-alpha. Furthermore, our data suggest that an alternative signaling pathway may be involved in TNF-alpha-induced Mo7e cell proliferation, because the common mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription (STAT) signaling pathways activated by other cytokines that induce Mo7e cell proliferation are not activated by TNF-alpha.

Hematopoietic Abnormalities in Patients With Cancer

Understanding the concepts of normal hematopoiesis and the mechanisms of both disease- and treatment-related cytopenias assists in the proper management of patients and rational uses of hematopoietic growth factors, particularly in those cancer patients receiving chemotherapy with or without stem and progenitor cell transplantation.

Clonality in juvenile chronic myelogenous leukemia

Juvenile chronic myelogenous leukemia (JCML) is a myeloproliferative disease in which morbidity and mortality are primarily caused by nonhematopoietic organ failure from myelomonocytic infiltration or by failure of the normal bone marrow. Morphologic evidence of maturation arrest, karyotypic abnormalities, and progression to blast crisis are infrequent events. Viral infections and other reactive processes can initially mimic the clinical course of JCML, creating diagnostic problems. Because of the rarity of JCML and technical limitations, formal clonality studies have not been reported previously. Nine female JCML patients were identified by clinical criteria, characteristic 'spontaneous' in vitro cell growth, and negative cultures and titers for various viral agents. Peripheral blood and bone marrow samples were obtained at the time of diagnosis for cell separation and RNA and DNA isolation. To assess clonality, X-chromosome inactivation patterns were evaluated using three different, recently developed polymerase chain reaction-based clonality assays. All nine female JCML patients showed evidence for monoclonal origin of mononuclear cells at the time of diagnosis. Cell separation studies further traced the monoclonal origin back to at least the most primitive myeloid progenitor cell. Reversion to a polyclonal state was demonstrated after bone marrow transplant and also in one patient following treatment with 13-cis retinoic acid. This demonstration of clonality in JCML delineates it from the reactive processes and provides a basis for molecular genetic strategies to identify causally associated mutations.

A pilot study of isotretinoin in the treatment of juvenile chronic myelogenous leukemia

BACKGROUND

Juvenile chronic myelogenous leukemia (CML) is a rare myeloproliferative disease of infants and young children for which there is no effective therapy other than allogeneic bone marrow transplantation. In vitro, isotretinoin (13-cis-retinoic acid) attenuates both the spontaneous proliferation of leukemic peripheral-blood progenitor cells (granulocyte-macrophage colony-forming units) and their selective hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF). We conducted a pilot study to evaluate the clinical efficacy of isotretinoin in juvenile CML.

METHODS

To be eligible the patients had to have newly diagnosed untreated disease, leukocytosis with monocytosis, marrow with less than 25 percent blasts, hepatosplenomegaly, no chromosomal abnormalities, and negative viral cultures and antibody titers. Isotretinoin was administered orally in single daily doses of 100 mg per square meter of body-surface area. When possible, patients subsequently underwent bone marrow transplantation.

RESULTS

Ten children (median age, 10 months) were enrolled in the study. In all 10 there was spontaneous colony formation of leukemic progenitor cells in vitro. In the eight patients tested there was hypersensitivity to GM-CSF. The only toxic effect of isotretinoin therapy was cheilitis in two patients. Four children had disease progression. Two children had complete responses to isotretinoin (normalization of the white-cell count and disappearance of organomegaly), three had partial responses (more than a 50 percent reduction in the white-cell count and degree of organomegaly), and one had a minimal response (more than a 50 percent reduction in the white-cell count, but a 26 to 50 percent reduction in the degree of organomegaly). The median duration of response was 37 months (range, 6 to 83). Three of the four children who had a complete or partial response and who did not undergo bone marrow transplantation were alive 36 to 83 months after the diagnosis of juvenile CML. The spontaneous colony formation in vitro was reduced in samples from the five patients in whom this factor was reassessed during treatment. There was also a reduction in the hypersensitivity of leukemic progenitor cells to GM-CSF in the two patients retested.

CONCLUSIONS

Isotretinoin can induce durable clinical and laboratory responses in patients with juvenile CML.

