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Query: UMLS:C0598934 (tumor growth)
 58,965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The potential of the immune system to inhibit or stimulate tumor growth is a vivid example of the "two-edged sword" nature of immune responses. Our results provide evidence that this dual capacity can be attributed, in part, to the dual pathways of arginine metabolism exhibited by intratumor macrophages. Specifically, i.p. tumor rejection in P815-preimmunized mice is accompanied by an upshift in intratumor macrophage arginine metabolism to the nitric oxide (NO) synthase pathway that yields citrulline and NO. A rapid and marked local increase in IFN-gamma (both mRNA and protein) in preimmunized mice during tumor rejection suggests that this cytokine plays a role in up-regulating nitric oxide production in vivo. Unlike tumor rejection, progressive i.p. P815 tumor growth in naive mice is associated with a marked decline in the production of citruline/NO by intratumor macrophages. Examination of macrophage arginine metabolism via arginase revealed a pattern opposite that of NO synthase. The local production of ornithine/urea markedly increases during progressive tumor growth whereas arginase activity decreases during tumor rejection. Inasmuch as nitric oxide inhibits tumor cell replication whereas ornithine is the precursor of polyamines required for cell replication, these results are consistent with the conclusion that the pathway macrophages use to metabolize arginine can influence the type of host immune responses against cancer and other conditions.
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PMID:Macrophage arginine metabolism and the inhibition or stimulation of cancer. 140 10

Limiting factors in systemic recombinant interleukin-2 (rIL2) therapy may be overcome by intratumoral (IT) administration. A series of experiments was conducted to assess the efficacy of IT rIL2 alone and in combination with LAK cells and IFN-gamma. C57BL/6 mice bearing B16-F10 subcutaneous tumors were randomly assigned to treatment groups including: noninjected controls, IT placebo (NaCl, D5W), IT bovine serum albumin (BSA), IT rIL2 (centrally and peripherally), IT rIL2/LAK, IT rIL2/IFN-gamma, and intraperitoneal (IP) rIL2. A tumor size-dependent dose of cytokine was injected daily and LAK cells were given weekly. Systemic immune response was assessed by splenocyte mitogenesis and T-cell subset distribution using thymidine radioassay and flow cytometry, respectively. In terms of survival and tumor growth rate, IT rIL2 was superior to noninjected control, IT placebo, IT BSA, and IP rIL2 (P less than 0.05). The addition of IT LAK cells conferred no therapeutic advantage. The combination of rIL2 and gamma IFN-gamma had a slight survival benefit over rIL2 alone (30.8 days vs 20.4 days). Histologic analysis demonstrated an increase presence of intratumoral macrophages in the IT rIL2-treated tumors (P less than 0.05). Lymphocyte mitogenesis and L3T4+ subset were not altered by any treatment. In vitro thymidine uptake by tumor cells was not affected by rIL2 nor IFN-gamma alone but the combination of rIL2 and IFN-gamma resulted in significant tumor cell growth inhibition. Spontaneous lung metastases were more prevalent following central IT rIL2 (75% vs 29%, P = 0.07) not accountable by needle trauma but avoidable by the use of peritumoral injection.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intratumoral rIL2-based immunotherapy in B16 melanoma. 140 10

Metastatic Lewis lung carcinoma (LLC) tumors stimulate myelopoiesis and, consequently, induce bone marrow cells to become immune suppressive to T cell blastogenesis and macrophage activation for tumor necrosis factor alpha (TNF-alpha) secretion. The suppressor cells phenotypically resembled granulocytic-monocytic progenitor cells. In order to diminish the presence of these immune suppressor cells, LLC-bearing mice were treated with low doses of gamma interferon (IFN-gamma) (100 units/mouse) plus TNF-alpha (10 units/mouse). Treatment of LLC-bearing mice with these low doses of IFN-gamma plus TNF-alpha diminished the suppressive activity of their bone marrow cells, as measured by the effect on normal macrophage activation to secrete TNF-alpha. In in vivo adoptive transfer studies, bone marrow from placebo-treated LLC-bearers stimulated tumor establishment and metastasis, while the bone marrow of IFN-gamma-plus TNF-alpha-treated tumor-bearers diminished LLC establishment and metastasis. The effect of the low dose treatments with IFN-gamma and/or TNF-alpha on the recurrence of excised s.c. tumors was also assessed. Treatment of mice following tumor excision with either IFN-gamma, TNF-alpha, or the combination of IFN-gamma plus TNF-alpha reduced recurrence. However, in the animals with recurring tumors only the combined IFN-gamma plus TNF-alpha treatment effectively diminished the development of lung metastases. These results demonstrate that low dose IFN-gamma plus TNF-alpha treatment diminishes the presence of suppressor and tumor growth-promoting activities of bone marrow and reduces tumor recurrence and metastasis.
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PMID:Myelopoiesis-associated immune suppressor cells in mice bearing metastatic Lewis lung carcinoma tumors: gamma interferon plus tumor necrosis factor alpha synergistically reduces immune suppressor and tumor growth-promoting activities of bone marrow cells and diminishes tumor recurrence and metastasis. 142 79

