Cytogenetic study of human lymphoid T-cell lines derived from lymphocytic leukemia

Development of Novel Peptides That Target the Ninjurin 1 and 2 Pathways to Inhibit Cell Growth and Survival via p53

Ninjurin 1 and 2 (NINJ1, NINJ2) belong to the homophilic cell adhesion family and play significant roles in cellular communication and tissue development. While both NINJ1 and NINJ2 are found to be over-expressed in several types of cancers, it remains unclear whether they can be targeted for cancer treatment. In this study, we aimed to develop NINJ1/2 peptides derived from the N-terminal extracellular domain that can elicit growth suppression and thus possess therapeutic potentials. We found that peptide NINJ1-A, which is derived from the N-terminal adhesion motif of NINJ1, was able to inhibit cell growth in a NINJ1- or p53-dependent manner. Similarly, peptide NINJ2-A, which is derived from the N-terminal adhesion motif of NINJ2, was able to inhibit cell growth in a NINJ2- or p53-dependent manner. We also found that NINJ1 and NINJ2 physically interact via their respective N-terminal domains. Interestingly, NINJ1-B and NINJ2-B peptides, which were derived from the N-terminal amphipathic helix domains of NINJ1 and NINJ2, respectively, were able to disrupt NINJ1-NINJ2 interaction and inhibit cell growth in a NINJ1/NINJ2-dependent manner. Notably, NINJ1-B and NINJ2-B peptides demonstrated greater potency in growth suppression than NINJ1-A and NINJ2-A peptides, respectively. Mechanistically, we found that NINJ1-B and NINJ2-B peptides were able to induce p53 expression and suppress cell growth in a p53-dependent manner. Together, our findings provide valuable insights into the development of NINJ1/NINJ2 peptides as potential cancer therapeutics, particularly for cancers harboring wild-type p53.

Increased MYB alternative promoter usage is associated with relapse in acute lymphoblastic leukemia

Therapy-resistant disease is a major cause of death in patients with acute lymphoblastic leukemia (ALL). Activation of the MYB oncogene is associated with ALL and leads to uncontrolled neoplastic cell proliferation and blocked differentiation. Here, we used RNA-seq to study the clinical significance of MYB expression and MYB alternative promoter (TSS2) usage in 133 pediatric ALLs. RNA-seq revealed that all cases analyzed overexpressed MYB and demonstrated MYB TSS2 activity. qPCR analyses confirmed the expression of the alternative MYB promoter also in seven ALL cell lines. Notably, high MYB TSS2 activity was significantly associated with relapse (p = 0.007). Moreover, cases with high MYB TSS2 usage showed evidence of therapy-resistant disease with increased expression of ABC multidrug resistance transporter genes (e.g., ABCA2, ABCB5, and ABCC10) and enzymes catalyzing drug degradation (e.g., CYP1A2, CYP2C9, and CYP3A5). Elevated MYB TSS2 activity was further associated with augmented KRAS signaling (p < 0.05) and decreased methylation of the conventional MYB promoter (p < 0.01). Taken together, our results suggest that MYB alternative promoter usage is a novel potential prognostic biomarker for relapse and therapy resistance in pediatric ALL.

RUNX1 colludes with NOTCH1 to reprogram chromatin in T cell acute lymphoblastic leukemia

Runt-related transcription factor 1 (RUNX1) is oncogenic in diverse types of leukemia and epithelial cancers where its expression is associated with poor prognosis. Current models suggest that RUNX1 cooperates with other oncogenic factors (e.g., NOTCH1, TAL1) to drive the expression of proto-oncogenes in T cell acute lymphoblastic leukemia (T-ALL) but the molecular mechanisms controlled by RUNX1 and its cooperation with other factors remain unclear. Integrative chromatin and transcriptional analysis following inhibition of RUNX1 and NOTCH1 revealed a surprisingly widespread role of RUNX1 in the establishment of global H3K27ac levels and that RUNX1 is required by NOTCH1 for cooperative transcription activation of key NOTCH1 target genes including MYC, DTX1, HES4, IL7R, and NOTCH3. Super-enhancers were preferentially sensitive to RUNX1 knockdown and RUNX1-dependent super-enhancers were disrupted following the treatment of a pan-BET inhibitor, I-BET151.

Synthetic oleanane triterpenoids suppress MYB oncogene activity and sensitize T-cell acute lymphoblastic leukemia cells to chemotherapy

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy with poor prognosis. The MYB oncogene encodes a master transcription factor that is activated in the majority of human T-ALLs. In the present study, we have performed a large-scale screening with small-molecule drugs to find clinically useful inhibitors of MYB gene expression in T-ALL. We identified several pharmacological agents that potentially could be used to treat MYB-driven malignancies. In particular, treatment with the synthetic oleanane triterpenoids (OTs) bardoxolone methyl and omaveloxolone decreased MYB gene activity and expression of MYB downstream target genes in T-ALL cells with constitutive MYB gene activation. Notably, treatment with bardoxolone methyl and omaveloxolone led to a dose-dependent reduction in cell viability and induction of apoptosis at low nanomolar concentrations. In contrast, normal bone marrow-derived cells were unaffected at these concentrations. Bardoxolone methyl and omaveloxolone treatment downregulated the expression of DNA repair genes and sensitized T-ALL cells to doxorubicin, a drug that is part of the standard therapy of T-ALL. OT treatment may thus potentiate DNA-damaging chemotherapy through attenuation of DNA repair. Taken together, our results indicate that synthetic OTs may be useful in the treatment of T-ALL and potentially also in other MYB-driven malignancies.

Physicochemistry of Cereblon Modulating Drugs Determines Pharmacokinetics and Disposition

Immunomodulatory drugs (IMiDs) thalidomide, lenalidomide, and pomalidomide engage cereblon and mediate a protein interface with neosubstrates such as zinc finger transcription factors promoting their polyubiquitination and degradation. The IMiDs have garnered considerable excitement in drug discovery, leading to exploration of targeted protein degradation strategies. Although the molecular modes-of-action of the IMiDs and related degraders have been the subject of intense research, their pharmacokinetics and disposition have been relatively understudied. Here, we assess the effects of physicochemistry of the IMiDs, the phthalimide EM-12, and the candidate drug CC-220 (iberdomide) on lipophilicity, solubility, metabolism, permeability, intracellular bioavailability, and cell-based potency. The insights yielded in this study will enable the rational property-based design and development of targeted protein degraders in the future.

