Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The susceptibility of cloned cell lines of the 13762NF rat mammary adenocarcinoma to macrophage-mediated cytolysis was investigated using both intra- and extratumoral macrophages. The percentage of Fc receptor-positive cells in tumors growing s.c. in syngeneic F344 rats ranged from 8 to 20%, but we could not demonstrate a significant correlation between the number of Fc receptor-positive cells within tumors and their spontaneous metastatic potentials. In macrophage-mediated cytolysis assays, cloned 13762NF cell lines of differing metastatic potential, established from tissue culture lines, fresh tumor explants, or short-term cultures (one passage in vitro), were used as targets. Effector cells were thioglycolate-elicited peritoneal macrophages (activated in vitro with bacterial lipopolysaccharide) or intratumoral macrophages (activated in vitro with lipopolysaccharide). When the effector cells were peritoneal macrophages, established cloned 13762NF cell lines showed little correlation in their susceptibility to macrophage-mediated cytolysis and metastatic potential, while this was not observed when fresh tumor explants were used. Highly metastatic MTLn3 cells were the least sensitive, less metastatic MTF7 and MTLn2 cells were more susceptible, and the low metastatic parental MTPa cells were the most sensitive in 72-h cytolysis assays. When the effector cells were intratumoral macrophages, all 13762NF cell lines showed less sensitivity in cytolysis assays than similar assays using thioglycolate-elicited peritoneal macrophages. With the exception of line MTLn2, short-term cultures (one passage in vitro) did not differ substantially in susceptibility to intratumoral macrophages compared to fresh explants. In this system, the sensitivity of 13762NF cells to macrophage-mediated cytolysis is a function of effector as well as target cell source.
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PMID:Heterogeneity in the sensitivities of the 13762NF rat mammary adenocarcinoma cell clones to cytolysis mediated by extra- and intratumoral macrophages. 397 11

Inbred RIII mice, known to be infected neonatally with murine mammary tumor virus so that females develop mammary adenocarcinoma by 12-15 months of age, were examined with regard to antisheep red blood cell antibody responses at the cellular level. Female mice, 3-11 months old, compared to male mice of the same ages had consistent and significant depression of the antibody response of their splenocytes. Furthermore, female mice with adenocarcinoma showed an even greater depression of the antibody response. Spleen sizes were consistently increased in females as compared to those of male mice throughout the first year of life. The blastogenic responsiveness of the splenocytes to the B-cell mitogen Escherichia coli lipopolysaccharide and the T-cell mitogen phytohemagglutinin-P was not significantly different between male and female mice during the same periods, although the responses of the older tumor-bearing female mice to phytohemagglutinin-P were lower than those of non-tumor-bearing female mice. A complex relationship between age, sex, and immune responsiveness was evident in these mammary tumor virus-infected mice, which made it difficult to attribute a specific immune event to emergence of the mammary adenocarcinomas in the female as compared to male mice.
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PMID:Age- and sex-related differences in antibody formation and blastogenic responsiveness of splenocytes from RIII mice developing virus-induced mammary adenocarcinoma. 627 37

Following our previous demonstration that both viable and heat-killed Mycoplasma orale induce selective tumor cell killing by murine peritoneal macrophages, further investigations reported here showed that also macrophages from a continuously proliferating cell line established from long-term cultures of murine bone marrow explants can effectively be induced by the heat-killed mycoplasmas to express cytolysis. The use of single-cell suspensions of M. orale from a 0.45-micron filtrate or following either sonication or treatment with DNase did not significantly affect the level of cytolysis. Minute quantities of M. orale acted synergistically with ineffectively low levels of either lymphokines (LK) or lipopolysaccharide (LPS) to produce killing. The exceptional resistance of M109 lung adenocarcinoma cells to macrophage-mediated killing induced by LK and LPS, as previously reported by us, could not be overcome by the addition of M. orale. These data appear to indicate a mechanism of macrophage activation by M. orale similar to that caused by LPS.
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PMID:Studies on the mechanism of macrophage-mediated tumor cell lysis induced by Mycoplasma orale. 651 64

