Lymphoblastic Lymphoma Cell Line Research Articles

Proteomic characterization of EL4 lymphoma-derived tumors upon chemotherapy treatment reveals potential roles for lysosomes and caspase-6 during tumor cell death in vivo.

The murine mouse lymphoblastic lymphoma cell line (EL4) tumor model is an established in vivo apoptosis model for the investigation of novel cancer imaging agents and immunological treatments due to the rapid and significant response of the EL4 tumors to cyclophosphamide and etoposide combination chemotherapy. Despite the utility of this model system in cancer research, little is known regarding the molecular details of in vivo tumor cell death. Here, we report the first in-depth quantitative proteomic analysis of the changes that occur in these tumors upon cyclophosphamide and etoposide treatment in vivo. Using a label-free quantitative proteomic approach a total of 5838 proteins were identified in the treated and untreated tumors, of which 875 were determined to change in abundance with statistical significance. Initial analysis of the data reveals changes that may have been predicted, such as the downregulation of ribosomes, but demonstrates the robustness of the dataset. Analysis of the dataset also reveals the unexpected downregulation of caspase-3 and an upregulation of caspase-6 in addition to a global upregulation of lysosomal proteins in the bulk of the tumor.

Analysis of the cytotoxic effects of ruthenium-ketoconazole and ruthenium-clotrimazole complexes on cancer cells.

Ruthenium-based compounds have intriguing anti-cancer properties, and some of these novel compounds are currently in clinical trials. To continue the development of new metal-based drug combinations, we coupled ruthenium (Ru) with the azole compounds ketoconazole (KTZ) and clotrimazole (CTZ), which are well-known antifungal agents that also display anticancer properties. We report the activity of a series of 12 Ru-KTZ and Ru-CTZ compounds against three prostate tumor cell lines with different androgen sensitivity, as well as cervical cancer and lymphoblastic lymphoma cell lines. In addition, human cell lines were used to evaluate the toxicity against non-transformed cells and to establish selectivity indexes. Our results indicate that the combination of ruthenium and KTZ/CTZ in a single molecule results in complexes that are more cytotoxic than the individual components alone, displaying in some cases low micromolar CC50 values and high selectivity indexes. Additionally, all compounds are more cytotoxic against prostate cell lines with lower cytotoxicity against non-transformed epidermal cell lines. Some of the compounds were found to primarily induce cell death via apoptosis yet weakly interact with DNA. Our studies also demonstrate that the cytotoxicity induced by our Ru-based compounds is not directly related to their ability to interact with DNA.

Molecular Cloning of a Novel PPEF-1 Gene Variant from a T-Cell Lymphoblastic Lymphoma Cell Line

To determine if there is a gene variant of protein serine-threonine phosphatase with EF hand (PPEF-1) in T-cell lymphoblastic lymphoma SUP-T1 cell line, both in silico and in vitro approaches were conducted. In silico, a cDNA clone showing similar sequence to PPEF-1 was isolated from the SUP-T1 cDNA library and named PPEF-1V. The full-length of the PPEF-1V cDNA clone is a 2135bp containing a 1503bp open reading frame extending from 188bp to 1690bp, which corresponds to an encoded protein of 501 amino acid residues with a predicted molecular mass of 57.8 kDa. Alignment on both PPEF-1V and PPEF-1 sequences showed that PPEF-1V is a 350bp deletion in the nucleotide sequence of PPEF-1 from 128-477bp and a 152-amino-acid N-terminal deletion in the amino acid sequence of PPEF-1. In vitro, PPEF-1V transcript fragment was only highly expressed in T-cell lymphoblastic lymphoma cell line. In conclusion, the present patent showed that PPEF-1V could be a potential target for diagnosis or treatment of T-cell lymphoblastic lymphoma.