Characterization of Camptothecin-induced Genomic Changes in the Camptothecin-resistant T-ALL-derived Cell Line CPT-K5

Acquisition of resistance to topoisomerase I (TOP1)-targeting camptothecin (CPT) derivatives is a major clinical problem. Little is known about the underlying chromosomal and genomic mechanisms. We characterized the CPT-K5 cell line expressing mutant CPT-resistant TOP1 and its parental T-cell derived acute lymphoblastic leukemia CPT-sensitive RPMI-8402 cell line by karyotyping and molecular genetic methods, including subtractive oligo-based array comparative genomic hybridization (soaCGH) analysis. Karyotyping revealed that CPT-K5 cells had acquired additional structural aberrations and a reduced modal chromosomal number compared to RPMI-8402. soaCGH analysis identified vast copy number alterations and >200 unbalanced DNA breakpoints distributed unevenly across the chromosomal complement in CPT-K5. In addition, the short tandem repeat alleles were found to be highly different between CPT-K5 and its parental cell line. We identified copy number alterations affecting genes important for maintaining genome integrity and reducing CPT-induced DNA damage. We show for the first time that short tandem repeats are targets for TOP1 cleavage, that can be differentially stimulated by CPT.

Sphingolipid Microdomains Mediate CD38 Internalization: Topography of the Endocytosis

Plasma membranes of several cell types contain specialized microdomains (or lipid rafts) enriched in sphingolipids, cholesterol, sphingomyelin, and glycosyl-phosphatidylinositol-anchored proteins. These membrane domains are characterized by detergent insolubility at low temperatures and low buoyant density. Human CD38 is the prototype of a gene family encoding surface molecules endowed with multiple functional activities. The endocytosis of the human CD38 molecule has been investigated in normal lymphocytes and in a number of leukemia- and lymphoma-derived cell lines demonstrating that internalization after CD38 ligation is a reproducible event involving only a fraction of the whole amount of the surface molecule. This study reports the results obtained by conventional, confocal, and electron microscopy on the effects induced by the engagement of the molecule with agonistic mAb, reproducing the signals mediated by its natural ligand. The results demonstrate that the endocytosis induced as consequence of CD38 ligation is preceded by a thorough rearrangement of the cell surface with formation of glycosphingolipid- and cholesterol-rich plasma membrane microdomains. These data suggest that specialized raft microdomains might be the plasma membrane structure through which CD38 translocates at intracellular level. The CD38/lipid interactions during the coated pit formation trigger a process that generate membrane curvature, considered as the first step of CD38 endocytosis. Moreover, ultrastructural studies show that early CD38+ endosomes are pleiomorphic and contain cisternal and vesicular regions. Late endosomes exhibit a complex organisation, containing uncoupled CD38-ligand multivesicular- or multilamellar-regions.

DMSO Modifies Structural and Functional Properties of RPMI-8402 Cells by Promoting Programmed Cell Death

Apoptosis in lymphoid cells can be induced in different ways depending on cell type and acquired signal. Biochemical modifications occur at an early phase of cell death while at late times the typical morphological features of apoptosis can be visualized. The aim of this study is to verify by multiparametric analyses the plasma membrane fluidity, the intracellular Ca2+ concentration and the nitric oxide synthase (NOS) activity during cell death progression induced by DMSO treatment. The RPMI-8402 human pre-T lymphoblastoid cell line was induced to cell death by DMSO. Analyses rescued at early times of treatment prove a substantial modification of plasma membrane fluidity associated with an increase of intracellular Ca2+. Moreover, these modifications are associated with an up regulation of NOS activity. Our results are consistent with the hypothesis that programmed cell death can be induced by up regulation of the intracellular Ca2+ associated with an increase of cell membrane fluidity. The apoptotic mechanisms seem to involve not only membrane damage and increased intracellular calcium levels but also production of nitric oxide.

Changes of Plasma Membrane Properties in a Human Pre-T Cell Line Undergoing Apoptosis

A variety of cellular functions are modulated by the physical properties of the cell membrane, and the modification of intracellular transfer, resulting from loss of membrane integrity, may contribute toward setting the cell onto the pathway of apoptosis. Apoptosis in lymphoid cells can be induced in different ways and biochemical modifications occur at an early phase of cell death, while the morphological features of apoptosis are evident later. We previously reported that DMSO is an efficient apoptosis-inducing factor in the human RPMI-8402 pre-T cell line. The aim of the present study was to verify the effect of DMSO on the plasma membrane fluidity, the intracellular calcium concentration and the phosphodiesterase activity in DMSO-induced apoptosis. Our results show a modification of membrane fluidity associated with an increase of intracellular Ca(2+) concentration. Moreover, we demonstrate that these modifications are related to a decrease in the phosphodiesterase (PDE) activity. The correlation between the proceedings of added DMSO and the induction of apoptosis will provide significant information regarding the first part of the apoptotic process.

The c-myc gene regulates the polyamine pathway in DMSO-induced apoptosis

It is accepted that apoptosis is a gene-controlled process of cellular self-destruction. It occurs during physiological regulation and in pathological situations in the life of a cell. In the immune system, several different intracellular and extracellular factors have been associated with the induction of apoptosis, and the final responses depend on the cell system and the acquired signals. In lymphoid cells, dexamethasone-induced apoptosis is associated with c-myc downregulation in cells that remain in G0-G1 until the point of death. Ornithine decarboxylase (ODC), a key enzyme involved in polyamine biosynthesis, is regulated by c-myc, which is a transcriptional activator implicated not only in the control of cell proliferation and differentiation but also in programmed cell death. As dimethylsulphoxide (DMSO) induces apoptosis in the RPMI-8402 human pre-T cell line, the present study analysed the involvement of the c-myc proto-oncogene and polyamine pathway as mediators of apoptosis. Cell growth, programmed cell death, c-myc expression, ODC activity and intracellular polyamine content were detected after DMSO and difluoromethylornithine (DFMO) treatment. DMSO-treated cells exhibit a decrease in ODC activity and polyamine levels associated with cell growth arrest and programmed cell death induction. The expression of c-myc proto-oncogene, as its mRNA or protein, is specifically down-regulated. DFMO, a well defined polyamine biosynthesis inhibitor, completely blocks ODC activity, resulting in growth inhibition but not apoptosis. Moreover, in these samples no evidence of changes of c-myc expression were found. The results obtained suggest that, in RPMI-8402 cells, DMSO provokes a c-myc-dependent decrease of ODC activity followed by a depletion of intracellular polyamine levels, associated with programmed cell death and cell growth arrest.

Involvement of caspace-3 in the cleavage of terminal transferase

To investigate the in vivo role of caspase-3 in Terminal Transferase metabolism DMSO-treated RPMI-8402, a human pre-T cell line was used. In DMSO treated samples (3)H-dGTP incorporation and TdT phosphorylation occurs after 4 hours of treatment. After 8 hours cells undergo TdT proteolysis in addition to its inactivation. The cleavage of TdT into 32- and 58-KDa proteolytic fragments occurred simultaneously with the activation of Caspase-3, but preceded changes associated with the apoptotic process described after 48 hours of treatment. The Caspase-3 peptide inhibitor V, used as a specific inhibitor, prevented TdT proteolysis prolonging its activity and rescued cells from apoptosis. Our experiments suggest that TdT is a nuclear substrate for Caspase-3, the main apoptotic effector protease in many cell types, and that the cleavage of TdT represents a primary step in a signal cascade leading to pre-T cell apoptosis.

