AATYK: a novel tyrosine kinase induced during growth arrest and apoptosis of myeloid cells

Apoptosis, or programmed cell death, is a process where developmental or environmental stimuli activate a genetic program to implement a series of events that culminate in cell death. To study the nature of genes that are induced during the apoptotic death of myeloid precursor cells, we utilized the 32Dcl3 cell line, which is derived from normal mouse bone marrow, is non-tumorigenic and diploid. These cells are strictly dependent on IL-3 for growth and apoptose when deprived of IL-3. However, when these cells are transferred to medium containing G-CSF, the cell number increases 4-5-fold and after 12 days the entire population is differentiated into granulocytes followed by apoptotic death. In our search for genes that are induced during apoptosis and/or terminal differentiation of 32Dcl3 cells, we identified a novel gene termed AATYK (Apoptosis Associated Tyrosine Kinase), whose expression is dramatically upregulated during IL-3 deprivation as well as G-CSF-induced terminal differentiation. In this report, we describe the sequence of the cDNA clone, derived from the mRNA transcript of this gene. These studies show that this gene encodes a protein with a tyrosine kinase domain at the N-terminal end and a proline-rich domain at the C-terminal end. We also report that the expression of this gene is blocked in v-abl or bcr-abl transformed myeloid cells which are unable to apoptose when grown in the absence of IL-3. However, AATYK expression is induced in 32D cells transformed by the v-abl gene when these cells are incubated in the presence of DMSO, which induces growth arrest and apoptotic death of the cells. On the other hand, DMSO fails to induce apoptosis or AATYK expression in 32D cells transformed by the bcr-abl oncogene, suggesting that AATYK expression may be a necessary pre-requisite for the induction of growth arrest and/or apoptosis of myeloid precursor cells.

Basic fibroblast growth factor stimulates DNA synthesis in cells overexpressing the insulin-like growth factor-I receptor

Insulin-like growth factor-I (IGF-I), by itself, cannot sustain the growth of BALB/c 3T3 cells, but requires the cooperation of other growth factors, such as platelet-derived growth factor or epidermal growth factor. In 3T3 cells constitutively overexpressing the human IGF-I receptor, called p6 cells, IGF-I by itself is fully mitogenic. We show here that p6 cells are also stimulated to enter DNA synthesis by the sole addition of basic fibroblast growth factor (bFGF), which, by itself, is incapable of stimulating parental 3T3 cells. Although bFGF does not bind directly to the IGF-I receptor, it induces its autophosphorylation. Stimulation of p6 cells by bFGF is not inhibited by an antibody to the IGF-I receptor that inhibits IGF-I-mediated DNA synthesis, and IGF-I is not detectable in the medium of bFGF-treated p6 cells. Stimulation cannot be explained by an increased number of FGF receptors, because p6 cells actually have slightly fewer FGF receptors than parental BALB/c 3T3 cells. Basic FGF also stimulates DNA synthesis in 3T3 cells overexpressing a mutant IGF-I receptor that does not autophosphorylate in response to IGF-I and has lost its mitogenic potential. Although we were unable to demonstrate directly that bFGF causes transphosphorylation of the IGF-I receptor, we conclude that in cells overexpressing the IGF-I receptor, bFGF can stimulate DNA synthesis either by an unknown mechanism or through transphosphorylation of the IGF-I receptor.

Use of cell-free retroviral vector preparations for transduction of cells from the marrow of chronic phase and blast crisis chronic myelogenous leukemia patients and from normal individuals