It has been reported that treatment with cimetidine, a histamine H2-receptor antagonist, increased survival and decreased the number of lung metastases in mice bearing the Lewis Lung carcinoma [29]. It was suggested that this effect was due to the ability of cimetidine to block histamine activation of suppressor lymphocytes and hence allow host defence mechanisms to inhibit tumour growth. In the present studies, C3H/He mice were implanted with a C3H mouse mammary adenocarcinoma on Day 0. This tumour metastasizes to the lungs in 30-50 days. Primary tumours were ablated with X-rays when they had grown to about 0.2 g and animals were given drinking water with or without cimetidine (10 mg ml-1) until the end of the experiment. Cimetidine reduced the number of mice dying from metastatic disease from 7/15 (controls) to 3/13. Cimetidine treatment also prolonged survival of mice that did succumb to metastatic disease by about 12 days. The response of spleen lymphocytes to the mitogens phytohaemagglutinin and lipopolysaccharide was assessed in vitro by uptake of 3H-thymidine 0, 16, 45 and 58 days after tumour implantation. Lymphocyte responsiveness was depressed by tumour burden. The influence of cimetidine treatment was equivocal being dependent upon time after tumour implantation and dose of mitogen. In this mouse-tumour system, the mechanism of the antimetastic effect of cimetidine is different from that previously suggested [29].
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PMID:Antimetastatic effect of cimetidine on mice bearing a C3H mouse mammary adenocarcinoma: survival and lymphocyte function studies. 654 88

Rat alveolar macrophages (AM) were exposed in vivo or in vitro to nitrogen dioxide (NO2) and subsequently tested for phagocytic and tumoricidal activities. AM obtained by lavage from Fischer 344/N rats exposed for 4 h to 40 ppm NO2 were significantly more phagocytic to opsonized sheep red blood cells (SRBC), exhibited an increased cytotoxic response toward syngeneic mammary adenocarcinoma cells, and were more sensitive to activation by agents such as lipopolysaccharide, muramyl dipeptide, and macrophage-activating factor, as compared with the response of AM obtained from unexposed control rats. Repeated 4 h/d NO2 exposures over 7-d or 14-d periods usually resulted in AM activity similar to control levels, with some instances of increased phagocytic activity of the AM but not to the extent of that observed for a single 4 h exposure. There were no significant decreases in the cytotoxic or phagocytic activities of the AM during any of the exposure periods. For the in vitro exposures, AM were lavaged from normal rats and then exposed for various periods to 10, 20, or 40 ppm NO2. A dose-related and time-dependent enhanced cytotoxic response of AM was observed. Maximum AM-mediated cytotoxicity occurred after an in vitro exposure to 10 ppm NO2 for 2 h. The cytotoxic response was directed toward syngeneic mammary adenocarcinoma cells but not against syngeneic embryoblast cells, indicating that the AM retained the ability to distinguish between normal and abnormal cells. No inhibitory effects of NO2 on AM-mediated cytotoxicity were observed. These experiments suggest that the host AM-mediated immune defense of the lung may be modulated by host exposure to inhaled chemicals.
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PMID:In vivo and in vitro NO2 exposures enhance phagocytic and tumoricidal activities of rat alveolar macrophages. 682 22

Treatment of DBA/2J mice bearing a T1699 syngeneic mammary adenocarcinoma (Ts) with a single intraperitoneal (i.p.) injection of 100 ug melphalan produced complete tumor regression in about 65% of the animals treated; however, tumors recurred in about 85% of these regressors after 15-25 days' remission. The drug regimen was ineffective against Ts tumors growing in immunosuppressed or immunodeficient animals. Stimulation of immunologically intact Ts tumor-bearers with bacterial lipopolysaccharide (LPS) or with phytohemagglutinin (PHA) 3 days prior to melphalan therapy, on the other hand, produced not only higher rates of tumor regression but also significant increases in the number of permanent cures. A tumor induced by T1699 subline TR2 was resistant to the same regimen, although Ts and TR2 cells were equally susceptible to the cytotoxic and growth-inhibiting activities of the drug in vitro. In contrast, the combination of specifically armed monocytes and melphalan in vitro produced enhanced killing of Ts cells but not of TR2 cells. Analysis of the collaborative cytotoxicity between immune effector cells and melphalan indicated that exposure of tumor cells to killer cells increased the drug susceptibility of the tumor cells, but not the reverse. These results suggest a possible mechanism for in vivo resistance of tumors to chemotherapeutic agents that is not directly associated with the drug resistance of the tumor cells in vitro.
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PMID:Collaboration between specific anti-tumor immunity and chemotherapeutic agents. 696 55