A Nuclear Factor Y (NFY) Site Positively Regulates the Human CD34 Stem Cell Gene

Proper regulation of the human CD34 gene requires a combinatorial action of multiple proximal and long-range, ciselements. This report shows that, like the murine CD34 5′ untranslated region (UTR), the corresponding region of the human CD34 gene is necessary for optimal promoter activity. We localized the most critical element of this region to base pairs +48/+75. Through oligonucleotide competition and antibody supershift experiments in electrophoretic mobility shift assays, we found that this sequence contains a binding site (CCAAT box) for the transcription factor NFY (nuclear factor Y), a factor mediating cell type-specific and cell-cycle regulated expression of genes. Mutating this site led to a 5-fold decrease in CD34 promoter activity in transient transfection experiments. Interestingly, NFY binds adjacently to the earlier identified c-myb binding site. Here we show that both binding sites are important for CD34 promoter function: mutating either site alone decreased CD34 promoter-driven reporter gene activity 4-fold. We also show that the integrity of the c-myb binding site is necessary for stabilization of NFY binding to its site. Such cooperation between c-myb, which is expressed in early hematopoietic cells, and NFY, which is expressed in many cell types, might contribute to specific activation of CD34 in stem cells. The CCAAT box motif was also noted in the 5′ UTR of the murine CD34 gene, however, NFY did not bind to this region. Thus, our results indicate that the functional similarities between the human and murine CD34 5′ UTRs are achieved through different molecular mechanism(s).

A Nuclear Factor Y (NFY) Site Positively Regulates the Human CD34 Stem Cell Gene

Proper regulation of the human CD34 gene requires a combinatorial action of multiple proximal and long-range, ciselements. This report shows that, like the murine CD34 5′ untranslated region (UTR), the corresponding region of the human CD34 gene is necessary for optimal promoter activity. We localized the most critical element of this region to base pairs +48/+75. Through oligonucleotide competition and antibody supershift experiments in electrophoretic mobility shift assays, we found that this sequence contains a binding site (CCAAT box) for the transcription factor NFY (nuclear factor Y), a factor mediating cell type-specific and cell-cycle regulated expression of genes. Mutating this site led to a 5-fold decrease in CD34 promoter activity in transient transfection experiments. Interestingly, NFY binds adjacently to the earlier identified c-myb binding site. Here we show that both binding sites are important for CD34 promoter function: mutating either site alone decreased CD34 promoter-driven reporter gene activity 4-fold. We also show that the integrity of the c-myb binding site is necessary for stabilization of NFY binding to its site. Such cooperation between c-myb, which is expressed in early hematopoietic cells, and NFY, which is expressed in many cell types, might contribute to specific activation of CD34 in stem cells. The CCAAT box motif was also noted in the 5′ UTR of the murine CD34 gene, however, NFY did not bind to this region. Thus, our results indicate that the functional similarities between the human and murine CD34 5′ UTRs are achieved through different molecular mechanism(s).

Influence of amino acid substitutions on antigenicity of immunodominant regions of the HTLV type I envelope surface gylcoprotein: a study using monoclonal antibodies raised against relevant peptides

By the use of sera of human T cell leukemia virus type I (HTVL-I)-infected individuals it was shown that amino acid substitutions at positions 192 (proline to serine) and 250 (serine to proline) in major immunodominant regions (175-199 and 239-261) of the surface envelope glycoprotein (gp46) of the virus may influence the humoral response. Since human sera are polyclonal in nature, one cannot readily discriminate between an immunoglobulin-specific recognition and multiple bindings of diverse antibodies. To overcome this difficulty we generated murine monoclonal antibodies to synthetic peptides mimicking all or portions of these gp46 regions. The reactivity of some of these antibodies to synthetic peptides harboring (or not harboring) the preceding amino acid substitutions at position 192 or 250, to denatured gp46 by Western blotting, and to live (variously substituted) HTLV-I-infected cells, combined with blocking experiments with various peptides, allow us to conclude that the major epitopes (positions 183-191, 190-197, 190-199, and 246-252) in the two immunodominant regions may elicit different antibody responses according to their sequences. It is worth noting that in a reporter gene inhibition assay, it was found that a neutralizing monoclonal antibody (MF1), the epitope for which is located between residues 190 and 197, had a high level of activity when cells (2060) harboring a gp46 with proline at position 192 were used and had no activity toward cells (1010) with a serine at this position. Therefore our results establish that certain amino acid substitutions of gp46 may drastically affect the antigenicity of the molecule and the biological activity of the antibodies elicited.

The immunoglobulin lambda light chain enhancer consists of three modules which synergize in activation of transcription

V(D)J rearrangement, high level expression and somatic hypermutation of assembled Ig genes is tightly controlled by a number of regulatory sequence elements located in the vicinity of the J-, (D)-, and C-gene segments. During B cell maturation these elements become accessible to binding of trans-acting factors, reflecting the opening of the chromatin structure through an as yet unidentified mechanism. The mapping of regions of an altered chromatin structure (DNase I hypersensitivity) therefore is a powerful approach in identifying regulatory sequence elements. We here show that the human Ig lambda enhancer consists of three modules previously identified by us as DNase I-hypersensitive sites HSS-1, -2, and -3. The three sequence elements synergize in transcriptional activation of a reporter gene and together constitute a powerful tissue-specific enhancer which is a much stronger transcriptional activator than the kappa enhancers alone or in combination. We further show that the accessibility of the kappa and lambda enhancer elements for DNase I in the chromatin of a pre-B cell line (207) correlates with the transcriptional enhancer activities of kappa and lambda enhancer constructs. This finding is in support of an ordered model for Ig light chain activation (kappa before lambda).

