Human Malignant Lymphoma Cells Research Articles

NRF1-regulated CircNSUN2 promotes lymphoma progression through activating Wnt signaling pathway via stabilizing HMGA1

ABSTRACT Lymphoma is the malignant tumor in the lymphatic system. Circular RNAs (circRNAs) are non-coding RNAs with closed structure, which have been reported to perform critical functions in various tumor progressions. However, the role of circNSUN2 in lymphoma has not been well explored. Quantitative reverse transcription real-time polymerase chain reaction (RT-qPCR) assay was performed to test the expression of circNSUN2 in malignant lymphoma tissues and normal lymph tissues, as well as in human peripheral blood lymphocyte cell line and malignant lymphoma cell lines. Cell counting kit-8 (CCK-8) assay and Transwell assays were used to evaluate the function of circNSUN2 on lymphoma cell proliferation, migration and invasion. DNA pull-down assay, chromatin immunoprecipitation (ChIP) and luciferase reporter assay were employed to test the interaction between circNSUN2 and NRF1. TOP/FOP flash reporter assay was performed to detect influence of circNSUN2 on Wnt pathway. Luciferase reporter assay and RNA pull-down assay were performed to explore interaction between HMGA1 and circNSUN2 through Wnt pathway. CircNSUN2 expression was abnormally high in malignant lymphoma tissues and cell lines. CircNSUN2 inhibition could reduce proliferation and invasion of lymphoma. Bioinformatic analysis, DNA pull-down, ChIP and luciferase reporter experiments confirmed that circNSUN2 could be modulated by transcription factor NRF1. Through RT-qPCR, western blot and luciferase reporter assays, circNSUN2 was proved to influence Wnt pathway by modulating HMGA1. CircNSUN2 regulated by transcription factor NRF1 could promote lymphoma progression through activating Wnt pathway via stabilizing HMGA1.

CBMT-09. THERAPEUTIC EFFECT OF INDUCTION OF POLYGLUTAMYLATION IN HIGH-DOSE METHOTREXATE THERAPY TO PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA

Abstract BACKGROUND Polyglutamylation is a reversible protein modification with a high occurrence rate in tumor cells. Methotrexate (MTX) incorporated into cells is polyglutamylated and strongly binds to dihydrofolate reductase without competitive inhibition by leucovorin (LV). Tumor cells with high polyglutamylation levels are selectively killed, whereas normal cells with lower polyglutamylation are rescued by LV. In this study, we investigated the therapeutic response of PCNSL to HD-MTX therapy with LV rescue based on polyglutamylation status and evaluated the combined effect of MTX and the drugs which upregulated polyglutamylation of MTX. METHODS Among 113 consecutive PCNSL patients who underwent HD-MTX therapy in our department between 2001 and 2014, polyglutamylation was evaluated by immunostaining in 82 cases, with relationships between polyglutamylation and therapeutic response retrospectively examined. Human malignant lymphoma cell lines were used for in vitro and in vivo experiments. The association of polyglutamylation and the response to MTX with LV rescue was assessed in these cell lines. Histone-deacetylase inhibitor (HDACI) has been reported to induce polyglutamylation by elevating folpolyglutamate synthetase (FPGS) expression, so the effects of HDACIs on polyglutamylation were evaluated. Combined effects of MTX and HDACI were evaluated by cell viability assay and xenograft mouse models. RESULTS The complete response rate was significantly higher in the group with polyglutamylation than in the non-polyglutamylation group [58.1% (25/43) and 33.3% (13/39), respectively] (p < 0.05), and progression-free survival was also significantly increased in the group with polyglutamylation (p < 0.01). The combined effect of MTX and HDACI was significantly enhanced in cell viability assay in vitro (p< 0.05), in subcutaneous (p< 0.001) and intracranial tumor xenografts (p< 0.001). CONCLUSION These findings suggested that polyglutamylation could be a predictor of therapeutic response to HD-MTX therapy with LV rescue in PCNSL. Combined therapy with HD-MTX and HDACIs might represent a promising treatment for HD-MTX resistant intractable PCNSL.

