Continuous hematopoietic cell lines as model systems for leukemia-lymphoma research

In Vitro Diffuse Large B-Cell Lymphoma Cell Line Models as Tools to Investigate Novel Immunotherapeutic Strategies

Despite the high incidence of diffuse large B-cell lymphoma (DLBCL), its management constitutes an ongoing challenge. The most common DLBCL variants include activated B-cell (ABC) and germinal center B-cell-like (GCB) subtypes including DLBCL with MYC and BCL2/BCL6 rearrangements which vary among each other with sensitivity to standard rituximab (RTX)-based chemoimmunotherapy regimens and lead to distinct clinical outcomes. However, as first line therapies lead to resistance/relapse (r/r) in about half of treated patients, there is an unmet clinical need to identify novel therapeutic strategies tailored for these patients. In particular, immunotherapy constitutes an attractive option largely explored in preclinical and clinical studies. Patient-derived cell lines that model primary tumor are indispensable tools that facilitate preclinical research. The current review provides an overview of available DLBCL cell line models and their utility in designing novel immunotherapeutic strategies.

Generation and functional characterization of a multigene-modified NK101 cell line exerting diverse mechanisms of antitumor action

Clonal cell line-based, multigene-modified, off-the-shelf NK cell therapeutics are emerging as the new frontier of adoptive cellular immunotherapy. Here, we utilized a newly established NK cell line, NK101, as a backbone to derive multifaceted killer cells armored with various antitumor modalities through repeated cycles of genetic modification and clonal selection. First, NK101 cells were transduced with a tricistronic lentiviral vector expressing CD7, CD28, and cytosine deaminase (CD). The resulting cell line demonstrated enhanced cytotoxicity against B7⁺ tumors and exerted bystander killing effects on neighboring tumor cells upon 5-FC treatment. Second, engineered NK101 cells were again transduced with a bicistronic vector expressing membrane-bound interleukin-15 (mbIL-15) and dominant negative TGFβ type II receptor (DNTβRII). Ectopic expression of mbIL-15 resulted in further augmentation of lytic activities against all tested target cells by inducing upregulation of multiple activating receptors, while that of DNTβRII allowed the cells to maintain heightened cytotoxicity in the presence of TGFβ. Finally, dual-transduced NK101 cells were modified to express chimeric antigen receptors (CARs) targeting either a solid tumor antigen (EpCAM) or a hematologic tumor antigen (FLT3). The final engineered products not only demonstrated antigen-specific killing activities in vitro but also exerted strong tumor-inhibitory effects in preclinical models of metastatic solid tumor and hematologic malignancy. Notably, combined treatment with 5-FC further enhanced antitumor efficacy of engineered NK101 in the solid tumor model. Our results demonstrate successful generation of multigene-modified NK101 cell therapeutics exerting diverse mechanisms of antitumor action - activation receptor-mediated innate killing, antigen-specific killing, and bystander effect-mediated killing.

The LL-100 Cell Lines Panel: Tool for Molecular Leukemia-Lymphoma Research

Certified cell line models provide ideal experimental platforms to answer countless scientific questions. The LL-100 panel is a cohort of cell lines that are broadly representative of all leukemia–lymphoma entities (including multiple myeloma and related diseases), rigorously authenticated and validated, and comprehensively annotated. The process of the assembly of the LL-100 panel was based on evidence and experience. To expand the genetic characterization across all LL-100 cell lines, we performed whole-exome sequencing and RNA sequencing. Here, we describe the conception of the panel and showcase some exemplary applications with a focus on cancer genomics. Due diligence was paid to exclude cross-contaminated and non-representative cell lines. As the LL-100 cell lines are so well characterized and readily available, the panel will be a valuable resource for identifying cell lines with mutations in cancer genes, providing superior model systems. The data also add to the current knowledge of the molecular pathogenesis of leukemia–lymphoma. Additional efforts to expand the breadth of available high-quality cell lines are clearly warranted.

Establishment and characterization of a novel 'double-hit' follicular lymphoma cell line, FL-SJC

About 5 per cent of follicular lymphoma (FL) cases are double-hit (DH) lymphomas. Double-hit follicular lymphoma (DHFL) cell lines can improve our understanding and drug development on FL. But there are only few DHFL cell lines. Here, we established a new MYC/BCL2 DHFL cell line, FL-SJC. The cells were obtained from the hydrothorax of a patient with MYC/BCL2 DHFL and cultured for 140 passages in vitro. FL-SJC cells demonstrated CD19⁺⁺ , CD20⁺ , CD22⁺⁺ , HLA-DR⁺ , CD10⁺ , CD38⁺ , Lambda⁺ CD23^- , CD5^- and Kappa^- . The chromosome karyotypic analysis confirmed the co-existence of t(8;22)(q24;q11) and t(14;18)(q32;q21), as well as additional abnormalities involving chromosomes 2 and 3. Fluorescence in situ hybridization analysis (FISH) showed IGH/BCL2 fusion gene and the MYC rearrangement. In addition, the FL-SJC cells displayed KMT2D/MLL2 and CREBBP gene mutations. After subcutaneous inoculation of FL-SJC cells, the SCID mice developed solid tumour masses within 6-8 weeks. FL-SJC cells were proven to be free of Epstein-Barr (EB) virus infection and be multidrug-resistant. In a conclusion, the FL-SJC cell line has been identified as a novel MYC/BCL2 double-hit follicular lymphoma that can be used as a potentially available tool for the clinical and basic research, together with the drug development for MYC/BCL2 DHFL.

Establishment and characterization of a DOT1L inhibitor-sensitive human acute monocytic leukemia cell line YBT-5 with a novel KMT2A-MLLT3 fusion

Immortalized cell lines are useful for deciphering the pathogenesis of acute leukemia and developing novel therapeutic agents against this malignancy. In this study, a new human myeloid leukemia cell line YBT-5 was established. After more than 1-year cultivation from the bone marrow of a patient with acute monocytic leukemia, YBT cell line was established. Then a subclone, YBT-5, was isolated from YBT using single cell sorting. Morphological and cytogenetical characterizations of the YBT-5 cell line were determined by cytochemical staining, flow cytometry analysis, and karyotype analysis. Molecular features were identified by transcriptomic analysis and reverse transcription-polymerase chain reaction. To establish a tumor model, 5 × 10⁶ YBT-5 cells were injected subcutaneously in nonobese diabetic/severe combined immune-deficiency (NOD/SCID) mice. DOT1L has been proposed as a potential therapeutic target for KMT2A-related leukemia; therefore, to explore the potential application of this new cell line, its sensitivity to a specific DOT1L inhibitor, EPZ004777 was measured ex vivo. The growth of YBT-5 does not depend on granulocyte-macrophage colony-stimulating factor. Cytochemical staining showed that α-naphthyl acetate esterase staining was positive and partially inhibited by sodium fluoride, while peroxidase staining was negative. Flow cytometry analysis of YBT-5 cells showed positive myeloid and monocytic markers. Karyotype analysis of YBT-5 showed 48,XY,+8,+8. The breakpoints between KMT2A exon 10 and exon 11 (KMT2A exon 10/11) and MLLT3 exon 5 and exon 6 (MLLT3 exon 5/6) were identified, which was different from all known breakpoint locations, and a novel fusion transcript KMT2A exon 10/MLLT3 exon 6 was formed. A tumor model was established successfully in NOD/SCID mice. EPZ004777 could inhibit the proliferation and induce the differentiation of YBT-5 cells. Therefore, a new acute monocytic leukemia cell line with clear biological and molecular features was established and may be used in the research and development of new agents targeting KMT2A-associated leukemia.