Epratuzumab (Humanized Anti-CD22 MAb) Conjugated with SN-38, a New Antibody-Drug Conjugate (ADC) for the Treatment of Hematologic Tumors: Preclinical Studies Alone and In Combination with Veltuzumab, a Humanized Anti-CD20 MAb

AbstractAbstract 3941 Background:Monoclonal antibody (MAb) therapy has had a significant impact on the management of B-cell malignancies, but is most often used in combination with chemotherapy. We developed an ADC that combines SN-38, the active component of irinotecan, a topoisomerase I inhibitor, with the internalizing, humanized, anti-CD22 IgG, epratuzumab, and determined its activity alone and in combination with an anti-CD20 antibody therapy (veltuzumab). Methods:Epratuzumab was conjugated with SN-38 (E-SN-38) at a mole ratio of ∼6:1. The conjugate is designed specifically to be released slowly in the presence of serum (50% released over ∼1.5 days), allowing liberation of the drug when internalized, but also being released locally after being bound to the tumor. In vitro and in vivo studies were performed to assess the activity of the conjugate against several subcutaneously- or intravenously-inoculated B-cell lymphoma cell lines. In vivo studies also examined combination therapy using E-SN-38 and the veltuzumab (V). Results:In vitro studies in 4 B-cell lymphoma cells lines (Daudi, Raji, Ramos, WSU-FSCCL) and 4 acute lymphoblastic lymphoma cell lines (697, REH, MN-60, and RS4;11) expressing varying amounts of CD22 showed an IC50 for E-SN-38 in the nanomolar range, confirming potent activity. Nude mice bearing SC Ramos human lymphoma had significant selective anti-tumor activity compared to a control, non-targeting, IgG-SN-38 conjugate, at a dosing regimen of 75 to 250 μg of the conjugates given twice-weekly for 4 weeks. Significant anti-tumor activity was also found in several other cell lines. When combined with veltuzumab, significant improvement in therapeutic activity was observed. For example, median survival in a WSU-FSCCL human follicular B-cell lymphoma IV model with treatment initiated 5 days after implantation was 42 d (0/10 surviving at 160 d) and 91 d (2/10 surviving) for untreated and veltuzumab-treated animals, respectively; 63d (0/10 surviving after 160 d) and >160 d (with 6/10 surviving) for E-SN-38 and E-SN-38 + V, respectively; and 63 d (0/10) and 91 d (2/10) for non-targeting IgG-SN-38 conjugate alone and combined with V). The E-SN-38 conjugate combined with V was significantly better than all treatment or control groups (P ≤ 0.05). Conclusion:E-SN-38 ADC is a potent therapeutic, even at non-toxic dose levels, and shows significantly enhanced efficacy when combined with anti-CD20 immunotherapy, representing an important new ADC treatment regimen. Disclosures:Goldenberg:Immunomedics, Inc.: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Govindan:Immunomedics, Inc.: Employment. Cardillo:Immunomedics, Inc.: Employment.

Side Population Cells of Human B-Cell Non-Hodgkin Lymphoma Cell Lines May Contain Lymphoma-Stem Cells Responsible for Lymphoma Initiation