Stat3 inhibitor abrogates the expression of PD-1 ligands on lymphoma cell lines.

Recent studies have indicated the significance of immune checkpoint molecules including programmed death-1 (PD-1), cytotoxic T-lymphocyte associated protein 4, and T-cell immunoglobulin and mucin domain-containing molecule-3 for anti-tumor immune responses. We previously investigated PD-1 ligand 1/2 (PD-L1/2) expression in lymphoma cell lines, and found that PD-L1/2 is expressed on the adult T-cell leukemia/lymphoma (ATL-T) and B-cell lymphoma (SLVL) cell lines. In the present study, we investigated whether the Stat3 inhibitor WP1066 abrogated PD-L1/2 expression in lymphoma cell lines. Incubation with WP1066 inhibited lymphoma cell growth and induced cell apoptosis. PD-L1/2 expression in the ATL-T, SLVL, and human brain malignant lymphoma (HKBML) cell lines was significantly abrogated by WP1066 treatment. These data indicated that a Stat3 inhibitor abrogated PD-L1/2 expression in lymphoma cells. Such an inhibitor is therefore considered to be useful for additional immunotherapy in patients with advanced lymphoma.

Iron chelator-induced apoptosis via the ER stress pathway in gastric cancer cells.

Many reports have shown the anticancer effects of iron deficient on cancer cells, but the effects of iron-chelators on gastric cancer have not been clearly elucidated. Recently, we reported that iron chelators induced an antiproliferative effect in human malignant lymphoma and myeloid leukemia cells. In the present study, we investigated the antitumor activity of these two iron-chelating agents, deferoxamine (DFO) and deferasirox (DFX), with gastric cancer cell lines, and their apoptosis-inducing effects as the potential mechanism. We found that iron chelators displayed significant antiproliferative activity in human gastric cancer cell lines, which may be attributed to their induction of G1 phase arrest and apoptosis. We also found that iron chelators induced reactive oxygen species (ROS) production, resulting in the activation of both c-Jun N-terminal kinase (JNK) and endoplasmic reticulum (ER) stress apoptotic pathways in gastric cancer cells. Taken together, our data suggest that iron chelators induced apoptosis in gastric cancer, involving ROS formation ER stress and JNK activation.

Sialylation and glycosylation modulate cell adhesion and invasion to extracellular matrix in human malignant lymphoma: Dependency on integrin and the Rho GTPase family.

To determine the biological roles of cell surface glycosylation, we modified the surface glycosylation of human malignant lymphoma cell lines using glycosylation inhibitors. The O-glycosylation inhibitor, benzyl-α-GalNAc (BZ) enhanced the fibronectin adhesion of HBL-8 cells, a human Burkitt's lymphoma cell line, and of H-ALCL cells, a human anaplastic large cell lymphoma cell line, both of which were established in our laboratory. The N-glycosylation inhibitor, tunicamycin (TM) inhibited the surface expression of Phaseolus vulgaris leukoagglutinating (L-PHA) lectin- and Canavalia ensiformis (ConA) lectin-reactive oligosaccharides in the HBL-8 cell line. Assay of the adhesion of HBL-8 cells to fibronectin showed that fibronectin adhesion is mediated by the integrin very late antigen (VLA)-4 and that not only BZ but also TM treatment enhanced HBL-8 cell adhesion to fibronectin. Furthermore, although BZ treatment also enhanced H-ALCL cell adhesion to fibronectin, this effect was not mediated by VLA-5 or the RGD sequence of fibronectin. We also showed that H-ALCL cell adhesion to galectin-3 was enhanced by pre-treatment with neuraminidase, which cleaves cell surface sialic acid. Additionally, H-ALCL cell adhesion to galectin-3 was inhibited by pre-treatment with the RGD peptide suggesting that cell adhesion to galectin-3 is mediated by integrin (VLA-5). Furthermore, H-ALCL cell invasion of galectin-1 and galectin-3 was inhibited by pre-treatment with the RGD peptide. Therefore, cell adhesion to and invasion of galectin-1 and galectin-3 are integrin-dependent. In addition to these findings, cell adhesion to galectin-3 was markedly inhibited by treatment with β-lactose compared to treatment with sucrose. Therefore, interactions between integrins and galectin-3 may be mediated through β-galactose that is linked to glycans of integrins. AZA1, an inhibitor of Ras homolog oncoprotein (Rho) GTPase family proteins, RAS-related C3 botulinus toxin substrate 1 (Rac 1) and Cell division control protein 42 homolog (Cdc42) markedly inhibited cell invasion of galectin-1 and galectin-3 suggesting that Rac 1 and Cdc42 may be involved in the regulation of H-ALCL cell invasion of galectins. In conclusion, artificial modification of cell surface glycosylation revealed the biological roles of glycosylation in the adhesion to and invasion of the extracellular matrix (ECM) by human malignant lymphoma cell lines. These findings will provide new insight into the glycobiology of human malignant lymphoma.