Cloning and sequencing of the cDNAs encoding two alternative splicing-derived variants of the alpha subunit of the granulocyte-macrophage colony-stimulating factor receptor

Two distinct cDNA clones, corresponding to alternative mRNA splicing variants of the alpha subunit of the granulocyte-macrophage colony-stimulating factor receptor (GM-CSF-R alpha) were isolated from human blood mononuclear cells by RT-PCR. The first one lacks 179 bp, and the second one lacks 136 bp of the major variant, GM-CSF-R alpha 1. Both of variants result in shifts in the reading frame and are expected to encode 377- and 285-amino-acid membrane anchoring and soluble receptor isoforms, respectively.

Chemotherapy of intermediate- and high-grade non-Hodgkin's lymphomas with an intensive epirubicin-containing regimen

An intensive chemotherapy regimen (EVDAC), including high-dose epirubicin, vincristine, and dexamethasone followed by cyclophosphamide and high-dose cytarabine, was administered to 54 untreated adults with intermediate or high-grade non-Hodgkin's lymphomas (NHL). The median age was 59, 61% were Ann Arbor Stage IV, 57% had "B" symptoms, 50% had serum lactate dehydrogenase greater than 250 U/L, and 48% had masses greater than 7 cm (33% > 10 cm) in diameter. Seventy-six percent of patients attained complete or probable complete remissions. The Kaplan-Meier actuarial failure-free survival at 7 years is 50%, and 59% (32 of 54) of all patients started on therapy remain alive and in first remission at a median of 62+ (range, 49+ to 76+) months from completion of therapy. Nearly all patients developed severe neutropenia. Febrile episodes requiring hospitalization during neutropenia occurred after 56% of courses of epirubicin, vincristine, and dexamethasone and after 9% of courses of cyclophosphamide and cytarabine; 80% of patients were hospitalized at least once. Platelet count nadirs of less than 20,000/microL occurred after only 1 of 146 evaluable courses of epirubicin and after none of the cyclophosphamide/cytarabine courses. Although 8 patients had decreases of at least 0.12 in their left ventricular ejection fractions (5 to below normal levels), none have developed clinically evident congestive heart failure. Clinically significant mucositis occurred after only 8% of courses of high-dose epirubicin. Three deaths from infections and one from hyperkalemia with cardiac arrest occurred during therapy. These results confirm that high remission and sustained, failure-free survival rates can be achieved in patients with aggressive NHL, using high-dose anthracycline-containing chemotherapy regimens. Epirubicin appears to have an advantage over doxorubicin at high doses because of decreased toxicity at a therapeutically equivalent dose. These phase II study results need to be validated in a randomized phase III trial, and growth factors should be used to attempt to reduce the neutropenia-associated complications.

Transplantation of umbilical cord blood after myeloablative therapy: analysis of engraftment

The possibility that umbilical cord and placental blood from an HLA-identical sibling might produce stable donor-derived lymphohematopoietic engraftment was tested in a patient with juvenile chronic myelogenous leukemia (JCML). After conditioning with high-dose busulfan and cyclophosphamide, cryopreserved umbilical cord blood, containing 0.5 x 10(8) nucleated cells/kg and 2.7 x 10(4) colony forming units-granulocyte, macrophage (CFU-GM)/kg, was infused. A leukocyte count greater than 1,000/microL, absolute neutrophil count (ANC) greater than 500/microL, and platelet count greater than 20,000/microL (untransfused) were observed on days 39, 39, and 47 after transplantation, respectively. Donor cell engraftment was documented in the peripheral blood and bone marrow by cytogenetic analysis, restriction fragment length polymorphism (RFLP), and polymerase chain reaction (PCR) as early as day 21. Furthermore, the donor origin of each lymphohematopoietic lineage (ie, CD5+ T cells, CD19/20+ B cells, CFU-GM, and burst-forming unit-erythrocyte [BFU-E]) was confirmed. On day 200, assays of the peripheral blood and bone marrow showed an abnormal proliferation of CFU-GM at low seeding densities in the absence of exogenous growth factors, as well as a hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF), both pathophysiologic characteristics of JCML. Recurrent disease was confirmed histologically on day 225. Together, these results demonstrate that umbilical cord blood contains sufficient numbers of hematopoietic stem cells necessary for the engraftment of leukemia patients treated with myeloablative therapy and that the detection of "spontaneous" CFU-GM and hypersensitivity to GM-CSF after treatment is a marker of residual or recurrent disease in patients with JCML.