AbstractAbstract 3105 Background:Cancer stem cells are considered to initiate cancer development, and such populations might be related with the resistance to treatment and relapse. There are accumulated data supporting the presence of cancer stem cells in several human cancers such as breast and colon cancers. In hematologic malignancy, the presence of cancer stem cells was supported by the previous studies from leukemia. However, there are few reports regarding the possibility of lymphoma stem cells. Side population cells are defined as cells that efficiently extrude the Hoechst 33342 dye, and hence remain negative for this fluorescent marker in flow cytometric analysis. The isolation of SP cells from total tumor cells has been used as a tool for cancer stem cell research. Methods:We performed the side-population analysis to isolate a stem-like cell population. The side population analysis was based on the modified Hoechst 33342 dye efflux assay. Thus, cells expressing ATP binding cassette (ABC) transporter subfamily G number 2 (ABCG2) on their surface efflux Hoechst 33342 dye. On the other hand, cells without ABCG2 expression cannot efflux dye. According to this different nature, we discriminated side population from non-side population. We isolated side population from three lymphoma cell lines, 1A2 (B-cell lymphoblastic lymphoma cell line), Raji (Burkitt lymphoma cell line), and Toledo (Diffuse large B-cell lymphoma cell line). We compared the SP cells with NSP cells from each cell line via in vitro propagation and colony forming assay. We also evaluated the ability of tumorigenesis in NOD/SCID mice and compared the gene expression via performing microarray. Results:We isolated a subset of cells (side population) from three cell lines. The number of side population was extremely small, so the ratio of SP to NSP was from 0.01% to 0.25% regardless of the type of lymphoma cell lines. The in vitro propagation for 3 weeks showed that the growth rate of the side population was significantly higher than non-side population in three cell lines. The life span of non-side population was limited while side population could continuously proliferate. Thus, non-side population could not be cultured over four weeks, and the proportion of viable cells was higher in the side population (≥95%) than non-side population (≤80%). The RT-PCR and confocal microscopy demonstrated the higher expression of ABCG2 in the side population compared to the non-side population. The inoculation of lymphoma cells (200 – 1000) into NOD/SCID mice showed the tumor formation in mice inoculated with side population cells while there was no tumor in non-side population. The hierarchical clustering of differentially expressed genes showed the different pattern of gene expression between side and non-side population in each cell line. Conclusion:This study suggests that the side population may contain a cell population highly capable of proliferation, and this population may have the characteristics of lymphoma stem-like cells. Disclosures:No relevant conflicts of interest to declare.

Humanized Anti CD-40 Antibody SGN-40 Effectively Induces Cytotoxicity Against Chronic Lymphocytic Leukemia (CLL) Cells through Antibody Mediated Cytotoxicity and Demonstrates Modest Biologic Evidence of CD40 Activation.

The CD40 antigen is involved in cell survival and differentiation of B-cells and is uniformly expressed on chronic lymphocytic leukemia (CLL) cells. The CD40/CD40L interaction stimulates B-cells, dendritic cells and monocytes to proliferate, differentiate, up regulate co-stimulatory molecules and increase antigen presentation. While activation of CD40 can protect CLL cells against early fludarabine-induced apoptosis, these cells become sensitive to delayed death by extrinsic pathway apoptosis. (Blood , 105: 3193–8, 2005). SGN-40 is a humanized anti-CD40 antibody entering clinical trials and has been reported to have weak agonistic properties following CD40 ligation. To pursue rational clinical development of SGN-40, we studied the effects of this antibody in fresh, non-cryopreserved primary CLL cells. These studies included classic antibody mediated killing mechanisms and evidence of both CLL cell activation and protection against early fludarabine-mediated apoptosis. CLL cells treated with SGN-40 (10 mcg/ml) for 2 hours (hrs) in the presence of human serum promoted no complement mediated cytoxicity (CDC) in 8 pts tested. Direct SGN-40 induced apoptosis of human CLL cells with or without anti-Fc IgG cross-linking at 24, 48 and 72 hrs was not increased over that observed with the isotype control antibody trastuzumab in 8 pts studied. In contrast, SGN-40 induced antibody dependent cellular cytotoxicity (ADCC) against CLL cells an average of 12% (±11.39 SD, range 2–32%) killing at 4 hrs (effector to target cell ratio 25:1) in 6 pts tested. The SGN-40 induced ADCC against CLL cells were similar to that observed with alemtuzumab (average 19%, SD 6.9, range10–30%) or rituximab (average 18%, SD 12.48, range 8–42.5%). SGN-40 also mediated death in Raji and 697 lymphoblastic lymphoma cell lines via ADCC. Similar to reports by others with CD40 ligand, SGN-40 mediated activation was noted with modest up-regulation of CD80 and HLA-DR at 48hrs. When administered prior to fludarabine, SGN-40 also protected against death in 5 consecutive samples, although this was less than observed with CD40 ligand transfected HeLa cells, consistent with incomplete CD40 activation. Concurrent administration of SGN-40 and fludarabine did not protect from drug-mediated apoptosis. In conclusion, these findings suggest that SGN-40 has dual property of mediating cytotoxic effect by ADCC and partial CD40 activation. Development of SGN-40 as a therapeutic agent in CLL is justified and future studies by our group are focusing on enhancing SGN-40 mediated ADCC against CLL cells and potentially designing combination studies with SGN-40 to exploit this agent's ability to engage the CD40/CD40L network.