Cancer Cell Lines Are Useful Model Systems for Medical Research

Cell lines are in vitro model systems that are widely used in different fields of medical research, especially basic cancer research and drug discovery. Their usefulness is primarily linked to their ability to provide an indefinite source of biological material for experimental purposes. Under the right conditions and with appropriate controls, authenticated cancer cell lines retain most of the genetic properties of the cancer of origin. During the last few years, comparing genomic data of most cancer cell lines has corroborated this statement and those that were observed studying the tumoral tissue equivalents included in the The Cancer Genome Atlas (TCGA) database. We are at the disposal of comprehensive open access cell line datasets describing their molecular and cellular alterations at an unprecedented level of accuracy. This aspect, in association with the possibility of setting up accurate culture conditions that mimic the in vivo microenvironment (e.g., three-dimensional (3D) coculture), has strengthened the importance of cancer cell lines for continuing to sustain medical research fields. However, it is important to consider that the appropriate use of cell lines needs to follow established guidelines for guaranteed data reproducibility and quality, and to prevent the occurrence of detrimental events (i.e., those that are linked to cross-contamination and mycoplasma contamination).

Establishment of cell line with NK/NKT phenotype from myeloid NK cell acute leukemia

Acute Myeloid Leukemia (AML) is the most common malignancy in adults with a 5-year survival rate of 27% of the total affected population. For effective treatment and new drug discovery, cell lines are considered as a very important tool. Here we report an establishment of a continuous human cell line AML-004 with a hypo-diploid chromosome 44 and presence of both NK/NKT phenotypes. The cell line was isolated from the blood sample of myeloid NK cell acute leukemia patients and extensively characterized by flow cytometery, morphology, and cytogentic analysis. Cytotoxicity by standard chemotherapeutic drugs was also examined. As characterized by Giemsa staining, the predominant cell type in the culture had high nuclear/cytoplasmic ratio. Cytogenetic analysis revealed high chromosome instability and structural abnormalities confirming the source of cell line from a patient with AML. The karyotype of the isolated cells did not alter up to around 40 passages. These AML-004 cells lacked specific markers for B and T lymphoid cells, but expressed surface receptors for lymphoid/NK cells. Cells also lacked the presence of early progenitors. The proliferation of the isolated cells was inversely proportional to the IL-2 concentration confirming presence of NK phenotype. AML-004 was resistant against standard chemotherapeutic drugs excluding cisplatin. Thus, AML-004 cells provide a continuous source of human cells for designing novel therapies for patients with T-lymphoblastic leukemia/lymphoma.

Establishment of a novel human lymphoblastic cell strain with the long arm of chromosome 11 aberration without MLL rearrangement

At present, all cell strains derived from acute lymphoblastic leukemia (ALL) patients with the long arm of chromosome 11 aberration are accompanied with mixed lineage leukemia (MLL) gene rearrangement. In this study, we established a permanent ALL cell strain CHH-1 with the long arm of chromosome 11 aberration and without MLL rearrangement, hoping that it could be used for the research of ALL with such genetic abnormality. CHH-1 cell strain was certified through morphology, immunophenotype, genetics and immunoglobulin (Ig) gene rearrangement analysis. Cell characteristics including tumorigenic ability, semisolid colony forming ability, telomerase activity, autocrine and invasion were further detected. Cells were with an add(11)(q23) structural abnormality without MLL rearrangement, and were consistent with the genetic abnormality of the patient. In addition, these cells had features of tumor-forming ability, high colony forming capacity, unique cytokine autocrine mode, high telomerase activity, and high invasion ability. CHH-1 may prove to be a useful cell model for the research of human leukemia with genetic aberration in chromosome 11, and help explore the role of such genetic abnormality in the pathogenesis, progression and prognosis of ALL, and in developing new target drugs.

Comprehensive genomic characterization of five canine lymphoid tumor cell lines

BACKGROUND

Leukemia/lymphoma cell lines have been critical in the investigation of the pathogenesis and therapy of hematological malignancies. While human LL cell lines have generally been found to recapitulate the primary tumors from which they were derived, appropriate characterization including cytogenetic and transcriptional assessment is crucial for assessing their clinical predictive value.

RESULTS

In the following study, five canine LL cell lines, CLBL-1, Ema, TL-1 (Nody-1), UL-1, and 3132, were characterized using extensive immunophenotyping, karyotypic analysis, oligonucleotide array comparative genomic hybridization (oaCGH), and gene expression profiling. Genome-wide DNA copy number data from the cell lines were also directly compared with 299 primary canine round cell tumors to determine whether the cell lines represent primary tumors, and, if so, what subtype each most closely resembled.

CONCLUSIONS

Based on integrated analyses, CLBL-1 was classified as B-cell lymphoma, Ema and TL-1 as T-cell lymphoma, and UL-1 as T-cell acute lymphoblastic leukemia. 3132, originally classified as a B-cell lymphoma, was reclassified as a histiocytic sarcoma based on characteristic cytogenomic properties. In combination, these data begin to elucidate the clinical predictive value of these cell lines which will enhance the appropriate selection of in vitro models for future studies of canine hematological malignancies.

Preclinical model for identification of therapeutic targets for CML offers clues for handling imatinib resistance

Success of imatinib in chronic myeloid leukemia (CML) therapy has undoubtedly proved utility of signalling molecules as therapeutic targets. However, development of imatinib resistance and progression to blastic crisis are the current challenges in clinics. To develop therapeutic alternatives for CML, understanding of signalling events downstream of bcr-abl might be helpful. Current CML cell lines do not give comprehensive picture of signalling events involved in pathogenesis of CML. Hence, there is a major unmet need for a better preclinical model for CML. Here, we report on development of RIN9815/bcr-abl, a novel cell line model that mimics signalling events in CML PMNL. Studies on crucial signalling molecules i.e., ras, rac, rhoA and actin in this cell line identified rhoA as the key regulator involved in CML cell function as well as proliferation of both, imatinib sensitive and resistant cells. Hence, RIN9815/bcr-abl could serve as the unique preclinical model in understanding pathogenesis of CML and in drug development.

Apoptosis- and differentiation-inducing activities of jacaric acid, a conjugated linolenic acid isomer, on human eosinophilic leukemia EoL-1 cells

Conjugated linolenic acids (CLNAs) are a group of naturally occurring positional and geometrical isomers of the C18 polyunsaturated essential fatty acid, linolenic acid (LNA), with three conjugated double bonds (C18:3). Although previous research has demonstrated the growth-inhibitory effects of CLNA on a wide variety of cancer cell lines in vitro, their action mechanisms and therapeutic potential on human myeloid leukemia cells remain poorly understood. In the present study, we found that jacaric acid (8Z,10E,12Z-octadecatrienoic acid), a CLNA isomer which is present in jacaranda seed oil, inhibited the in vitro growth of human eosinophilic leukemia EoL-1 cells in a time- and concentration-dependent manner. Mechanistic studies showed that jacaric acid triggered cell cycle arrest of EoL-1 cells at the G0/G1 phase and induced apoptosis of the EoL-1 cells, as measured by the Cell Death Detection ELISAPLUS kit, Annexin V assay and JC-1 dye staining. Notably, the jacaric acid-treated EoL-1 cells also underwent differentiation as revealed by morphological and phenotypic analysis. Collectively, our results demonstrated the capability of jacaric acid to inhibit the growth of EoL-1 cells in vitro through triggering cell cycle arrest and by inducing apoptosis and differentiation of the leukemia cells. Therefore, jacaric acid might be developed as a potential candidate for the treatment of certain forms of myeloid leukemia with minimal toxicity and few side effects.

APC2 and Axin promote mitotic fidelity by facilitating centrosome separation and cytoskeletal regulation

To ensure the accurate transmission of genetic material, chromosome segregation must occur with extremely high fidelity. Segregation errors lead to chromosomal instability (CIN), with deleterious consequences. Mutations in the tumor suppressor adenomatous polyposis coli (APC) initiate most colon cancers and have also been suggested to promote disease progression through increased CIN, but the mechanistic role of APC in preventing CIN remains controversial. Using fly embryos as a model, we investigated the role of APC proteins in CIN. Our findings suggest that APC2 loss leads to increased rates of chromosome segregation error. This occurs through a cascade of events beginning with incomplete centrosome separation leading to failure to inhibit formation of ectopic cleavage furrows, which result in mitotic defects and DNA damage. We test several hypotheses related to the mechanism of action of APC2, revealing that APC2 functions at the embryonic cortex with several protein partners, including Axin, to promote mitotic fidelity. Our in vivo data demonstrate that APC2 protects genome stability by modulating mitotic fidelity through regulation of the cytoskeleton.