Peritumoral injection of human IL-2-activated natural killer cells into nude mice consistently induced regression of xenografts of human squamous cell carcinoma of the head and neck (SCCHN). To determine the mechanisms responsible for the tumor regression, the lymphoid cells infiltrating the tumor stroma at 24 to 48 h after adoptive immunotherapy were examined by in situ hybridization for the presence of mRNA for cytokines or IL-2R. Numerous lymphoid cells expressing cytokine or IL-2R genes were observed in these tumors, whereas the cultured IL-2-activated NK cells used for therapy were negative. Thus, it appeared that the transferred NK cells became activated in situ after coming into proximity with the tumor cells. To analyze this phenomenon, fresh or cultured human NK cells were coincubated in vitro with irradiated human SCCHN cell line, PCI-1, with or without the presence of IL-2. Expression of mRNA for IL-2R, perforin, and various cytokines was observed within 5 h. Contact with the tumor cells stimulated NK cells to proliferate, secrete IFN-gamma, TNF-alpha, and soluble IL-2R, up-regulate cell surface expression of IL2R p55 and p75 as well as CD16 Ag, and mediate higher levels of antitumor activity in 51Cr-release assays. In addition, supernatants of in vitro-activated NK cells significantly inhibited proliferation of SCCHN cell lines. By examining the effects of neutralizing mAb to various cytokines, this inhibitory activity was shown to be partially attributable to IFN-gamma. To determine the possible in vivo role of soluble factors produced by activated human NK cells, the supernatants (0.2 ml) or rIFN-gamma (10(5) U) were injected perilesionally each day for 2 wk into 3-day SCCHN established in immunosuppressed nude mice. These treatments caused significant (p less than 0.02) inhibition of tumor growth. The results of our studies indicate that human NK cells are strongly activated by SCCHN cells and that the consequent release of cytokines contribute to the regression of SCCHN growing in nude mice.
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PMID:Role of cytokines in the adoptive immunotherapy of an experimental model of human head and neck cancer by human IL-2-activated natural killer cells. 153 88

Eight patients with epithelial ovarian carcinoma persisting after chemotherapy, selected for having a residual tumor no larger than 1 cm in diameter, were treated intra-peritoneally (i.p.) with recombinant interferon-gamma twice weekly for 3 months. Toxicity consisted of fever and malaise in all patients and a transient rise in hepatic enzyme levels in 3 patients. The cytotoxic function of peripheral blood and peritoneal tumor-associated lymphocytes (TAL) and macrophages (TAM), was studied using cell lines as targets. I.p. IFN-gamma augmented the cytotoxic activity of lymphocytes and mononuclear phagocytes: stimulation was more marked and more frequently observed with TAL and occasionally TAM than with blood effectors, suggesting preferential modulation at the site of tumor growth and IFN administration. Surgical laparotomy revealed that 1 patient had a complete response, 2 a partial response and 2 had stable disease, while 3 patients had progressive disease. In this small series of patients there was no obvious, strict correlation between immunomodulation by IFN-gamma and clinical response. These results indicate that, in contrast to its lack of activity in advanced ovarian carcinoma, IFN-gamma has definite immunomodulatory and antitumor activity in the presence of limited tumor burden.
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PMID:Anti-tumor and immunomodulatory activity of intraperitoneal IFN-gamma in ovarian carcinoma patients with minimal residual tumor after chemotherapy. 156 43

The formation of blood vessels in vivo (angiogenesis) is an important process and is usually initiated in response to injury, tumor growth, or normal tissue development. We have studied the effect of human interferon (IFN) alpha (alpha) and gamma (gamma) on the capillary-like network formation in an in vitro model of angiogenesis using human umbilical vein endothelial cells (HUVEC). When HUVEC cells are plated on Matrigel (reconstituted basement membrane matrix enriched in laminin), a network of capillary like structures (endotubes) rapidly forms. IFN-alpha enhanced the tube formation in a dose-dependent manner, whereas IFN-gamma significantly inhibited the tube formation. In addition, both the enhancement and inhibition of angiogenesis by IFN-alpha and gamma was found to be greater if the cells were pretreated with IFN for 12 hr before plating on the Matrigel. These results suggest that IFN may play an important role in several vascular processes including early stages of wound healing, recanalization of thrombi, tumor growth, metastasis, normal growth, and development.
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PMID:Differential effects of interferon gamma and alpha on in vitro model of angiogenesis. 170 47

