The chimeric oncoprotein E2A-HLF, generated by the t(17;19) chromosomal translocation in pro-B-cell acute lymphoblastic leukemia, incorporates the transactivation domains of E2A and the basic leucine zipper (bZIP) DNA-binding and protein dimerization domain of HLF (hepatic leukemic factor).The ability of E2A-HLF to prolong the survival of interleukin-3 (IL-3)-dependent murine pro-B cells after IL-3 withdrawal suggests that it disrupts signaling pathways normally responsible for cell suicide, allowing the cells to accumulate as transformed lymphoblasts.To determine the structural motifs that contribute to this antiapoptotic effect, we constructed a panel of E2A-HLF mutants and programmed their expression in IL-3-dependent murine pro-B cells (FL5.12 line), using a zinc-inducible vector.Neither the E12 nor the E47 product of the E2A gene nor the wild-type HLF protein was able to protect the cells from apoptosis induced by IL-3 deprivation.Surprisingly, different combinations of disabling mutations within the HLF bZIP domain had little effect on the antiapoptotic property of the chimeric protein, so long as the amino-terminal portion of E2A remained intact.In the context of a bZIP domain defective in DNA binding, mutants retaining either of the two transactivation domains of E2A were able to extend cell survival after growth factor deprivation.Thus, the block of apoptosis imposed by E2A-HLF in pro-B lymphocytes depends critically on the transactivating regions of E2A.Since neither DNA binding nor protein dimerization through the bZIP domain of HLF is required for this effect, we propose mechanisms whereby protein-protein interactions with the amino-terminal region of E2A allow the chimera to act as a transcriptional cofactor to alter the expression of genes regulating the apoptotic machinery in pro-B cells.
Fourteen children, 4 males and 10 females, with malignant histiocytosis (MH) were treated between July 1980 and June 1986. None of them had an affected sibling with a similar disorder. Septic-type fever was the most prominent symptom in all cases. Hepatosplenomegaly was present in 13 cases, lymphadenopathy, skin rash and jaundice in 8, pulmonary infiltration or pleural effusion on chest X-ray in 8, convulsion in 6, and renal involvement in 5 out of the 14 cases. Disseminated intravascular coagulation (DIC) was seen in 13 cases and this occurred within two weeks from onset in 6 cases. Pancytopenia, abnormal results of liver function tests, hypofibrinogenemia and hypocholesterolemia were common. The diagnosis was made for all 14 cases by characteristic clinical symptoms, signs, and bone marrow findings. In 8 cases, biopsy or autopsy specimens confirmed the diagnosis. Two patients died prior to chemotherapy. Twelve patients were treated with adriamycin, cyclophosphamide, vincristine and prednisone (ACOP). Complete response (CR) was achieved in five patients, and another two patients attained CR after subsequent treatment with other combinations including VP 16-213. These 7 complete responders are now alive and free of disease 11+ to 70+ months (median, 50+ months) from the onset of disease. All partial and non-responders died within 6 months with a median survival of 20 days. Among several clinical features as prognostic indicators, renal involvement, convulsion, and DIC occurring within 2 weeks were significantly related to poor outcome. Although MH is an aggressive disease with a poor prognosis, prompt diagnosis and early treatment with intensive systemic combination chemotherapy should further improve the outcome.
PUFAs such as GLA (n-6) or DHA (n-3) were shown to exert antitumor activity on a human neuroblastoma cell line (NCG) and its VCR-resistant subline (NCG/VCR1, 8.6-fold resistant to VCR) in vitro. The NCG/VCR1 line had markedly decreased intracellular accumulation of [3H]-VCR and an accelerated drug efflux, compared to the NCG. The cytotoxic activity of PUFAs was correlated with the generation of MDA-like products in these cells. When VCR was added simultaneously with GLA or DHA to culture medium, the cytotoxic effect of VCR was about 2-fold enhanced, accompanied by about 1.5-2.0-fold increase of intracellular [3H]-VCR in both cell lines. Fatty acid analysis of membrane phospholipids of the NCG and the NCG/VCR1 cells treated with GLA or DHA showed an increased total PUFAs and SFAs, associated with markedly decreased total MUFAs and an inverted PUFAs/MUFAs ratio. Such phospholipid modification may have altered the membrane physical properties and enhanced the VCR cytotoxicity by increasing intracellular VCR accumulation; however, these PUFAs did not affect the drug efflux sufficiently enough to overcome completely the VCR resistance in the NCG/VCR1 cells. These results indicate that PUFAs partially alleviate the VCR-resistance in human neuroblastoma cells, not directly acting on VCR-resistance mechanism(s).