A versatile drug delivery system using streptavidin-tagged pegylated liposomes and biotinylated biomaterials

Here we have developed a versatile liposome-mediated drug delivery system (DDS) allowing a strong bridge between the streptavidin-tagged liposome (SAL) and biotin (Bi)-tagged biomaterials which has strong affinity to surface proteins expressed in restricted cell lineages. This DDS was effective and specific for many leukemia cells in vitro and in vivo. When examining 6 human leukemia cell lines using calcein-encapsulated SALs in combination with Bi-granulocyte colony-stimulating factor (G-CSF), Bi-anti-CD33 monoclonal antibody (MAb) or Bi-anti-CD7 MAb, the fluorescent positive rate of each cell line was in almost proportion to degree of G-CSF receptor, CD33 or CD7 expression, respectively. More importantly, the binding ability was shown to be well maintained in a mouse xenograft model. Furthermore the cytosine arabinoside (AraC)-encapsulated SALs could kill the corresponding cells much more effectively in combination with Bi-biomaterials than free AraC, as expected. These findings strongly indicate that our SAL/Bi-biomaterial system could allow various types of medical agents to be delivered reliably and stably to the cells targeted.

Classical and molecular cytogenetic analysis

Cytogenetic analysis is performed on cell cultures for several reasons, notably, to perform identity checks by verifying species of origin or the retention of key chromosome rearrangements in cell lines described previously. De novo chromosome analysis is usually performed when characterizing cancer cell lines for the presence of neoplastic rearrangements associated with specific tumors. This usually involves fluorescence in situ hybridization (FISH) using clones covering gene loci near recurrent chromosome breakpoints. Chromosome breakage is an important endpoint in radiation biology and mutagenesis, enabling cell lines to be used for measuring genotoxic dosage and repair. Finally, cytogenetic analysis may be performed to monitor stability in culture. Unlike most preparative techniques, chromosome preparation resists standardization. Hence, procedures must be optimized for each cell line. Thus, evidence-based protocols are described for hypotonic harvesting, rapid G-banding, FISH, and Spectral Karyotyping (SKY) analysis of cell cultures to allow troubleshooting and fine-tuning to suit the requirements of individual cell lines.

VR09 cell line: an EBV-positive lymphoblastoid cell line with in vivo characteristics of diffuse large B cell lymphoma of activated B-cell type

BACKGROUND

small B-cell neoplasms can show plasmacytic differentiation and may potentially progress to aggressive lymphoma (DLBCL). Epstein-Barr virus (EBV) infection may cause the transformation of malignant cells in vitro.

DESIGN AND METHOD

we established VR09 cell line with plasmacytic differentiation, obtained from a case of atypical, non-CLL B-cell chronic lymphoproliferative disease with plasmacytic features. We used flow cytometry, immunohistochemistry, polymerase chain reaction, cytogenetic analysis and florescence in situ hybridization in the attempt at thoroughly characterizing the cell line. We showed VR09 tumorigenic potential in vivo, leading to the development of activated DLBCL with plasmacytic features.

RESULTS

VR09 cells displayed plasmacytic appearance and grew as spherical tumors when inoculated subcutaneously into immunodeficient Rag2(-/-) γ-chain(-/-) mice. VR09 cell line and tumors displayed the phenotype of activated stage of B cell maturation, with secretory differentiation (CD19+ CD20+ CD79a+ CD79b+/- CD138+ cyclin D1- Ki67 80% IgM+ IgD+ MUM1+ MNDA+ CD10- CD22+ CD23+ CD43+ K+, λ- Bcl2+ Bcl6-) and they presented episomal EBV genome, chromosome 12 trisomy, lack of c-MYC rearrangement and Myd88 gene mutation, presence of somatic hypermutation in the VH region, and wild-type p53.

CONCLUSION

This new EBV-positive cell line may be useful to further characterize in vivo activated DLBCL with plasmacytic features.

Establishment and characterization of a new human acute myelomonocytic leukemia cell line JIH-3

Here, a new acute myelomonocytic leukemia (AMML) cell line, JIH-3, is reported, and its biological characteristics are described. JIH-3 cells were maintained without any cytokines for 27 months. The JIH-3 cell line showed typical myelomonocytic morphological features. Additionally, it mainly expressed myeloid and monocytic markers (CD13, CD14, CD11b, CD15 and CD33), although it also expressed other antigens such as the markers of T and B lymphocytic lineage as well as stem cell, progenitor cell, and natural killer cell-related antigens (CD4, CD5, CD7, CD10, CD22, CD34, CD38, HLADR, CD16/CD56 and CD56); the expression of these markers, suggested that this cell line was in the early stage of myelomonocytic differentiation. Cytogenetic analysis initially showed a karyotype of 46, XY, del(7) (p1?3p2?2). During the passage period, the cells with this karyotype gradually decreased and were replaced by cells with a 45,XY,dic(4;7)(p11;p11),del(15)(q2?2) karyotype. Chromosome painting showed a deletion in the short arm of chromosome 7 for del(7)(p1?3p2?2) and der(4;7)(p11;p11). The latter had larger deleted segment than the former. Fluorescence in situ hybridization (FISH) revealed the dicentric nature of der(4;7), and Multiplex FISH (M-FISH) confirmed that der(4;7) was an unbalanced translocation. A deletion involving the 7p region on dic(4;7)(p11;p11) harbors many genes, including CDC2L5, C7ORF11, C7ORF10 and INHBA. Haploinsufficiency of the genes on 4p, 7p and 15q caused by deletions of 4p, 7p and 15q2?2 that resulted from dic(4;7)(p11;p11) and del(15)(q2?2) may play important roles in leukemogenesis and in the establishment of the JIH-3 cell line. JIH-3 cells did not express multidrug resistance (MDR)-related genes and apoptosis-related genes such as MDR1, multidrug resistance-related protein, lung resistance protein, BCL-2, Bax, GS-π or Fax, only P21 expression was detected, which probably leads the MDR indirectly through inhibition of the activities of cyclin-dependent kinase (CDK). JIH-3 cells had tumorigenic capacity in nude mice. In conclusion, JIH-3 is a new acute myelomonocytic leukemia cell line. It is from a well-characterized background and provides a new useful tool for the study of leukemia patients with a 7p deletion.

Cytogenetic analysis of cancer cell lines

Cancer genes are often deregulated by genomic rearrangements. Accordingly, analysis of the participant chromosomes responsible now occupies a key role in characterizing and identifying cancer cell lines. Cytogenetics may also be used to study the nature and extent of chromosome breakage induced by radiation or chemicals ("clastogenesis"), to distinguish individual cells or clones within a tumor cell population and to monitor the stability of chromosome rearrangements. This chapter describes cytogenetic procedures for characterizing cancer cells in culture. Cell lines allow the use of a wider range of harvesting and hypotonic treatments to optimize metaphase chromosome preparations than that possible with primary cultures. This assists improved banding, fluorescence in situ hybridization (FISH), and Spectral Karyotyping (SKY) analysis for research, rendering cell lines ideal tools for oncogenomics, ideally in parallel with transcriptomic analysis of the same cells. The experience of the writers with more than 800 cell lines has shown that no single hypotonic harvesting protocol is adequate consistently to deliver satisfactory chromosome preparations. Thus, evidence-based protocols are described for hypotonic harvesting, rapid G-banding, and FISH and SKY analysis of cell cultures to allow troubleshooting and fine-tuning to suit the requirements of individual cell lines.

