Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

GRIM-19 (gene associated with retinoid-IFN-induced mortality 19), isolated as a cell death activator in a genetic screen used to define mechanisms involved in IFN-beta- and retinoic acid-induced cell death, codes for a approximately 16-kDa protein that induces apoptosis in a number of cell lines. Antisense ablation of GRIM-19 caused resistance to cell death induced by IFN plus retinoic acid and conferred a growth advantage to cells. To understand the molecular bases for its cell death regulatory activity, we used a yeast two-hybrid screen and identified that the transcription factor STAT3 (signal transducer and activator of transcription 3) binds to GRIM-19. GRIM-19 inhibits transcription driven by activation of STAT3, but not STAT1. It neither inhibits the ligand-induced activation of STAT3 nor blocks its ability to bind to DNA. Mutational analysis indicates that the transactivation domain of STAT3, especially residue S727, is required for GRIM-19 binding. Because GRIM-19 does not bind significantly to other STATs, our studies identify a specific inhibitor of STAT3. Because constitutively active STAT3 up-regulates antiapoptotic genes to promote tumor survival, its inhibition by GRIM-19 also demonstrates an antioncogenic effect exerted by biological therapeutics.
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PMID:The cell death regulator GRIM-19 is an inhibitor of signal transducer and activator of transcription 3. 1286 95

Human natural killer (NK) cell lines (YT and NK-92) and freshly isolated human NK cells were used to determine signal pathway (s) and their cytolysis-related molecules involved in IFNalpha-stimulated natural cytotoxicity. NK cells displayed apparently augmented cytotoxicity against target tumor cells (K562) and up-regulated gene expression of cytolytic effectors Fas-L and perforin in response to IFNalpha stimulation. Meanwhile, the tyrosine phosphorylation of STAT1 of NK cells was quickly induced, but other pathways including STAT3, STAT6, ERK1/2, p38 MAPK, JNK/SAPK, PI-3K, NF-kappaB were not or only weakly activated. Transient expression of dominant-negative form of STAT1 (DN STAT1) markedly inhibited STAT1 activation and then alleviated cytolysis activity of IFNalpha-treated YT cells, which was correlated to a markedly down-regulated expression of IRF-1, a key transcription factor necessary for cytotoxicity of IFNalpha/beta-activated NK cells. The results indicate that STAT1 activation play a crucial role in IFNalpha signaling for cytolysis function of NK cells.
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PMID:IFNalpha regulates NK cell cytotoxicity through STAT1 pathway. 1296 44

Induced chemoresistance leads to the reduction of apoptotic responses. Although several drugs are in development that circumvent or decrease existing chemoresistance, none has the potential to prevent or reduce its induction. Here, we present data from a drug that could perhaps fill this gap. Cotreatment of chemotherapy with (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU, RP101) prevented the decrease of apoptotic effects during the course of chemotherapy and reduced nonspecific toxicity. Amplification of chemoresistance genes (Mdr1 and Dhfr) and overexpression of gene products involved in proliferation (DDX1) or DNA repair (UBE2N and APEX) were inhibited, whereas activity of NAD(P)H: quinone oxidoreductase 1 (NQO1) was enhanced. During recovery, when treatment was with BVDU only, microfilamental proteins were up-regulated, and proteins involved in ATP generation or cell survival (STAT3 and JUN-D) were down-regulated. That way, in three different rat tumor models, the antitumor efficiency of chemotherapy was optimized, and toxic side effects were reduced. Because of these beneficial properties of BVDU, a clinical pilot Phase I/II study with five human tumor entities has been started at the University of Dresden (Dresden, Germany). So far, no unwanted side effects have been observed.
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PMID:Inhibition of induced chemoresistance by cotreatment with (E)-5-(2-bromovinyl)-2'-deoxyuridine (RP101). 1452 95

