Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0178874 (tumor progression)
 40,807 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tumors escape immune-mediated rejection by a variety of mechanisms during tumor progression. The elucidation of these mechanisms in vivo suffers from a lack of suitable models of spontaneous tumor formation escaping active specific immunotherapy (ASI). In a rat neu transgenic (rNeu-TG) mouse model of spontaneous breast tumor formation, we showed that rNeu-TG mice developed late escape tumors despite the presence of a persistent rNeu-specific immune response after ASI. Cell suspensions derived from these escape tumors grew in vaccinated tumor-free mice, whereas injected spontaneous tumor cells were rejected. Escape tumors retained rNeu or MHC class I expression but significantly upregulated Fas (CD95, Apo-1) ligand. We further demonstrated that Fas-L on escape tumor cells correlated with apoptosis of infiltrating T lymphocytes. Thus, our results provide evidence that spontaneous breast tumors upregulate Fas-L expression after vaccination that may promote tumor escape in vivo after ASI.
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PMID:Role of Fas ligand expression in promoting escape from immune rejection in a spontaneous tumor model. 1125 77

Tumors may escape a host's immune response by means of various mechanisms. The Fas (CD95/APO-1)/Fas ligand (FasL) system is one of the major apoptotic pathways. Recently, it has been reported that tumor cells can express FasL, induce apoptosis in tumor infiltrating lymphocytes, and thus can escape host immune surveillance. In gastric carcinoma, tumor progression by way of the lymphatics is often seen, and lymph node metastasis is a critical factor influencing the recurrence of cancer and its prognosis. We, therefore, investigated the relationship between the expression of FasL and the lymphatic spread of gastric carcinoma. FasL-expression was examined by an immunohistochemical method using 100 surgically resected gastric carcinomas and 55 metastatic lymph nodes. Apoptotic cells among tumor infiltrating T lymphocytes were detected by T lymphocyte staining and the terminal deoxynucleotidyl transferase (TdT) mediated dUTP nick end labeling (TUNEL) method in a series of sections of metastatic lymph nodes. FasL-expression was detected in 86% of primary lesions and 71% of metastatic lymph nodes. In cases with high levels of FasL-expression, the observed expression of lymph node metastases was significant (p=0.047). Moreover, FasL-positive cases with both primary lesions and metastatic lymph nodes showed also distant lymph node metastasis beyond the regional lymph nodes (p=0.030). Apoptosis among tumor infiltrating T lymphocytes was more frequently seen in FasL-positive lesions (p=0.057). Furthermore, patients with FasL-negative primary lesions tended to exhibit longer survival times than patients with FasL-positive primary lesions. The results suggest tumor escape through the lymphatic pathway via FasL-expression in gastric carcinomas.
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PMID:Expression of Fas ligand in gastric carcinoma relates to lymph node metastasis. 1135 Dec 45

Glioblastoma multiforme (WHO grade IV; GBM) is the most common primary brain tumor with a median survival of less than one year despite multimodal treatment regimens. However, a small subgroup of GBM patients has a better clinical outcome, with a small number of patients surviving several years. Apoptosis, a genetically determined program of cell suicide, may be induced as a consequence of critical DNA damage. However, due to defects in the signaling pathways, cancer cells may escape apoptosis, despite carrying irreversible DNA damage. In the present study, we have analyzed tumors of two age-matched, equally treated groups of GBM patients with different postoperative time to tumor progression (TTP), defined as 'short-term' for TTP of less than 6 months (n = 54), and 'long-term' for TTP of more than 12 months (n = 39) for alterations in apoptosis regulatory pathways: Mutations of the TP53 tumor suppressor gene and/or nuclear accumulation of its gene product p53, expression of Waf/p21, CD95 (Apo1/Fas), and Bcl-2. TP53 mutations were found in 12 out of 54 (22%) GBMs of short-term survivors and 8 out of 35 (23%) tumors of long-term survivors; the respective numbers for nuclear p53 protein accumulation were 12/53 (23%) and 10/37 (27%). Waf1/p21 expression was found in 13/53 (25%) tumors of short-term survivors and 9/35 (26%) GBMs of long-term survivors. The respective numbers for Bcl-2 expression were 25/42 (60%) and 22/36 (61%) and for CD95 (Apo1/Fas) expression 20/49 (41%) and 14/36 (39%) GBMs. The percentage of alterations in genes/proteins involved in the apoptotic pathway investigated here was virtually identical in the two groups of clinically different GBM patients. Thus, our data imply that none of these alterations investigated per se has a strong impact on the overall survival of GBM patients.
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PMID:TP53 gene mutations, nuclear p53 accumulation, expression of Waf/p21, Bcl-2, and CD95 (APO-1/Fas) proteins are not prognostic factors in de novo glioblastoma multiforme. 1151 57

