The Effects of Human BDH2 on the Cell Cycle, Differentiation, and Apoptosis and Associations with Leukemia Transformation in Myelodysplastic Syndrome.

Iron overload is related to leukemia transformation in myelodysplastic syndrome (MDS) patients. Siderophores help to transport iron. Type 2-hydroxybutyrate dehydrogenase (BDH2) is a rate-limiting factor in the biogenesis of siderophores. Using qRT-PCR, we analyze BDH2mRNA expression in the bone marrow (BM) of 187 MDS patients, 119 de novo acute myeloid leukemia (AML) patients, and 43 lymphoma patients with normal BM. Elevated BDH2mRNA expression in BM is observed in MDS patients (n = 187 vs. 43, normal BM; P = 0.009), and this is related to ferritin levels. Patients with higher BDH2 expression show a greater risk of leukemia progression (15.25% vs. 3.77%, lower expression; P = 0.017) and shorter leukemia-free-survival (medium LFS, 9 years vs. 7 years; P = 0.024), as do patients with a ferritin level ≥350 ng/mL. Additionally, we investigate the mechanisms related to the prognostic ability of BDH2 by using BDH2-KD THP1. The cell cycle analysis, surface markers, and special stain studies indicate that BDH2-KD induces differentiation and decreases the growth rate of THP1 cells, which is associated with the retardation of the cell cycle. Moreover, many genes, including genes related to mitochondrial catabolism, oncogenes, tumor suppressor genes, and genes related to cell differentiation and proliferation influence BDH2-KD THP1 cells. Herein, we demonstrate that BDH2 is involved in cell cycle arrest and the inhibition of differentiation in malignant cells. Furthermore, the high BDH2 expression in MDS patients could be suggestive of a poor prognostic factor. This study provides a foundation for further research on the roles of BDH2 and iron metabolism in the pathogenesis of MDS.

Cytochrome P4501B1 mediates induction of bone marrow cytotoxicity and preleukemia cells in mice treated with 7,12-dimethylbenz[a]anthracene.

Humans are exposed to polycyclic aromatic hydrocarbons (PAHs) through many environmental pollutants, especially cigarette smoke. These chemicals cause a variety of tumors and immunotoxic effects, as a consequence of bioactivation by P-450 cytochromes to dihydrodiol epoxides. The recently identified cytochrome P4501B1 (CYP1B1) bioactivates PAHs but is also a physiological regulator, as evidenced by linkage of CYP1B1 deficiency to congenital human glaucoma. This investigation demonstrates that CYP1B1 null mice are almost completely protected from the acute bone marrow cytotoxic and preleukemic effects of the prototypic PAH 7,12-dimethylbenz[a]anthracene (DMBA). CYP1B1 null mice did not produce the appreciable amounts of bone marrow DMBA dihydrodiol epoxide DNA adducts present in wild-type mice, despite comparable hepatic inductions of the prominent PAH-metabolizing P-450 cytochrome, CYP1A1. Wild-type mice constitutively expressed low levels of bone marrow CYP1B1. These findings suggest that CYP1B1 is responsible for the formation of DMBA dihydrodiol epoxides in the bone marrow. Furthermore, this study substantiates the importance of DMBA dihydrodiol epoxide generation at the site of cancer initiation and suggests that tissue-specific constitutive CYP1B1 expression may contribute to cancer susceptibility in the human population.

Arylsulfatase B in Kurloff cells: increased activity of anionic isoforms in guinea pig acute lymphoblastic leukemia.

We examined the in vivo role of Kurloff cells (KC), guinea pig natural killer cells, during the development of L2C leukemia, by analysing changes in the arylsulfatases (Asases) in the lysosomal Kurloff body. The Kurloff body is rich in acid phosphatase, esterase and proteoglycans, as are large granular lymphocyte granules. Moreover, the Kurloff body contains lysosomal Asase B, with unusual anionic isoforms. Injection of L2C cells elicited a three-fold increase in KC Asase activity on day 6. The increase in KC Asase activity was correlated with the number of circulating L2C cells. The basic Asase form (pl 8) was lost, and a concomitant increase in anionic isoforms (pl 5-6) was observed on day 6. The role of the latter in cytolysis was investigated by examining their capacity to lyse L2C target cells. We conclude that Asase participates in cytolysis when lysis is mediated by the complete assembly of cytolytic proteins. Changing and increasing KC Asase activity during leukemia development may be a marker for activated KC in vivo. These findings suggest that the cytolytic activation of KC occurs during the preleukemic period.

Biologic relevance of elevated red cell adenosine deaminase activity in myelodysplastic syndromes and paroxysmal nocturnal hemoglobinuria.

Red cell adenosine deaminase (ADA-RBC) activity in patients with myelodysplastic syndromes and paroxysmal nocturnal hemoglobinuria is significantly increased compared to that observed in normal controls. ADA-RBC activity is not related to fetal hemoglobin concentration, but it is significantly correlated with hemoglobin concentration at diagnosis and with the degree of morphologic dysplasia in the erythroid lineage. The results of our study suggest that the observed enzymatic abnormality may constitute a non-specific manifestation of the stem cell alteration that determines these disorders.