The role of monocyte-derived hemopoietic growth factors in the regulation of myeloproliferation in juvenile chronic myelogenous leukemia

Juvenile chronic myelogenous leukemia (JCML) is a rare pediatric malignancy characterized by marked hepatosplenomegaly, leukocytosis with prominent monocytosis, elevated fetal hemoglobin, no Philadelphia chromosome, and generally a poor prognosis. In vitro, JCML peripheral blood granulocyte-macrophage progenitors (granulocyte-macrophage colony-forming units, CFU-GM) demonstrate the unique characteristic of "spontaneous" proliferation at very low cell densities in the absence of exogenous growth factors. The "spontaneous" CFU-GM proliferation can be abolished by prior adherent cell (monocyte) depletion, suggesting a paracrine mode of cellular proliferation. Although previous studies using a [3H]thymidine ([3H]TdR) incorporation assay suggested an important role for granulocyte-macrophage colony-stimulating factor (GM-CSF) in JCML, many non-growth factor-related reasons for [3H]TdR incorporation and the relatively low level of inhibition of [3H]TdR uptake left those conclusions open to question. Therefore, we performed clonal CFU-GM assays, which more specifically reflect cytokine effects on CFU-GM, using JCML peripheral blood mononuclear cells (PBMNC) and neutralizing antibodies against GM-CSF, granulocyte colony-stimulating factor (G-CSF), macrophage colony-stimulating (M-CSF), interleukin 3 (IL-3), interleukin 1 alpha (IL-1 alpha), interleukin 1 beta (IL-1 beta), interleukin 4 (IL-4), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF alpha), and interferon gamma (IFN gamma). Cultures containing anti-GM-CSF alone inhibited "spontaneous" JCML CFU-GM by 87% +/- 9% (mean +/- standard error of the mean [SEM]). No other anti-cytokine antibody produced a significant inhibition of CFU-GM growth. Various combinations of antibodies, excluding anti-GM-CSF, failed to demonstrate any synergistic inhibitory effects upon CFU-GM. Because this apparent paracrine cellular stimulation could be due to excessive cytokine production, by monocytes or other accessory cells, we examined cytokine levels in conditioned media from various JCML cell populations using enzyme-linked immunosorbent assays (ELISAs). Monocytes from only a minority of JCML patients produced higher than normal quantities of GM-CSF, G-CSF, IL-1 beta, IL-6, and/or TNF alpha, but no obvious pattern could be discerned. Further, only 7 of 15 JCML monocyte-conditioned media (MCM) had elevated GM-CSF, and 6 of 15 JCML patients had normal levels of all nine cytokines tested. The monocyte depletion experiments and the inhibition experiments with anti-cytokine antibodies taken together demonstrate clearly that the "spontaneous" growth of JCML CFU-GM in vitro critically depends on at least one monocyte-derived growth factor, GM-CSF.(ABSTRACT TRUNCATED AT 400 WORDS)

Selective hypersensitivity to granulocyte-macrophage colony-stimulating factor by juvenile chronic myeloid leukemia hematopoietic progenitors

Juvenile chronic myelogenous leukemia (JCML) is a good model for the study of myeloproliferation because JCML hematopoietic progenitor cells grow in vitro at very low cell densities without the addition of exogenous stimulus. Previous studies have demonstrated that this proliferation is dependent on granulocyte-macrophage colony-stimulating factor (GM-CSF), and that removal of monocytes from the cell population before culture eliminates this "spontaneous" myeloproliferation, suggesting a paracrine role of monocyte stimulation. However, subsequent studies have shown that increased GM-CSF production from the JCML monocytes is not a consistent finding and therefore not a plausible sole mechanism. In examining hematopoietic growth factor dose-response curves, both JCML GM and erythroid nonadherent progenitor cell populations displayed a marked and selective hypersensitivity to GM-CSF. Responses to interleukin-3 and G-CSF were identical to control dose-response curves. This is the first demonstration of a myeloid leukemia in which hypersensitivity to a specific growth factor appears to be involved in the pathogenesis of the disease.