Factors that govern host-tumor interaction play a critical role in tumor progression. In previous studies we have shown that oncogenic Ras inhibits the expression of Fas (CD95) and renders Ras-transformed cells resistant to Fas-induced death. We now demonstrate that culture of Ras-transformed cells in the presence of the farnesyltransferase inhibitor (FTI) LB42722 leads to up-regulation of Fas expression, both under basal growth conditions and in the presence of the inflammatory cytokines IFN-gamma and tumor necrosis factor alpha. This is manifested by an increase in fas mRNA, Fas cell surface expression, and Fas-induced apoptosis. Whereas FTI up-regulates expression of FAS in Ras-transformed cells, it inhibits the expression of vascular endothelial growth factor. Culture of Ras-transformed cells in the presence of the histone deacetylase inhibitor trichostatin A resulted in morphological reversion and G(1) arrest (as observed with FTI); however, no induction of Fas was observed. Furthermore, the effects of FTI on Fas-induced death were shown to be independent of RhoB. Therefore, inhibition of oncogenic Ras by FTI can result in two events that alter host-tumor interactions: up-regulation of Fas, rendering tumors more sensitive to immune cytotoxic effector cells, and down-reglation of VEGF, which may inhibit tumor angiogenesis.
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PMID:Farnesyltransferase inhibitors reverse Ras-mediated inhibition of Fas gene expression. 1180 95

Studies concerning the expression of the receptor CD95 (Fas) by tumor cells and the role of this protein in apoptosis induced by the effector host cells that bear Fas-ligand are mainly focused on the membrane-bound form of Fas. There are only a few data about the production of the soluble form of Fas by the tumor cells, its role in the interaction with the effector host cells, and the possible changes in the synthesis of this protein during tumor progression. In the present work, three in vitro transformed parental cell lines of different origin and 24 of their variants isolated after a short cycle of natural selection in vivo were studied. It was demonstrated for the first time that: 1) production of the soluble Fas by all selected in vivo variant tumor cell lines increased significantly (2-10-fold) in comparison to the initial (parental) cell lines and did not depend on the origin of the parental lines. At the same time, the expression of the membrane-bound form of Fas decreased considerably; 2) variations of the balance between membrane-bound and soluble forms of Fas in selected in vivo variant cells and the expression of the [H(2)O(2)(CA) + PGE(S)]-phenotype by these cells (this phenotype determines one of the essential mechanisms of the protection of a tumor cell in vivo) possibly represent independent secondary changes acquired during tumor progression in vivo.
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PMID:Changes in the balance between membrane-bound and soluble forms of CD95 (Fas) during selection of tumor cells in vivo. 1195 21

Attractive targets for cancer therapy are gene products whose inactivation is not detrimental in essential tissues. The GAGE family of Cancer/Testis Antigens is a group of appealing candidates for cancer therapy since they are expressed in a wide variety of human tumors and are silent in most adult tissues, with the exception of testis. Interestingly, expression of GAGE has been associated with poor prognosis in some cancers. Nevertheless, no function has been reported for any of the GAGE family members. Here we describe for the first time an anti-apoptotic activity exerted by GAGE. We have cloned GAGE-7C from HeLa cells and showed that it renders transfected cells resistant to apoptosis induced by Interferon-gamma (IFN-gamma) or by the death receptor Fas/CD95/APO-1. Similarly, transfection of GAGE-7/7B also confers resistance to Fas induced apoptosis. In the Fas pathway, the anti-apoptotic activity of GAGE-7C maps downstream of caspase-8 activation and upstream of poly (ADP-ribose) polymerase (PARP) cleavage. Furthermore, GAGE-7C renders the cells resistant to the therapeutic agents Taxol and gamma-irradiation. Following the various apoptotic stimuli, the surviving GAGE-7C transfectants actively proliferate and exhibit enhanced long term survival in colony formation assays. Overall, our data establishes a functional link between GAGE-7C and two aspects of human tumor progression; namely, resistance to Fas induced apoptosis and to chemo- and radio-therapy.
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PMID:A member of the GAGE family of tumor antigens is an anti-apoptotic gene that confers resistance to Fas/CD95/APO-1, Interferon-gamma, taxol and gamma-irradiation. 1243 52

