New insights into the cell biology of the marginal zone of the spleen

In the marginal zone of the spleen the bloodstream passes through an open system of reticular cells and fibers in which various myeloid and lymphoid cells are located. Macrophages in this region are well equipped to recognize pathogens and filter the blood by virtue of unique combinations of pattern recognition receptors. They interact with a specific set of B cells that can be found only in the marginal zone and that are able to react rapidly to bacterial antigens in particular. This combination of strategically located cells is an important factor in our defense against blood-borne pathogens. New data on the development of the marginal zone itself and the marginal zone B cells are reviewed and discussed in light of the function of the spleen in host defense.

Polymorphisms for interleukin-4 (IL-4) -590 promoter, IL-4 intron3, and tumor necrosis factor alpha -308 promoter: non-association with endometriosis

Interleukin-4 (IL-4) is a cytokine with anti-inflammatory properties. Tumor necrosis factor alpha (TNF-alpha), a pluripotent proinflammatory cytokine, plays an important role in the process of numerous inflammatory and autoimmune diseases. We aimed to investigate whether gene polymorphisms for the IL-4 -590 promoter, IL-4 intron3 and TNFalpha -308 promoter could be used as markers of susceptibility in endometriosis. The subjects, 226 premenopausal Taiwan Chinese women with surgically diagnosed endometriosis and nonendometriosis, were divided into two groups: 1) endometriosis (n = 120) and 2) nonendometriosis (n = 106). Polymorphisms for the IL-4 -590 promoter, IL-4 intron3, and TNFalpha -308 G-to-A promoter were detected by polymerase chain reaction (PCR). Genotypes and allelic frequencies for these gene polymorphisms in both groups were compared. We observed no significant differences in genotype distribution and allele frequency of the IL-4 -590 promoter, IL-4 intron3, and TNFalpha gene polymorphism between both groups. The proportions of the -590*C homozygote/heterozygote/-590* T homozygote for the IL-4 promoter in both groups were 1.6/31.6/66.6% in group 1, and 5.8/33.0/61.2% in group 2. The proportions of the RP1 homozygote/heterozygote/RP2 homozygote for IL-4 intron3 in both groups were 62.5/34.1/2.5% (group 1), and 64.1/32.0/3.9% (group 2). The proportions of -308*A homozygote/heterozygote/-308*G homozygote for the TNFalpha promoter in both groups were 7.5/20.8/71.7% (group 1), and 7.5/17/75.5% (group 2). We concluded that there is no association between endometriosis and the IL-4 and TNFalpha gene polymorphisms. The IL-4 -590 promoter, IL-4 intron3, and TNFalpha -308 G-to-A polymorphisms are not useful markers for predicting susceptibility to endometriosis.

Down-regulation of CXCR1 and CXCR2 expression on human neutrophils upon activation of whole blood by S. aureus is mediated by TNF-alpha

It was suggested that bacterial products can inhibit the expression of leucocyte chemokine receptors during sepsis and affect leucocyte functions in septic syndrome. Superantigens and toxins produced by Staphylococcus aureus are capable of activating leucocytes via binding to MHC-II antigens on monocytes and T-cell receptor molecules on T lymphocytes. It was recently shown that staphylococcal enterotoxins directly down-regulate the expression of CC chemokine receptors on monocytes through binding to MHC class II molecules. We studied the effects of killed S. aureus on the expression of interleukin-8 receptors, CXCR1 and CXCR2, on polymorphonuclear leucocytes (PMN), which are known to lack the expression of MHC-II antigens. It was shown that S. aureus down-regulated the cell-surface expression of CXCR1 and CXCR2 on PMN in the whole blood and total blood leucocyte fraction containing PMN and monocytes, but did not modulate IL-8 receptor expression in purified PMN suspension. Antibody to TNF-alpha abrogated down-regulation of IL-8 receptors induced by S. aureus. In contrast, LPS reduced CXCR1 and CXCR2 expression in purified PMN and whole blood in a TNF-alpha-independent manner. We further showed that TNF-alpha-induced decrease of CXCR1 and CXCR2 expression was associated with lower IL-8 binding and lower CXCR1 and CXCR2 mRNA levels, and was abrogated by protease inhibitors. We suggest that during septicemia, S. aureus may inhibit neutrophil responsiveness to IL-8 and other CXC chemokines via TNF-alpha- mediated down-regulation of CXCR1 and CXCR2.

