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Query: UMLS:C0178874 (tumor progression)
 40,807 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The contribution of bacterial infection to tumorigenesis is usually ascribed to infection-associated inflammation. An alternate view is that direct interaction of bacteria with tumor cells promotes tumor progression. Here, we show that the microenvironment of large tumors favors bacterial survival, which in turn directly accelerates tumor growth by activating tumor cell Toll-like receptors (TLR). Listeria monocytogenes (Lm) survives in the microenvironment of large but not small tumors, resulting in the promotion of tumor growth. Lm did not affect the percentage of regulatory T cells or myeloid suppressor cells in the tumor. Through TLR2 signaling, Lm activated mitogen-activated protein kinases and nuclear factor-kappaB in tumor cells, resulting in the increased production of nitric oxide and interleukin-6 and increased proliferation of tumor cells. All of these effects were abrogated by silencing expression of TLR2, but not TLR4. The interaction of Helicobacter pylori with tumor cells from gastric carcinoma patients resulted in similar effects. These findings provide a new insight into infection-associated tumorigenesis and illustrate the importance of antibiotic therapy to treat tumors with bacterial infiltration.
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PMID:Listeria monocytogenes promotes tumor growth via tumor cell toll-like receptor 2 signaling. 3141 50

Circulating heat shock protein (HSP)-27 is associated with tumor progression and increased post-injury infection. Extracellular HSP-27 might alter monocyte (MO)-derived DC and/or MPhi function to mediate immunosuppression. HSP-27 treatment inhibited expression of CD1a and CD1b/c, antigen uptake, and allogeneic T cell induction (MLR) by IL-4 + GM-CSF-differentiated human DC while increasing some MPhi characteristics ( upward arrowCD14, upward arrowCD16, upward arrowCD163). MO cytokine receptor profiles elicited by 24-h exogenous HSP-27 treatment remained supportive of immature DC (iDC) emergence ( upward arrowIL-4R, downward arrowIL-6R, downward arrowM-CSFR). IL-10, IL-6, and M-CSF (which promote MPhi differentiation) were significantly increased in IL-4 + GM-CSF + HSP-27 MO-->iDC differentiation cultures. However, HSP-27 treatment during MO differentiation to DC increased programmed cell death ligand 1 coinhibitor and depressed CD86 costimulator expression in parallel to decreased iDC MLR activity. This suggested that increased MPhi differentiation was not solely responsible for HSP-27 reduction of differentiating DC activity. HSP-27 treatment actually depressed the phagocytic capacity of MO differentiated to MPhi by IL-10 or M-CSF culture. CD163 (hemoglobin receptor) expression was depressed on M-CSF + HSP-27 MO-derived MPhi. HSP-27-mediated inhibition of MO-->iDC differentiation was reversed by p38alpha & beta inhibitor (SB202190) addition or TLR4 receptor modulation. HSP-27 impaired appropriate MO-->iDC and MO-->MPhi differentiation modulating expression of receptors necessary for their proper functions. This suggests that endogenous HSP-27 has immunoregulatory activities which could contribute to immunopathology.
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PMID:Exogenous heat shock protein 27 uniquely blocks differentiation of monocytes to dendritic cells. 1782 91

Toll-like receptors (TLRs) are involved in the production of inflammatory mediators upon specific ligands stimuli. Chemokines are important inflammatory mediators capable of chemoattracting diverse immune cells. In addition to normal immune cells, the expression of TLRs and chemokines has been detected in various tumor cells. However, the roles of TLRs and chemokines expressed by tumor cells in the processes of tumor progression and immune escape have not been fully elucidated. Here we report that TLR4 ligation by lipopolysaccharide (LPS) significantly promotes CT-26 colon cancer cells to produce chemokine CCL20 via activation of TLR4 signaling pathways. We find that LPS treatment of CT-26 cells can significantly increase the chemoattraction of immature dendritic cells (DC) by the autocrine CCL20. Our studies suggest that TLR4 expressed by tumor cells may be involved in the induction of chemokines like CCL20, providing a potential linkage between chronic inflammation and tumor immune escape.
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PMID:TLR4 signaling in cancer cells promotes chemoattraction of immature dendritic cells via autocrine CCL20. 1808 11