Marrow cells were exposed to the LNL6 or G1N safety-modified variants of the N2 retrovirus, which contain the G418 bacterial resistance gene neo. The frequency of acquisition of the G418 resistance phenotype following exposure to LNL6 or G1N was compared among hematopoietic progenitor cells from the marrow of patients with chronic phase chronic myelogenous leukemia (CML), blast crisis CML, or from nonleukemic individuals. Under the conditions of our experiments, the myeloid committed progenitor cells from 3 of 6 nonleukemic individuals, 9 of 18 chronic-phase CML patients, and 2 of 4 blast crisis CML patients acquired resistance to at least 1 mg/ml G418 following incubation with cell-free supernatants from the PA317 LNL6 or PA317 G1N producer cell lines. Ten of the 32 colonies growing up in 0.8 mg/ml G418 from chronic-phase marrow exposed to LNL6 were shown to contain the neo gene by polymerase chain reaction (PCR) assay of DNA. These results were consistent with estimates of the transduction frequency based on acquisition of resistance to G418 as the number of colonies growing under G418 selection was always greater at 0.8 mg/ml G418 than at higher concentrations of G418 (1.0-1.4 mg/ml). The average transduction frequency at each G418 concentration (1.0, 1.2, and 1.4 mg/ml) in cells from blast crisis CML cells ranged from 2 to 14%, as measured by acquisition of G418 resistance. Chronic-phase CML showed slightly lower average frequencies of transduction (0.6-2.8% of the colonies are G418 resistant). The average transduction frequency of cells from nonleukemic marrow was as high as that seen from the marrow of chronic-phase CML individuals.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular analysis of retroviral transduction in chronic myelogenous leukemia

We have developed a polymerase chain reaction (PCR) assay for detection of integrated retroviral transgenomes containing the neo G418 resistance gene in colonies (40 cells or more) grown in G418 selection after exposure to the neo-positive retrovirus LNL6. This assay also provides for simultaneous characterization of these colonies as belonging to a chronic myelogenous leukemic (bcr-abl positive) or nonleukemic population (bcr-abl negative). Using these techniques, we assessed transduction of the LNL6 retrovirus into the normal and leukemic cells of a blast-crisis chronic myelogenous leukemia (CML) patient. This work was designed to support the use of the LNL6 retroviral marker to help identify the origin of relapse after autologous marrow infusion. The data from these experiments show that the majority of CML blast crisis cells that, following exposure to the LNL6 virus, produce colonies under rigorous G418 selection are indeed transduced by the virus, as shown by the presence of the neo retroviral gene. Most of these colonies are also shown to be leukemic by PCR detection of the bcr-abl RNA. This demonstrates the feasibility of the study of CML marrow for retroviral marking. These procedures will be of use in establishing if relapse arises from leukemic blasts which contaminate purged autologous bone marrow infused following intensive therapy for leukemia.

Therapy of acute phase chronic myelogenous leukemia with intensive chemotherapy, blood cell autotransplant and cyclosporine A

The expansion of the Philadelphia (Ph) chromosome positive clone in chronic myeloid leukemia (CML) may depend on its capacity to suppress the proliferation of Ph-negative stem cells, but this proliferative advantage might, in certain circumstances, be reversible. Various lines of evidence suggest that Ph-negative cells, albeit in a suppressed state, must still be present. As recently suggested, the expansion of 'putative' normal Ph-negative hemopoietic stem cells might have, in certain circumstances, a proliferative advantage over the Ph clone in CML. This suggests that the treatment of CML with intensive chemotherapy might allow the collection of Ph-negative hemopoietic cells in the early phase of recovery. Eight patients with acute phase chronic myelogenous leukemia (AP-CML) were treated with idarubicin, intermediate dose cytarabine and etoposide. During recovery from bone marrow aplasia, when the white blood cell count reached 0.3-1 x 10(-9), blood cells were collected with 2-5 (median 3) consecutive leukapheresis. In 5/8 patients, these peripheral cells were Ph-negative at the cytogenetic analysis. Moreover, in one case the polymerase chain reaction analysis performed to detect the presence of minimal residual disease in the cells collected by leukapheresis was negative, further confirming that this approach may induce a very high degree of suppression of the Ph-positive clones. After complete recovery, these five patients were subsequently treated with high-dose etoposide, cyclophosphamide and total body radiation (10 Gy, single dose) followed by reinfusion of Ph-negative peripheral blood stem cells. All these patients received cyclosporine A post-autotransplant in an attempt to induce acute graft-versus-host-disease. Three of 5 patients remain in clinical and cytogenetic remission 5-15 months post-transplant. It is concluded that Ph-negative peripheral blood stem cells can be recovered from patients with AP-CML and used successfully to restore Ph-negative hemopoiesis after high dose therapy.