Enhancement of in vivo antitumor activity of a novel antimitotic 1-phenylpropenone derivative, AM-132, by tumor necrosis factor-alpha or interleukin-6

TK5048 and its derivatives, AM-132, AM-138, and AM-97, are recently developed antimitotic (AM) compounds. These 1-phenylpropenone derivatives induce cell cycle arrest at the G2 / M phase of the cell cycle. TK5048 inhibited tubulin polymerization in human lung cancer PC-14 cells in a concentration-dependent manner. In a polymerization assay using bovine brain tubulin, AM-132 and AM-138 were quite strong, AM-97 was moderately strong, and TK5048 was a relatively weak inhibitor of tubulin polymerization. A murine leukemia cell line resistant to a sulfonamide antimitotic agent, E7010, which binds to colchicine-binding sites on tubulin, was cross-resistant to the in vitro growth-inhibitory effect of AM compounds. Inhibition of tubulin polymerization is therefore one of the mechanisms of action of these AM compounds against tumor cells. To profile the antitumor effect of AM compounds, the in vivo antitumor effect of AM-132 was evaluated against cytokine-secreting Lewis lung carcinoma (LLC). Tumor-bearing mice were treated with intravenous AM-132 using three different treatment schedules. LLC tumors expressing tumor necrosis factor-alpha (TNF-alpha), granulocyte macrophage colony-stimulating factor (GM-CSF), or interleukin (IL)-6 were very sensitive to AM-132. In particular, LLC tumors expressing IL-6 were markedly reduced by AM-132 treatment, and showed coloring of the tumor surface and unusual hemorrhagic necrosis. These results suggest a combined effect of AM-132 and cytokines on the blood supply to tumors.

Synergistic suppressive effect of double transfection of tumor necrosis factor-alpha and interleukin 12 genes on tumorigenicity of Meth-A cells

Tumor necrosis factor-alpha (TNF-alpha) and interleukin 12 (IL-12), both potent antitumor cytokines, are known to be involved in the host's antitumor immune surveillance in tumor bearers, via different mechanisms. The former enhances the activities of dendritic cells, natural killer / lymphocyte-activated killer (NK / LAK) and cytotoxic T lymphocyte (CTL), while the latter induces Th1-type cellular immunity and enhances the activities of natural killer T (NKT), NK / LAK and CTL. In the present study, in the expectation of synergistic actions of these cytokines in stimulating the host's immune responses, we investigated the feasibility of a cancer vaccine involving double transfection with both genes in a murine model. The expression of major histocompatibility complex (MHC) class I, class II and B7.1 on the surface of the double transfectants was enhanced as revealed by FACS analysis. A significant decrease in tumorigenicity was observed in mice inoculated with the double transfectants. Cytotoxicity assay revealed that the activities of NK / LAK and CTL from spleens of mice bearing the double transfectants were enhanced. The induction of tumor-specific immunity was confirmed by rechallenge with parental Meth-A cells in mice that had rejected the double transfectants. Thus, double transfection of TNF-alpha and IL-12 genes was considered to bring about synergistic suppressive effects on the tumorigenicity of transfectants through the activation of killer cells by produced cytokines and the enhancement of expression of MHC class I, II and B7.1 molecules.