Specific inhibition of interleukin 3 bioactivity by a monoclonal antibody reactive with hematopoietic progenitor cells

HIM1, originally designated HI98, a murine monoclonal IgM antibody raised against human mononuclear cells, has been reported at the Fourth International Leukocyte Typing Workshop (called antibody M0141) to be the only one of 157 antibodies tested that inhibited binding of interleukin 3 (IL-3) to KG-1 human acute myelogenous leukemia cells and normal human monocytes. We have carried out detailed studies of the selective effect of HIM1 on IL-3-mediated stimulation of hematopoietic progenitors. Preincubation of normal human bone marrow mononuclear cells, depleted of adherent cells and T cells, with HIM1 antibody resulted in a dose-dependent inhibition of IL-3-mediated stimulation of both erythroid burst-forming units (maximum inhibition 55%) and granulocyte/macrophage colony-forming units (maximum inhibition 49%). HIM1 antibody had no effect on growth of erythroid colony-forming units in culture. In addition, preincubation of the cells with HIM1 antibody had no deleterious effect on granulocyte/macrophage colony-stimulating factor-induced growth of either erythroid bursts or granulocyte/macrophage colonies. To be certain that the HIM1 antibody did not react directly with IL-3 itself, we attempted to use immunodepletion to remove IL-3 that had been added to our culture medium. Although we were able to remove IL-3 bioactivity by immunodepletion with anti-IL-3 antibody bound to Sepharose beads, beads with attached HIM1 did not remove IL-3 activity from the medium. Polymorphonuclear neutrophils bind high levels of HIM1, although they have very few or no detectable IL-3 receptors. Therefore, this antibody appears to recognize a cell surface antigen that is critical for optimal IL-3 binding and bioactivity but is not the actual IL-3 receptor.

Chemotherapy of intermediate- and high-grade non-Hodgkin's lymphomas with a high-dose doxorubicin-containing regimen

Forty-seven previously untreated patients with intermediate- or high-grade non-Hodgkin's lymphoma were treated with four courses of a regimen that consisted of high-dose (120 mg/m2) Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), vincristine (2 mg), cytarabine (3 gm/m2), and dexamethasone (50 mg intravenously [IV] on day 1 and 20 mg/day orally on days 2 to 5) (AVAD), which was administered every 3 to 4 weeks. The median age of the patients was 58 years; 72% were Ann Arbor stage IV, 49% had "B" symptoms, 62% had masses larger than 7 cm, 40% had masses at least 10 cm in diameter, and 49% had serum lactate dehydrogenase (LDH) greater than 250 U/L. Overall, 72% of the patients (89% of diffuse large-cell lymphoma [DLCL] patients) attained complete (CR) or probable complete responses (PCR), and relapses occurred in 32%. There were no episodes of clinical congestive heart failure, but one patient developed recurrent ventricular arrhythmias. Fever during neutropenia occurred with 65% of treatment courses. Three deaths were attributed primarily to complications of therapy. The lymphoma-free survival of all entered patients is 51% (24 of 47), with a follow-up of 30 to 67 months (median, 58 months). These results confirm that high CR/PCR and long-term survival rates can be achieved in patients with aggressive histologies of non-Hodgkin's lymphomas, even in groups with poor prognostic factors, using high-dose anthracycline-containing chemotherapy regimens delivered over a short period of time. However, the apparently higher relapse rate in comparison to our previous study leads us to speculate that consolidation with noncross-resistant agents may be helpful in increasing even further the cure rate in this group of patients.