A combination of lentinan and bacterial lipopolysaccharide (LPS), previously reported to have strong antitumor activity against some tumors, was only slightly effective on solid-type MH134 hepatoma and colon 38 adenocarcinoma and was not effective on ascitic L1210 in CDF1 mice. On the other hand, additional combination therapy with cyclophosphamide (CY), that is, lentinan plus LPS plus CY, strongly inhibited the growth of solid-type MH134 and colon 38 adenocarcinoma even when administered from day 12 after tumor inoculation. The antitumor delayed hypersensitivity reaction against MH134 hepatoma, measured by means of the footpad test, was augmented by this combination. The possible role of CY is discussed in relation to the importance of inhibition of immune suppressive mechanisms in this combination therapy.
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PMID:Combination therapy of murine tumors with lentinan plus lipopolysaccharide plus cyclophosphamide. 716 May 85

The culture fluid taken from a human colonic adenocarcinoma cell line, SKCO-1, inhibited mitogenic stimulation of mouse lymphocytes measured by reductions in blast information or [3H]thymidine uptake. The inhibitor was not cytotoxic to lymphocytes nor did it alter the growth rates of 21 other cell lines examined. However, the in vitro growth rates of two murine lymphoid tumor lines were also markedly reduced by the SKCO-1 medium. The tumor cell culture media could be added up to 40 hr after concanavalin A stimulation and still effect complete inhibition of [3H]thymidine uptake. A similar inhibition was observed for phytohemagglutinin (from red kidney bean), lipopolysaccharide, and mixed lymphocyte response assays. The inhibitor has a molecular weight of greater than 100,000 and is stable to heat and ultraviolet radiation, but is destroyed by mild periodate oxidation. The inhibitor may play a role in immunosuppression.
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PMID:An inhibitor of lymphocyte proliferation produced by a human colonic adenocarcinoma cell line in culture. 734 1

Bacterial lipopolysaccharide (LPS) has been recognized as one of the most potent activating signals for mouse peritoneal macrophages. In macrophages primed by interferon-gamma (IFN-gamma) or trehalose dimycolate (TDM), LPS induces NO synthase and the events associated with a high nitric oxide output: antitumor and antiparasitic activities. In the present report, it is shown that drugs (calcium ionophores or thapsigargin) which elevate the concentration of cytosolic calcium, [Ca2+]i, induce NO synthase and antitumor activities in primed macrophages, mimicking LPS action. Calcium ionophores and thapsigargin trigger NO synthase activity in macrophages primed in vivo by TDM, in thioglycollate-elicited macrophages primed in vitro by IFN-gamma, and in IFN-gamma-treated EMT6 adenocarcinoma cells. However, activation of TDM-primed macrophages by LPS does not seem to involve calcium fluxes: (i) no change in [Ca2+]i was detectable in TDM-primed macrophages loaded with Fura-2 and exposed to LPS, and (ii) activation of TDM-primed macrophages by LPS can be obtained in the presence of 4 mM EGTA. NO synthase expression is thus controlled in primed macrophages by two different pathways; calcium ionophores can replace LPS but do not act through the same intracellular cascade.
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PMID:Role of calcium in the activation of mouse peritoneal macrophages: induction of NO synthase by calcium ionophores and thapsigargin. 750 25

Activated rodent macrophages inhibit micro-organism and tumour cell growth through a high output of nitric oxide; generated by an isoform of nitric oxide synthase which is induced, for example, in murine macrophages, by concomitant stimulation with interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS). We show here that LPS could be replaced as a co-stimulant by the mycobacterial derivative muramyl dipeptide (MDP) in macrophages, and by interleukin-1 (IL-1) in EMT-6 adenocarcinoma cells. Moreover, our results indicate that nitric oxide synthase RNA synthesis required either simultaneous or sequential exposure to IFN-gamma and MDP/IL-1; whereas exposure to MDP/IL-1 followed by exposure to IFN-gamma was ineffective. Thus, two kinds of signal could be distinguished: IFN-gamma on the one hand, acting first in an irreversible way, and LPS, MDP, IL-1 on the other hand, which seemed to be permanently required for continuous transcription of the nitric oxide synthase gene.
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PMID:Involvement of nitric oxide synthase in antiproliferative activity of macrophages: induction of the enzyme requires two different kinds of signal acting synergistically. 752 17


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