Cyclosporine-induced graft-versus-host disease after autologous bone marrow transplantation in hematological malignancies

In the attempt to induce graft-vs-host disease (GVHD) in patients undergoing autologous bone marrow transplantation (ABMT) or blood stem cell transplantation (BSCT), 12 consecutive patients received cyclosporin A (CyA) post transplant. CyA was given at a dose of 1.5 mg/kg/day intravenously for 28 days, starting on the day of transplant. Histologically proven acute GVHD of the skin occurred in seven patients 9-14 days after ABMT and lasted 7-11 days. CyA-induced GVHD after ABMT resembles mild GVHD after allogeneic bone marrow transplantation (BMT). Although the preliminary data reported here show that it is possible to induce GVHD in patients undergoing ABMT, it is not yet known whether GVHD after ABMT will have an antitumor activity.

RFLP analysis with cDNA probes for DQ/DP region in HLA identical sibling marrow transplants: lack of correlation with GvHD

BACKGROUND

The role of HLA-DP as transplantation antigen in contributing to GvHD is a matter of current debate. HLA-DP, is encoded centromeric to DR-DQ and its alleles are in weak linkage disequilibrium with the rest of the MHC; thus a certain number of HLA matched pairs could be actually DP incompatible to study a possible correlation between HLA-DP matching and GvHD, 24 HLA identical BMT/donor-recipient sibling pairs (serologically tested for HLA Class I and DR antigens) were tested for DQ and DP genes using restriction fragment length polymorphism (RFLP) analysis.

METHODS

DNA extracts were digested according to a standard procedure with two different restriction enzymes (HIND III and MSP I) and hybridised with DQ (alpha and beta) and DP (alpha and beta) specific probes. Highly stringent hybridization and washing conditions were used to prevent cross-hybridizations.

RESULTS

Twenty four out of 24 pairs proved to be DQ and DP identical. GvHD developed in 16 out of 24 (66.6%) recipients.

DISCUSSION

These data suggest that DNa analysis of DQ-DP regions, with the probes and enzymes used, does not give predictive informations for GvHD in HLA genotypically identical pairs.

Clinical use of GM-CSF in autologous bone marrow transplantation

Over the last decade, the key role of specific glycoproteins (hematopoietic growth factors) in the proliferation and maturation of hematopoietic cells (in conjunction with some of their particular functional activities) has been demonstrated through in vitro and in vivo studies. These glycoproteins have been evaluated for their potential application in reducing the duration of myelosuppression following conventional chemotherapy and autologous bone marrow transplantation. Preliminary results using granulocyte-macrophage colony-stimulating factor to restore neutrophil competence seem to be encouraging.

Idarubicin in combination with intermediate-dose cytarabine in the treatment of refractory or relapsed acute leukemias

13 patients with refractory or relapsed acute lymphoblastic leukemia (ALL) and 7 patients with acute myeloid leukemia (AML) were treated with a regimen that included idarubicin 12 mg/m2 intravenously daily for 3 d plus cytarabine 2 g/m2 by infusion over 3 hours daily for 3 d. There were 10 remissions (ALL:7; AML:3) in the 15 relapsed patients and 4 (ALL:3) in the 5 patients with primary refractory disease. Severe myelosuppression was observed in all patients. Toxicity of this regimen caused nausea and vomiting, stomatitis, infections and/or liver enzymes increase. Cardiac toxicity was not observed. 2 patients died in aplasia of Gram-negative septicemia and brain hemorrhage. In conclusion, the combination of idarubicin and intermediate-dose cytarabine (IDARA-C) seems to be highly effective and sufficiently well-tolerated for the treatment of refractory and relapsed acute leukemias.

