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

Leukocyte homing is a complex, multistep process involving the coordinated expression of adhesion molecules and certain chemotactic cytokines, termed chemokines. Although chemokines initially burst into the literature as potent inflammatory mediators, it is now clear that they are involved in a variety of processes including lymphocyte maturation, angiogenesis, and tumor growth. Furthermore, a variety of important pathogens manipulate various chemokine/receptor pathways to infect the host and evade the immune system.
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PMID:Key role of chemokines and chemokine receptors in inflammation, immunity, neoplasia, and infectious disease. 1049 Feb 3

Despite the youth of the chemokine field, many antagonists of chemokine function have already been identified and tested at the preclinical level. These include neutralizing antibodies, peptidyl and non-peptidyl antagonists and non-specific immunosuppressive agents. These early studies suggest that chemokine agonists have the potential to regulate many diseases, ranging from HIV-1 infection and tumor growth to acute and chronic inflammation. Clinical application will depend on pharmaceutical development. Great strides have been made in defining structural domains of the chemokines involved in receptor binding and activation. The identification of receptors is rapidly progressing, but with 50 potential ligands and 15 characterized receptors, it is obvious that additional molecular studies are needed. The intriguing observation that several pathogens either use chemokine receptors as entry portals or produce chemokine decoys to subvert the immune system suggests that there is much to be learned about the immune system from studies of "virokines." Future studies should lead to the discovery and design of more effective inhibitors and antagonists with therapeutic benefit.
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PMID:Chemokines as molecular targets for therapeutic intervention. 1053 4

The systemic transfer of ex vivo-activated tumor-sensitized T lymphocytes can mediate immunologically specific regression of established tumors. However, it has not been conclusively established whether the infiltration of systemically transferred T cells into metastases is required for their effector function. In this study, T cells from lymph nodes draining the murine fibrosarcoma MCA 205 cells were activated ex vivo with anti-CD3 monoclonal antibody and interleukin-2. During the final 24 h of culture, the T cells were treated with pertussis toxin (PTX) to inhibit signaling through G protein-coupled chemokine receptors required for diapedesis. Systemically transferred PTX-treated cells did not have any therapeutic efficacy against 3-day established pulmonary metastases. This lack of efficacy correlated with their failure to infiltrate the tumor parenchyma. However, PTX-treated cells responded to tumor antigen stimulation with IFN-gamma secretion in vitro. More importantly, PTX-treated effector T cells prevented tumor growth when they were admixed with tumor cells and inoculated s.c. These results demonstrate that systemically transferred tumor-reactive T lymphocytes need to infiltrate the tumor parenchyma through the endothelium to initiate tumor regression, but PTX-sensitive proteins are not required for either antigen recognition or effector functions.
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PMID:Infiltration of tumors by systemically transferred tumor-reactive T lymphocytes is required for antitumor efficacy. 1053 4

Monocyte chemotactic protein-1 (MCP-1, CCL2) is an important determinant of macrophage infiltration in tumors, ovarian carcinoma in particular. MCP-1 binds the chemokine receptor CCR2. Recent results indicate that proinflammatory and anti-inflammatory signals regulate chemokine receptor expression in monocytes. The present study was designed to investigate the expression of CCR2 in tumor-associated macrophages (TAM) from ovarian cancer patients. TAM isolated from ascitic or solid ovarian carcinoma displayed defective CCR2 mRNA (Northern blot and PCR) and surface expression and did not migrate in response to MCP-1. The defect was selective for CCR2 in that CCR1 and CCR5 were expressed normally in TAM. CCR2 gene expression and chemotactic response to MCP-1 were decreased to a lesser extent in blood monocytes from cancer patients. CCR2 mRNA levels and the chemotactic response to MCP-1 were drastically reduced in fresh monocytes cultured in the presence of tumor ascites from cancer patients. Ab against TNF-alpha restored the CCR2 mRNA level in monocytes cultured in the presence of ascitic fluid. The finding of defective CCR2 expression in TAM, largely dependent on local TNF production, is consistent with previous in vitro data on down-regulation of chemokine receptors by proinflammatory molecules. Receptor inhibition may serve as a mechanism to arrest and retain recruited macrophages and to prevent chemokine scavenging by mononuclear phagocytes at sites of inflammation and tumor growth. In the presence of advanced tumors or chronic inflammation, systemic down-regulation of receptor expression by proinflammatory molecules leaking in the systemic circulation may account for defective chemotaxis and a defective capacity to mount inflammatory responses associated with advanced neoplasia.
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PMID:Defective expression of the monocyte chemotactic protein-1 receptor CCR2 in macrophages associated with human ovarian carcinoma. 1062 17