Preferential activity of wild-type and mutant tumor necrosis factor-alpha against tumor-derived endothelial-like cells

Tumor-derived endothelial-like cells (tEC) were prepared by culturing human umbilical vein endothelial cells (HUVEC) in the presence of HT1080 human fibrosarcoma-conditioned medium. tEC showed higher permeability and less cell-adhesion activity than normal HUVEC (nEC). Tumor necrosis factor-alpha (TNF) is known to have tumor-vasculature disrupting activity. tEC showed higher cytotoxicity to recombinant human TNF (rhTNF) than nEC, and was not observed using HUVEC cultured with WI38 human diploid cell-conditioned medium as a medium-control. These results demonstrate that tEC acquire physiological properties of tumor-associated vasculature, and may be a useful model system for the study of the mechanisms of TNF antitumor action. The TNF-mutant RGD-V29 (code No. F4614), which has an inserted 4Arg-Gly-Asp sequence and an 29Arg-->Val replacement, was found to induce greater preferential destruction of tEC compared to rhTNF. When the preferential activities were evaluated in terms of 30% cytotoxicity (IC30) ratio (nEC/tEC), the ratio was 460 for RGD-V29 compared to 4.2 for rhTNF. RGD-V29 also exhibited cell-adhesive function and bound preferentially to the p55 TNF-receptor. Both these properties of RGD-V29 contributed to the tEC selective cytotoxicity, indicating that the RGD ligands and selective p55 receptor binding on the cells, although uncharacterized, are involved in tEC targeting. Therefore, the TNF mutant RGD-V29 may show greater selectivity toward tumor vasculature than wild-type TNF.

Mechanistic aspects of green tea as a cancer preventive: effect of components on human stomach cancer cell lines

It is now well accepted that (-)-epigallocatechin gallate (EGCG) inhibits carcinogenesis in the digestive tract in rodents. To understand the mechanisms of anticarcinogenesis, we first studied growth inhibition by EGCG in human stomach cancer cell lines established at Seoul National University (SNU cell lines). Inhibition by EGCG of [3H]thymidine incorporation into eight SNU cell lines was examined, in relation to transforming growth factor-beta (TGF-beta) responsiveness. Various tea polyphenols derived from green tea and black tea induced growth inhibition and apoptosis of human stomach cancer cell line KATO III, and inhibition of tumor necrosis factor-alpha (TNF-alpha) release from the cells, in the order of (-)-epicatechin gallate (ECG), EGCG, (-)-epigallocatechin (EGC), teaflavins (TF) and (-)-epicatechin (EC). In addition, we demonstrated that EGCG inhibited TNF-alpha gene expression in KATO III cells, as well as okadaic acid-induced AP-1 and NF-kappa B activation. The inhibitory potencies of EGCG for AP-1 and NF-kappa B binding to DNA were different between KATO III cells and mouse fibroblast cell line BALB/3T3. Thus, EGCG and other tea polyphenols may interact with various transcription factors, in addition to AP-1 and NF-kappa B, in nuclei of various cells, resulting in inhibition of TNF-alpha gene expression and TNF-alpha release.

Disaccharide esters screened for inhibition of tumor necrosis factor-alpha release are new anti-cancer agents

Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine playing a part in various pathological states. Non-toxic inhibitors of TNF-alpha release are thought to be promising agents for cancer prevention. We found that the acetone fraction of the tobacco leaf surface lipid containing glucose esters and sucrose esters inhibited both TNF-alpha release from BALB/3T3 and KATO III cells induced by okadaic acid and tumor promotion by okadaic acid on mouse skin initiated with 7,12-dimethylbenz(a)anthracene (DMBA). Next, we investigated the inhibition of TNF-alpha release with synthetic disaccharide esters, such as 6,6'-di-O-alkanoyl-alpha, alpha-trehaloses (6,6'-diester-trehaloses), 4,4'-di-O-alkanoyl-alpha, alpha-trehaloses (4,4'-diester-trehaloses) and 6,6'-diamino-6,6'-dideoxy-N,N'-dialkanoyl-alpha, alpha-trehaloses (6,6'-diamide-trehaloses) bearing fatty acids of various chain lengths, and n-dodecyl-beta-D-maltoside as a disaccharide monoester. 6,6'-Diester-trehaloses and 4,4'-diester-trehaloses of C8 to C12 fatty acids, 6,6'-diamide-trehaloses of C8 to C14 fatty acids, and n-dodecyl-beta-D-maltoside all inhibited TNF-alpha release in a dose-dependent manner. The IC50 values are 7.4-14.8 microM for 6,6'-diester-trehaloses (C8 to C12), 14.6-21.6 microM 4,4'-diester-trehaloses (C8 to C12), 2.9-15.0 microM for 6,6'-diamide-trehaloses (C8 to C14) and 23 microM for dodecyl-beta-D-maltoside. Both 6,6'-di-O-octanoyl-alpha, alpha-trehalose (C8, designated as SS555) and n-dodecyl-beta-D-maltoside (C12) inhibited tumor promotion by okadaic acid on mouse skin initiated with DMBA. Percentages of tumor-bearing mice in week 15 of tumor promotion were reduced from 60.0 to 13.3 with SS555, and to 46.7 with n-dodecyl-beta-D-maltoside. Moreover, SS555 inhibited TNF-alpha gene expression mediated through inhibition of AP-1 activation, but not NF-kappa B activation. This paper reports that diester-trehaloses of C8 to C12 fatty acids and mimics of disaccharide monoesters such as n-dodecyl-beta-D-maltoside appear to be potential cancer-preventive agents of a new type.