The CD95 (Apo-1/Fas) receptor-ligand system is a key regulator of apoptosis. Down-regulation of CD95 receptor and up-regulation of CD95 ligand has been reported in a variety of human tumors and is thought to confer a selective survival advantage. To explore the relevance of the CD95 system for tumor progression and prognosis in clear cell renal cell carcinomas (RCCs), we analyzed CD95 receptor and ligand expression in formalin-fixed tissue from 149 clear cell RCCs by immunohistochemistry. CD95 ligand expression could not be detected in nonneoplastic tubule epithelia and in clear cell RCCs. In contrast, CD95 receptor expression was found in the great majority of clear cell RCCs, and no down-regulation of CD95 receptor protein was evident when compared with nonneoplastic tubule epithelia. Although a significant increase (P = 0.004) of CD95 receptor expression was evident from well-differentiated (G1) to poorly differentiated (G3) RCCs, CD95 receptor expression was not correlated with tumor stage or survival of RCC patients. In conclusion, clear cell RCCs differ from other types of human cancer by their failure to down-regulate CD95 receptor expression or up-regulate CD95 ligand expression during tumor progression. These ex vivo observations suggest that down-regulation of CD95 receptor expression may not provide an additional selective growth advantage to RCC cells and thus further confirm our previous in vitro observations on a functional impairment of CD95-mediated apoptosis in RCC.
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PMID:Prognostic implications of CD95 receptor expression in clear cell renal carcinomas. 1261 86

FasL (CD95L) is a well-known and well-characterized death-inducing ligand. Spontaneous mutations in FasL and its cognate receptor Fas (CD95) have helped understand the role of these molecules in the disease. Once thought to be mainly involved in the homeostasis of immune system, the territory of FasL regulation has been expanded to angiogenesis and tumor progression. Here, we review what is currently known about the role of FasL in many areas of biology.
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PMID:Biology of FasL. 1278 69

Many tumors express the death ligand CD95L (CD178, APO-1L, FasL) and can kill activated T cells in vitro. This may enable the tumor cells to suppress anti-tumor immune responses, a phenomenon called "tumor counterattack". Preliminary evidence of tumor counterattack in human tumors exists. However, CD95L-expressing tumors are rapidly rejected in mice. In order to clarify this controversial situation we investigated whether the level or the time point of CD95L expression might be critical factors determining tumor counterattack versus tumor rejection. We generated CD95-resistant tumor cell lines expressing different levels of CD95L (LKC-CD95L). In nude mice the CD95L expression level had no influence on the growth of the CD95L(+) tumors. In contrast, a CD95L(-) control tumor cell line (LKC) grew much faster. In addition, we generated a CD95-resistant cell line in which CD95L was induced via the tet system (LKCR-tetCD95L). Induction of CD95Lin established tumors in nude and NOD/SCID mice led to rapid rejection of the tumors. Induction of lower CD95L expression levels delayed tumor rejection only marginally. These results demonstrate that rejection of CD95L-expressing tumors in mice is not a result of overexpression and does not depend on the presence of CD95L at the onset of tumor progression.
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PMID:The influence of CD95L expression on tumor rejection in mice. 1451 65

Resistance to apoptosis may be related to tumor progression, due to the implications it might have on both tumor mass and genetic instability. We compared the tendency to spontaneous apoptosis and the proliferative capacity of metastatic growths of several AKR lymphoma variants (TAU-45, TAU-47, TAU-44, TAU-33, TAU-42 and TAU-46, in the order of increasing metastatic potential). We further compared the expression of several apoptosis-related genes. Cell proliferative capacity did not appear to determine malignant behavior since, on the whole, a decrease in S + G2M fraction was observed with increasing malignancy. Sensitivity to apoptotic cell death decreased with increasing malignancy when comparing the TAU-45, TAU-47, TAU-44 and TAU-33 variants, suggesting a role of reduced apoptosis in this T-cell lymphoma. An increase in Bcl-2 content with increasing aggressiveness among these variants, implicates this protein in this tumor progression-related resistance to apoptosis. However, the two variants of highest malignancy, TAU-42 and TAU-46, did not follow the same trend, since they displayed a relatively high content in apoptotic cells and a low Bcl-2 content. Fas receptor expression did not correlate with tendency to apoptosis, indicating that malignant behavior in the AKR lymphoma does not depend on CD95/Fas/APO1 downregulation. Overexpression of p53 was observed only in one of the variants of lowest malignancy.
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PMID:Apoptotic cell death and related gene expression in metastatic tumors of AKR lymphomas of varying malignancy. 1463 27


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