Multiple control elements are required for expression of the human CD34 gene

Two cis regulatory elements of the human CD34 gene, the promoter and a 3' enhancer, have previously been described. In transient transfection assays, the promoter was not sufficient to direct cell type specific expression. In contrast, the 3' enhancer was active only in CD34+ cell lines, suggesting that this element might be responsible for stem cell-restricted expression of the CD34 gene. In the current work, through deletion and transient transfection experiments, we delineated the core enhancer sequence. We examined the role of this element upon stable integration. Our data suggested the presence of additional control elements. In order to identify them, using DNaseI hypersensitivity and methylation studies, we determined the chromatin structure of the entire CD34 locus. Amongst a number of DNaseI hypersensitive sites, we detected a strong CD34+ cell type-specific site in intron 4. This region, however, did not work as an enhancer by itself. By analyzing stable transfectants and transgenic animals, we demonstrated that the 3' enhancer and intron 4 hypersensitive regions, either alone or together, did not function as a locus control region upon chromosomal integration. In contrast, a 160kb genomic fragment encompassing the entire CD34 gene contained regulatory elements sufficient for high-level CD34 mRNA expression in murine stable lines. Our data indicate that combinatorial action of multiple, proximal and long-range, cis elements is necessary for proper regulation of CD34 expression.

Phorbol ester synergizes the dimethyl sulfoxide-dependent programmed cell death through diacylglycerol increment

The regulation of cell proliferation or cell death by extracellular factors are the most intensely studied subjects in cell biology. Many conceptual problems remain to be clarified concerning the mechanisms that regulate the programmed cell death. In this work, we focus our attention on the possible role of protein kinase C activation during dimethyl sulfoxide (DMSO)-induced cell death. The present results suggest that the frequency of DMSO-dependent apoptosis of RPMI 8402 thymic lymphoma cells is increased by phorbol ester acetate supplementation. Enhancement of apoptosis can be abolished by cotreatment with the bisindolylmaleimide, a specific PKC inhibitor. The association between PMA and DMSO treatment provokes an early activation of an intracellular signaling mechanism that results, via sustained diacylglycerol elevation, in a possible long-term PKC activation.

Neutralizing human monoclonal antibodies to conformational epitopes of human T-cell lymphotropic virus type 1 and 2 gp46

Ten human monoclonal antibodies derived from peripheral B cells of a patient with human T-cell lymphotropic virus (HTLV)-associated myelopathy are described. One monoclonal antibody recognized a linear epitope within the carboxy-terminal 43 amino acids of HTLV gp21, and two monoclonal antibodies recognized linear epitopes within HTLV type 1 (HTLV-1) gp46. The remaining seven monoclonal antibodies recognized denaturation-sensitive epitopes within HTLV-1 gp46 that were expressed on the surfaces of infected cells. Two of these antibodies also bound to viable HTLV-2 infected cells and immunoprecipitated HTLV-2 gp46. Virus neutralization was determined by syncytium inhibition assays. Eight monoclonal antibodies, including all seven that recognized denaturation-sensitive epitopes within HTLV-1 gp46, possessed significant virus neutralization activity. By competitive inhibition analysis it was determined that these antibodies recognized at least four distinct conformational epitopes within HTLV-1 gp46. These findings indicate the importance of conformational epitopes within HTLV-1 gp46 in mediating a neutralizing antibody response to HTLV infection.

Identification of a DNA segment exhibiting rearrangement modifying effects upon transgenic delta-deleting elements

Control of the rearrangement and expression of the T cell receptor alpha and delta chains is critical for determining T cell type. The process of delta deletion is a candidate mechanism for maintaining separation of the alpha and delta loci. Mice harboring a transgenic reporter delta deletion construct show alpha/beta T cell lineage-specific use of the transgenic elements. A 48-basepair segment of DNA, termed HPS1A, when deleted from this reporter construct, loses tight lineage-specific rearrangement control of transgenic elements, with abundant rearrangements of transgenic delta-deleting elements now in gamma/delta T cells. Furthermore, HPS1A augments recombination frequency of extrachromosomal substrates in an in vitro recombination assay. DNA binding proteins recognizing HPS1A have been identified and are restricted to early B and T cells, during the time of active rearrangement of endogenous TCR and immunoglobulin loci. These data are consistent with delta deletion playing an important role in maintaining separate TCR alpha and delta loci.

Octamer binding factors and their coactivator can activate the murine PU.1 (spi-1) promoter

PU.1 (spi-1), a member of the Ets transcription factor family, is predominantly expressed in myeloid and B cells, activates many B cell and myeloid genes, and is critical for development of both of these lineages. Our previous studies (Chen, H. M., Ray-Gallet, D., Zhang, P., Hetherington, C. J., Gonzalez, D. A., Zhang, D.-E., Moreau-Gachelin, F., and Tenen, D. G. (1995) Oncogene 11, 1549-1560) demonstrate that the PU.1 promoter directs cell type-specific reporter gene expression in myeloid cell lines, and that PU.1 activates its own promoter in an autoregulatory loop. Here we show that the murine PU.1 promoter is also specifically and highly functional in B cell lines as well. Oct-1 and Oct-2 can bind specifically to a site at base pair -55 in vitro, and this site is specifically protected in B cells in vivo. We also demonstrate that two other sites contribute to promoter activity in B cells; an Sp1 binding site adjacent to the octamer site, and the PU.1 autoregulatory site. Finally, we show that the B cell coactivator OBF-1/Bob1/OCA-B is only expressed in B cells and not in myeloid cells, and that OBF-1/Bob1/OCA-B can transactivate the PU.1 promoter in HeLa and myeloid cells. This B cell restricted coactivator may be responsible for the B cell specific expression of PU.1 mediated by the octamer site.

Dimethyl sulfoxide induces programmed cell death and reversible G1 arrest in the cell cycle of human lymphoid pre-T cell line

In human B- and T-differentiated lymphoid cell lines DMSO was found to arrest the proliferation at the G1 stage of the cell cycle, without any detectable differentiation and DMSO itself was found to prevent apoptosis. Programmed cell death, or apoptosis, is now thought to be an important regulatory process in normal hemopoiesis and in the lymphoid system this program is started in the immune process such as autoreactive T-cell elimination in the thymus, and antigen-driven B-cell selection in the terminal centre. For this purpose, we have analysed the effect of DMSO using undifferentiated pre-B (KM-3) and pre-T (RPMI-8402) human lymphoid cells. Results obtained by multiparametric analyses show that DMSO affect only the pre-T cell line inducing a reversible G1 arrest of the cell cycle with a significant presence of apoptotic cells and modification of terminal transferase (TdT) expression. Pre-B cell line is resistant to DMSO treatment. These data provide evidence of a new model for the study of the selective cell type depending effect of DMSO in the immune system.