Sialylation by β-galactoside α-2,6-sialyltransferase and N-glycans regulate cell adhesion and invasion in human anaplastic large cell lymphoma.

The interaction between cell surface glycans and extracellular matrix (ECM) including galectins is known to be closely associated with tumor cell adhesion, invasion and metastasis. We analyzed the roles of cell surface sialylation or glycosylation in galectin or ECM-mediated cell adhesion and invasion of human malignant lymphoma cells. Neuraminidase from Arthrobacter ureafaciens (AU) treatment resulted in reduction of cell adhesion to galectin-8 in human anaplastic large cell lymphoma (H-ALCL) which was established in our laboratory. The knockdown of β-galactoside α-2,6-sialyltransferase (ST6Gal1) by siRNA showed inhibition of ST6Gal1 expression in the cytoplasm of H-ALCL cells on immunohistochemical findings, and showed dramatic enhancement of cell adhesion to galectin-8. On the other hand, α-2,3-specific neuraminidase treatment resulted in moderate enhancement of cell adhesion to galectin-8. We performed chemically artificial modification of cell surface O-glycans by treatment of benzyl 2-acetamido-2-deoxy-α-D-galactopyranoside (Bz-α-GalNAc) in H-ALCL. Cell adhesion to galectin-8 was enhanced by treatment of Bz-α-GalNAc suggesting that inhibition of elongation of O-glycans may enhance cell adhesion to galectin-8 in H-ALCL cells. On the other hand inhibition of elongation of N-glycosylation by tunicamycin (TM) resulted in inhibition of Phaseolus vulgaris-L (L-PHA) lectin-binding activity and inhibited cell adhesion to galectin-8,laminin and fibronectin. Neuraminidase treatment enhanced cell adhesion to laminin, and knockdown of ST6Gal1 resulted in enhancement of cell adhesion to laminin, but not to fibronectin, collagen type 1 and 4. Galectin-8 pre-treatment dramatically enhanced cell adhesion to laminin and neuraminidase treatment also enhanced cell adhesion to laminin in combination with galectin-8. Rho inhibitor, C3-transferase pre-treatment resulted in inhibition of cell invasion to galectin-8. Phosphatidylinositol 3-phosphate kinase (PI3K) inhibitor, wortmannin inhibits the cell invasive capacity to galectin-8. Neuraminidase treatment induces growth inhibition of lymphoma cells by galectin-8.