Establishment and characterization of a novel acute myeloid leukemia cell line, JIH-4, carrying a t(16;21)(p11.2;q22) and expressing the FUS-ERG fusion

Human leukemia cell lines are powerful tools in the study of leukemogenesis, particularly for rare but recurrent subtypes such as acute myeloid leukemia (AML) with the t(16;21)(p11.2;q22) and FUS-ERG fusion. Four AML cell lines carrying a t(16;21)(p11.2;q22) have been described previously. We report a novel AML cell line, designated JIH-4, for which karyotypic analysis demonstrated a single abnormality, t(16;21)(p11.2;q22). The FUS-ERG fusion transcript was identified by reverse transcriptase polymerase chain reaction (RT-PCR). Neither Epstein-Barr virus nor mycoplasma was detected in JIH-4 cells. The morphology and immunoprofile of JIH-4 cells display typical features of myelogenous lineage, and short tandem-repeat PCR comparison with the donor patient's bone marrow cells confirm the cell line's authenticity. Tumor masses were found in 50% of inoculated mice 83 days after subcutaneous injection with JIH-4 cells. Our results confirm that JIH-4 cells are derived from the donor patient's leukemia cells and support using the JIH-4 cell line as a valuable tool in the study of leukemogenesis.

Use of transcriptional signatures induced in lymphoid and myeloid cell lines as an inflammatory biomarker in Type 1 diabetes

Inflammation is common to many disorders and responsible for tissue and organ damage. In many disorders, the associated peripheral cytokine milieu is dilute and difficult to measure, necessitating development of more sensitive and informative biomarkers for mechanistic studies, earlier diagnosis, and monitoring therapeutic interventions. Previously, we have shown that plasma of recent-onset (RO) Type 1 diabetes patients induces a disease-specific proinflammatory transcriptional profile in fresh peripheral blood mononuclear cells (PBMC) compared with that of healthy controls (HC). To eliminate assay variance introduced through the use of multiple donors or multiple draws of the same person over time, we evaluated human leukemia cell lines as potential surrogates for fresh PBMC. We 1) tested seven different cell lines in their power to differentiate RO from HC plasma and 2) compared the similarity of the signatures generated across the seven cell lines to that obtained with fresh PBMC. While each cell line tested exhibited a distinct transcriptional response when cultured with RO or HC plasma, the expression profile induced in any single cell line shared little identity with that of the other cell lines or fresh PBMC. In terms of regulated biological pathways, the transcriptional response of each cell line shared varying degrees of functional identity with fresh PBMC. These results indicate that use of human leukemia cell lines as surrogates for fresh PBMC has potential in detecting perturbations to the peripheral cytokine milieu. However, the response of each is distinct, possessing varying degrees of functional relatedness to that observed with PBMC.

Establishment and culture of leukemia-lymphoma cell lines

The advent of continuous human leukemia-lymphoma cell lines as a rich resource of abundant, accessible, and manipulable living cells has contributed significantly to a better understanding of the pathophysiology of hematopoietic tumors. The first leukemia-lymphoma cell lines were established in 1963 and since then large numbers of new cell lines have been described. The major advantages of continuous leukemia-lymphoma cell lines are the unlimited supply and worldwide availability of identical cell material and the infinite viable storability in liquid nitrogen. These cell lines are characterized generally by monoclonal origin and differentiation arrest, sustained proliferation in vitro under preservation of most cellular features, and by specific genetic alterations. Here some of the more promising techniques for establishing new leukemia-lymphoma cell lines and the basic principles for culturing these cells are described. Several clinical and cell culture parameters might have some influence on the success rate, e.g., choice of culture medium and culture conditions, specimen site of the primary cells, and status of the patient at the time of sample collection.

Modeling the human 8p11-myeloproliferative syndrome in immunodeficient mice

The 8p11 myeloproliferative syndrome (EMS), also referred to as stem cell leukemia/lymphoma, is a chronic myeloproliferative disorder that rapidly progresses into acute leukemia. Molecularly, EMS is characterized by fusion of various partner genes to the FGFR1 gene, resulting in constitutive activation of the tyrosine kinases in FGFR1. To date, no previous study has addressed the functional consequences of ectopic FGFR1 expression in the potentially most relevant cellular context, that of normal primary human hematopoietic cells. Herein, we report that expression of ZMYM2/FGFR1 (previously known as ZNF198/FGFR1) or BCR/FGFR1 in normal human CD34(+) cells from umbilical-cord blood leads to increased cellular proliferation and differentiation toward the erythroid lineage in vitro. In immunodeficient mice, expression of ZMYM2/FGFR1 or BCR/FGFR1 in human cells induces several features of human EMS, including expansion of several myeloid cell lineages and accumulation of blasts in bone marrow. Moreover, bone marrow fibrosis together with increased extramedullary hematopoiesis is observed. This study suggests that FGFR1 fusion oncogenes, by themselves, are capable of initiating an EMS-like disorder, and provides the first humanized model of a myeloproliferative disorder transforming into acute leukemia in mice. The established in vivo EMS model should provide a valuable tool for future studies of this disorder.

Quality of Cell Products: Authenticity, Identity, Genomic Stability and Status of Differentiation

Cellular therapies that either use modifications of a patient's own cells or allogeneic cell lines are becoming in vogue. Besides the technical issues of optimal isolation, cultivation and modification, quality control of the generated cellular products are increasingly being considered to be more important. This is not only relevant for the cell's therapeutic application but also for cell science in general. Recent changes in editorial policies of respected journals, which now require proof of authenticity when cell lines are used, demonstrate that the subject of the present paper is not a virtual problem at all. In this article we provide 2 examples of contaminated cell lines followed by a review of the recent developments used to verify cell lines, stem cells and modifications of autologous cells. With relative simple techniques one can now prove the authenticity and the quality of the cellular material of interest and therefore improve the scientific basis for the development of cells for therapeutic applications. The future of advanced cellular therapies will require production and characterization of cells under GMP and GLP conditions, which include proof of identity, safety and functionality and absence of contamination.

A comparison of gene expression profiles between primary human AML cells and AML cell line

In acute myeloid leukemia (AML), hematologic malignancies are characterized by recurring chromosomal abnormalities. Chromosome translocation t(9;11)(p22;q23) is one of the most common genetic aberrations and results in the formation of the MLL-AF9 fusion gene that functions as a facilitator of cell growth directly. In order to study this type of AML, the cell lines with cytogenetically diagnosed t(9;11)(p22;q23), such as Mono Mac 6 (MM6), have been widely used. To examine whether there is any difference in gene expression between the primary human t(9;11) AML cells and MM6 cell line, genome-wide transcriptome analysis was performed on MM6 cell line using SAGE and the results were compared to the profile of primary human t(9;11) AML cells. 884 transcripts which were alternatively expressed between MM6 cells and primary human t(9;11) cells were identified through statistical analysis (P < 0.05) and 4-fold expression change. Of these transcripts, 830 (94%) matched to known genes or EST were classified by functional categories (http://david.abcc.ncifcrf.gov/). The majority of alternatively expressed genes in MM6 were involved in biosynthetic and metabolic processes, but HRAS, a protein that is known to be associated with leukemogenesis, was expressed only in MM6 cells and several other genes involved in Erk1/Erk2 MAPK pathway were also over-expressed in MM6. Therefore, since MM6 cell line has a similar expression profile to primary human t(9;11) AML in general and expresses uniquely a strong Erk1/Erk2 MAPK pathway including HRAS, it can be used as a model for HRAS-positive t(9;11) AML.

