Induction of tumor necrosis factor (TNF) by OK-432

The induction of tumor necrosis factor (TNF) by OK-432 was investigated. The results were as follows: Serum from OK-432 injected into NZW rabbits treated with LPS was cytotoxic to tumor cells in vitro. With respect to the target cell spectrum this factor was cytotoxic to L929, Lewis, M7609 and K562, but not to Chang liver cells, HMV cells or HeLa cells. The cytotoxic activity of this factor was found to be M.W. 48,000 on H.P.L.C., and the pI was revealed to be 5.4 by isoelectric focusing. These results were consistent with previously reported findings on TNF.     

Antitumor activity of tumor necrosis factor (TNF) in vitro and in vivo

The antitumor activity of highly purified tumor necrosis factor (TNF) was tested. TNF had direct cytotoxic activity on all cancer cells examined in vitro, and no species specificity. Normal cells showed no damage on addition of TNF. TNF showed excellent curative effects against all types of murine and human tumors tested in vivo. A great difference in curative effects of TNF was observed between Meth A sarcoma transplanted into Balb/c nu/+ and Balb/c nu/nu mice with a single intravenous administration. This experiment suggested that in addition to direct cytotoxicity against tumor cells, TNF-induced host-mediated factor which contributed to the antitumor effects Murine TNF has on inhibitory effect against multiple pulmonary metastasis of Lewis Lung-tumor. Very few references to this field could be found in the literature and the present paper mainly presented our own research.     

Mechanisms of production of tumor necrosis factor (TNF)--reconstitution experiment white nude mice

In order to investigate the role of T cells in the production of tumor necrosis factor (TNF), a reconstitution experiment was performed with nude mice (Balb/c, nu/nu). The results obtained were as follows: The cytotoxic activity of tumor necrosis serum (TNS) from Balb/c, nu/nu mice treated with P. acnes-LPS was 1/22 against that from Balb/c, nu/+ mice. TNF activity increased 14 times in reconstituted nude mice against Balb/c, nu/nu mice. Investigation of the production of the cytotoxic activity per cell was carried out using T cell and macrophage fractions separated from the spleens of both Balb/c, nu/nu and Balb/c, nu/+ mice treated with P. acnes as a priming agent. Elicitation employing LPS was done in vitro. Cytotoxic activity released into culture medium was observed in the macrophage fraction, but not in the T cell fraction. However, no significant difference was shown in species. With P. acnes treatment, the population of macrophages in the spleens from Balb/c, nu/+ mice increased 25.5 times, whereas that from Balb/c, nu/nu mice only increased 6.8 times. The above results suggest that the mechanism of the incremental effect of T cells on TNF production was due to the promotion of macrophage proliferation during the priming period after injection of P. acnes.     

Induction of intratumoral tumor necrosis factor (TNF) synthesis and hemorrhagic necrosis by 5,6-dimethylxanthenone-4-acetic acid (DMXAA) in TNF knockout mice.

5,6-Dimethylxanthenon-4-acetic acid (DMXAA) is a new antitumor drug currently undergoing clinical trial. Administration of DMXAA to mice with tumors leads to cessation of tumor blood flow and the onset of tumor hemorrhagic necrosis, accompanied by the production of the cytokine tumor necrosis factor (TNF). Previous studies have shown that DMXAA induces both tumor and host cells to synthesize TNF and that induced intratumoral TNF production correlates with the antitumor activity of DMXAA. To explore the hypothesis that TNF production by tumor cells contributed to the induction of hemorrhagic necrosis by DMXAA, TNF-/- (C57Bl/6 background) mice were used as recipients for the s.c. implantation of (TNF positive) colon 38 adenocarcinoma. Tumors removed 24 h after treatment with DMXAA (66 or 100 micromol/kg) were found to be hemorrhagic and necrotic. Cells expressing TNF mRNA in tumors removed 2 h after treatment with DMXAA (160 micromol/kg) were found by in situ hybridization to be comparable in frequency and distribution with those in tumors from C57Bl/6 TNF-positive mice. However, the amount of TNF protein extracted from tumors from TNF knockout mice was lower than that from TNF-positive mice. Spleen and liver tissue from TNF knockout mice, in contrast to that from TNF-positive mice, produced no TNF mRNA. TNF protein was undetectable in liver and spleen tissue from TNF knockout mice, but was evident in tissue from TNF-positive mice. These results confirm that DMXAA has the novel ability of inducing tumors to synthesize TNF in situ.     