Enhancement of antiproliferative effects of interleukin-1beta and tumor necrosis factor-alpha on human prostate cancer LNCaP cells by coculture with normal fibroblasts through secreted interleukin-6

The cell-cell interactions between tumor cells and stromal cells are considered to be important in the regulation of tumor development at primary and metastatic secondary sites. We studied the effects of various cytokines on the cell-cell interactions between androgen-dependent LNCaP or androgen-independent PC-3 human prostate cancer cell lines and normal fibroblasts using a co-culture system. Among the tested combinations of cytokines and fibroblasts, strong modulations of cytokine actions were seen in coculture with human normal fibroblasts WI-38. While interleukin (IL)-1beta or tumor necrosis factor-alpha (TNF-alpha) partially suppressed LNCaP cell growth in monoculture, each cytokine completely inhibited it in the case of coculture with WI-38 cells. On the other hand, they did not inhibit PC-3 cell growth significantly, regardless of monoculture or coculture. Conditioned medium prepared from WI-38 cells pretreated with IL-1beta or TNF-alpha also strongly inhibited LNCaP cell growth. In the conditioned medium, marked IL-6 secretion was induced from WI-38 cells by IL-1beta or TNF-alpha. Furthermore, neutralizing antibodies to IL-6 or IL-6 receptor abrogated the antiproliferative effects of IL-1beta- and TNF-alpha-pretreated WI-38 conditioned medium. These results demonstrate that the antiproliferative effects of IL-1beta and TNF-alpha on prostate cancer cells are enhanced by coculture with normal fibroblasts through some diffusible factor(s), such as IL-6, from the stimulated fibroblasts.

Analysis of serum cytokine levels in primary biliary cirrhosis patients and healthy adults

By using commercially available ELISA kits, serum IL-6 and TNF-alpha levels in healthy adults, and the levels of various cytokines in patients with primary biliary cirrhosis or chronic viral liver diseases, were investigated. IL-6 levels of healthy subjects were distributed in a wide range, and the distribution pattern was similar to those of the patients. TNF-alpha levels tended to be low in females in their 30s, but there were no abnormalities in the patients. Characteristic findings, in the primary biliary cirrhosis patients, were an increase of IFN-gamma and IL-2 levels, and a decrease of GM-CSF levels (P < 0.05). IL-8 levels were higher in the patients than in the healthy subjects (P < 0.05), and the increase was remarkable in chronic viral liver disease patients. We believe that measurement of serum cytokine levels as a clinical immunological test is highly useful. Further development of simpler, more rapid, and more sensitive analysis methods is desired.