Identification of HTLV-I- or HTLV-II-producing cells by cocultivation with BHK-21 cells stably transfected with a LTR-lacZ gene construct

The Syrian Hamster kidney cell line (BHK-21) was stably transfected with a plasmid vector containing the lacZ bacterial gene under the control of a HTLV-I-LTR promoter. In these cells termed pA18G-BHK-21, this lacZ construct is inducible by the tax protein produced by a tax expression vector. It was also shown that beta-galactosidase synthesis was detected within 48 h after cocultivation of pA18G-BHK-21 cells with HTLV-I (HUT-102, MT2, C91/PL, 2060) or HTLV-II (MoT strain) -producing cells. The number of positive cells was directly related to the number of HTLV-I or -II-infected cells seeded. In addition, the LTR transactivation observed in coculture with HTLV-I-infected cells was specifically inhibited by sera containing antibodies directed against HTLV-I proteins, but not, or only weakly, by sera containing HTLV-II antibodies. Conversely, beta-galactosidase expression induced by HTLV-II-infected cells was inhibited by sera of HTLV-II-infected individuals, but not, or only weakly, by HTLV-I-positive sera. Irrespective of the inducer cell, sera from uninfected people did not inhibit LTR-driven expression of the lacZ gene in pA18G-BHK-21 cells cocultivated with HTLV-producing cells. This assay may thus be employed profitably for the detection and quantification of both HTLV-producing cells and HTLV-specific antibodies.

P53 mutation in acute T cell lymphoblastic leukemia is of somatic origin and is stable during establishment of T cell acute lymphoblastic leukemia cell lines

Samples donated by patients with T cell acute lymphoblastic leukemia (T-ALL) were screened for mutations of the p53 tumor suppressor gene. Peripheral blood cells of T-ALL relapse patient H.A. were found to possess a heterozygous point mutation at codon 175 of the p53 gene. To determine whether this was an inherited mutation, a B cell line (HABL) was established. Leukemic T cell lines (HATL) were concurrently established by growing peripheral blood leukemic T cells at low oxygen tension in medium supplemented with IGF-I. Previously we had shown that > 60% of leukemic T cell lines possessed mutations in the p53 gene (Cheng, J., and M. Hass. 1990. Mol. Cell. Biol. 10:5502), mutations that might have originated with the donor's leukemic cells, or might have been induced during establishment of the cell lines. To answer whether establishment of the HATL lines was associated with the induction of p53 mutations, cDNAs of the HATL and HABL lines were sequenced. The HATL lines retained the same heterozygous p53 mutation that was present in the patient's leukemic cells. The HABL line lacked p53 mutations. Immunoprecipitation with specific anti-p53 antibodies showed that HATL cells produced p53 proteins of mutant and wild type immunophenotype, while the HABL line synthesized only wild-type p53 protein. The HATL cells had an abnormal karyotype, while the HABL cells possessed a normal diploid karyotype. These experiments suggest that (a) p53 mutation occurred in the leukemic cells of relapse T-ALL patient HA; (b) the mutation was of somatic rather than hereditary origin; (c) the mutation was leukemia associated; and (d) establishment of human leukemia cell lines needs not be associated with in vitro induction of p53 mutations. It may be significant that patient HA belonged to a category of relapse T-ALL patients in whom a second remission could not be induced.

Characterization of cDNA clones encoding the human homologue of Saccharomyces cerevisiae ribosomal protein L30

We have isolated cDNA clones encoding the human homologue (hL30) of yeast ribosomal protein (r-protein) L30. The hL30 nucleotide (nt) sequence shows high homology to the yeast sequences and also to a partial Xenopus laevis sequence previously identified as an immunoglobulin heavy chain. The 5' end of hL30 is pyrimidine-rich, as is the case for most other mammalian r-protein mRNAs. The open reading frame consists of 157 codons with a C-terminal region that is different from corresponding regions of the yeast proteins. In several human tissue culture cells, the mRNA encoding hL30 is approx. 700 nt in length.

Intracellular localization of terminal transferase during the cell cycle

Changes in the localization of terminal transferase during the cell cycle in random cultures of human pre-T leukemia line RPMI-8402 were examined by light and electron microscopy on immunoperoxidase-stained preparations. Paraformaldehyde-fixed and saponin-permeabilized human cells were used with a monoclonal anti-human terminal deoxynucleotidyl transferase (TdT) primary reagent to demonstrate changes in enzyme distribution occurring between interphase and mitosis. Nuclear localization is found uniformly during interphase. At metaphase, however, the majority of TdT staining appears randomly distributed in the cytoplasm and traces of TdT staining remain associated with mitotic chromatin. At later phases, when the daughter cells are forming, the enzyme again appears to be restricted to the new nuclear structure.

T-cell acute lymphoblastic leukemia with t(11;14) in children

We review and update our examination of the clinical and biologic findings in 19 cases of acute lymphoblastic leukemia (ALL) with the t(11;14) and discuss the literature relevant to the clinical, biologic, and molecular aspects of these translocations. In nine consecutively diagnosed cases at St. Jude Children's Research Hospital and 10 cases reported by other institutions, clinical features did not differ among T-cell ALL patients with and without the t(11;14), although leukemic cells with this translocation were more likely to coexpress CD4 and CD8 antigens. The t(11;14)(p13;q11) appears to occur exclusively in T-cell malignancies of intermediate- or late-stage thymocyte differentiation; further studies will be needed to determine whether it has prognostic significance.

Infection of peripheral blood mononuclear cells and cell lines by cell-free human T-cell lymphoma/leukemia virus type I

Previous studies of in vitro infection by human T-cell lymphoma/leukemia virus type I (HTLV-I) have required cocultivation of target cells with HTLV-I cell lines or vesicular stomatitis virus pseudotypes containing HTLV-I envelope proteins. We report here the development of a cell-free infection assay for HTLV-I. Target cells were incubated with purified, DNase-treated HTLV-I virions for 4 h at 37 degrees C. Target cell DNA was then analyzed for the presence of newly synthesized HTLV-I proviral DNA by the highly sensitive polymerase chain reaction. Using this assay system, we have been able to consistently detect in vitro infection of a variety of cellular targets by different HTLV-I isolates. Optimal infection required the presence of 10 micrograms of DEAE-dextran per ml. The assay was dose dependent with respect to virus input. In general, the amount of proviral DNA detected correlated with the level of HTLV-I receptors present on the surface of the target cells, as measured by fluorochrome-labelled HTLV-I binding. Finally, the specificity of the assay was confirmed by demonstrating that the cell line, L1q, a somatic cell hybrid containing human chromosome 17q, to which the gene for the HTLV-I receptor has been mapped, was susceptible to infection by HTLV-I, while the parental mouse cell line from which it was derived, LMTK-, which lacks human chromosome 17q, was not.

CD7+, CD4-/CD8- acute leukemia with t(11;14)(p15;q11) in a child

A t(11;14)(p15;q11) was the sole chromosome abnormality observed in the malignant cells of a 10-year-old boy with acute leukemia. Morphologically, these cells were classified as L1 by the criteria of the French-American-British Working Group. Cytochemical analysis revealed that the leukemic cells were negative for Sudan Black B, periodic acid Schiff, and esterases, and positive for acid phosphatase. Immunophenotyping disclosed that the cells expressed a very immature antigenic profile [CD34+, CD7+, cytoplasmic CD3+, membrane CD3-, CD4-, and CD8-]. In spite of very intensive chemotherapy, complete remission was never induced, and the child died of progressive disease. The relationship of this case to other reported cases of acute leukemia arising from immature pluripotent hematopoietic cells is discussed.