Analysis of intermittent blood flow in experimental tumor using a transparent chamber

Using a transparent chamber under a microscopic recording system equipped with a CCD camera, we measured real-time fluctuations of microvessel blood flow in an experimental murine tumor. Seven microvessels of the tumor showed 3-4 fluctuations in blood flow (intermittent blood flow) during the observation period (2 hours). Within the 120 min. monitoring period, we obtained approximately a maximum 52.5% of decreased blood flow. The duration of change in blood flow ranged from 15-45 min. Similar temporal fluctuations were seen in experimental animal tumors. Our data clearly demonstrated that fluctuations in blood flow (intermittent blood flow) in tumors are a common feature.     

Properties of monoclonal antibodies to human tumor necrosis factor alpha (TNF alpha).

Four murine monoclonal antibodies were produced against human recombinant tumor necrosis factor alpha (TNF alpha). They were characterized with respect to specificity, affinity, neutralization of in vitro L929 cell killing by TNF alpha and neutralization of the in vivo biological activities of toxicity and tumor necrosis. The monoclonal antibodies were further investigated for reactivity with TNF alpha in Western blotting. All four monoclonal antibodies reacted with human TNF alpha. One of then also reacted with mouse TNF alpha and human TNF beta (lymphotoxin), this antibody did not neutralize in vitro cytotoxicity or in vitro biological activities of TNF alpha. The other antibodies were neutralizing and it appeared that, in some cases, the systemic toxic effect of TNF alpha could be reversed by anti-TNF alpha monoclonal antibody therapy while retaining significant anti-tumour effects.     

The involvement of oxidative stress in tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in HeLa cells

To identify specific allelic losses that might correlate with postoperative mortality of breast cancer patients treated with high-dose adjuvant chemotherapy consisting of cyclophosphamide, methotrexate and fluorouracil, we examined tumors from a cohort of 150 such patients, who were followed clinically for 5 years postoperatively, for allelic losses (loss of heterozygosity, LOH) among 18 microsatellite markers throughout the genome. Patients whose tumors had lost an allele at 8p22 had significantly higher risks of mortality than those whose tumors retained both alleles at those loci. At 8p22, the 5-year mortality rate was 31% among patients with losses vs. 8% with retention (P=0.0354). No other region showed correlation between LOH and prognosis. The data indicate that LOH at 8p22 is a significant predictor of postoperative mortality for breast cancer patients who received high-dose postoperative adjuvant chemotherapy. Thus, LOH at 8p22 can serve as a negative prognostic indicator to guide postoperative management of patients.     

A regulatory role for tumor necrosis factor (TNF) in ML-1 human myeloblastic leukemia cell maturation

ML-1 human myeloblastic leukemia cells are induced to differentiate to monocytes by conditioned medium (CM) derived from tetradecanoylphorbol acetate (TPA)-treated ML-1 cells. Antibodies to tumor necrosis factor (TNF) inhibited the differentiation-stimulating activity of CM, indicating that this activity is due to the presence of TNF in CM. TNF added to non-conditioned medium was as effective as CM in stimulating ML-1 cell differentiation. In the presence of a low (0.12 ng/ml) concentration of TPA, TNF-induced maturation was synergistically increased and Type I macrophages were formed. With higher (1-10 ng/ml) TPA concentrations, Type II macrophages were also obtained. As the TNF/TPA concentration increased, ML-1 cell differentiation was increasingly inhibited. Mature cells derived from ML-1 cells were found to secrete TNF at concentrations ranging from less than 2 U/ml to greater than 180 U/ml, the amount depending upon the number of cells and the stage of cell maturation. These results indicate that TNF participates in the regulation of precursor cell maturation. Low concentrations of TNF produced by small numbers of mature cells stimulate differentiation, whereas high concentrations of TNF generated by elevated numbers of macrophages inhibit the maturation process, possibly in combination with other cytokines. Because TNF serves as a competence factor for ML-1 cells, (Guan X.-P., Takuma T., Hromchak R. & Bloch A. (1990) Competence and progression in cell differentiation. Proc. Am. Assoc. Cancer Res. 31, 28.), the TNF-induced stimulation of differentiation depends additionally on the action of serum-contained differentiation-specific progression factors.     