Effect of gene transfer of tumor necrosis factor receptors into human lung carcinoma cell line

The human lung adenocarcinoma cell line A549 is known to be resistant to tumor necrosis factor alpha (TNF-alpha)-mediated tumor cell lysis in spite of the expression of 55 kDa TNF receptor (TNF-R55) mRNA and its cell surface protein. In this study, we investigated the mechanism of TNF-alpha resistance and the role of two types of TNF receptors (TNF-R55 and TNF-R75 (75 kDa TNF receptor)). TNF-R55 or TNF-R75 cDNA was transfected into A549 cells. In addition, a C-terminal deletion mutant of TNF-R75 which lacks the intracellular domain of TNF-R75 was also transfected into A549 cells. We assessed the TNF-alpha-mediated tumor cell lysis of these transfected clones, and found that the cytotoxic effect increased in transfected clones highly expressing TNF- R55, but not in low-expression clones. As for TNF-R75, the cytotoxic effect of TNF-alpha was observed in TNF-R75-transfected clones even when expression was low. Furthermore, the cytotoxic effect was also observed in clones transfected with the deletion mutant of TNF-R75, as well as the complete TNF-R75. These results indicate that a certain level of expression of TNF-R75 is necessary for obtaining TNF-alpha-mediated tumor cell lysis in the absence of TNF-R75. On the other hand, the expression of TNF-R75 strongly induces TNF-alpha-mediated cytotoxicity through TNF-R55 in the absence of an intracellular signal via TNF-R75.

Selective enhancement by tumor necrosis factor-alpha of vascular permeability of new blood vessels induced with agarose hydrogel-entrapped Meth-A fibrosarcoma cells

We have previously developed a simple and quantitative method for assessment of in vivo tumor cell-induced angiogenesis by means of microencapsulation of tumor cells in agarose hydrogel and mouse hemoglobin ELISA (mHb-ELISA). In this article, we report that the new blood vessels induced with agarose-encapsulated tumor cells have the same sensitivity to tumor necrosis factor-alpha (TNF-alpha) as the original solid-tumor vessels. Agarose beads (average diameter = 200 microns), in which Meth-A fibrosarcoma cells were microencapsulated, were subcutaneously implanted in non-syngeneic ddY mice. Ten days later, extensive angiogenesis was observed on the implanted sites of Meth-A agarose heads, whereas no new blood vessels were induced with cell-free agarose heads. The vascular permeability of the new blood vessels induced with agarose-microencapsulated Meth-A cells was selectively and significantly enhanced by the i.v. injection of TNF-alpha, and it reached the maximum level at 2 h after the injection of TNF-alpha. At 4 h after the injection of TNF-alpha, the vascular permeability was reduced to the basal level. This permeability profile in Meth-A agarose beads in ddY mice is very similar to that in Meth-A solid tumor in syngeneic BALB/c mice. On the other hand, TNF-alpha-treatment did not affect the vascular permeability of other normal tissues or inflammatory tissue in ddY mice. These results strongly suggest that the new blood vessels induced with agarose-microencapsulated tumor cells have the specific characteristics of tumor vessels. Our in vivo angiogenesis assay system should be useful not only to screen anti-angiogenetic agents, but also to elucidate the mechanism of tumor angiogenesis.

Tumor necrosis factor-alpha gene transfer augments anti-Fas antibody-mediated apoptosis in human glioma cells

To effectively induce apoptosis in human glioma cells, we tried to transfer the tumor necrosis factor (TNF)-alpha gene into glioma cells to produce TNF-alpha locally in these cells. The stable transfectants of three glioma cells (U251-SP, U251-MG, and T98G) were resistant to exogenous TNF-alpha, but their cell surface expression of the Fas antigen was dramatically enhanced by about 10 to 100-fold as compared with untransfected glioma cells exposed to exogenous TNF-alpha. The Fas antigen is a transmembrane cytokine receptor protein of the nerve growth factor/TNF receptor superfamily. Although the untransfected glioma cells tested were resistant to anti-Fas antibody-mediated apoptosis, the TNF-alpha gene-transfected glioma cells exhibited high susceptibility to anti-Fas antibody-mediated apoptosis. Thus, TNF-alpha gene transfer combined with anti-Fas antibodies may be useful for the treatment of malignant glioma.