Continuous expression of the MGSA/GROalpha, beta, or gamma chemokine bestows tumor-forming capacity to the immortalized murine melanocyte cell line, melan-a. The mechanism for this transformation is unclear, although both autocrine and paracrine processes are possible because melan-a cells as well as endothelial cells express a low level of the receptor for this ligand. To further define the role of MGSA/GRO proteins in melanocyte transformation, two types of experiments were designed to neutralize the biological effects of MGSA/GRO in the transfected melan-a clones: (1) the effect of neutralizing antiserum to MGSA/GRO proteins on melan-a tumor growth was assessed; (2) the tumor-forming capacity of melan-a clones expressing ELR motif-mutated forms of MGSA/GRO with compromised receptor affinity was compared to the tumor-forming capacity of clones expressing wild-type MGSA/GRO. These experiments revealed that SCID mice inoculated with MGSA/GROalpha- or gamma-expressing melan-a cells and subsequently treated with antiserum to the respective chemokine exhibited decreased tumor growth. This reduction in tumor growth was accompanied by declining angiogenic activity in MGSA/GROgamma-expressing tumors. Moreover, athymic nude mice injected with melan-a cells expressing ELR-mutant forms of MGSA/GROalpha exhibited markedly impaired tumor-forming capacity compared with those mice injected with melan-a clones expressing wild-type MGSA/GRO. These data suggest that continuous expression of MGSA/GRO proteins may facilitate tumor growth by stimulating the growth of microvessels into the tumor (paracrine) and by affecting melanocyte growth (autocrine).
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PMID:The tumorigenic and angiogenic effects of MGSA/GRO proteins in melanoma. 1064 98

Paclitaxel is a frontline therapy for ovarian cancer. Our laboratory has shown that paclitaxel induces IL-8, a member of the C-X-C family of chemokines, in subsets of human ovarian cancer cells. However, the critical issue concerns the biological significance of this chemokine in human ovarian cancer. To study the influence of IL-8 on tumor growth, human ovarian cancer cell lines were transfected with an expression vector for human IL-8 and tested for their ability to form tumors in nude mice. IL-8 expression by the transfected cells did not alter their growth properties in vitro. In contrast, tumor growth in vivo was significantly attenuated in animals receiving IL-8-expressing cells when compared with mice injected with control cells. As additional evidence that IL-8 is a crucial factor in tumor growth, it was noted that ovarian cell lines in which constitutive IL-8 expression is elevated did not form tumors. Injection of neutralizing Ab to IL-8 reverted the phenotype and caused tumor growth in vivo. Examination of tissue from the inoculation site revealed a dramatically elevated cellularity, containing neutrophils and macrophages, in mice receiving IL-8-expressing tumor cells. These results suggest that IL-8 production by human ovarian tumor cells can play a role in reducing the rate of tumor growth; this effect may be mediated by the increased targeting of neutrophil and other mononuclear cells to the tumor injection site. These studies indicate a role for IL-8 in ovarian cancer control and suggest that chemotherapy-induced IL-8 may have a positive role in controlling tumor growth.
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PMID:IL-8 reduced tumorigenicity of human ovarian cancer in vivo due to neutrophil infiltration. 1067 19

As an antitumor agent, interleukin-12 (IL-12) has been revealed to be a key regulator of the immune response, particularly that involving CTL and natural killer (NK) cells. We report herein the antiangiogenesis effect of IL-12 on human as well as murine tumors in NK-depleted severe-combined immunodeficient mice using fibroblasts genetically engineered to secrete this cytokine. Although the in vitro growth of tumor cells was not affected by the presence of IL-12, coinoculation of IL-12-secreting fibroblasts strongly inhibited tumor growth in immunodeficient mice. The neovascularization surrounding the tumor was remarkably inhibited in the area in which the IL-12-secreting fibroblasts were implanted, resulting in the suppression of tumor growth. Lectin staining in tumor sample sections also showed a significant reduction in the number of vessels. The RNA expression of IFN-gamma and its inducible antiangiogenic chemokine IFN gamma-inducible protein 10 was stimulated in endothelial cells cultured with IL-12. It was also found that IL-12 down-regulated the expression of the endothelial cell mitogens vascular endothelial growth factor and basic fibroblast growth factor. The antitumor effects of IL-12 were accompanied by interesting histological changes consisting of a high degree of keratinization and apoptosis and a decrease in the proliferation rate of human tumors and extensive necrosis in the murine ones.
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PMID:Direct in vitro evidence and in vivo analysis of the antiangiogenesis effects of interleukin 12. 1070 32