Selective formation of tumor necrosis factor-alpha (TNF) degradation products contributes to TNF mediated cytotoxicity.

We compared tumor necrosis factor (TNF) metabolism by wild-type MCF-7 (WT) cells, by 40-fold doxorubicin resistant (40F) breast cancer cells and by PC3 and LNCaP prostate cancer cell lines. MCF-7 WT and LNCaP cell lines were sensitive to TNF cytotoxicity and both lines produced two major intracellular TNF degradation products of 15 kDa and 5.5 kDa. The MCF-7 40F and the PC3 cell lines were resistant to TNF and produced multiple TNF degradation products with molecular weights lower than 15 kDa. Both the breast and prostate lines showed TNF receptor crosslinking patterns consistent with a molecular weight of 55 kDa. The breast and LNCaP lines expressed TNF receptors with an apparent dissociation constant (Kd) of 0.4 to 0.6 nM, while the TNF resistant line had a Kd of 2 nM. Similar receptor numbers per cell were found for all cell types (4,000 to 8,000/cell), and comparable levels of TNF internalization were noted. TNF-conditioned medium from the TNF-sensitive cell types was cytotoxic toward both the TNF-sensitive and TNF-resistant lines, and the toxicity was significantly blocked by an anti-TNF monoclonal antibody. Hydrophobic interaction column HPLC fractionation of the TNF-degradation products produced by MCF-7 WT and LNCaP cells revealed that the trimeric, monomeric, and 5.5 kDa fractions possessed the greatest in vitro antitumor activity. These findings suggest that a TNF degradation product, produced selectively by TNF-sensitive cells, may contribute to the antitumor action of TNF.     

肿瘤坏死因子-β基因型多态性与膀胱肿瘤的关系

目的探讨肿瘤坏死因子-β（TNF-β）基因型多态性与膀胱肿瘤的关系。方法用聚合酶链式反应-限制性片段长度多态性（PCR—RFLP）方法，检测所有研究对象的TNF-β基因＋A252G位点的基因型，探讨其基因型与膀胱肿瘤的关系。结果TNF-β基因型多态性与膀胱肿瘤的发病率相关，且膀胱肿瘤患者中，TNF-β基因型多态性与肿瘤的分级相关（P〈0．01）。结论检测膀胱肿瘤患者的TNF-β基因型多态性有助于为研究膀胱肿瘤的发生发展提供一个新的思路。     

Recombinant human soluble tumor necrosis factor (TNF) receptor (p75) fusion protein Enbrel in patients with refractory hematologic malignancies