Transcription Factor Expression in Cell Lines Derived from Natural Killer-Cell and Natural Killer-Like T-Cell Leukemia-Lymphoma

Although a number of transcription factors (TFs) have been identified that play a pivotal role in the development of hematopoietic lineages, only little is known about factors that may influence development and lineage commitment of natural killer (NK) or NK-like T (NKT)-cells. Obviously to fully appreciate the NK- and NKT-cell differentiation process, it is important to identify and characterize the TFs effecting the NK- and NKT-cell lineage. Furthermore, these TFs may play a role in NK- or NKT-cell leukemias, in which the normal differentiation program is presumably disturbed. The present study analyzed the expression of the following 13 TFs: AML1, CEBPA, E2A, ETS1, GATA1, GATA2, GATA3, IKAROS, IRF1, PAX5, PU1, TBET and TCF1 in 7 malignant NK-cell lines together with 5 malignant NKT-cell lines, 5 T-cell acute lymphoblastic leukemia (ALL) cell lines including 3 gamma/delta T-cell receptor (TCR) type and 2 alpha/beta TCR type, and 3 B-cell precursor (BCP) leukemia cell lines. AML1, E2A, ETS1, IKAROS and IRF1 were found to be positive for all cell lines tested whereas GATA1 turned out to be universally negative. CEBPA, PAX5 and PU1 were negative for all cell lines tested except in the three positive BCP-cell lines. GATA2 was positive for 3/5 T-cell lines but negative for the other cell lines. GATA3 was positive for 7/7 NK-, 4/5 NKT-, 5/5 T- and 2/3 BCP-cell lines. TBET was positive for all NK- and NKT-cell lines and negative for all T- and BCP-cell lines except one BCP-cell line. In contrast to the expression of TBET, TCF1 was negative for all NK- and NKT-cell lines, being positive for 4/5 T- and 1/3 BCP-cell lines. Expression analysis of TFs revealed that NK- and NKT-cell lines showed identical profiles, clearly distinct from those of the other T-ALL or BCP-ALL leukemia-derived cell lines..

Establishment and characterization of a new human acute myelocytic leukemia cell line SH-2 with a loss of Y chromosome, a derivative chromosome 16 resulting from an unbalanced translocation between chromosomes 16 and 17, monosomy 17, trisomy 19, and p53 alteration

OBJECTIVE

To report here a new acute myelocytic leukemia (AML) cell line SH-2 and describe its biological characteristics.

MATERIALS AND METHODS

Mononuclear cells isolated from a patient with AML-M2 subtype were passaged by liquid culture medium. Interleukin-3 and bone marrow stromal cells were used to support cell proliferation at the first 3 months. Various methods, including cytogenetic analysis, fluorescence in situ hybridization (FISH), multiplex FISH (M-FISH), reverse transcriptase polymerase chain reaction (RT-PCR), multiplex RT-PCR, short tandem repeat (STR)-PCR, direct sequencing of DNA, clonogenic assay, and tumorigenicity in nude and severe combined immunodeficient (SCID) mice were employed to identify and characterize SH-2 cell line.

RESULTS

SH-2 cells were maintained without cytokine and stromal cells for 3 years. It had no Epstein-Barr virus or mycoplasma contamination. The SH-2 cell line showed typical myelocytic features in morphology and simultaneous strongly expressed myeloid antigens (CD13, 99.6% and CD33, 99.26%) and natural killer (NK)-related antigens (CD56, 99.5% and CD16/56, 99.62%) suggesting that SH-2 is an AML cell line with NK-antigen expression. SH-2 cell line initially showed a karyotype of 45, X, -Y, der(16)t(16;17)(q24;q12), -17, +19. During the passage period, the cells with a hypodiploid karyotype gradually decreased and were replaced by the near-tetraploid cells with a karyotype of 71-105(86), XX, -Y, -Y, der(16)t(16;17)x2, -17, -17, +19, +19. FISH and M-FISH delineated all abnormalities. SH-2 cells had the approximately same morphological, immunophenotypical, and cytogenetic features as the patient's leukemia cells had. STR-PCR provided powerful evidence for the derivation of SH-2 cell line from the patient's leukemia cells. SH-2 cells showed multiple drug resistance (MDR), which may be related to the p53 gene alteration, including the loss of one p53 allele due to the monosomy 17 and a point mutation of CAG to CAT at codon 576 of exon 5 in another p53 allele resulting in the loss of p53 gene function. In addition, SH-2 cell line did not express MDR-related genes, such as MDR1, multidrug resistance-related protein, and lung resistance protein, but expressed apoptosis-related genes, such as Bcl-2, Fas, glutathione S-transferase-pi, and p21, which were also related to the MDR. SH-2 cell line had tumorigenic capacities in nude and SCID mice.

CONCLUSION

Because SH-2 cell line had a clear biology background, it will provide a useful tool for the study of the pathogenesis and treatment strategy of AML with MDR.

Identification of genes deregulated during serum-free medium adaptation of a Burkitt's lymphoma cell line

OBJECTIVE

Serum is usually added to growth media when mammalian cells are cultured in vitro to supply the cells with growth factors, hormones, nutrients and trace elements. Defined proteins and metal ions, such as insulin, growth factors, transferrin and sodium selenite, are sometimes also included and can in some cases substitute serum components. How adaptation to serum free media influences cells has not been studied in detail.

MATERIALS AND METHODS

We have adapted the Burkitt's lymphoma line Ramos to a serum-free medium that supports long-term survival and studied gene expression changes that occurred during the adaptation process.

RESULTS AND CONCLUSIONS

The adaptation process was characterized by initial cell population growth arrest, and after that extensive cell death, followed by proliferation and long-term survival of clonal cultures. Proliferation and cell cycle progression of the serum-free cultures closely mimicked that of serum-dependent cells. Affymetrix micro-array technology was used to identify gene expression alterations that had occurred during the adaptation. Most changes were subtle, but frequently the genes with altered expression were involved in basal cellular functions such as cell division, cell cycle regulation, apoptosis and cell signalling. Some alterations were restored when the cells were transferred back to serum-containing medium, indicating that expression of these genes was controlled by components in serum. Others were not, and may represent changes that were selected during the adaptation process. Among these were, for example, several genes within the Wnt signalling pathway.

Thymic adult T-cell acute lymphoblastic leukemia stratified in standard- and high-risk group by aberrant HOX11L2 expression: experience of the German multicenter ALL study group

Adult T-cell acute lymphoblastic leukemia (T-ALL) continues to represent an unfavorable disease. Molecularly based treatment stratifications could help improve outcome. The prognostic impact of HOX11 and HOX11L2 expression has been an area of controversy. We have investigated 286 adult T-ALL patients enrolled into the German Multicenter ALL (GMALL) therapy protocols by comparative real-time RT-PCR. High HOX11 expression and HOX11L2 expression were predominantly seen in thymic T-ALL (P<or=0.031). In a multivariate analysis HOX11L2 expression proved to be an independent adverse risk factor for relapse-free survival (RFS) with a hazard ratio (HR) of 2.02 (P=0.023) and an HR for overall survival (OS) of 1.81 (P=0.021), both adjusted for the immunophenotype. HOX11 expression was found to have a favorable impact on RFS (HR 0.51; P=0.048) but did not exhibit a significant impact on OS. A subgroup analysis for thymic T-ALL revealed a more pronounced negative correlation of HOX11L2 expression with RFS (HR 3.26; P=0.002) and OS (HR 2.38; P=0.009). Although the prognostic impact of HOX11 in T-ALL is less clear, HOX11L2 expression identifies a small subset of high-risk patients, who are so far classified as standard-risk group. Thus, patients with aberrant HOX11L2 expression should be considered early as candidates for intensified treatment regimes.