Dipyridamole combined with tumor necrosis factor-alpha enhances inhibition of proliferation in human tumor cell lines

In the search for cytokines whose antiproliferative action could be enhanced by combination with dipyridamole, 2,6-bis(diethanolamino)-4,8-dipiperidinopyrimido[5,4-d]pyrim idine, the combination of tumor necrosis factor-alpha (TNF-alpha) with this agent was evaluated in various human tumor cell lines. Inhibition of the proliferation of human melanoma cell lines MM-1CB and HMV-1 by TNF-alpha (1-10(2) U/ml) was enhanced in culture dishes by combination treatment with dipyridamole (0.1-10 microM). The enhancement effect was also detected in other tumor cell lines: T98 (glioma), SCC-1CB (squamous cell carcinoma), HAC-2 (ovarian clear-cell carcinoma), HLE (hepatoma), HEC-1 (endometrial adenocarcinoma) and HOC-21 (ovarian serous cystadenocarcinoma). The incorporation of [14C]amino acids and [3H]uridine into acid-insoluble cell materials in the combination-treated cells was not significantly different from that in cells treated with TNF-alpha or dipyridamole. However, the incorporation of [3H]thymidine was specifically inhibited in all cell lines examined after more than 12 h of the TNF-alpha and dipyridamole combination treatment, although neither agent alone inhibited this incorporation. On the other hand, the growth of tumors induced by the injection of MM-1CB and HMV-1 cells into nude mice was more markedly inhibited by the subcutaneous administration of TNF-alpha in combination with orally administered dipyridamole than by either agent alone. The results presented suggested that dipyridamole is beneficial in assuring the effectiveness of anti-cancer cytokine therapy.

Inhibition of tumor-induced angiogenesis by a synthetic lipid A analogue with low endotoxicity, DT-5461

We investigated the effect of a synthetic lipid A analogue with low endotoxicity, DT-5461, on the neovascularization induced by B16-BL6 melanoma in syngeneic mice. A systemic single administration of DT-5461 caused a marked decrease in the number of vessels oriented toward the tumor mass and in the tumor size during the early phase of vasculogenesis (on day 4 after tumor inoculation), with little or no inhibition in the following phases. Multiple i.v. administrations of DT-5461 at intervals of 4 days (an effective schedule for inhibiting tumor metastasis) significantly reduced the number of capillary vessels and tumor growth over a period of 14 days after the tumor implantation. Multiple systemic administrations of DT-5461 on days 1, 5 and 9 after tumor inoculation caused a high production of endogenous tumor necrosis factor-alpha (TNF-alpha) in tumor sites although this treatment modality induced a low production in serum of tumor-bearing mice. Tumor homogenate from mice treated with DT-5461 suppressed the proliferation of endothelium in vitro, whereas sera from animals given DT-5461 had little effect. Furthermore, the antiproliferative effect of the tumor homogenate from mice treated with DT-5461, was completely abrogated by anti-mTNF-alpha monoclonal antibody (mAb). The anti-angiogenic effect of DT-5461 was also completely abrogated by rabbit anti-mouse tumor necrosis factor-alpha (anti-mTNF-alpha) antiserum, whereas the inhibition of tumor growth by DT-5461 was only slightly diminished. Tumor homogenate from mice treated with DT-5461 suppressed the proliferation of endothelium in vitro, whereas sera from animals given DT-5461 had little effect. Furthermore, the antiproliferative effect of the tumor homogenate from mice treated with DT-5461 was completely neutralized by anti-mTNF-alpha mAb. Multiple i.v. administrations of DT-5461 after s.c. implantation of B16-BL6 cells significantly inhibited the growth of primary tumors measured at the time of tumor excision on day 21, and the lung metastasis of melanoma cells as compared with the untreated control in the spontaneous metastasis model. These results suggested that the suppressive effect upon tumor-associated angiogenesis by DT-5461 contributes in part to the inhibition of tumor metastasis.