PURPOSE: Tumor necrosis factor-alpha (TNF-alpha) is an important effector and regulatory cytokine involved in the pathophysiology of hematologic malignancies, including hairy cell leukemia (HCL), chronic lymphocytic leukemia (CLL), agnogenic myeloid metaplasia (AMM) and Philadelphia-negative myeloproliferative disorders (MPD). We conducted a pilot study to assess the safety of the soluble TNF receptor, etanercept (p75 TNFR:Fc; Enbrel) in patients with refractory hematologic malignancies. METHODS: Patients were eligible if they had refractory HCL, CLL, AMM, or Philadelphia-negative MPD. Enbrel was administered twice weekly at a dose of 25 mg subcutaneously for a minimum of eight doses, and was continued in patients without overt progression. RESULTS: Among the 26 patients enrolled on study, 25 patients were evaluable. Nine patients had AMM, eight CLL, three HCL, and five Philadelphia-negative MPD. Their median age was 60 years (range 30-83 years). A total of 70 courses consisting of 486 doses of Enbrel were administered. Enbrel was well tolerated, without any overt increase in infectious episodes. Stable disease/no objective response was seen in 22 patients (88%) and progression in 3 patients (12%). Three patients with AMM improved (two showed hematologic improvement, and one showed a reduction in liver and spleen size), and two patients (one with CLL and one with Philadelphia-negative MPD) showed improvement in disease-related symptoms. CONCLUSIONS: Enbrel was well tolerated, but no responses were noted in these immunosuppressed patients with refractory hematologic malignancies.     

Correlation of tumor necrosis factor alpha (TNF alpha) with high Caspase 3-like activity in myelodysplastic syndromes.

Increased intramedullary apoptotic death of hematopoietic cells is thought to contribute to the ineffective hematopoiesis in myelodysplastic syndromes (MDS). Furthermore, high amounts of tumor necrosis factor alpha (TNF alpha) have previously been correlated with apoptosis in MDS marrows. The present studies were undertaken to examine the status of two key downstream effectors of TNF alpha signaling, i.e. Caspase 1 and Caspase 3 enzymes, using a fluorometric assay in the bone marrow aspirate mononuclear cells (BMMNC) in relation to apoptotic DNA fragmentation detected by in situ end-labeling (ISEL) of DNA and with localization of TNF alpha in the corresponding biopsies from 14 MDS patients. Both Caspase 1 and 3 were detectable in freshly harvested BMMNC, albeit median Caspase 3 levels (47.5 units/mg protein) being almost 10 times higher than Caspase 1 (4.0 units/mg protein). Upon short-term culture for 4 h in a serum-supplemented medium in vitro a significant increase was seen in Caspase 3 activity (58.8 +/- 13.9 at 0 h vs. 177.8 +/- 55.2 units/mg protein at 4 h, n = 14, P = 0.017) and in percent cells labeled by ISEL (apoptotic index or AI%: 0.76% +/- 0.25% vs. 3.99% +/- 1.1%, n = 14, P = 0.004, respectively). Caspase 1 activity increased after 15 min in culture. Interestingly, TNF alpha levels measured by immunohistochemistry correlated with the net increase in Caspase 3 activity after 4 h (p = 0.517, n = 13, P = 0.07) and the starting levels of Caspase 1 at 0 h correlated with the Caspase 3 levels attained at 4 h (p = 0.593, n = 13, P = 0.033). Additionally when TNF alpha-positive bone marrows (8/14) were compared with the negative marrows (6/14) the Caspase 3 levels were significantly higher in the TNF alpha-positive marrows (189.6 +/- 66.2 vs. 25.0 +/- 14.6 units/mg protein, respectively, P = 0.043). The increase in AI%, though not statistically significant, was also higher in the TNF alpha-positive marrows. Finally in HL60 cells the effects of different Caspase inhibitors and pentoxifylline (PTX) (interferes with lipid signaling of cytokines) on TNF alpha-induced apoptosis were evaluated. TNF alpha treatment significantly increased AI% (P < 0.003) as compared to the untreated controls. A co-treatment with three Caspase inhibitors, zVAD.FMK (inhibitor of Caspases 1 and 3, 10 microM/l), Ac.YVAD.FMK (Caspase 1 inhibitor, 1 microM/l), Ac.DEVD.FMK (Caspase 3 inhibitor, 10 microM/l) as well as PTX (250 microM/l) significantly curtailed the AI% induced by TNF alpha. The present studies thus identify the downstream effectors of TNF alpha-inducible apoptosis in MDS and so also the suppressors of TNF alpha apoptotic signaling. These results may have significant clinical implications in the therapy of MDS in the future.     