Low membrane transport activity for cystine in resting and mitogenically stimulated human lymphocyte preparations and human T cell clones

In order to determine whether the cysteine requirement of human T lineage cells is met primarily by extracellular cysteine or by cystine, amino-acid-transport activities were measured in resting and mitogenically stimulated human peripheral blood lymphocytes (PBL) and several human T cell clones and T cell tumors. The transport activity of the small neutral amino acids cysteine and alanine (ASC system) and the transport of the cationic amino acid arginine (y+ system) were found to be markedly increased after stimulation of PBL by the T cell mitogen phytohemagglutinin from Phaseolus vulgaris. The anionic transport activity for cystine and glutamate (Xc- system), in contrast, was extremely weak in both resting and activated human PBL and also in all human T cell lines under test. The weak system Xc- activity of human T lineage cells was further confirmed by an independent line of experiments showing that an increase of the extracellular concentration of glutamate, i.e. a competitive inhibitor of cystine transport, causes a decrease in the intracellular cystine levels in cells of the promonocytic line U937, but not in T lineage cells (Molt-4). A third set of experiments showed that the rate of DNA synthesis in mitogenically stimulated human PBL is strongly influenced by variations of the extracellular cysteine level, even in cultures with relatively high and approximately physiological concentrations of cystine. Cysteine cannot be replaced in this case by the addition of corresponding amounts of cystine or methionine. This demonstrates an important functional consequence of the weak cystine transport activity of human lymphocytes. The results may be relevant for the pathogenetic mechanism of the acquired immunodeficiency syndrome, since the mean plasma cysteine concentration of human-immunodeficiency-virus-1-seropositive persons was found to be strongly decreased in comparison with that of healthy blood donors, and since the cysteine level even of healthy persons is extremely low in comparison with all other protein-forming amino acids.

Disruption of the human SCL locus by "illegitimate" V-(D)-J recombinase activity

A fusion complementary DNA in the T cell line HSB-2 elucidates a provocative mechanism for the disruption of the putative hematopoietic transcription factor SCL. The fusion cDNA results from an interstitial deletion between a previously unknown locus, SIL (SCL interrupting locus), and the 5' untranslated region of SCL. Similar to 1;14 translocations, this deletion disrupts the SCL 5' regulatory region. This event is probably mediated by V-(D)-J recombinase activity, although neither locus is an immunoglobulin or a T cell receptor. Two other T cell lines, CEM and RPMI 8402, have essentially identical deletions. Thus, in lymphocytes, growth-affecting genes other than immune receptors risk rearrangements.

Frequent mutations in the p53 tumor suppressor gene in human leukemia T-cell lines

Human T-cell leukemia and T-cell acute lymphoblastic leukemia cell lines were studied for alterations in the p53 tumor suppressor gene. Southern blot analysis of 10 leukemic T-cell lines revealed no gross genomic deletions or rearrangements. Reverse transcription-polymerase chain reaction analysis of p53 mRNA indicated that all 10 lines produced p53 mRNA of normal size. By direct sequencing of polymerase chain reaction-amplified cDNA, we detected 11 missense and nonsense point mutations in 5 of the 10 leukemic T-cell lines studied. The mutations are primarily located in the evolutionarily highly conserved regions of the p53 gene. One of the five cell lines in which a mutation was detected possesses a homozygous point mutation in both p53 alleles, while the other four cell lines harbor from two to four different point mutations. An allelic study of two of the lines (CEM, A3/Kawa) shows that the two missense mutations found in each line are located on separate alleles, thus both alleles of the p53 gene may have been functionally inactivated by two different point mutations. Since cultured leukemic T-cell lines represent a late, fully tumorigenic stage of leukemic T cells, mutation of both (or more) alleles of the p53 gene may reflect the selection of cells possessing an increasingly tumorigenic phenotype, whether the selection took place in vivo or in vitro. Previously, we have shown that the HSB-2 T-cell acute lymphoblastic leukemia cell line had lost both alleles of the retinoblastoma tumor suppressor gene. Taken together, our data show that at least 6 of 10 leukemic T-cell lines examined may have lost the normal function of a known tumor suppressor gene, suggesting that this class of genes serves a critical role in the generation of fully tumorigenic leukemic T cells.

Frequent mutations in the p53 tumor suppressor gene in human leukemia T-cell lines

Human T-cell leukemia and T-cell acute lymphoblastic leukemia cell lines were studied for alterations in the p53 tumor suppressor gene. Southern blot analysis of 10 leukemic T-cell lines revealed no gross genomic deletions or rearrangements. Reverse transcription-polymerase chain reaction analysis of p53 mRNA indicated that all 10 lines produced p53 mRNA of normal size. By direct sequencing of polymerase chain reaction-amplified cDNA, we detected 11 missense and nonsense point mutations in 5 of the 10 leukemic T-cell lines studied. The mutations are primarily located in the evolutionarily highly conserved regions of the p53 gene. One of the five cell lines in which a mutation was detected possesses a homozygous point mutation in both p53 alleles, while the other four cell lines harbor from two to four different point mutations. An allelic study of two of the lines (CEM, A3/Kawa) shows that the two missense mutations found in each line are located on separate alleles, thus both alleles of the p53 gene may have been functionally inactivated by two different point mutations. Since cultured leukemic T-cell lines represent a late, fully tumorigenic stage of leukemic T cells, mutation of both (or more) alleles of the p53 gene may reflect the selection of cells possessing an increasingly tumorigenic phenotype, whether the selection took place in vivo or in vitro. Previously, we have shown that the HSB-2 T-cell acute lymphoblastic leukemia cell line had lost both alleles of the retinoblastoma tumor suppressor gene. Taken together, our data show that at least 6 of 10 leukemic T-cell lines examined may have lost the normal function of a known tumor suppressor gene, suggesting that this class of genes serves a critical role in the generation of fully tumorigenic leukemic T cells.