A 6-month-old boy with familial erythrophagocytic lymphohistiocytosis (FEL) received allogeneic bone marrow transplantation (BMT) from an HLA-identical brother, after first achieving remission with Etoposide (VP16) and prednisone. The conditioning regimen for BMT consisted of high dose busulfan (16 mg/kg), cyclophosphamide (120 mg/kg), high dose VP16 (60 mg/kg) and intrathecal methotrexate and was well tolerated. Engraftment was achieved, and grade II GVHD was controlled with prednisone. Impaired NK activity present on admission gradually improved after BMT. The patient continues to be in complete remission more than 10 months after BMT.
The E2A-HLF (hepatic leukemia factor) oncoprotein, generated in pro-B lymphocytes by fusion of the trans-activation domain of E2A to the basic region/leucine zipper (bZIP) domain of HLF, functions as an anti-apoptotic transcription factor in leukemic cell transformation. When introduced into interleukin 3 (IL-3)-dependent mouse pro-B lymphocytes, E2A-HLF prevents apoptosis induced by growth factor deprivation, suggesting that IL-3 mediates cell survival through activation of a transcription factor whose activity can be constitutively replaced by the chimeric oncoprotein. We considered four bZIP transcription factors as candidates for this putative IL-3-regulated factor, each of which binds avidly to the DNA consensus sequence recognized by E2A-HLF and is related to the Caenorhabditis elegans CES-2 (cell death specification protein) neuron-specific mediator of cell death. The expression and binding activity of the Nfil3 protein (also called E4bp4), but not of Hlf, Dbp, or Tef, was found to be regulated by IL-3 in mouse pro-B cell lines (Baf-3 and FL5.12). Northern blot analysis showed that Nfil3 / E4bp4 is regulated as a “delayed-early” IL-3-responsive gene, requiring de novo protein synthesis. In the absence of IL-3, enforced expression of the human NFIL3/E4BP4 cDNA promoted the survival but not the growth of IL-3-dependent pro-B cells. Our results implicate NFIL3/E4BP4 (nuclear factor regulated by IL-3/adenovirus E4 promoter binding protein) in a distinct growth factor-regulated signaling pathway that is responsible for the survival of early B-cell progenitors, and whose alteration by E2A-HLF leads to childhood B lineage leukemia.
Serum ferritin level was measured serially in three malignant histiocytosis (MH) and five virus-associated hemophagocytic syndrome (VAHS) patients. Serum ferritin levels were greater than 1000 ng/ml at the early phase of disease. When disseminated intravascular coagulation (DIC) developed in patients, serum ferritin levels elevated further to greater than 12,000 ng/ml. MH patients were treated by combination chemotherapy, and VAHS patients were given prednisone. Each MH and VAHS patient died within 1 week from the onset of DIC, without decrease of serum ferritin level. One MH patient with continued high serum ferritin levels for 3 months after DIC also died. The remaining patients with decreased serum ferritin values less than 1000 ng/ml at 3 months after DIC are now alive with normal serum ferritin levels. These results suggest that serum ferritin level in histiocytic proliferative disorders is a useful indicator of disease activity in both neoplastic and reactive conditions rather than only a marker of malignant process.
A two‐year‐old infant with intractable diarrhea and lymphoproliferative disease of granular lymphocytes attributed to a persistent cytomegalovirus infection showed an increase in cells bearing the gamma/delta T‐cell receptor (TCR), which accounted for approximately 20% of total peripheral blood lymphocytes and 40% of CD3+ T cells. Of the gamma/delta TCR+ cells, two‐thirds were double negative (CD4–/CD8–) and the other one‐third CD8 positive. The majority of gamma/ delta + cells were delta TCS 1 positive. The predominance of delta TCS 1 positive cells was also confirmed on biopsy of lymphoid tissues from the colon. After improvement of watery diarrhea and malnutrition following three‐month hyperalimentation, the number of gamma/delta TCR+ cells decreased. The patient subsequently died of pneumonia at the age of 2 years and 11 months. A possible site‐specific role for the gamma/delta TCR + cells, particularly delta TCS 1 + cells, in the human intestine is discussed.
Abstract We describe a patient who had aggressive natural killer cell leukemia with profound hemophagocytosis. This combination must be underscored as one of several hemophagocytic syndromes. Activated phagocytes in the bone marrow appeared morphologically normal and could possibly be proliferating in response to some cytokine(s) such as interferon‐gamma produced by leukemic cells, whose serum level was found to be extremely elevated in this case.