Transendothelial migration of myeloma cells is increased by tumor necrosis factor (TNF)-alpha via TNF receptor 2 and autocrine up-regulation of MCP-1.

The proinflammatory cytokine tumor necrosis factor (TNF)-alpha has been shown to facilitate leukocyte transendothelial migration. In multiple myeloma, TNF-alpha is an important factor in the promotion of growth and survival of the malignant cells. Studies have shown that enhanced TNF-alpha levels in myeloma patients correlated with aggressive disease. Therefore, we investigated the effect of recombinant human TNF-alpha on the migrational behavior of myeloma cells across the physiological barrier of the major disease compartment, i.e., human bone marrow endothelial cells. In the presence of TNF-alpha, we observed significantly increased migration both in established myeloma cell lines and in plasma cells from myeloma patients. Expression of TNF-receptor 2 (TNF-R2) but not TNF-receptor 1 (TNF-R1) was detected in myeloma cell lines. Myeloma cells of patients also showed expression of TNF-R2 but not TNF-R1. The effect of TNF-alpha could not be explained by altered expression of adhesion molecules or metalloproteases. Instead, we found an up-regulation of monocyte chemoattractant protein (MCP)-1 and confirmed that myeloma cells express the relevant receptor C-C chemokine receptor 2. Preincubation of myeloma cells with recombinant human MCP-1 also enhanced cell migration, and this effect, as well as the effect of TNF-alpha, was abolished by treatment with anti-MCP-1 antibody. In contrast, migration of myeloma cells in the direction of an MCP-1 gradient, i.e., chemotaxis, could not be observed in the cell lines investigated. Additionally, the mRNA level of TNF-alpha was up-regulated by the cytokine treatment, which points to an autocrine loop augmenting and/or stabilizing the TNF-alpha-MCP-1 pathway. In summary, our data clearly support additional investigations using anti-MCP-1 antibodies in myeloma progression.     

Antitumor activity of murine tumor necrosis factor (TNF) against transplanted murine tumors and heterotransplanted human tumors in nude mice

The antitumor activity of highly purified tumor necrosis factor (TNF) was tested against eight kinds of murine tumor and five kinds of human tumor heterotransplanted into nude mice. Mice were treated by intravenous or intratumoral injection of TNF, commencing when the tumors were well established. TNF showed an excellent curative effect against all kinds of murine and human tumors tested. Meth A sarcoma, Colon 26, Ehrlich, sarcoma 180, MM 46, MH 134, B16 melanoma, and Lewis lung tumors transplanted into mice underwent tumor necrosis and regression following a single injection of TNF. Sometimes a complete cure was observed in Meth A sarcoma, sarcoma 180, Ehrlich, and MM 46 tumors. Human cancers, SEKI, HMV-I, KATO-III, MKN 45, or KB, heterotransplanted into nude mice, also exhibited tumor necrosis and regression in size following several intratumoral injections of TNF. A great difference in curative effects of TNF was observed in Meth A sarcomas between those transplanted into BALB/c nu/+ and into BALB/c nu/nu mice: following a single intravenous administration the effect was stronger in BALB/c nu/+ than in nu/nu mice. In contrast, tumor necrosis was almost the same in nu/+ and nu/nu mice following intratumoral administration. The present results thus indicate that TNF from mice had an antitumor activity against not only murine tumors but also human tumors. In addition to direct cytotoxicity against tumor cells, TNF induced a host-mediated factor which contributed to the antitumor effects.     