The t(11;14)(p15;q11) in a T-cell acute lymphoblastic leukemia cell line activates multiple transcripts, including Ttg-1, a gene encoding a potential zinc finger protein

Interchromosomal translocations within lymphoid neoplasms frequently involve the antigen receptor genes. We cloned the breakpoints of the t(11;14)(p15;q11) in a CD3-negative T-cell acute lymphoblastic leukemia cell line (RPMI 8402) in order to identify new genes potentially involved in T-cell neoplasia. An extensive comparison of both breakpoints and their germ line counterparts indicated that an inadvertant recombinase-mediated break at chromosome segment 11p15 recombined with the delta T-cell receptor at 14q11. The derivative 11 breakpoint resembles a coding joint in which 11p15 rather than a variable region was introduced 5' to a D delta 1 D delta 2 J delta 1 intermediate rearrangement. Conversely, the derivative 14 breakpoint corresponds to a signal joint between the 5' heptamer-spacer-nonamer recombinational signal of D delta 1 and an isolated heptamer at 11p15. Multiple, apparently distinct transcripts were found flanking both breakpoints of 8402. RNAs of 3.5, 4.4, 1.4, and 8.0 kilobases originating from either side of the derivative 14 breakpoint were highly expressed in 8402 compared with other cells. This suggests that this translocation deregulated multiple genes and provides the opportunity to assess any multifactorial contribution they may have to malignancy. We cloned and sequenced several cDNAs representing the 1.4-kilobase transcript (termed Ttg-1 [T-cell translocation gene 1]) from an 8402 library. The predicted protein of 156 amino acids contained two internal repeats which could potentially form zinc fingers.

The t(11;14)(p15;q11) in a T-cell acute lymphoblastic leukemia cell line activates multiple transcripts, including Ttg-1, a gene encoding a potential zinc finger protein

Interchromosomal translocations within lymphoid neoplasms frequently involve the antigen receptor genes. We cloned the breakpoints of the t(11;14)(p15;q11) in a CD3-negative T-cell acute lymphoblastic leukemia cell line (RPMI 8402) in order to identify new genes potentially involved in T-cell neoplasia. An extensive comparison of both breakpoints and their germ line counterparts indicated that an inadvertant recombinase-mediated break at chromosome segment 11p15 recombined with the delta T-cell receptor at 14q11. The derivative 11 breakpoint resembles a coding joint in which 11p15 rather than a variable region was introduced 5' to a D delta 1 D delta 2 J delta 1 intermediate rearrangement. Conversely, the derivative 14 breakpoint corresponds to a signal joint between the 5' heptamer-spacer-nonamer recombinational signal of D delta 1 and an isolated heptamer at 11p15. Multiple, apparently distinct transcripts were found flanking both breakpoints of 8402. RNAs of 3.5, 4.4, 1.4, and 8.0 kilobases originating from either side of the derivative 14 breakpoint were highly expressed in 8402 compared with other cells. This suggests that this translocation deregulated multiple genes and provides the opportunity to assess any multifactorial contribution they may have to malignancy. We cloned and sequenced several cDNAs representing the 1.4-kilobase transcript (termed Ttg-1 [T-cell translocation gene 1]) from an 8402 library. The predicted protein of 156 amino acids contained two internal repeats which could potentially form zinc fingers.

Complex rearrangements within the human J delta-C delta/J alpha-C alpha locus and aberrant recombination between J alpha segments

We have examined DNA rearrangements within a 120 kb cloned region of the human T cell receptor J delta-C delta/J alpha-C alpha locus. Three types of pattern emerge from an analysis of T cell lines and clones. Firstly, cells with two rearrangements within J delta-C delta; secondly, cells with one rearrangement within J delta-C delta and one or more J alpha rearrangements, and finally, cells with rearrangements within J alpha and consequential deletion of the delta locus. Further analysis by cloning of rearrangements within the J alpha locus show that, in addition to V alpha-J alpha joins, J alpha-J alpha aberrant recombinations occur and rearrangement data indicate that such events are frequent. A model is presented to account for such recombinations.

Hemophagocytic syndrome complicating T-cell acute lymphoblastic leukemia with a novel t(11;14)(p15;q11) chromosome translocation

A case of hemophagocytic syndrome that developed in a patient with T-cell acute lymphoblastic leukemia (ALL) with a novel chromosome translocation involving 14q11 is reported. A 15-year-old boy with T-cell ALL in relapse showed leukemic cells with an abnormal karyotype of 46,XY,-15,t(11;14)(p15;q11), +der(15)t(15;?)(p11;?). Pancytopenia and extensive hemophagocytosis by macrophages in the bone marrow were observed after reinduction chemotherapy and again at the terminal stage. At autopsy, infiltration of such cells was also found in other organs. The findings suggested occurrence of hemophagocytic syndrome probably associated with cytomegalovirus (CMV) infection. The t(11;14)(p15;q11) may be a novel translocation specific for T-cell ALL, and conceivably, the association of T-cell ALL with the histiocytosis in this patient may not have been coincidental.

Upstream regulatory sequences of immunoglobulin genes are recognized by nuclear proteins which also bind to other gene regions

The decanucleotide sequence (dc) TNATTTGCAT is an upstream regulatory sequence of immunoglobulin genes and occurs also upstream of certain other eukaryotic and prokaryotic genes (compiled in the accompanying paper). We now investigated the binding of proteins from nuclear extracts of a number of cell types and organisms to the dc sequence using a sensitive gel electrophoretic DNA binding assay. Binding studies with specifically designed oligonucleotides led to the following conclusions: the central T of the dc sequence can be altered with only a slight decrease of protein binding activity: the sequences in the neighborhood of dc have a positive or negative effect on the efficiency of protein binding; C-rich sequences which occur in many K chain promoters have a protein binding activity independent of dc; the dc binding protein(s) of human lymphoid cells elute from a Sephadex column in the 30.000-60.000 molecular weight range; dc binding proteins were found in nuclear extracts of lymphoid as well as non-lymphoid human and murine cell lines, of Xenopus oocytes, and of yeast cells. The finding of dc binding proteins in a wide variety of different organisms and the occurrence of dc-related sequences in the regulatory regions of several gene families point to a general role in the transcriptional regulation of the respective genes.

The human CK gene segment and the kappa deleting element are closely linked

The element which mediates the deletion of the CK gene segment (abbreviations ref. 1) in human lambda light chain producing B-cells was found to be located 24 kb downstream of CK. The kappa deleting element is flanked by hepta- and nonanucleotide recognition sequences similar to the ones adjacent to the JK gene segments. Complementary recognition sequences with a 30 bp spacer were found in the JK-CK intron. For the first time the two partners of a recombination event in a mammalian immunoglobulin gene system have been linked on a physical map. The orientation of the recombination signals of the intron and the Kde sequences allows a joining by a simple deletion mechanism. Similarities and possible differences to the mechanism of V-J joining are discussed.