Effects of oral iron chelator deferasirox on human malignant lymphoma cells

BackgroundIron is essential for cell proliferation and viability. It has been reported that iron depletion by a chelator inhibits proliferation of some cancer cells. Deferasirox is a new oral iron chelator, and a few reports have described its effects on lymphoma cells. The goal of this study was to determine the anticancer effects of deferasirox in malignant lymphoma cell lines.MethodsThree human malignant lymphoma cell lines (NCI H28:N78, Ramos, and Jiyoye) were treated with deferasirox at final concentrations of 20, 50, or 100 µM. Cell proliferation was evaluated by an MTT assay, and cell cycle and apoptosis were analyzed by flow cytometry. Western blot analysis was performed to determine the relative activity of various apoptotic pathways. The role of caspase in deferasirox-induced apoptosis was investigated using a luminescent assay.ResultsThe MTT assay showed that deferasirox had dose-dependent cytotoxic effects on all 3 cell lines. Cell cycle analysis showed that the sub-G1 portion increased in all 3 cell lines as the concentration of deferasirox increased. Early apoptosis was also confirmed in the treated cells by Annexin V and PI staining. Western blotting showed an increase in the cleavage of PARP, caspase 3/7, and caspase 9 in deferasirox-treated groups.ConclusionWe demonstrated that deferasirox, a new oral iron-chelating agent, induced early apoptosis in human malignant lymphoma cells, and this apoptotic effect is dependent on the caspase-3/caspase-9 pathway.

Inhibition of eIF4E phosphorylation reduces cell growth and proliferation in primary central nervous system lymphoma cells

The mRNA cap-binding protein eukaryotic initiation factor 4E (eIF4E) plays an important role in mRNA translation; its activity is implicated in cell growth and proliferation. In experimental models, eIF4E over-expression induces cellular transformation, tumorigenesis, and lymphomagenesis. The activity of eIF4E is regulated by the Akt/mTOR and MAPK/MAP kinase-interacting kinase-1 (MNK1) pathways. While investigating the participation of the MNK1/eIF4E signaling pathway in primary central nervous system lymphoma (PCNSL), we noted the over-expression of eIF4E and phosphorylated eIF4E (p-eIF4E) in specimens from PCNSL patients. Western blot analysis using B-cell lymphoma cell lines showed that eIF4E phosphorylation was serum-independent and was selectively inhibited by the MNK1 inhibitor. Furthermore, MNK1 inhibitor led to reduced cyclin D1 expression and caused inhibition of cell proliferation and cell death in human brain malignant lymphoma cell line (HKBML). Also, the growth of the subcutaneous HKBML xenografts in mice was inhibited by intraperitoneal administration of MNK1 inhibitor compared with mice treated with vehicle (P = 0.026). Our data suggest that in PCNSL cells eIF4E phosphorylation plays an important role in proliferation and our results identify inhibition of the MNK1/eIF4E pathway as a potential therapeutic target in patients with PCNSL.

Detection of Minimal Malignant Clone in Lymphocytes and Bone Marrow Cells by Cytogenetic and Molecular Genetic Studies in Healthy Atomic Bomb Survivors

In order to assess the minimal malignant clone (MMC) for the development of leukemia, we studied the bone marrow and lymphocytes of total 44 healthy atomic - bomb survivors by cytogenetic technique. In the cytogenetic study, we compared the frequencies of chromosome aberration and quality of chromosome aberrations detected in the bone marrow and peripheral lymphocytes from 13 and 39 samples from 44 healthy atomic bomb survivors, respectively, relevant to the nonrandom aberrations prevalent in the human leukemic and malignant lymphoma cells. The frequencies of chromosome aberrations in bone marrow cells were slightly lower than those in lymphocytes and a few percent of clone were found in both bone marrow and lymphocytes. Although the completely same type chromosome aberrations as those found in leukemia and lymphomas were not observed, out of 3,846 cells with chromosome aberrations found in 52 samples for 44 survivors, 35 percent were related to the sites of oncogenes involving in the leukemogenesis and lymphomagenesis such as 8q24, 9q34 and 22q11. In addition, molecular genetic studies using PCR techniques for RAS point mutations in 3 survivors, specific chromosome translocations such as t(14;18), and t(7;14) in the bone marrow and peripheral lymphocytes of 3 healthy survivors revealed that any MMC was detected. On the other hand, by in vivo selection assay could detect transforming genes of N-and K-RAS in bone marrow samples from all 4 survivors. Three of the 4 survivors had development cancer or leukemia 7-10 years after present examination. Even though, we couldn't detect any MMC by chromosome analysis, the finding that 20 fragile sites were correlated with higher number of breakpoint of 52 atomic bomb survivors might also significantly an important role MMC in the initiation of radiation-related leukemogenesis and lymphomagenesis process, as seen presently, there is still an increase in the development