Mechanism of antitumor activity of tumor necrosis factor alpha with hyperthermia in a tumor necrosis factor alpha-resistant tumor

Cells from a radiation-induced fibrosarcoma (RIF-1) are exceedingly resistant to tumor necrosis factor alpha (TNF-alpha) in vitro. We tested whether the addition of mild hyperthermia (42.5 degrees C, 30 minutes) could enhance TNF-alpha activity against RIF-1 tumors growing in syngeneic hosts (C3H mice). TNF-alpha was administered intratumorally. Tumor cell killing essentially was not measurable following TNF-alpha, hyperthermia, or a combination of the two. Single-modality treatments also had no effect on tumor growth delay or on the x-ray dose (given 24 hours after the primary treatment) required to sterilize 50% of the tumors. The combination of TNF-alpha and hyperthermia, however, resulted in a marked increase in tumor doubling time and a highly significant reduction in the x-ray dose required to sterilize the tumors. Syngeneic lymph nodal lymphocytes and blood leukocytes did not appear to mediate the action of TNF-alpha on RIF-1 cells in vitro. Necrosis and hemorrhage were the most prominent histopathological alterations in the treated tumors. Electron microscopic studies 6 hours after therapy showed increased damage to capillary endothelial cells and accumulation of neutrophils in the capillaries of tumors treated with TNF-alpha with or without heat, suggesting that neutrophils may mediate the endothelial cell injury. These observations indicate a greater than additive tumoricidal effect of TNF-alpha with hyperthermia. Furthermore, they support the concept that the interaction between the two agents damages the vasculature, compromising the microcirculation and ultimately causing ischemic tumor necrosis.     

Triggering of antitumor activity through melanoma-specific transduction of a constitutively active tumor necrosis factor (TNF) R1 chimeric receptor in the absence of TNF-alpha

Tumor necrosis factor-alpha (TNF-alpha) has been intensively studied because of the specific toxicity of this cytokine toward cells that undergo malignant transformation. However, its proinflammatory and immunoregulatory properties always represented a drawback to the TNF-alpha administration in cancer therapy. In this study, we describe an adenovirus-based strategy in which the tumoricidal activity of TNF-alpha can be selectively triggered to eradicate tumors without administering TNF-alpha. This strategy might allow us to prevent TNF-alpha effects on normal tissues and, therefore, to bypass its systemic toxic effects. We inserted the constitutively active version of the Mr 55,000 TNF receptor, which was shown previously (F. Bazzoni et al., Proc. Natl. Acad. Sci. USA, 92: 5376-5380, 1995) to be capable of killing cells upon expression in the absence of its ligand, into a replication-deficient adenovirus, and under the control of a melanoma-specific promoter/enhancer element. We show that, upon infection, the recombinant gene reaches high level of expression in melanoma cell lines and triggers apoptosis by activating the caspase cascade. Expression and function of this receptor is restricted to melanoma cell lines, because morphology, viability, and proliferation of other cell types exposed to the recombinant adenovirus infection are not affected. We show for the first time that a TNF-like apoptotic response can be triggered in the absence of TNF-alpha and can be selectively confined to specific cellular targets. Killing activity and tissue specificity of the recombinant TNF receptor adenovirus, together with the advantage of triggering a TNF-like antitumor activity in the absence of TNF-alpha itself, are ideal features for a vector that might be the choice for gene therapy aimed to eradicate malignant cells.     

The anticancer drug mithramycin A sensitises tumour cells to apoptosis induced by tumour necrosis factor (TNF)

In this report we show that mithramycin considerably increases the direct cytotoxic effect of tumour necrosis factor (TNF) on tumour cells in vitro. Sensitisation to TNF-induced apoptosis was prevented by the broad caspase inhibitor zVAD-fmk, whereas overexpression of Bcl-2 had no effect. Mithramycin also potentiated cell death induced by Fas agonistic antibodies. In contrast, mithramycin reduced the percentage of cells undergoing apoptosis due to factor withdrawal. TNF-induced activation of NF-kappaB (NF-kappaB)-dependent gene expression was not modulated by mithramycin treatment. Concomitantly with the increased sensitivity, the protein level of the short-spliced cFLIP variant was downregulated. These results indicate that mithramycin enhances TNF-induced cell death in an NF-kappaB-independent manner, and suggest that the Fas-associated death domain protein plays a crucial role in the TNF-sensitising effect of mithramycin.