In vivo regulation of human leukocyte 3-hydroxy-3-methylglutaryl coenzyme A reductase: increased enzyme protein concentration and catalytic efficiency in human leukemia and lymphoma.

The activity of microsomal HMG-CoA reductase in freshly isolated leukocytes from patients with a variety of hematologic malignancies was significantly increased (up to 20-fold) when compared to enzyme activity in leukocytes from normal subjects (average 10.3 +/- 0.8 pmol/min per mg). Increased enzyme activity was not due to nonspecific leukocyte stimulation or to the presence of a malignancy, since normal enzyme activity was observed in subjects with either viral illnesses or solid tumors. Increased HMG-CoA reductase activity accompanying hematologic malignancy could also not be attributed to alterations in enzyme-substrate kinetic parameters (Km), or to alterations in the phosphorylation state or thiol-disulfide status of the enzyme, nor was it correlated with differences in serum lipid or lipoprotein concentrations. The increase (3.6-fold) in HMG-CoA reductase activity in leukocytes from patients with preleukemia was due entirely to a rise in enzyme catalytic efficiency (specific activity), whereas the increase (4.3-fold) observed in leukocytes from patients with overt leukemia or non-Hodgkin's lymphoma was due to a concomitant increase in both enzyme catalytic efficiency (2.5-fold) and enzyme protein concentration (1.6-fold). Similar increases in HMG-CoA reductase activity and catalytic efficiency were also noted for both transformed, nonmalignant, and malignant cultured leukocytes, suggesting that increased enzyme catalytic efficiency is not a nonspecific consequence of physiological changes occurring in response to the malignancy but may be an integral aspect of the malignant phenotype. HMG-CoA reductase protein concentrations, however, were not elevated in either transformed, nonmalignant, or malignant cultured leukocytes, suggesting that increases in enzyme protein levels may be secondary to other physiological changes that occur during the development of overt leukemia. Taken together, these observations suggest that an increase in the activity of HMG-CoA reductase, the rate-controlling enzyme in cholesterol synthesis, is a common occurrence in human hematologic malignancies and that a biphasic elevation of enzyme activity may exist in malignant leukocytes, such that changes in catalytic activity may occur early in tumorigenesis and may be followed by secondary changes in enzyme levels.

Serum deoxythymidine kinase in adult T-cell leukemia-lymphoma and its related disorders.

Serum deoxythymidine kinase (TK) was measured in 15 patients with the acute type of adult T-cell leukemia (ATL), in 4 with chronic ATL, in 10 with lymphoma type ATL, in 9 with pre-ATL, in 11 with human T-cell leukemia virus type I (HTLV-I) associated with myelopathy (HAM) and in 19 HTLV-I carriers. All these patients were positive for anti-HTLV antibody. The level of TK in pretreatment serum was highest in acute ATL (15.6-1600 U/l, median 107 U/l). It was elevated in chronic ATL (5.4-55.0 U/l, median 37.6 U/l) and lymphoma ATL (6.8-316 U/l, median 16.8 U/l) but normal in pre-ATL (1.8-4.7 U/l, median 2.8 U/l), HAM (1.2-6.0 U/l, median 3.0 U/l) and HTLV-I carriers (1.1-4.6 U/l, median 2.3 U/l). Statistical examination revealed a significant difference between the levels of acute ATL and chronic ATL/lymphoma ATL. In the patients of this series, a close correlation between the level of TK and lactic dehydrogenase (LDH) was statistically present (p less than 0.01). These facts indicate that TK level is a useful indicator of the aggressiveness of ATL cells.

Lysosomal enzyme abnormalities in preleukaemic Sweet's disease: case report.

Quantitative and qualitative abnormalities in marrow lysosomal enzymes, suggestive of acute myeloid leukaemia, were detected in a patient with Sweet's disease and monocytosis 12 months before she presented with acute myelomonocytic leukaemia. Biochemical characterisation of blood and marrow cell extracts may help to identify those patients with Sweet's disease and other preleukaemic conditions who are most at risk of developing leukaemia.

Preleukemia manifested by hemolytic anemia with pyruvate-kinase deficiency.

A 27-year-old patient manifested severe hemolytic anemia during a preleukemia phase. Low levels of adenosine triphosphate and decreased activity of pyruvate kinase were found. Acute myeloblastic leukemia developed in this patient 20 months later. The case suggests that acquired enzyme deficiency may play a role in the development of anemia in the preleukemic state.

Suppressed expression of blood group B antigen and blood group galactosyltransferase in a preleukemic subject.

The B antigen activity was severely diminished in a patient's RBCs at the preleukemic stage prior to chemo- or radiotherapy. The amount of H sites of the patient's RBC membranes was found to be comparable to that of O RBC membranes. The activity of alpha (1----2) fucosyltransferase (H enzyme) was not severely decreased in the patient's plasma and bone marrow. However, the activity of alpha (1----3) galactosyltransferase (B enzyme), which converts H substance to B substance, was drastically reduced in the patient's bone marrow. Thus, the diminished B antigen in the patient's RBCs was caused mainly by the blockage of conversion of the H substance to B substance. It is suggested that the viral oncogene linked to the ABO locus at q34 of chromosome No. 9 would occasionally suppress the expression of blood group A and B enzymes and A and B antigens.