Detection of minimal malignant clone in lymphocytes and bone marrow cells by cytogenetic and molecular genetic studies in healthy atomic bomb survivors

In order to assess the minimal malignant clone (MMC) for the development of leukemia, we studied the bone marrow and lymphocytes of total 44 healthy atomic – bomb survivors by cytogenetic technique. In the cytogenetic study, we compared the frequencies of chromosome aberration and quality of chromosome aberrations detected in the bone marrow and peripheral lymphocytes from 13 and 39 samples from 44 healthy atomic bomb survivors, respectively, relevant to the nonrandom aberrations prevalent in the human leukemic and malignant lymphoma cells. The frequencies of chromosome aberrations in bone marrow cells were slightly lower than those in lymphocytes and a few percent of clone were found in both bone marrow and lymphocytes. Although the completely same type chromosome aberrations as those found in leukemia and lymphomas were not observed, out of 3,846 cells with chromosome aberrations found in 52 samples for 44 survivors, 35 percent were related to the sites of oncogenes involving in the leukemogenesis and lymphomagenesis such as 8q24, 9q34 and 22q11. In addition, molecular genetic studies using PCR techniques for RAS point mutations in 3 survivors, specific chromosome translocations such as t(14;18), and t(7;14) in the bone marrow and peripheral lymphocytes of 3 healthy survivors revealed that any MMC was detected. On the other hand, by in vivo selection assay could detect transforming genes of N-and K-RAS in bone marrow samples from all 4 survivors. Three of the 4 survivors had development cancer or leukemia 7-10 years after present examination. Even though, we couldn’t detect any MMC by chromosome analysis, the finding that 20 fragile sites were correlated with higher number of breakpoint of 52 atomic bomb survivors might also significantly an important role MMC in the initiation of radiation-related leukemogenesis and lymphomagenesis process, as seen presently, there is still an increase in the development of leukemia among survivors than the normal population. Keywords: Atomic bomb survivors, chromosome aberrations, bone marrow, lymphocytes, minimal clone, PCR, RAS gene

Establishment and Characterization of Human Malignant Lymphoma Cell Line Derived from Uterine Cervix

Human uterine cervical malignant lymphoma (B-cell type) was cultured and the cell line (HIUML) was newly established. The HIUML cells were round in shape and had a tendency to make floating clusters. The cells had a smooth surface or protrusion on the margin of the cytoplasm, and proliferate in floatation. The population doubling time was about 32 hours and 42 or more passages were successfully observed in two years. The HIUML cells were not transplantable into nude mice but were successfully done in the cheek pouch of hamster with formation of malignant lymphoma. Epstein-Barr virus was detected in the HIUML cells.

ニンニクオリゴ糖の精製とその生理的活性

A novel oligosaccharide was purified from garlic (Allium sativum L.) bulbs via hot water extraction, ammonium sulfate precipitation, gel filtration and ion exchange chromatography. The molecular weight of the oligosaccharide was determined to be 1800. A nuclear magnetic resonance (NMR) study showed that ten fructose molecules were connected by beta1-2 linkage to a terminal glucose. The oligosaccharide had cytotoxic activities against human malignant lymphoma cells (U937) and colon adenocarcinoma cells (WiDr) in vitro. Furthermore, this oligosaccharide significantly suppressed the growth of murine colon adenocarcinoma cells (colon 26) in vivo. The oligosaccharide also stimulated interferon-gamma production by human peripheral blood lymphocyte in vitro, indicating that it may activate the immunological pathways and suppress the growth of tumors in vivo.