Effect of survivin antisense mRNA transfection on the growth and chemotherapy sensitivity of lymphoma cells

To study the effect of transfecting survivin antisense mRNA on growth and chemotherapy sensitivity of lymphoma cells. Eukaryotic expression plasmid pcDNA3. 1-antisense (As) survivin was constructed and transfected into Jurkat T lymphoblastic lymphoma cell lines with high expression survivin mRNA by use of lipofectmine gene transfer technique. Expression of survivin mRNA and protein were detected by reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemical and Western blot. The effect of transfecting survivin antisense mRNA on the growth of Jurkat cell lines was monitored by population doubling time (PDT) and Apoptotic indexes (AI). The morphologic features were observed in transfected cells by light and electric microscopes. MTT assay was used to analyze the response of transfected cells to CTX and MTX. Compared with the control cells, the expression of survivin mRNA and protein were reduced after transfected pcDNA3. 1-Assurvivin 48 h, 5 w and 6 w, PDT (52 h) was prolonged. Apoptotic indexes were higher in transfected antisense survivin mRNA cells [20.2% (48 h)], 6.2% (5 w) and 6.8% (6 w) than control ones [2.1%, 1.3% (48 h)] and [1.3% (5 w) and 1.0% (6 w)]. The cells grow slowly and the dead cells increase and some swelling and apoptotic cells were observed in transfected pcDNA3. 1-Assurvivin groups by invert, light and electric microscopes. The Jurkat cell line of transfected pcDNA3. 1-Assurvivin had higher sensitivity to CTX and MTX. The rate of inhibition was higher in transfected group. There is a significant difference between the transfected group and untransfected one, P < 0.05. The result indicated that survivin gene was very important for growth of Jurkat cells. To inhibit the expression of survivin will be significant in therapy of T lymphoblastic lymphoma. Survivin gene might be a target of therapy.

Molecular cytogenetic analysis of the breakpoint region at 6q21-22 in T-cell lymphoma/leukemia cell lines.

Chromosome band 6q21 is reported to be one of the most frequent target regions in T-cell lymphoma for both translocations and deletions. To explore whether the breakpoint clustering in T-cell malignancy indicates the presence of a common breakpoint region in 6q, we employed fluorescence in situ hybridization analysis using various YAC, BAC, and PAC clones aligned at 6q21-22. We identified two T-cell lymphoma/leukemia cell lines with different differentiation stages that had breakpoints within the same novel gene, TCBA1 (T-cell lymphoma breakpoint associated target 1). In a T-cell lymphoblastic lymphoma cell line, HT-1, the TCBA1 fused to SUSP1 (SUMO-1-specific protease), creating a SUSP1-TCBA1 chimeric gene. However, in an adult T-cell leukemia cell line, ATN-1, no chimeric gene was detected, although aberrant TCBA1 transcripts were produced. We conclude that TCBA1 is a possible target gene for T-cell lineage-specific chromosome aberrations at 6q21.