Increasing evidences suggest that the aberrant expression of certain gangliosides on malignant cells could affect host's anti-tumour-specific immune responses. We have recently documented the relevance of the N-glycolylated variant of GM3 ganglioside (NGcGM3), a tumour-specific non-human sialic acid containing ganglioside, for tumour progression. However, evidences about the implication of host's immunity in NGcGM3-promoted cancer progression had not been obtained previously. In this work, we compared tumour growth of X63 myeloma cells pre-treated or not with an inhibitor of the glucosylceramide synthase enzyme, in wild or CD4+ T cell-depleted BALB/c mice. Results clearly showed a relationship between the agonistic effect of NGcGM3 in tumour growth and the presence of CD4+ T lymphocytes. For the first time, a description of a ganglioside-differential effect over purified CD4+CD25- and naturally occurring regulatory CD4+CD25+ T cells is provided. While NGcGM3 similarly down-modulated the CD4 expression in both cell populations, the inhibitory capacity of the CD4+CD25+ lymphocytes and their proliferation, induced by an anti-CD3 mAb and IL2, were not modified. In a different fashion, a reduction in proliferative capacity and a noteworthy secretion of anti-inflammatory cytokines were detected when CD4+CD25- T cells were cultured in the presence of NGcGM3. Considering the relevance of dendritic cells (DC) on primary activation of T cells, the effect of NGcGM3 over DC differentiation and TLR4-mediated maturation was also assessed. Our results indicate that NGcGM3 contributes to cancer progression mainly by influencing DC and CD4+CD25- T lymphocyte functions, rather than increasing the inhibitory capacity of naturally occurring regulatory T cells.
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PMID:Differential influence of the tumour-specific non-human sialic acid containing GM3 ganglioside on CD4+CD25- effector and naturally occurring CD4+CD25+ regulatory T cells function. 1831 Jun 17

Toll-like receptor 4 (TLR4) signaling in tumor cells can mediate tumor cell immune escape and tumor progression, being regarded as one of the mechanisms for chronic inflammation in tumorigenesis and progression. So, intervention of TLR4-mediated immune escape and metastasis has been proposed as one of the approaches to cancer prevention and treatment. Rapamycin, an immunosuppressant agent widely used for treatment of autoimmune diseases and transplantation rejection, is recently used for cancer therapy. However, the underlying mechanisms remain to be fully understood. In the present study, we demonstrate that rapamycin can significantly inhibit TLR4-triggered IL-6 and PGE(2) production and invasion of colon cancer cells. Suppression of TLR4-induced IL-6 and PGE(2) production is responsible for the rapamycin-mediated decrease of TLR4-evoked invasion of colon cancer cells. Furthermore, disruption of NF-kappaB pathway contributes to the inhibition of TLR4-induced IL-6, PGE(2) production and invasion by rapamycin in colon cancer cells. Rapamycin can also downregulate TLR4 expression. Therefore, we demonstrate that rapamycin may abrogate TLR4-triggered tumor cell immune escape and invasion by downregulating TLR4 expression and inhibiting TLR4-activated NF-kappaB pathway, thus providing new mechanistic explanation for the antitumor effect of rapamycin.
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PMID:Rapamycin suppresses TLR4-triggered IL-6 and PGE(2) production of colon cancer cells by inhibiting TLR4 expression and NF-kappaB activation. 3243 16

Toll-like receptor 4 (TLR4) signaling in tumor cells can promote tumor escape and tumor progression, for which TLR4-triggered resistance of tumor cells to apoptosis has been proposed as one of the mechanisms. Rapamycin is an immunosuppressant agent widely used for treatment of transplantation rejection and autoimmune diseases, and recently used for cancer therapy. However, the underlying mechanisms responsible for antitumor effects of rapamycin remain to be fully elucidated. Here we report that rapamycin can reverse TLR4-triggered resistance of colon cancer cells to oxaloplatin- or doxorubicin-induced apoptosis by disrupting Akt and subsequent NF-kappaB activation, suppressing upregulation of anti-apoptotic protein Bcl-xL. Furthermore, Akt/NF-kappaB inhibitors also reverses the apoptosis resistance, accordingly, Akt constitutive activation rescues NF-kappaB activation and Bcl-xL expression in rapamycin-pretreated colon cancer cells, suggesting Akt disruption is critical to the process. Therefore, rapamycin may abrogate TLR4-triggered tumor apoptosis resistance by inhibiting Akt/NF-kappaB pathways and Bcl-xL expression, providing experimental evidence for the anti-tumor effect of rapamycin.
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PMID:Rapamycin reverses TLR4 signaling-triggered tumor apoptosis resistance by disrupting Akt-mediated Bcl-xL upregulation. 3213 22

Toll-like receptors (TLR) have been shown to be expressed on various types of cancers; however, their functional activity is not known. We examined TLR profiles of human melanoma cells and showed that TLR2, TLR3, and TLR4 were found to be highly expressed. By PCR array analysis, specific stimulation of TLR2, TLR3, and TLR4 on melanoma cells showed significant activation of the adaptor protein MyD88, as well as downstream signal transduction factors nuclear factor-kappaB and inflammatory response-related factors. Specific ligand activation of TLR2, TLR3, and TLR4 was shown to induce cell migration. Peripheral blood lymphocytes and melanoma purified RNA was shown to activate TLR3 on melanoma cells. These studies show expression and functional activity of specific TLRs on melanoma cells and as potential therapeutic targets to control tumor progression.
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PMID:Activation of Toll-like receptors 2, 3, and 4 on human melanoma cells induces inflammatory factors. 1900 46