Establishment of transplantable porcine tumor cell lines derived from MHC-inbred miniature swine

The lack of transplantable tumors has limited assessment of graft-versus-tumor effects following hematopoietic cell transplantation in clinically relevant large-animal models. We describe the derivation and characterization of porcine tumor cell lines with initial efforts of tumor transplantation using immunocompromised mice and highly inbred sublines of Massachusetts General Hospital major histocompatibility complex (MHC)-inbred miniature swine. Autopsies were performed routinely on swine that died unexpectedly or had suspicion of malignancy based on clinical symptoms or peripheral blood analysis. Tissue samples were obtained for pathology, phenotyped by flow cytometry, and placed in culture. Based on growth, lines were selected for passage into nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice and miniature swine. Porcine tumor recipients were preconditioned with total body irradiation from 0 to 500 cGy or with a 30-day course of oral cyclosporine. We identified 19 cases of hematologic tumors. Nine distinct tumor cell lines were established from 8 of these cases, including 3 derived from highly inbred sublines. In vivo tumor growth and serial transfer were observed in immunocompromised mice for one tumor cell line and in miniature swine for 1 of 2 tumor cell lines expanded for this purpose. These results suggest the possibility of developing a transplantable tumor model in this large-animal system.

Establishment of transplantable porcine tumor cell lines derived from MHC-inbred miniature swine

The lack of transplantable tumors has limited assessment of graft-versus-tumor effects following hematopoietic cell transplantation in clinically relevant large-animal models. We describe the derivation and characterization of porcine tumor cell lines with initial efforts of tumor transplantation using immunocompromised mice and highly inbred sublines of Massachusetts General Hospital major histocompatibility complex (MHC)-inbred miniature swine. Autopsies were performed routinely on swine that died unexpectedly or had suspicion of malignancy based on clinical symptoms or peripheral blood analysis. Tissue samples were obtained for pathology, phenotyped by flow cytometry, and placed in culture. Based on growth, lines were selected for passage into nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice and miniature swine. Porcine tumor recipients were preconditioned with total body irradiation from 0 to 500 cGy or with a 30-day course of oral cyclosporine. We identified 19 cases of hematologic tumors. Nine distinct tumor cell lines were established from 8 of these cases, including 3 derived from highly inbred sublines. In vivo tumor growth and serial transfer were observed in immunocompromised mice for one tumor cell line and in miniature swine for 1 of 2 tumor cell lines expanded for this purpose. These results suggest the possibility of developing a transplantable tumor model in this large-animal system.

A novel canine lymphoma cell line: a translational and comparative model for lymphoma research

A novel canine lymphoma cell line, OSW, was established from the malignant pleural effusion of a dog with peripheral T-cell lymphoma. The immunoprofile as determined by flow cytometry was as follows: positive for CD45, CD49d, CD18, CD11a; weakly positive for CD11b, CD11c, CD11d; and negative for CD45RA, CD1a, CD1c, CD3, TCRalphabeta, TCRgammadelta, CD4, CD5, CD8a, CD8b, CD90(Thy1), CD21, MHCII, CD14(TUK4), CD34, and MPO. Immunocytochemistry of cytospin preparations was negative for cytoplasmic CD3, CD79a, and MPO, but was positive for CD20. The cell line had an oligoclonal T-cell receptor gamma (TCRgamma) gene rearrangement. Array comparative genomic hybridization (aCGH) and single locus probe (SLP) analysis showed that there were copy number increases of loci on dog chromosome 13 (CFA 13), and copy number decreases were evident for regions of CFA 11, 22, 26, 30 and 32, which include several of the more common chromosomal aberrations reported previously in canine lymphoma. The OSW cell line grows rapidly in vitro and is tumorigenic as a xenograft in SCID/NOD mice. OSW represents one of only a few reported canine lymphoma cell lines and is the most thoroughly characterized. This cell line and xenograft represent significant in vitro and in vivo models, respectively, for comparative and translational lymphoma research.

Effects of human monoclonal antibody 216 on B-progenitor acute lymphoblastic leukemia in vitro

BACKGROUND

Human monoclonal antibody (mAb) 216 is a naturally occurring IgM cytotoxic mAb that binds to a glycosylated epitope on the surface of B-lymphocytes. This study investigated if this mAb could bind and kill acute lymphoblastic leukemia (ALL) B-progenitor lymphoblasts in vitro. ALL cell lines were used to determine if combining mAb 216 with chemotherapeutic drugs would enhance killing and cell lines were used to measure cytotoxicity by mAb 216 with human complement.

PROCEDURE

Expression of cell surface markers and mAb 216 epitope on fresh and banked ALL bone marrow samples was determined by flow cytometry. Fresh lymphoblasts were incubated for 20 hr with mAb 216 without complement to measure cytotoxicity. Cytotoxicity of ALL cell lines incubated with mAb 216 and vincristine (VCR) or human complement was determined using flow cytometry.

RESULTS

Pre-B-ALL cells but not T-ALL cells are bound and killed by mAb 216. The combination of mAb 216 and VCR at sub-therapeutic levels demonstrated enhanced cytotoxicity beyond that observed for either agent alone. Incubation of mAb 216 with human complement increased cytotoxicity of ALL cell lines.

CONCLUSION

This increased cytotoxicity with chemotherapy and the functional ability of mAb 216 to use multiple pathways to induce cell death identify mAb 216 as a potentially novel therapeutic tool in the treatment of B-progenitor ALL. Based on the results from this preclinical study, a Phase I clinical trial with mAb 216 for the treatment of patients with relapsed or refractory B-lineage ALL is ongoing.

Molecular profiling reveals myeloid leukemia cell lines to be faithful model systems characterized by distinct genomic aberrations

To model and investigate different facets of leukemia pathogenesis, a widely accepted approach is to use immortalized leukemia cell lines. Although these provide powerful tools to our knowledge, few studies have addressed the question whether hematopoietic cell lines represent accurate and reliable model systems. To improve the molecular characterization of these model systems, we analyzed 17 myeloid leukemia cell lines using DNA microarray technology. By array-based comparative genomic hybridization, we identified recurrent genomic DNA gains and losses, as well as high-level amplifications. Parallel analysis of gene expression helped delineate potential candidate genes, and unsupervised analysis of gene expression data revealed cell lines to cluster in part based on underlying cytogenetic abnormalities. Comparison with clinical leukemia specimens showed that key signatures were retained, as myeloid cell lines with characteristic cytogenetic aberrations co-clustered with leukemia samples carrying the respective abnormality. Signatures were also quite robust, as expression data from cell lines correlated highly with published data. Thus, our analyses demonstrate myeloid cell lines to exhibit conserved and stable signatures reflecting the underlying primary cytogenetic aberrations. Our refined molecular characterization of myeloid cell lines supports the utility of cell lines as faithful and powerful model systems and provides additional insights into the molecular mechanisms of leukemogenesis.

Establishment of a myeloid leukemia cell line, TRL-01, with MLL-ENL fusion gene

We established a leukemia cell line derived from therapy-related acute myeloid leukemia with the t(11;19) by xenotransplantation into the NOD/SCID mouse with IL-2Rgamma(c)-/- (NOG mouse). The cell line, TRL-01, could be serially transplanted from mouse to mouse and also grown in an adherence-dependent manner on a murine bone marrow stroma cell line, HESS-5. TRL-01 had the same immunophenotype as the original leukemia cells: positive for CD13, CD33, CD11a, CD18, CD29, CD49d, CD49e, CD54, CD62L, and CD117, and negative for CD3, CD4, CD8, CD19, CD34, CD41a, CD41b, CD135, and myeloperoxidase. Translocation (11;19)(q23;p13) in both the original sample and TRL-01 generated MLL-ENL chimeric transcripts joining exon 6 and exon 4, respectively, which has a novel isoform. In cultures of TRL-01, addition of GM-CSF, SCF, and G-CSF and adhesion to fibronectin-coated plates promoted transient proliferation and survival, although they did not support long-term culture. Subcutaneous injection caused a tumor to form only when HESS-5 was coinjected at the same site. These results suggest that TRL-01 is a useful cell line for studying not only the leukemia-related biology of MLL-ENL but also the intercellular association between leukemia and stroma.