The neuro-steroid, 3β androstene 17α diol exhibits potent cytotoxic effects on human malignant glioma and lymphoma cells through different programmed cell death pathways

The neuro-steroids 3β-androstene-17α-diol (17α-AED), 3β-androstene-17β-diol (17β-AED), 3β-androstene-7α,-17β-triol (7α-AET) and 3β-androstene-7β,-17β-triol (7β-AET) are metabolites of dehydroepiandrosterone and are produced in neuro-ectodermal tissue. Both epimers of androstenediols (17α-AED and 17β-AED) and androstenetriols (7α-AET and 7β-AET) have markedly different biological functions of their chemical analogue. We investigated the cytotoxic activity of these neuro-steroids on human T98G and U251MG glioblastoma and U937 lymphoma cells. Proliferation studies showed that 17α-AED is the most potent inhibitor, with an IC50 ∼15 μM. For T98G glioma, 90% inhibition was achieved with 25 μM of 17α-AED. Other neuro-steroids tested only marginally suppressed cell proliferation. Reduced cell adherence and viability could be detected after 18 h of 17α-AED exposure. Treatment with 17α-AED induced a significant level of apoptosis in U937 lymphoma cells, but not in the glioma cells. Cytopathology of 17α-AED-treated T98G cells revealed the presence of multiple cytoplasmic vacuoles. Acridine orange staining demonstrated the formation of acidic vesicular organelles in 17α-AED-treated T98G and U251MG, which was inhibited by bafilomycin A1. These findings indicate that 17α-AED bears the most potent cytotoxic activity of the neuro-steroids tested, and the effectiveness may depend on the number of hydroxyls and their position on the androstene molecule. These cytotoxic effects may utilize a non-apoptotic pathway in malignant glioma cells.

Camptothecin induces urokinase-type plasminogen activator gene-expression in human RC-K8 malignant lymphoma and H69 small cell lung cancer cells.

We previously reported that anthracyclines, which could generate reactive oxygen species (ROS), could induce the urokinase-type plasminogen activator (uPA) gene expression in human RC-K8 malignant lymphoma cells and in H69 small cell lung cancer (SCLC) cells. In screening other uPA-inducible anti-cancer agents, we found that camptothecin (CPT) and its derivative, SN38, could induce uPA in RC-K8 and H69 cells. CPT and SN38, which are also used for the treatment of lymphoma and SCLC, significantly increased the uPA accumulation in the conditioned media of both cells in a dose-dependent manner. The maximum induction of uPA mRNA levels was observed 24 h after stimulation. Pretreatment with pyrrolidine dithiocarbamate (PDTC), an anti-oxidant, inhibited the CPT-induced uPA mRNA expression. Thus, CPT induces uPA through gene expression, and, therefore, CPT may influence the tumor-cell biology by up-regulating the uPA/plasmin system.

In Vitro Effects of Recombinant Human IL-11 on Human Malignant Lymphoma Cells.

In Vitro Effects of Recombinant Human IL-11 on Human Malignant Lymphoma Cells.

Oxidative stress induces urokinase-type plasminogen activator in RC-K8 human malignant lymphoma cells and H69 human small cell lung carcinoma cells

Reactive oxygen species act as second messengers in the signal transduction induced by inflammatory stimuli such as interleukin-1 (IL-1), tumor necrosis factor-α (TNFα), and lipopolysaccharide (LPS). We have previously shown that both IL-1 and LPS induce the urokinase-type plasminogen activator (uPA) gene expression in RC-K8 human malignant lymphoma cells. Here, we provide evidence that an oxidative stimulation by eit her hydrogen peroxide (H2O2) or menadione (2-methyl-1,4-naphthoquinone (MQ)), a quinone compound that generates reactive oxygen species, causes the up-regulation of uPA expression in both RC-K8 cells and H69 human small cell lung carcinoma cells. uPA accumulation in their conditio ned media was significantly increased after treatment with H2O2or MQ and it was dose-dependent of the stimulus. Northern blotting analysis revealed that uPA mRNA levels in both RC-K8 and H69 cells were increased approximately 2-fold 9h after treatment with H2O2. The half-lives of uPA mRNA were not changed before and after H2O2stimulation. A synthetic antioxidant, N-acetylcysteine (NAC), completely inhibited the H2O2-induced uPA mRNA accumulation. The inhibition of the on-going protein synthesis by cycloheximide (CHX) did not inhibit the H2O2-induced uPA mRNA accumulation. These results suggest that the oxidative stress induces uPA accumulation through activating uPA gene transcription. Therefore, the stimuli that generate reactive oxygen species may influence many biological cell-functions mediated by the uPA/plasmin system by regulating uPA expression in malignant cells.