Effect of tamoxifen on cell lines displaying the multidrug-resistant phenotype [see comments

We examined the effect of tamoxifen (Tmx), verapamil, and daunorubicin (DNR) in two cell lines that displayed the multidrug-resistant (MDR) phenotype and used laser flow cytometry to quantitate intracellular DNR content. In the vinblastine-resistant human lymphoblastic lymphoma cell line CEM-VBL, simultaneous incubation of DNR with Tmx 10 mumol/L or Tmx 50 mumol/L increased intracellular DNR fluorescence in a dose-dependent manner and demonstrated an uptake pattern similar to that seen with DNR and verapamil. Similar results were obtained in the vincristine-resistant human myeloid leukemia cell line HL-60/RV+. Cellular retention of DNR was also measured in both cell lines and results suggested that continuous exposure of the cells to Tmx resulted in higher intracellular DNR content compared with cells resuspended in fresh medium. No effect of Tmx or verapamil was observed in the drug-sensitive parent cell lines CEM or HL-60. Clonogenic experiments were then performed to determine whether Tmx was itself inhibitory to cell growth or whether Tmx potentiated DNR cytotoxicity. Tmx 10 mumol/L did not significantly inhibit either CEM-VBL or HL-60/RV+ cells after a 3-hour exposure followed by culture in methylcellulose. Tmx 50 mumol/L was significantly more inhibitory in both cell lines. However, cells that had been incubated with DNR and Tmx 10 mumol/L demonstrated a marked increment in growth inhibition compared with cells that had been incubated with DNR alone or Tmx 10 mumol/L alone. Based on the data presented here, we suggest that clinical testing of Tmx and DNR be pursued in the setting where MDR may play a role.

Effect of tamoxifen on cell lines displaying the multidrug-resistant phenotype [see comments

We examined the effect of tamoxifen (Tmx), verapamil, and daunorubicin (DNR) in two cell lines that displayed the multidrug-resistant (MDR) phenotype and used laser flow cytometry to quantitate intracellular DNR content. In the vinblastine-resistant human lymphoblastic lymphoma cell line CEM-VBL, simultaneous incubation of DNR with Tmx 10 mumol/L or Tmx 50 mumol/L increased intracellular DNR fluorescence in a dose-dependent manner and demonstrated an uptake pattern similar to that seen with DNR and verapamil. Similar results were obtained in the vincristine- resistant human myeloid leukemia cell line HL-60/RV+. Cellular retention of DNR was also measured in both cell lines and results suggested that continuous exposure of the cells to Tmx resulted in higher intracellular DNR content compared with cells resuspended in fresh medium. No effect of Tmx or verapamil was observed in the drug- sensitive parent cell lines CEM or HL-60. Clonogenic experiments were then performed to determine whether Tmx was itself inhibitory to cell growth or whether Tmx potentiated DNR cytotoxicity. Tmx 10 mumol/L did not significantly inhibit either CEM-VBL or HL-60/RV+ cells after a 3- hour exposure followed by culture in methylcellulose. Tmx 50 mumol/L was significantly more inhibitory in both cell lines. However, cells that had been incubated with DNR and Tmx 10 mumol/L demonstrated a marked increment in growth inhibition compared with cells that had been incubated with DNR alone or Tmx 10 mumol/L alone. Based on the data presented here, we suggest that clinical testing of Tmx and DNR be pursued in the setting where MDR may play a role.

Establishment and characterization of a human null‐cell lymphoblastic lymphoma cell line (K‐LL‐3)

A new cell line (K-LL-3) with exceptional characteristics was derived from a bone-marrow aspirate from a patient with poorly differentiated lymphoblastic lymphoma. The cell line was established and the cells maintained on agar feeders for over 1 year. The morphology and cytochemical staining of the primary tumor and the cell line were remarkably similar. The growth characteristics, chromosome pattern, cell-surface receptors and Epstein-Barr pattern, cell-surface receptors and Epstein-Barr virus studies clearly differentiated this cell line from non-malignant lymphoblastoid cell lines. The assay technique used was able to correlate in vitro colony growth with the patient's clinical course. The cells grew on the agar as colonies rather than as a single-cell suspension, and individual colonies could be aspirated and successfully passaged. The K-LL-3 cells lacked cell-surface markers (cytoplasmic and surface immunoglobulins, Fc receptors, C3 receptors, SRBC) except HL-A and thus were classified as null cells. These cells were EBNA (Epstein-Barr virus-specific nuclear antigen) negative and had a pseudodiploid 46XY karyotype.