Multicolor spectral karyotyping of the L5178Y Tk+/- -3.7.2C mouse lymphoma cell line

The L5178Y/Tk+/- -3.7.2C mouse lymphoma cell line is characterized, at the cytogenetic level, by a karyotype involving both numerical and complex structural aberrations. While the karyotype is remarkably normal for a transformed cell line that has been in culture for almost half a century, there are a number of chromosomal alterations that because of their complexity cannot be fully characterized by routine or even high-resolution G-banding studies. Multicolor spectral karyotyping (SKY) was performed on the cell line in anticipation of identifying the previously unresolved chromosome aberrations and confirming interpretations previously identified by banding studies. New chromosome aberrations detected by SKY include numerical aberrations of chromosome 15, duplications of regions of chromosomes 4, 5, 12, and 18, and deletion of chromosome 14. Complex unbalanced translocations involved segments of chromosomes 6, 14, and 15. In total, the SKY technique was able to provide new refined designations on segments of eight different chromosome pairs (4, 5, 6, 9, 12, 14, 15, 18) and identified all three previously unidentified marker chromosomes. This analysis provides an updated standard reference for the karyotype of the L5178Y/Tk+/- -3.7.2C cell line used in the in vitro mouse lymphoma mutation assay.

Establishment and characterization of a new erythroblastic leukemia cell line, EEB: phosphatidylglucoside-mediated erythroid differentiation and apoptosis

A new erythroblastic leukemia cell line (EEB) was established from a patient with early erythroblastic leukemia. The cells had features of immature erythroblasts, including an agranular basophilic cytoplasm and CD36, CD71, CD175s (sialyl-Tn) and CD235a (glycophorin A) expression without CD41 expression, myeloperoxidase activity and platelet-peroxidase activity. The cells were confirmed to be of the erythroid lineage based on expression of the gamma-globin message. They were induced to differentiate into benzidine-positive cells by hemin and delta-amino levulinic acid (delta-ALA). An analysis of cell membrane lipids showed that EEB cells contain a type of glycerolipid, phosphatidylglucose (PhGlc), but not unbranched type 2 chains, i antigens. GL-7 which is a recombinant Fab fragment of GL-2 and binds to PhGlc, induced production of hemoglobin F (HbF) associated with accumulation of the gamma-globin (gamma-globin) message in EEB cells. The GL-7-mediated erythroid differentiation was associated with apoptosis. These results suggest that direct signaling to PhGlc mediates erythroid differentiation and apoptosis in EEB cells.

Reappraisal of BCL3 as a Molecular Marker of Anaplastic Large Cell Lymphoma

The BCL3 gene was initially discovered through its involvement in a recurring translocation, t(14;19)(q32;q13), which is found in some patients with B-cell chronic lymphocytic leukemia (B-CLL). The translocation leads to the juxtaposition of BCL3 to the immunoglobulin heavy chain gene locus, resulting in high-level expression of the BCL3 transcript. The Bcl-3 protein includes 7 tandem copies of the ankyrin repeat element in the central domain, a structure that is characteristic of the IkappaB family of inhibitors of the nuclear factor kappaB transcription factors. Anaplastic large cell lymphoma (ALCL) is a subtype of aggressive non-Hodgkin's lymphoma that is characterized by expression of CD30 and the NPM/ALK chimeric protein, which is generated by t(2;5)(p23;q35). We compared the gene expression profiles of ALCL with those of another CD30+ neoplasm, Hodgkin's disease (HD), and found that BCL3 is expressed at higher levels in ALCL than in HD. A comparison by real-time polymerase chain reaction assay revealed that t(2;5)+ ALCL expresses a high level of BCL3 messenger RNA relative to the levels expressed in other hematologic tumors, and the level in ALCL is comparable to or even higher than that in t(14;19)+ B-CLL. An immunohistochemical analysis of ALCL tumor tissues showed that the lymphoma cells exhibited strong nuclear staining by a monoclonal antibody against Bcl-3. We suggest that Bcl-3 sequestrates the (p50)2 homodimer to the nucleus and that the kappaB sites are occupied by the (p50)2/Bcl-3 ternary complex. Future studies should identify the relationships among the 3 independent molecules (ie, NPM/ALK, CD30, and Bcl-3) that are activated in t(2;5)+ ALCL.

Stimulation of CD30 in anaplastic large cell lymphoma leads to production of nuclear factor-kappaB p52, which is associated with hyperphosphorylated Bcl-3

Anaplastic large cell lymphoma (ALCL) and Hodgkin lymphoma (HL) express CD30 at high levels, but stimulation of this molecule has been reported to induce contradictory effects. To elucidate the molecular mechanism of CD30-mediated apoptosis of ALCL, we compared the gene expression profiles of t(2;5)(p23;q35)-positive ALCL with those of HL altered by CD30 agonistic stimulation. The results showed that BCL3, the high-level expression of which in ALCL was previously reported, was further upregulated in response to CD30 stimulation, along with several pro-apoptotic genes. Bcl-3 protein was present as an intermediate phospho-form in the resting-state ALCL, becoming hyperphosphorylated (Bcl-3P) upon stimulation. We next found that the stimulation promoted de novo synthesis of the nuclear factor (NF)-kappaB2/p100 precursor as well as processing to p52, and a series of immunoprecipitation and western blotting analyses consistently showed association of Bcl-3P with p52 in CD30-stimulated ALCL. An electrophoretic mobility shift assay revealed the induction of kappaB binding activity of the p52 homodimer, and nuclear colocalization of Bcl-3 and p52 was demonstrated in anaplastic lymphoma kinase-positive ALCL tumor tissues by immunohistochemistry. As Bcl-3 can act as an anti-repressor or transactivator or both, we propose that the (p52)2/Bcl-3P ternary complex, which is specifically induced in CD30-stimulated ALCL, can modulate expression of apoptosis-related genes regulated by NF-kappaB, thereby accounting for CD30-mediated apoptosis of ALCL.

Dietary flavonoids as proteasome inhibitors and apoptosis inducers in human leukemia cells

It has been shown that proteasome activity is required for cancer cell survival and consumption of fruits and vegetables is associated with decreased cancer risk. Previously, we reported that grape extract could inhibit proteasome activity and induce apoptosis in tumor cells. In this study, we examined the flavonoids apigenin, quercetin, kaempferol and myricetin for their proteasome-inhibitory and apoptosis-inducing abilities in human tumor cells. We report that apigenin and quercetin are much more potent than kaempferol and myricetin at: (i) inhibiting chymotrypsin-like activity of purified 20S proteasome and of 26S proteasome in intact leukemia Jurkat T cells; (ii) accumulating putative ubiquitinated forms of two proteasome target proteins, Bax and Inhibitor of nuclear factor kappabeta-alpha in Jurkat T cells and (iii) inducing activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase in Jurkat T cells. The proteasome-inhibitory abilities of these compounds correlated with their apoptosis-inducing potencies. Results from computational modeling of the potential interactions of these flavonoids to the chymotrypsin site (beta5 subunit) of the proteasome were consistent with the obtained proteasome-inhibitory activities. We found that the C(4) carbon may be a site of nucleophilic attack by the OH group of N-terminal threonine of proteasomal beta5 subunit and that the C(3) hydroxyl may alter the ability of these flavonoids to inhibit the proteasome. Finally, apigenin neither effectively inhibited the proteasome activity nor induced apoptosis in non-transformed human natural killer cells. Our results suggested that the proteasome may be a target of these dietary flavonoids in human tumor cells and that inhibition of the proteasome by flavonoids may be one of the mechanisms responsible for their cancer-preventive effects.

CTCF regulates growth and erythroid differentiation of human myeloid leukemia cells

CTCF is a transcription factor and a candidate tumor suppressor that contains a DNA-binding domain composed of 11 zinc fingers. We reported previously that CTCF is differentially regulated during differentiation of human myeloid leukemia cells. In this study we aimed to investigate the role of CTCF in myeloid cell differentiation. A human cell line, K562, that can be chemically induced to differentiate into various hematopoietic lineages was chosen as a model system for this study. Several K562 cell lines with constitutive and conditional expression of CTCF have been generated. By using these model systems we demonstrated that: (i) ectopic expression of CTCF in K562 cells led to growth retardation and promotion of differentiation into the erythroid lineage; (ii) CTCF knock-down significantly inhibited differentiation of K562 cells into erythroid lineage; (iii) differentiation of K562 into the megakaryocytic lineage was not significantly affected; and (iv) down-regulation of MYC has been identified as one of the mechanisms by which CTCF promotes erythroid differentiation. Taken together our results demonstrate that CTCF is involved in the control of myeloid cell growth and differentiation.