Granulocyte-macrophage colony-stimulating factor is an endogenous regulator of cell proliferation in juvenile chronic myelogenous leukemia

Juvenile chronic myelogenous leukemia (JCML) is a rare myeloproliferative disorder of early childhood that is clinically and cytogenically distinct from the well-recognized adult type of chronic myeloid leukemia. Unlike the adult disease, growth of hematopoietic progenitors from peripheral blood (PB) occurs in the absence of exogenous stimulus even at low cell densities. This so-called "spontaneous" growth can be abrogated by adherent cell depletion and appears to depend on production of endogenous growth factors. We studied seven children with JCML to determine the nature of endogenous stimulators. With isolated PB mononuclear cells (PBMNCs) and a 3H-thymidine (3H-TdR) incorporation assay, JCML cells were shown to incorporate high levels of 3H-TdR when cultured in the absence of stimulus even at low cell densities. When neutralizing antisera prepared against each of the four known colony-stimulating factors (CSFs), GM-CSF, G-CSF, M-CSF, and interleukin-3 (IL-3), as well as antisera against interleukin-1 (alpha and beta) and tumor necrosis factor (TNF) were added to these cultures, only the antisera against recombinant human GM-CSF (rhGM-CSF) consistently resulted in significant inhibition of cell proliferation, achieving up to 72% inhibition of 3H-TdR incorporation in one case. Monoclonal antibodies (MoAbs) against rhGM-CSF resulted in a similar and highly significant degree of inhibition. A marked inhibitory effect of rhGM-CSF antiserum on "spontaneous" growth of PB CFU-GM derived colonies in semisolid medium was also demonstrated in four of five patients studied (87% to 90% inhibition). Production of growth factors by highly enriched JCML monocytes was variable. When initially studied in five of the seven patients, the monocytes from three of the patients revealed increased release of IL-1-like activities; two patients had levels similar to those of controls. One patient with normal levels when initially studied was later shown to have markedly increased amounts of IL-1-like activities in a second preparation of monocyte-conditioned medium (MCM). High levels of GM-CSF were detected in the initial MCM from one patient, but this may have indirectly reflected elevated IL-1-like activities present in the MCM. IL-3 and M-CSF levels were either low or undetectable in the patients studied as compared with MCM prepared with normal adult monocytes. These results clearly implicate GM-CSF as the primary endogenous regulator of JCML cell proliferation in culture and suggest that this malignant myeloproliferative disease may in part result from paracrine stimulation of marrow progenitor cells by growth factors/cytokines secreted by the malignant monocytes.

The t complex polypeptide 1 (TCP-1) is associated with the cytoplasmic aspect of Golgi membranes

The t complex polypeptide 1 (TCP-1) is a protein of unknown function expressed in large amounts during spermatogenesis. Rat monoclonal antibodies recognizing TCP-1 have been prepared and used to immunoprecipitate and Western blot a 57 kd protein from germ cell and tissue culture cell extracts. In tissue culture cells, indirect immunofluorescent localization of antigen indicated a perinuclear distribution similar to that of the Golgi apparatus. Analysis of the TCP-1 distribution in tissue culture cells showed that the polypeptide was associated with the cytoplasmic aspect of membranes of the trans-Golgi network (TGN). The distribution in spermatids suggested that TCP-1 was localized to structures often associated with the developing acrosome. The TCP-1 antigenic epitopes are highly conserved, allowing the protein to be identified in cells across a wide variety of vertebrate species and tissues. These experiments suggest that TCP-1 may be essential for transport of proteins through the exocytic pathway in all cells and required in large amounts for acrosome formation in developing spermatids.

Resistance of the stromal cell in murine long-term bone marrow cultures to damage by ionizing radiation

The ability of bone marrow stromal cells to survive and function after exposure to ionizing radiation remains controversial. Therefore, we used the murine long-term bone marrow culture system to analyze the effects of single doses of ionizing radiation (9-500 Gy) on the function of a preexisting, nearly confluent stroma that was supportive of hematopoiesis. Hematopoiesis ceased promptly in all the irradiated cultures and did not recover unless fresh marrow cells were inoculated. Radiation doses less than or equal to 100 Gy caused no obvious morphologic change in the cells. Total RNA, total protein, and collagen synthesis declined by 35%-60% within two days after even 9 Gy; but radiation doses up to 100 Gy caused minimal or no additional decline. Although RNA synthesis recovered nearly to normal within three weeks after radiation doses less than 100 Gy, total protein and collagen synthesis remained suppressed. Normal adherent layers irradiated with 9-50 Gy supported long-term hematopoiesis by fresh Sl/Sld marrow cells, although Sl/Sld marrow did not demonstrate sustained hematopoiesis when cultured in plain culture dishes or over normal stroma irradiated with 200 Gy. Thus, bone marrow stromal cells in long-term cultures did not show evidence of substantial cell death over at least the six-week period studied after irradiation with as much as 100 Gy, and they maintained hematopoietic supportive functions when irradiated with up to at least 50 Gy.