Recent studies have implicated inflammation in the initiation and progression of ovarian cancer, though the mechanisms underlying this effect are still not clear. Toll-like receptors (TLRs) allow immune cells to recognize pathogens and to trigger inflammatory responses. Tumor cell expression of TLRs can promote inflammation and cell survival in the tumor microenvironment. Here we sought to characterize the expression of TLRs in normal human ovaries, benign and malignant ovarian tumors from patients, and in established ovarian tumor cell lines. We report that TLR2, TLR3, TLR4, and TLR5 are strongly expressed on the surface epithelium of normal ovaries. In contrast to previous studies of uterus and endocervix, we found no cyclic variation in TLR expression occurred in murine ovaries. TLR2, TLR3, TLR4, and TLR5 are expressed in benign conditions, epithelial tumors, and in ovarian cancer cell lines. Variable expression of TLR6 and TLR8 was seen in benign and malignant epithelium of some patients, while expression of TLR1, TLR7, and TLR9 was weak. Normal and malignant ovarian stroma were negative for TLR expression. Vascular endothelial cells, macrophages, and occasional fibroblasts in tumors were positive. Functional activity for TLRs was demonstrated by stimulation of cell lines with specific ligands and subsequent activation and translocation of NFkappaB and release of the proinflammatory cytokines interleukin-6 and CCL-2. These studies demonstrate expression of multiple TLRs in the epithelium of normal ovaries and in ovarian tumor cells, and may indicate a mechanism by which epithelial tumors manipulate inflammatory pathways to facilitate tumor progression.
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PMID:Toll-like receptor expression in normal ovary and ovarian tumors. 1918 6

Myeloid-derived suppressor cells (MDSC) are potent inhibitors of anti-tumor immunity that facilitate tumor progression by blocking the activation of CD4(+) and CD8(+) T cells and by promoting a type 2 immune response through their production of IL-10 and down-regulation of macrophage production of IL-12. MDSC accumulate in many cancer patients and are a significant impediment to active cancer immunotherapies. Chronic inflammation has been shown recently to enhance the accumulation of MDSC and to increase their suppression of T cells. These findings led us to hypothesize that inflammation contributes to tumor progression through the induction of MDSC, which create a favorable environment for tumor growth. As chronic inflammation also drives type 2 immune responses, which favor tumor growth, we asked if inflammation mediates this effect through MDSC. We find that IL-1beta-induced inflammation increased IL-10 production by MDSC and induces MDSC, which are more effective at down-regulating macrophage production of IL-12 as compared with MDSC isolated from less-inflammatory tumor microenvironments, thereby skewing tumor immunity toward a type 2 response. Inflammation heightens MDSC phenotype by signaling through the TLR4 pathway and involves up-regulation of CD14. Although this pathway is well-recognized in other myeloid cells, it has not been implicated previously in MDSC function. These studies demonstrate that MDSC are an intermediary through which inflammation promotes type 2 immune responses, and they identify the TLR4 pathway in MDSC as a potential target for down-regulating immune suppression and promoting anti-tumor immunity.
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PMID:Inflammation enhances myeloid-derived suppressor cell cross-talk by signaling through Toll-like receptor 4. 1926 29

Chronic inflammation is a potential risk factor for tumor progression. The molecular mechanisms linking chronic inflammation and tumor growth have proven elusive. Herein, we describe a new role for Toll-like receptor 4 (TLR4) in tumor-associated macrophages (TAMs) in promoting tumor growth. TAMs can remodel tumor microenvironment and promote tumor growth. With the use of mice lacking TLR4 signaling, we show that TLR4 signaling influences tumor growth and that TLR4 signaling is a critical upstream activator of nuclear factor-kappa B (NF-kappaB) in TAMs. TLR4-deficient TAMs produce neither proinflammatory cytokines nor angiogenic factors, and activate no NF-kappaB activity in tumor cells. Furthermore, using macrophage/tumor cell coculture system and adoptive transfer of macrophages with functional TLR4 macrophages to TLR4-deficient mice bearing tumors, we demonstrate an essential role for TLR4 signaling in inducing NF-kappaB activity in tumor cells and enhancing tumor growth. Antibody neutralization experiments reveal that TAMs are stimulated by heat shock proteins derived from tumor cells through TLR4, leading to production of growth factors, which may in turn promote tumor growth via NF-kappaB signal pathway. Therefore, this signaling cascade may represent a therapeutic target in cancer.
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PMID:Toll-like receptor 4 signaling promotes tumor growth. 1995 54


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