Inhibition of proliferation of human leukaemic cell populations by deferoxamine

Deferoxamine is a hydroxylamine which binds ferric ions to form a highly stable complex. Since iron is thought to be required at a critical stage for cell proliferation, we investigated the effect of deferoxamine on the proliferative activity of human leukaemic cell populations in vitro by means of 3 permanent cell lines, HL60, U937 and 8402. We found deferoxamine to be a potent inhibitor of DNA synthesis and proliferation of leukaemic cells, acting by accumulating treated cells at the early S phase of the cell cycle. Suppression of leukaemic proliferation was obtained at deferoxamine concentrations in the range usually achieved in the treatment of patients for iron overload. Deferoxamine might therefore warrant further investigation as a potentially useful agent for leukaemia chemotherapy.

Nucleoside transport and cytosine arabinoside (araC) metabolism in human T lymphoblasts resistant to araC, thymidine and 6-methylmercaptopurine riboside

Alteration in cellular nucleoside transport characteristics, deoxynucleoside triphosphate (dNTP) pools and araCTP formation from cytosine arabinoside (araC) were determined for human T lymphoblasts (CCRF-CEM) resistant to araC, thymidine or 6-methylmercaptopurine riboside (6-MMPR). AraC resistance was accompanied by reduced activities of deoxycytidine and thymidine kinases, lowered cellular deoxycytidine triphosphate concentration and markedly reduced formation of araCTP from araC. The ID50 values for araC, araCTP formation and dNTP levels of thymidine-resistant lymphoblasts, which exhibited reduced thymidine kinase activity, and 6-MMPR-resistant cells, with reduced adenosine kinase activity, were similar to the corresponding parameters of wild type lymphoblasts. The nucleoside transport sites density determined by nitrobenzylmercaptopurine riboside binding was comparable for araC-resistant, wild type and thymidine- or 6-MMPR-resistant lymphoblasts.

Frozen RPMI 8402 cells: a reliable source of terminal deoxynucleotidyl transferase positive control material

A reliable source of positive control material is needed for immunoperoxidase or immunofluorescent terminal deoxynucleotidyl transferase (TdT) assays. The cell line RPMI 8402 was obtained from a patient with acute lymphoblastic leukemia and is positive for nuclear TdT. The kinetics of TdT expression in a series of cultured RPMI 8402 cells and the effect of cryopreservation on TdT expression were evaluated. The highest percentage of TdT+ cells was detected on days 5-8 of RPMI 8402 cell cultures. TdT positivity was preserved for more than 3 years in cells stored in suspension at -70 degrees C, and at least 76 days on slide preparations when fixed with methanol prior to freezing. We conclude that when RPMI 8402 cells with maximum TdT positivity are stored at -70 degrees C, aliquots can be used as a constant source of positive control material thereby eliminating the necessity and expense of a continuing culture system.

Chromosomes and causation of human cancer and leukemia. LIV. Near-tetraploidy in acute leukemia

Near-tetraploid cell populations were observed in a case of T-cell acute lymphoblastic leukemia (T-ALL) and in one of acute myeloblastic leukemia (AML). In the ALL case, hyperdiploid chromosomal changes, characterized by an isochromosome 17q [i(17q)], as well as other changes, were seen at the onset of the disease. At the first relapse, hypertetraploid cells appeared in about 10% of the mitoses in the bone marrow (BM), and by the second and third relapses, the hypertetraploidy was present in more than 90% of the mitoses in the BM. Even though karyotypic instability was evident, all abnormal karyotypes contained one or two i(17q) at every sampling. In spite of karyotypic instability at each relapse, karyotypic evolution was observed whenever relapse occurred. A normal female karyotype was confirmed in the BM of each period. Immunologic examinations performed at each sampling revealed no recognizable changes before and after the appearance of tetraploidy. In the AML case, which was classified as FAB M2, cytogenetic examination was performed at diagnosis and relapse. In both, hypotetraploid cells were observed in over 60% of the BM cells; the modal chromosome number was 90. Banding analysis was successful at relapse, and a pseudodiploid clone characterized by t(8;21) and a hypotetraploid clone with two t(8;21) and a loss of two Y chromosomes were observed in the same BM sample. A normal male karyotype was also observed in BM cells. In both cases, giant and bizarre blasts were seen in the BM. A close correlation between near-tetraploid mitoses and giant and bizarre blast cells in BM smears of the same samples was observed. Previously published tetraploid acute leukemia cases analyzed with banding methods were accumulated and compared with our two cases.

Lymphoma in macaques: association with virus of human T lymphotrophic family

Human T-cell leukemia virus has been linked with adult T-cell leukemia-lymphoma (ATLL), a tumor of mature T cells that occurs at elevated rates in southwestern Japan and in the Caribbean Basin. Human T-cell leukemia virus (HTLV) or a closely related virus, has also been found in varying proportions of healthy individuals of several species of Old World monkeys. In the present study, conducted with macaques from Taiwan and the New England Regional Primate Research Center, antibodies to membrane antigens of HTLV-infected cells (HTLV-MA) were found in 11 of 13 macaques with malignant lymphoma or lymphoproliferative disease but in only 7 of 95 of healthy macaques. This indicates that antibodies to HTLV are significantly associated with the development of naturally occurring lymphoid neoplasms in at least some species of nonhuman primates.

Human T-cell leukemia virus-associated membrane antigens: identity of the major antigens recognized after virus infection

Specific antibodies to cell membrane antigens found on human T-cell leukemia virus (HTLV)-infected cells have been detected in Japanese patients with adult T-cell leukemia/lymphoma and in asymptomatic carriers, using a live cell-membrane immunofluorescence assay. Reactivity of the positive antisera was analyzed using radioimmunoprecipitation and NaDodSO4/PAGE with the HTLV-infected tumor cell line Hut 102 (clone B2). The major cell-associated antigens identified include two glycoproteins of approximately equal to 61 and 45 kDa, which appear to be the most immunogenic species in exposed people, a nonglycosylated species of 42 kDa, and four additional species that contain gag gene-encoded antigens with sizes ranging from 19 to 55 kDa. The two glycoproteins ( gp61 and gp45 ) are encoded, at least in part, by the env gene of HTLV as evidenced by amino acid sequence analysis.

Identification by transfection of transforming sequences in DNA of human T-cell leukemias

DNA from human T-cell leukemia cell lines was tested for focus-inducing activity on cultures of NIH 3T3 cells. Three leukemias yielded DNA active in this assay; restriction enzyme sensitivity of this activity indicated that similar, relatively large DNA sequences were involved. Southern blot analysis revealed conserved size classes of restriction fragments containing human repetitive (Alu) sequences in serially transfected foci derived from the active DNAs. Similar blot hybridizations with a probe specific for the human N-ras oncogene detected a 9-kilobase EcoRI fragment in all cases. DNA containing this fragment from one of the leukemias, molecularly cloned in bacteriophage lambda, displayed highly amplified focus-inducing activity in transfection assays. Thus, the N-ras oncogene appears to be active in these three human leukemias of T-cell origin.