Sl/Sld mouse bone marrow stroma in vitro contains an active radiation-sensitive inhibitor of normal hemopoiesis

Sl/Sld mice have a defective hemopoietic microenvironment. It has been assumed, based upon previous studies, that the primary abnormality in these mice is simply lack of a necessary supportive or inductive material within the hemopoietic stroma. We used in vitro long-term bone marrow cultures to characterize further the nature of the hemopoietic microenvironmental defect in Sl/Sld mice. Sl/Sld mouse bone marrow cells consistently produced less than 10% of the total hemopoietic cells and multipotent and unipotent hemopoietic progenitor cells produced in cultures of marrow from normal, congenic +/+ mice. If fresh Sl/Sld and +/+ marrow cells were mixed prior to establishing long-term marrow cultures, there was a direct correlation between number of Sl/Sld cells added and degree of inhibition of +/+ hemopoiesis. A pre-established, confluent Sl/Sld adherent stromal layer inhibited hemopoiesis by fresh +/+ marrow cells by nearly 70%, as compared with dishes with irradiated +/+ or no stroma. This inhibitory effect was abrogated by irradiation of the Sl/Sld stroma prior to addition of the fresh +/+ marrow cells. Similarly, unirradiated, but not 9 to 200 Gy irradiated Sl/Sld stroma inhibited proliferation of the factor-dependent FDC-P1 hemopoietic progenitor cell line. Thus, the Sl/Sld hemopoietic microenvironment actively inhibits hemopoiesis in vitro, and this inhibition can be at least partially eliminated by irradiation of the Sl/Sld stroma.

Establishment of Tac-negative, interleukin-2-dependent cytotoxic cell lines from large granular lymphocytes (LGL) of patients with expanded LGL populations

Cell lines were established from purified large granular lymphocytes (LGL) isolated from the peripheral blood of seven patients with phenotypically homogeneous LGL expansions. LGL were stimulated with phytohemagglutinin (PHA) or recombinant interleukin-2 (rIL-2) and further expanded in vitro in IL-2-containing media. The surface phenotype of LGL, as assessed by monoclonal antibody staining, was T3+ T8+ in five patients, T3- T8- in one, and T3+ T8- in another patient. The cells also expressed Leu 7, Leu 11, and/or OKM 1 markers in various proportions and were identifiable as LGL by their morphological and cytochemical features. The original surface phenotype of the unstimulated LGL was retained in the IL-2-dependent cell lines from each individual patient, i.e., T3+ T8+ cells originated T3+ T8+ cell lines and T3- T8- cells originated T3- T8- cell lines. Other markers, such as Leu 11 and OKM 1, were generally lost in culture. LGL proliferated in response to rIL-2 but did not express detectable IL-2 receptors, even after prolonged periods of culture. All cell lines from each individual patient had the same surface phenotype, and within the single lines, all of the cells expressed the same markers. Cell lines from two patients consistently displayed chromosomal abnormalities. Although different in the two patients, the abnormalities were identical in all of the lines from the same patient and detectable in most of the cells examined, suggesting a clonal origin for the abnormally expanded LGL populations. Freshly isolated LGL did not exert NK activity. However, the IL-2-dependent LGL lines acquired the ability to kill K562 target cells and to produce gamma interferon (gamma-IFN). No direct correlation was observed between these two properties.