Acute myeloid leukemia cell lines MOLM-17 and MOLM-18 derived from patient with advanced myelodysplastic syndromes

The two acute myelomonocytic leukemia sister cell lines MOLM-17 and MOLM-18 and the Epstein-Barr-virus positive non-malignant B-lymphoblastoid cell lines (B-LCLs) B422 and B423 were established from the bone marrow sample of a 60-year-old Japanese male in the advanced leukemic phase of refractory anemia with excess of blasts, a subtype of myelodysplastic syndromes (MDS). MOLM-17/-18 are proliferatively responsive to the growth factors present in the culture supernatant of the 5637 cell line. The B-LCLs are constitutively growth factor-independent. MOLM-17 and B422 were established at eight months after the initial diagnosis, while MOLM-18 and B423 were derived from a sample one month later. Immunophenotyping of the first leukemia sample revealed a mixed lineage leukemia immunophenotype with positivity for terminal deoxynucleotidyl transferase (TdT), CD13 and CD19; the second sample revealed solely myeloid characteristics with positivity for CD13, CD41 and CD61, whereas TdT was negative. MOLM-17/-18 showed immunomarker profiles typical of the myelomonocytic lineage. The karyotype analysis of MOLM-17/-18 revealed various non-random numerical and structural abnormalities including del(5)(q?), -7, der(11)add(11)(p11.2)add(11)(q23), add(17)(p11.2), add(18)(p11.2), -20, -22 as common aberrations. Treatment with tumor necrosis factor-alpha induced pronounced cellular differentiation of both cell lines into macrophage-like cells. The overall profile of MOLM-17/-18 based on their extensive immunological, cytogenetic and functional characterization suggests that these cell lines together with the paired B-LCLs B422 and B423 may represent scientifically significant in vitro models which could facilitate investigations into the pathobiology of MDS.

Gene expression profiling of leukemic cell lines reveals conserved molecular signatures among subtypes with specific genetic aberrations

Hematologic malignancies are characterized by fusion genes of biological/clinical importance. Immortalized cell lines with such aberrations are today widely used to model different aspects of leukemogenesis. Using cDNA microarrays, we determined the gene expression profiles of 40 cell lines as well as of primary leukemias harboring 11q23/MLL rearrangements, t(1;19)[TCF3/PBX1], t(12;21)[ETV6/RUNX1], t(8;21)[RUNX1/CBFA2T1], t(8;14)[IGH@/MYC], t(8;14)[TRA@/MYC], t(9;22)[BCR/ABL1], t(10;11)[PICALM/MLLT10], t(15;17)[PML/RARA], or inv(16)[CBFB/MYH11]. Unsupervised classification revealed that hematopoietic cell lines of diverse origin, but with the same primary genetic changes, segregated together, suggesting that pathogenetically important regulatory networks remain conserved despite numerous passages. Moreover, primary leukemias cosegregated with cell lines carrying identical genetic rearrangements, further supporting that critical regulatory pathways remain intact in hematopoietic cell lines. Transcriptional signatures correlating with clinical subtypes/primary genetic changes were identified and annotated based on their biological/molecular properties and chromosomal localization. Furthermore, the expression profile of tyrosine kinase-encoding genes was investigated, identifying several differentially expressed members, segregating with primary genetic changes, which may be targeted with tyrosine kinase inhibitors. The identified conserved signatures are likely to reflect regulatory networks of importance for the transforming abilities of the primary genetic changes and offer important pathogenetic insights as well as a number of targets for future rational drug design.

Establishment and characterization of a new human erythroleukemic cell line, ERY-1

The growth factor-independent erythroleukemic cell line ERY-1 was established from the peripheral blood of a 87-year-old woman with chronic myeloid leukemia (CML) in the acute phase. Immunophenotyping showed that fresh leukemic cells were positive for CD13, CD33, CD36 and CD235a (glycophorin A), a phenotype compatible with that of erythroblastic cells. Cytogenetic and fluorescence in situ hybridization (FISH) analysis demonstrated classical t(9;22)(q34;q11) chromosomic translocation associated with a duplication of the BCR-ABL fusion gene. Other cytogenetic abnormalities were detected in all analyzed mitosis, the most frequent being a trisomy of chromosome 8. The established ERY-1 cell line retains these immunophenotypic and cytogenetic features, and light and electron microscopy confirmed the relatively mature erythroblastic phenotype of the cells. In addition, ERY-1 cell line expressed beta-globin mRNA and a non-phosphorylable form of the erythropoietin receptor, even in presence of erythropoietin. Of note, the proliferation of ERY-1 cells was inhibited by TGFbeta1 or STI-571 (Gleevec), without significant induction of further differentiation. In conclusion, ERY-1 is a new growth factor-independent human erythroleukemic cell line with a relatively mature phenotype that may be useful to study the molecular events involved in erythroblastic differentiation.

Malignant hematopoietic cell lines: in vitro models for the study of erythroleukemia

A panel of leukemia cell lines has been assembled over the last 30 years representing a spectrum of erythroid cells arrested at various stages of differentiation. The oldest cell line is K-562 which is one of the most prolific in use. Most cell lines have been established from acute myeloid leukemia M6 or chronic myeloid leukemia in blast crisis and generally express immunoprofiles typically seen in immature erythroid cells. Several cell lines are constitutively growth factor-dependent, responding proliferatively to a variety of cytokines. The predominant cytogenetic abnormalities are the t(9;22)(q34;q11) found exclusively in CML-derived cell lines, and rearrangements of chromosomes 5 and 7 which occur in all disease subtypes. Ph+ve cell lines consistently displayed structural and numerical changes associated with disease evolution, including +8, -17/17p-/i(17q), and +19. It is striking that many cell lines though committed to either the erythroid or megakaryocytic lineage tend to co-express features of the other lineage, consistent with the concept of a common erythroid-megakaryocytic progenitor. Several cell lines may be induced to differentiate along the erythroid, megakaryocytic or monocytic pathway by treatment with pharmacological or physiological reagents. Notable functional features include expression of various globin chains or the complete hemoglobins as erythroid attributes. Taken together, this class of cell lines is relatively well characterized and affords useful model systems for immature erythroid cells.

Establishment and characterization of an STI571-resistant human myelogenous leukemia cell line, SR-1

The tyrosine kinase inhibitor STI571 is an effective agent for the treatment of chronic myelogenous leukemia (CML). However, a lack of response to STI571 or the recurrence of the disease after a transient initial response is usually seen in patients with advanced stage CML. We have established a novel STI571 (Gleevec/Glivec, imatinib mesylate)-resistant acute myelocytic leukemia cell line (SR-1) from an STI571-resistant blast crisis patient. By flow cytometry, the immunophenotype of SR-1 was found to be compatible with a myeloid lineage (CD13+, CD33+, HLA-DR+, anti-MPO+). Conventional cytogenetics showed a three-way reciprocal translocation involving 7p22, 9q34, and 22q11.2, i.e., a variant Philadelphia chromosome translocation. The BCR/ABL rearrangement was detected by fluorescence in situ hybridization and reverse transcriptase polymerase chain reaction. To determine the tumorigenicity of the SR-1 cell line in vivo, cells were injected subcutaneously into severe combined immunodeficiency mice. Four weeks later, tumors had grown and showed the same laboratory findings as in SR-1. Although STI571 resistance is a known treatment complication, in vivo STI571-resistant cell lines have not been fully established. We hope that our SR-1 cell line may be useful in molecular pathogenetic investigations of STI571-resistant CML.