Autologous unpurged bone marrow transplantation for acute non-lymphoblastic leukaemia in first complete remission

Twenty-five patients with acute non-lymphoblastic leukemia (ANLL) in first complete remission underwent autologous bone marrow transplantation (ABMT) between March 1984 and March 1988. The high-dose therapy employed included cyclophosphamide followed by total body irradiation (10 Gy), administered as a single dose. The median time from complete remission to ABMT was 5 months (range 2-9 months). Thirteen (52%) patients remain in complete remission 10-51 months (median 25 months) after ABMT and 14-60 months (median 32 months) after achieving complete remission. Causes of death were recurrent leukemia (five patients), parenchymal toxicities (acute respiratory distress syndrome, veno-occlusive disease) (three patients), cerebral haemorrhage (one patient), cerebral aspergillosis (one patient) and viral hepatitis (one patient). Six patients relapsed at a median of 5 months after ABMT (range 4-10 months). In conclusion, this study has resulted in survival data comparable to those of other institutions and the best reported outcomes of conventional chemotherapy.

High-dose chemotherapy with autologous bone marrow transplantation in 50 advanced resistant Hodgkin's disease patients: an Italian study group report

Fifty patients with recurrent Hodgkin's disease have been treated with high-dose therapy followed by autologous bone marrow transplantation. Forty-one patients had extranodal sites of relapse and 31 patients had constitutional symptoms. Two patients had been treated with mechlorethamine, vincristine, procarbazine, and prednisone (MOPP), lomustine, vinblastine, procarbazine, and prednisone (CcVPP), and radiation; 16 patients with MOPP, doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD), radiation, and lomustine, etoposide, and prednisone (CEP); 20 patients with alternating MOPP/ABVD, and 12 patients with alternating MOPP/ABVD followed by CEP and radiation. Eighteen patients had progressive disease during alternating MOPP/ABVD protocol alone or during conventional salvage therapy; 32 patients had had a complete remission with first-line therapy but later relapsed, 25 of them having received conventional salvage therapy; 12 achieved no response or progression ("resistant-relapse" patients); and 13 responded partially or completely ("sensitive-relapse" patients). Complete remission occurred in 24 patients (48%) with a median duration of 24 months and 16 patients (32%) achieved partial response with a median duration of 9 months, for an overall response rate of 80%. Ten patients failed to respond and died in progressive disease 1 to 10 months (median, 6 months) after transplantation. Toxicity was significant including infections (20%), liver enzymes and alkaline phosphatase elevations (100%), and carmustine lung toxicity (7%). There were two treatment-related deaths; one patient died of Pseudomonas aeruginosa septicemia and another patient died of cerebral hemorrhage. These results validate the procedure of high-dose therapy followed by autologous bone marrow transplantation in inducing remission in these advanced, highly-treated patients. Clearly, the question of whether high-dose therapy and transplantation will eventually supersede new conventional salvage therapies will be addressed after controlled clinical studies.

Idarubicin in combination with etoposide and cytarabine in adult untreated acute non lymphoblastic leukemia

Thirty-one unselected patients with untreated acute non lymphoblastic leukemia (ANLL) ranging in age from 15 to 76 years received two courses of a new high-dose induction regimen consisting of idarubicin, etoposide and cytarabine. Patients who entered complete remission (CR) were then allocated to post-remission intensification (PRI). Patients under 40 years of age with a HLA-compatible donor were given bone marrow transplantation (BMT); those without an HLA identical donor received either autologous BMT (ABMT) or no subsequent therapy. Twenty-five out of 31 patients (80.6%) achieved CR (93.3% in young and 68.7% in old patients) and 14 (56%) after the first cycle. Six patients (five out six greater than 40 years) died of cerebral hemorrhage and/or infection during the induction phase and four additional patients (three elderly) died on the PRI for the same cause without recurrent disease. Eleven out 25 patients are disease-free survivors 2-34 months (median 10 months) after achievement of CR. In conclusion, this intensive chemotherapy regimen is effective both in young and older patients but the post-remission intensification is too aggressive in elderly patients.