Production of multilineage hemopoietic growth-stimulating activities by a human melanoma cell line

In this study, we report that conditioned medium (CM) from the human melanoma cell line Hs0294 contains growth-stimulating activity for human and murine hemopoietic progenitor cells of multiple lineages. Crude CM was assayed for hemopoietic progenitor cell growth-stimulating activity (HP-GSA) in plasma clot cultures of 10(5) C57B1/6J mouse bone marrow cells or 10(5) light-density, nonadherent human peripheral blood mononuclear cells. CM concentrations as low as 0.2% had demonstrable HP-GSA for murine and human hemopoietic progenitor cells, although peak activity for all hemopoietic progenitor cell types assayed (murine CFU-Mix, BFU-E, CFU-GM, and CFU-M and human BFU-E) was observed with 5%-10% Hs0294-CM. Growth-stimulating activity for human erythroid progenitors (BFU-E) was comparable to that produced by phytohemagglutinin-stimulated human mononuclear cell CM. Stimulation of murine hemopoietic progenitors by Hs0294-CM was comparable to the activity in pokeweed mitogen-stimulated mouse spleen cell CM. The Hs0294-CM did not contain detectable quantities of erythropoietin or interleukin 3. Human burst-promoting activity was stable through sequential freezing and thawing, heating to 50 degrees C for 1 h or 100 degrees C for 5 min, and incubation at pH 9.8 for 1 h, but lost 70% of its activity when incubated at pH 2.2 for 1 h. More than 95% of the HP-GSA was recovered in the 50%-80% fraction by (NH4)2SO4 precipitation. The HP-GSA had an estimated molecular weight of approximately 21,000. In conclusion, we have shown that a human melanoma cell line, Hs0294, produces multilineage HP-GSA.

Production of erythroid burst-promoting activity (BPA) and granulocyte-monocyte colony-stimulating activity (GM-CSA) by isolated human T-lymphocyte subpopulations

T-lymphocytes and monocytes are prominent among the classes of normal human cells that have been implicated in the production of the hemopoietic growth factors granulocyte-macrophage colony-stimulating activity (GM-CSA) and erythroid burst-promoting activity (BPA). To investigate the nature of the cooperativity that occurs during the elaboration of these growth factors by activated T-lymphocytes and monocytes in vitro, and to define the subsets of T cells involved in this response, we studied the production of GM-CSA and BPA by populations of T-lymphocytes isolated by fluorescence-activated cell sorting, using the monoclonal antibodies OKT3, OKT4, and OKT8. When OKT3+, OKT4+, or OKT8+ cells were incubated for five days in liquid suspension cultures, their production of GM-CSA and BPA was undetectably low. When 5% autologous monocytes were added to the cultures, no increase in the secretion of either of these classes of growth factors was noted. In the presence of concanavalin A (Con A), measurable quantities of both GM-CSA and BPA were elaborated by all three populations of T cells in the absence of monocytes; however, when autologous monocytes were added to the Con A-stimulated T cells, the secretion of both GM-CSA and BPA was markedly enhanced. In addition, we found that supernates of unfractionated T cells incubated with Con A contained not only GM-CSA and BPA but also a potent inhibitor(s) of BPA that could be demonstrated by dilution of the media and removed by gel filtration. In contrast, no inhibitor of GM-CSA was found. By molecular sieve chromatography of the supernates, GM-CSA and BPA coeluted as a single peak. However, the two biologic activities could be separated on the basis of heat stability, since GM-CSA proved to be heat labile whereas BPA did not. Our data indicate that GM-CSA and BPA derived from human T cells are similar in their apparent molecular weights and in the pattern of their production in suspension cultures in response to lectin stimulation. The secretion of both GM-CSA and BPA by Con A-stimulated T cells is facilitated by the presence of autologous monocytes, and is not restricted to either the OKT4- or the OKT8-defined subset.

Monocytes stimulate fibroblastoid bone marrow stromal cells to produce multilineage hematopoietic growth factors

In previous studies we have found that monocytes produce soluble factors that stimulate human umbilical vein endothelial cells to produce granulocyte-macrophage colony-stimulating activity (CSA), burst-promoting activity (BPA), and megakaryocyte colony-stimulating activity (Meg-CSA) as well as factors that stimulate T lymphocytes and neonatal fibroblasts to produce CSA. To test the hypothesis that monocytes would similarly stimulate the production of hematopoietic growth factors by autologous bone marrow stromal cells, multiply-passaged adherent fibroblastoid cells derived from the bone marrow of normal volunteers were exposed to conditioned media prepared by incubating autologous peripheral blood monocytes in complete medium for three days. When conditioned media from stromal cells incubated in monocyte-conditioned medium were compared with those of stromal cells cultured in the absence of monocyte-conditioned medium, BPA was increased fourfold and CSA was increased more than 30-fold. We conclude that mononuclear phagocytes recruit stromal cells of the marrow to produce multilineage growth factors in vitro. We suggest that these monocyte-derived recruiting activities may play an important role in orchestration of hematopoietic growth factor production by cells of the marrow microenvironment.