Platelet DNA polymerase levels in CML: implications for oncogenesis.

Partially purified platelet DNA polymerase (PDP) was able to synthesize DNA transcripts of platelet polyadenylated RNA. PDP was elevated in the earliest stages of CML and PV. In PV, successful chemotherapy resulted in rapid return of PDP to normal levels while in CML this was not the case. An hypothesis is presented proposing that PDP contributes to oncogenesis by regulating the expression of oncogenes.

Correlation of alkaline phosphatase activity to normal T-cell differentiation and to radiation leukemia virus-induced preleukemic cells in the C57BL mouse thymus.

Cytochemical methods at the light and electron microscopic level were used to define the pattern of alkaline phosphatase (APase) activity in normal thymus and to study its modifications after inoculation with the thymotropic leukemogenic radiation leukemia virus in correlation with the emergence of preleukemic cells and their thymus dependency. APase was found in numerous lymphoblasts of the fetal thymus. The enzyme was also detected in a few lymphoid blast cells of the normal young adult thymus, which were closely associated with thymic nurse cells. The observed distribution of APase in normal thymus suggests that its expression could be limited to an early stage of the T-cell differentiation pathway. After inoculation with radiation leukemia virus, APase activity remained normal for almost the entire latency period, during which virus replication spread to the cortex and thymus-dependent preleukemic cells appeared. An important increase in the number of APase-positive cells occurred later, i.e., at the end of the latency period, in nontumoral thymus, which displayed lymphocytic depletion and contained autonomous thymus-independent preleukemic cells. These latter features obviously reflected the malignant transformation of thymus lymphoblasts, which eventually led to the development of the thymic lymphomas. The results raise the question of the possible filiation between the thymic nurse cell-associated APase-positive lymphoid cells of the normal thymus and the target cells susceptible to productive infection and to neoplastic transformation after radiation leukemia virus infection.

Ph1-positive acute myelocytic leukemia with high TdT levels.

The authors have determined TdT levels in a case of Ph1-positive AML. Peripheral blood cells and bone marrow cells taken during the various phases of the disease were examined. Liquor cells were analyzed when symptomatic central nervous system involvement occurred. High TdT levels were found in all of the phases of the disease including the liquor. TdT eluted at various isoelectric points indicating a shifting of the activity to greater molarity during progress of the disease. Two different forms of TdT were present in the liquor. The authors speculate about the existence of a relation between TdT levels and Ph1-positive leukemia. They point out the importance of TdT levels as functional criterion of remission in acute leukemia. Finally, the existence of different forms of TdT could be the expression of a clonal selection caused by therapy or of a spontaneous clonal competition.

Partial myeloperoxidase deficiency in preleukemia.

In seven subjects with partial and apparently acquired form of myeloperoxidase (MPO) deficiency, some functional properties of neutrophils (PMNs) were studied. Five patients suffered from preleukemia, one from diabetes mellitus and one from carcinoma of the breast with bone marrow metastases. Intracellular bactericidal activity, oxygen consumption and superoxide radical production were within normal limits. In three patients with preleukemia, the serum opsonic activity was markedly reduced (less than m-3SD) in an autologous system, but normal in the presence of pooled normal serum. Decreased opsonic activity was also found when these patient's sera were assayed in the presence of normal PMNs. Since the levels of IgG and C3 were comparable in the patients' sera and the pooled serum, a deficiency of another unknown opsonin or the presence of an opsonization inhibitor has to be postulated. The partial MPO defect apparently doesn't decrease the intracellular killing of Staphylococcus aureus by PMNs. The known susceptibility to bacterial infections in preleukemia may be explained by the reduction of serum opsonization conducing to a secondary decrease of the ingestion and killing of bacteria by the PMNs.

Partial myeloperoxidase deficiency.

Neutrophil myeloperoxidase (MPO) activity was analyzed by a semi-quantitative cytochemical method in 268 subjects divided into several groups. 17 subjects with significantly reduced MPO activity were found: 11 of 23 in the preleukemia group, 2/14 AMLs, 1/20 myeloproliferative syndrome, 1/7 carcinoma with bone marrow metastases, 1/33 diabetes mellitus and 1/50 normals. Only in the preleukemia group, was MPO significantly reduced in comparison to the normal group (p less than 0.005). The high frequency of acquired MPO deficiency in preleukemia represents a useful criterium for this diagnosis. Furthermore, in these patients, as well as in the other subjects studied, no apparent correlation between MPO level and infection could be demonstrated.

Neutrophil function and diagnosis of pre-leukaemic states.

Haemopoietic dysplasia is a condition which often precedes the development of acute non-lymphocytic leukaemia. Before this event, however, patients are at risk from severe infections even in the absence of neutropenia. This paper describes 3 patients with haemopoietic dysplasias in whom neutrophil microbicidal activity was deficient in vitro. The important abnormality appeared to be defective release of myeloperoxidase into the phagocytic vacuole. Two of these patients suffered from numerous baterial infections.