We have compared the mechanisms by which human PBL targeted with bispecific antibodies either lyse tumor cells or block their growth in culture or in mice. We found that resting PBL were unable to mediate lysis, but were able to block tumor growth. Moreover, targeted PBL were unable to lyse bystander cells, whereas targeted PBL did block the growth of bystander tumor cells in culture and in nude mice. Supernatants from cultures of targeted PBL, or from PBL grown on anti-CD3-coated flasks, blocked the growth of tumor cells in the absence of added effector cells, and antibodies against TNF-alpha and IFN-gamma reversed the inhibition of tumor growth, but had no effect upon cytolysis mediated by targeted by PBL. Our results show that targeted human PBL mediate two different antitumor activities: lysis, which occurs rapidly and requires the direct attachment of the target cell to the cytotoxic cell, and tumor growth inhibition, which is mediated by cytokines released into the medium as a result of receptor cross-linking. The inhibition of bystander tumor growth in mice by targeted PBL suggests that factor release is sufficient to block tumor growth in vivo. Targeted factor release therefore provides a mechanism by which targeted PBL could block the growth of tumor cells in vivo that were not bound by the effector cells, but which were located in the vicinity of tumor cells that were bound.
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PMID:Human peripheral blood lymphocytes targeted with bispecific antibodies release cytokines that are essential for inhibiting tumor growth. 182 9

Spontaneous SP1 murine adenocarcinoma cells transfected with the murine gamma-interferon (IFN-gamma) gene expressed IFN-gamma (SP1/IFN-gamma) failed to grow in syngeneic hosts and grew in nude mice. The rejection of SP1/IFN-gamma cells was related to the amount of IFN-gamma produced and appeared to be mediated primarily by nonspecific cellular mechanisms, although some role for T-cells in the afferent arm of this response is possible. SP1 cells are H2-Kk negative but express class I antigens when producing IFN-gamma. However, class I major histocompatibility complex (MHC) expression, while likely necessary, was insufficient in itself to prevent tumor growth since secretion of greater than 64 units/ml IFN-gamma was needed to inhibit tumorigenicity while only 8 units/ml IFN-gamma could induce class I antigens. Similar results were obtained with the murine colon carcinoma CT-26, a tumor that constitutively expresses class I MHC antigens, further supporting the contention that class I MHC expression is not essential for the rejection response induced by IFN-gamma. The failure of SP1/IFN-gamma cells to protect against a challenge with parent SP1 cells argues that factors other than IFN-gamma production or class I MHC expression are needed to induce a protective response against weakly or nonimmunogenic tumor cells.
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PMID:Reduced tumorigenicity of murine tumor cells secreting gamma-interferon is due to nonspecific host responses and is unrelated to class I major histocompatibility complex expression. 190 37

We have examined the antitumor effects of rat gamma-interferon (IFN-gamma) and human tumor necrosis factor alpha (TNF) against androgen-dependent and -independent Dunning rat prostatic tumors. In vitro studies, using the double layer soft agar assay, showed a very limited antiproliferative activity of the drugs in the dose range tested (1-1000 units IFN-gamma and/or 1-1000 ng TNF/dish). For in vivo studies IFN-gamma and TNF were administered s.c., peritumorally. IFN-gamma was given 3 times/week, 8,000 or 80,000 units/rat, and TNF 5 times/week, 10 or 100 micrograms/rat. IFN-gamma and TNF monotherapy were not significantly effective in inhibiting tumor growth, except for IFN-gamma against the androgen-independent MatLyLu tumor. Combinations of IFN-gamma and TNF had synergistic antiproliferative effects against all four tumor lines tested; however, complete growth inhibitions could not be achieved. Survival studies showed significant increase in survival of tumor-bearing rats.
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PMID:Synergistic antitumor effects of rat gamma-interferon and human tumor necrosis factor alpha against androgen-dependent and -independent rat prostatic tumors. 190 59

Recombinant human gamma-interferon (IFN-gamma) has recently been shown to enhance localization of radiolabeled monoclonal antibodies (MAb) to human colon carcinoma xenografts in athymic mice. The present study investigates the ability of gamma-interferon to enhance radioimmunotherapy of a low carcinoembryonic antigen-expressing human colon cancer (WiDr) in athymic mice. Growth curve analysis, antibody localization, and dose estimation studies were performed. A significant tumor growth delay, measured as the time to reach 1.0 g, was noted for animals receiving specific anti-carcinoembryonic antigen 90Y-MAb (ZCE025, 120 microCi) plus IFN-gamma (61.8 days) as compared to animals that received specific 90Y-MAb with phosphate-buffered saline (34.9 days; P less than 0.005). IFN-gamma (100,000 units) was given i.p. every 8 h for 2 days before and 4 days after 90Y-MAb therapy. The time required to reach 1.0 g for animals treated with nonspecific 90Y-MAb (ZME018) was significantly less either with (38.3 days) or without (34.4 days) IFN-gamma. The difference was more apparent when compared to animals receiving IFN-gamma alone (30.0 days) or phosphate-buffered saline alone (28.9 days; P less than 0.001). Increased antibody localization in the tumors of animals treated with IFN-gamma plus specific 90Y-MAb (43.2% injected dose/g) was seen in comparison to animals treated with specific 90Y-MAb without IFN-gamma (18.2% injected dose/g). The estimate of radiation dose delivered to the tumors, based on biodistribution data over time, revealed significantly higher levels in animals treated with specific 90Y-MAb with IFN-gamma (2477 cGy) compared to animals treated without IFN-gamma (1217 cGy). These results provide support for the use of gamma-interferon as an immunomodulating agent prior to radioimmunotherapy.
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PMID:Interferon enhancement of radioimmunotherapy for colon carcinoma. 190 60


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