Transfection-induced tumor necrosis factor-alpha increases the susceptibility of human glioma cells to lysis by lymphokine-activated killer cells: continuous expression of intercellular adhesion molecule-1 on the glioma cells

To develop more effective adoptive immunotherapy, we transfected the human tumor necrosis factor-alpha (TNF-alpha) gene into human glioma cells (U251-SP), which were used as target cells. TNF-alpha is known to increase both the expression of intercellular adhesion molecule-1 (ICAM-1) on the surface of glioma cells and the susceptibility of glioma cells to lymphokine-activated killer (LAK) cell cytolysis. We compared the expression of ICAM-1 induced by TNF-alpha generated by the TNF-alpha gene-transfected cells with that induced by exogenously added TNF-alpha. When the TNF-alpha gene was transfected into U251-SP cells, the expression of ICAM-1 was detected on the cell surface from 3 days after the transfection and continued until at least 9 days. In contrast, it was expressed only transiently in the case of exogenously added TNF-alpha. Also, the cytolytic activity of LAK cells induced by transfection-induced TNF-alpha was significantly stronger than that induced by exogenously added TNF-alpha. The increased susceptibility was quenched by anti-ICAM-1 monoclonal antibody. These data indicated that continuous expression of ICAM-1 induced by TNF-alpha gene transfection of glioma cells resulted in higher cytolytic activity of LAK cells.

Autonomous expressions of cytokine genes by human lung cancer cells and their paracrine regulation

Cell-to-cell interaction between tumors and host inflammatory cells is important for the subsequent cancer progression or regression. We examined the expressions of mRNAs for various proinflammatory cytokines by nine human lung cancer cell lines and the influences of cytokines on their gene expressions. The cytokines used were interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), granulocyte-macrophage colony stimulating factor (GM-CSF) and monocyte chemotactic and activating factor. Gene expressions of cytokines were measured by Northern blot analysis. Substantial expressions of cytokine genes were detected in several lung cancer cell lines such as RERF-LC-MS, RERF-LC-OK and VMRC-LCD, although the levels of expression of each cytokine varied in different cell lines. Four lung cancer cell lines (RERF-LC-MS, RERF-LC-OK, A549 and YO-88) were used to examine the effects of exogenous cytokines (IL-1 beta, TNF-alpha and GM-CSF) on cytokine gene expressions by the cells. TNF-alpha and IL-1 beta caused significant changes in the levels of mRNA expressions of certain cytokines. Moreover, on stimulation with TNF-alpha, RERF-LC-OK cells produced IL-6 extracellularly. These extensive differences in the levels of gene expressions and productions of cytokines could have profound effects on the interactions between human lung cancer cells and the corresponding host cells.

Chemical modification of natural human tumor necrosis factor-alpha with polyethylene glycol increases its anti-tumor potency

Natural human tumor necrosis factor-alpha (TNF-alpha) was chemically modified with an active ester of monomethoxy polyethylene glycol (PEG). The molecular weight of PEG-modified TNF-alpha depended on the reaction time as well as the initial molar ratio of PEG to TNF-alpha. The specific activity of modified TNF-alpha was gradually reduced with increase in the degree of PEG-modification, but the plasma half-life of TNF-alpha was increased by up to 40-fold. Modified TNF-alpha showed approximately 100 times greater anti-tumor potency than unmodified TNF-alpha. Covalent attachment of PEG to TNF-alpha thus increased the bioavailability of TNF-alpha, and may facilitate its potential therapeutic use.

Tumor necrosis factor-alpha stimulates colony formation by a megakaryoblastic leukemia cell line, CMK

The CMK cell line is an acute megakaryoblastic leukemia cell line established from a patient with Down's syndrome, and is known to possess characteristics of normal megakaryocytes. Several cytokines with the ability to stimulate megakaryopoiesis, such as interleukin-3 (IL-3), interleukin-6 (IL-6) and granulocyte-macrophage colony-stimulating factor (GM-CSF), stimulated colony formation by CMK cells. The present study revealed that tumor necrosis factor-alpha (TNF-alpha) stimulated colony formation by CMK cells; the potency was almost equal to that of IL-3, IL-6 or GM-CSF. Scatchard plot analysis revealed that CMK cells possess two types of specific binding sites for TNF-alpha. The high-affinity binding sites had an affinity constant of 0.18 nM, and numbered 5,000. The low-affinity binding sites had an affinity constant of 1.8 nM and numbered 19,000. These results raise the possibility that TNF-alpha can act as a growth-stimulating agent on megakaryocyte-lineage cell line.