Inhibition of collagen deposition in the extracellular matrix prevents the establishment of a stroma supportive of hematopoiesis in long-term murine bone marrow cultures

Long-term production of murine hematopoietic cells in vitro is dependent on establishment of a complex microenvironment consisting of a variety of stromal cells and an extensive extracellular matrix which includes collagen, fibronectin, laminin, proteoglycans, and other undefined components adherent to the culture dishes. Cis-4-hydroxyproline (CHP), a relatively specific inhibitor of collagen secretion, was used to examine the role of extracellular collagen deposition in supporting hematopoiesis in long-term C57B1/6J mouse bone marrow cell cultures. Throughout the 10-wk culture period, all culture dishes contained either 0, 10, 25, or 50 micrograms/ml of CHP. All medium and nonadherent cells were removed at weekly intervals and replaced with fresh medium containing the previous concentrations of CHP. Nonadherent cells were assayed weekly for total cells and pluripotent, erythroid, megakaryocytic, and granulocytic-macrophage progenitor cells. Dishes were killed at selected intervals to assess protein and collagen synthesis in the adherent layer. Adherent cell numbers, as judged by microscopic examination and DNA assays, correlated inversely with CHP concentrations used and paralleled degree of collagen synthesis inhibition. The decreased hemopoietic progenitor cell production correlated closely with percent inhibition of collagen synthesis and stromal cellularity. The CHP concentrations tested were not directly toxic to hemopoietic progenitor cells. These studies demonstrate that collagen deposition in the extracellular matrix of murine bone marrow cell cultures is essential to the establishment of a functional stromal microenvironment that is supportive of long-term hematopoiesis.

A monokine stimulates production of human erythroid burst-promoting activity by endothelial cells in vitro

Conditioned media were prepared from human peripheral blood monocytes and human umbilical vein endothelial cells. These media were assayed for erythroid burst-promoting activity (BPA) using human peripheral blood monocyte-depleted mononuclear cells as targets and assessing the stimulatory effect of the conditioned media on growth of early erythroid progenitor cells. Both monocytes and endothelial cells produced modest amounts of detectable BPA. Addition of varying concentrations of media conditioned by monocytes to plateau concentrations (5-10%) of media conditioned by endothelial cells had no additive effect. Endothelial cells incubated in the presence of 50% monocyte-conditioned medium produced 2.5- to 6.6-fold more BPA than did endothelial cells incubated only in control tissue culture medium. In contrast, endothelial cell conditioned medium did not stimulate increased BPA production by monocytes. Neither neutrophil- nor marrow fibroblastoid cell-conditioned medium stimulated BPA production by endothelial cells. Therefore, both monocytes and endothelial cells produce BPA. Moreover, monocytes produce a monokine that, in turn, stimulates the production of BPA by endothelial cells. Inasmuch as a monokine also has been shown to stimulate production of granulocyte-macrophage colony-stimulating activity, we propose that monocytes play a critical role in regulating the production of humoral regulators of the very early stages of hemopoietic cell differentiation.

Colchicine therapy for refractory idiopathic thrombocytopenic purpura

Fourteen patients with idiopathic thrombocytopenic purpura (ITP) refractory to splenectomy and corticosteroids (prednisone, 1 to 2 mg/kg of body weight per day) received at least 1.2 mg of oral colchicine daily for a minimum of two weeks. Three patients had complete responses and one had a partial response (response rate, 29%). Responses were evident within two weeks of commencing therapy. Only the patient with a partial response was receiving concomitant therapy, a stable dose of prednisone. Responsiveness to colchicine did not seem to correlate with responsiveness to vincristine sulfate. Side effects of colchicine therapy were mild and complications did not occur. A possible mechanism of action for colchicine in ITP is decreased clearance of opsonized platelets secondary to inhibition of microtubule-dependent events in macrophages. Colchicine is useful in the treatment of ITP resistant to standard treatment.