Secondary lymphoid tissue chemokine (SLC, also referred to as Exodus 2 or 6Ckine) is a recently identified high endothelial-derived CC chemokine. The ability of SLC to chemoattract both Th1 lymphocytes and dendritic cells formed the rationale to evaluate this chemokine in cancer immunotherapy. Intratumoral injection of recombinant SLC evidenced potent antitumor responses and led to complete tumor eradication in 40% of treated mice. SLC-mediated antitumor responses were lymphocyte dependent as evidenced by the fact that this therapy did not alter tumor growth in SCID mice. Studies performed in CD4 and CD8 knockout mice also revealed a requirement for both CD4 and CD8 lymphocyte subsets for SLC-mediated tumor regression. In immunocompetent mice, intratumoral SLC injection led to a significant increase in CD4 and CD8 T lymphocytes and dendritic cells, infiltrating both the tumor and the draining lymph nodes. These cell infiltrates were accompanied by the enhanced elaboration of Th1 cytokines and chemokines monokine induced by IFN-gamma and IFN-gamma-inducible protein 10 but a concomitant decrease in immunosuppressive cytokines at the tumor site. In response to irradiated autologous tumor, splenic and lymph node-derived cells from SLC-treated tumor-bearing mice secreted significantly more IFN-gamma, GM-CSF, and IL-12 and reduced levels of IL-10 than did diluent-treated tumor-bearing mice. After stimulation with irradiated autologous tumor, lymph node-derived lymphocytes from SLC-treated tumor-bearing mice demonstrated enhanced cytolytic capacity, suggesting the generation of systemic immune responses. These findings provide a strong rationale for further evaluation of SLC in tumor immunity and its use in cancer immunotherapy.
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PMID:Secondary lymphoid tissue chemokine mediates T cell-dependent antitumor responses in vivo. 1077 57

During the last five years, the development of bioinformatics and EST databases has been primarily responsible for the identification of many new chemokines and chemokine receptors. The chemokine field has also received considerable attention since chemokine receptors were found to act as co-receptors for HIV infection (1). In addition, chemokines, along with adhesion molecules, are crucial during inflammatory responses for a timely recruitment of specific leukocyte subpopulations to sites of tissue damage. However, chemokines and their receptors are also important in dendritic cell maturation (2), B (3), and T (4) cell development, Th1 and Th2 responses, infections, angiogenesis, and tumor growth as well as metastasis (5). Furthermore, an increase in the number of chemokine/receptor transgenic and knock-out mice has helped to define the functions of chemokines in vivo. In this review we discuss some of the chemokines' biological effects in vivo and in vitro, described in the last few years, and the implications of these findings when considering chemokine receptors as therapeutic targets.
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PMID:The biology of chemokines and their receptors. 1083 58

Although several CXC chemokines have been shown to induce angiogenesis and play roles in tumor growth, to date, no member of the CC chemokine family has been reported to play a direct role in angiogenesis. Here we report that the CC chemokine, monocyte chemotactic protein 1 (MCP-1), induced chemotaxis of human endothelial cells at nanomolar concentrations. This chemotactic response was inhibited by a monoclonal antibody to MCP-1. MCP-1 also induced the formation of blood vessels in vivo as assessed by the chick chorioallantoic membrane and the matrigel plug assays. As expected, the angiogenic response induced by MCP-1 was accompanied by an inflammatory response. With the use of a rat aortic sprouting assay in the absence of leukocytic infiltrates, we ruled out the possibility that the angiogenic effect of MCP-1 depended on leukocyte products. Moreover, the direct effect of MCP-1 on angiogenesis was consistent with the expression of CCR2, the receptor for MCP-1, on endothelial cells. Assessment of supernatant from a human breast carcinoma cell line demonstrated the production of MCP-1. Treatment of immunodeficient mice bearing human breast carcinoma cells with a neutralizing antibody to MCP-1 resulted in significant increases in survival and inhibition of the growth of lung micrometastases. Taken together, our data indicate that MCP-1 can act as a direct mediator of angiogenesis. As a chemokine that is abundantly produced by some tumors, it can also directly contribute to tumor progression. Therefore, therapy employing antagonists of MCP-1 in combination with other inhibitors of angiogenesis may achieve more comprehensive inhibition of tumor growth.
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PMID:Human endothelial cells express CCR2 and respond to MCP-1: direct role of MCP-1 in angiogenesis and tumor progression. 1089 27


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