P53 gene mutations in non-Hodgkin's lymphoma.

To understand P53 gene change of non-Hodgkin's lymphoma (NHL) and human malignant lymphoma cell lines, the exons 5-7 of 29 patients with NHL and 9 kinds of human malignant lymphoma cell lines were studied by silver staining PCR-SSCP technique. Three cases of P53 gene point mutation was found in 29 cases of NHL. Mutation developed in exon 5 in 2 cases, and in exon 6 in 1 case. They were all diffuse lymphoma. In mutation cases, B-cell lymphoma accounted for 2 cases and the other one was T-cell lymphoma. There was no P53 gene mutation in low-grade follicular lymphoma. Seven strains out of 9 kinds of lymphoma cell lines had P53 gene point mutation. One strain had the mutation in exon 5; 5 strains in exon 6 and 1 strain in exons 5, 6, 7. There was a high mutation rate in lymphoma cell lines and low mutation rate in NHL patients. P53 gene plays an important role in lymphoma cell line establishment, cell regeneration and disease evolution.

N-Cadherin Expressed on Malignant T Cell Lymphoma Cells is Functional, and Promotes Heterotypic Adhesion Between the Lymphoma Cells and Mesenchymal Cells Expressing N-Cadherin

Cadherins are Ca2+-dependent cell-cell adhesion molecules, and are involved in the formation and maintenance of the organocellular architecture. Using a combination of molecular biologic and biochemical methods, we analyzed cadherins expressed on cultured human malignant lymphoma cell lines (adult T cell lymphomas, human T cell leukemia virus type 1-negative T cell lines, and thymus-derived lymphoma cell lines), and obtained evidence that N-cadherin is the major cadherin expressed on these cells. These cells were found to form cell aggregates in a Ca2+-dependent manner, and more importantly to coaggregate and adhere with cells expressing N-cadherin, suggesting that N-cadherin on lymphoma cells is functionally active. Therefore, N-cadherin expressed on lymphoma cells could underlie the frequent invasion of these cells into the mesenchymal tissue in the skin and the central nervous system.

Expression of cadherin-catenin complex in human malignant lymphoma cell lines

Expression of cadherin-catenin complex in human malignant lymphoma cell lines

Time-course of changes in the plasma-membrane lipid bilayer and cellular ultrastructure induced by tumour necrosis factor-alpha in K 562 and Daudi cells.

The time-course of changes in the plasma-membrane lipid bilayer induced by tumour necrosis factor-alpha (TNF) were investigated in cultured cells using spin-label electron-spin-resonance techniques. Treatment of K 562 cells, a human chronic myelocytic leukaemia cell line, in suspension culture with TNF for up to 6 h caused an initial increase in cell-membrane fluidity, which returned to the control level after 12 h of treatment. After 24 h of treatment, the cell-membrane fluidity had decreased and this decrease was maintained after 48 h of treatment. In Daudi cells, a human malignant lymphoma cell line, TNF, did not induce any changes in cell-membrane fluidity, indicating that the effect of TNF on membrane structure is cell-specific. The early and transient change in membrane fluidity in K 562 cells is probably related to signal generation, while the later, persistent change may reflect the phenotype of TNF-treated cells, in particular, changes in the plasma membrane-cytoplasmic complex. Histochemical electron microscopic studies indicated that the membrane fluidity changes induced by TNF have an ultrastructural correlate.