IL-6 is an inflammatory cytokine that has been linked to aggressive prostate cancer (PCa). Previous studies have demonstrated that IL-6 can enhance the differentiation of PCa cells toward a neuroendocrine (NE) phenotype, a possible indicator of hormone-refractory disease. In this report, we present evidence that the mechanism of IL-6-stimulated NE differentiation employs a detergent-resistant (lipid raft) membrane compartment for signal transduction in LNCaP PCa cells. Signal transducer and activator of transcription (STAT)3, a mediator of IL-6 signaling, was rapidly phosphorylated and translocated to the nucleus in LNCaP cells treated with IL-6. Both processes were inhibited by filipin, a cholesterol-binding compound that disrupts plasma membrane lipid rafts. Isolation of Triton X-100-insoluble raft fractions from LNCaP cells by discontinuous sucrose gradient centrifugation demonstrated that the 80-kDa IL-6 receptor localized almost exclusively to the raft compartment. Although STAT3 was located predominantly in the Triton X-100-soluble subcellular fraction in exponentially growing cells, abundant phosphorylated STAT3 was detected in the raft fraction after stimulation with IL-6. Increases in expression of the NE marker, neuron-specific enolase, and neuron-specific enolase promoter activity after IL-6 treatment were reduced after membrane rafts were disrupted by filipin treatment. LNCaP cells expressed the raft-resident proteins flotillin-2 and G(ialpha2), but notably not caveolins, the predominant structural protein present in caveolar membrane rafts in many tissues and tumor cells. These results are the first to define a role for lipid raft membrane microdomains in signal transduction mechanisms capable of promoting the NE phenotype in PCa cells, and they demonstrate that the raft compartment is capable of mediating such signals in the absence of caveolins. Our results also suggest a mechanistic role for membrane cholesterol in cell signaling events relevant to PCa progression.
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PMID:Involvement of cholesterol-rich lipid rafts in interleukin-6-induced neuroendocrine differentiation of LNCaP prostate cancer cells. 1456 1

Pancreatic ductal adenocarcinoma (PDAC) cell lines, MIA PaCa-2, and UK Pan-1, were used to investigate the role of ErbB2 in PDAC oncogenesis. Both these cell lines exhibit exogenous growth factor-independent proliferation that was attributed to the production of autocrine growth factors and/or overexpression of growth factor receptors. The exogenous growth factor-independent phenotype displayed by these PDAC cell lines was dependent on ErbB2 kinase activity since treatment of cells with tyrphostin AG879 prevented serum-free media (SFM) induction of cell proliferation. We determined that ErbB2 kinase contributed to aberrant cell cycle regulation in PDAC through the induction of cyclin D1 levels and the suppression of p21(Cip1) and p27(Kip1). Inhibition of ErbB2 kinase led to cell cycle arrest marked by an increased association of p27(Kip1) with cdk2 and reduced levels of phosphorylated pRb. We further observed constitutive STAT3 activation in the PDAC cell lines and an increase in STAT3 activation upon stimulating quiescent cells with SFM. Inhibitors of ErbB2 kinase blocked STAT3 activation, whereas inhibition of EGFR kinase led to a slight reduction of STAT3 activation. STAT3 was coimmunoprecipitated with ErbB2. SFM stimulation caused an increase in the association of ErbB2 and STAT3, which was blocked by inhibition of ErbB2 kinase. Expression of a STAT3 dominant negative prevented SFM-stimulated cell proliferation of MIA PaCa-2 cells, suggesting that activation of STAT3 by ErbB2 is required for a growth factor-independent phenotype of these cells. Consistent with this observation in PDAC cell lines, we found that most PDAC tumor specimens (10 of 11) showed constitutive activation of STAT3 and that ErbB2 was readily detected in most of these tumors (nine of 11). We believe that these findings indicate a novel mechanism of oncogenesis in PDAC and may suggest future therapeutic strategies in the treatment of PDAC.
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PMID:Autocrine-mediated ErbB-2 kinase activation of STAT3 is required for growth factor independence of pancreatic cancer cell lines. 1458 4

Abnormal differentiation of myeloid cells is one of the hallmarks of cancer. However, the molecular mechanisms of this process remain elusive. In this study, we investigated the effect of tumor-derived factors on Janus kinase (Jak)/STAT signaling in myeloid cells during their differentiation into dendritic cells. Tumor cell conditioned medium induced activation of Jak2 and STAT3, which was associated with an accumulation of immature myeloid cells. Jak2/STAT3 activity was localized primarily in these myeloid cells, which prevented the differentiation of immature myeloid cells into mature dendritic cells. This differentiation was restored after removal of tumor-derived factors. Inhibition of STAT3 abrogated the negative effects of these factors on myeloid cell differentiation, and overexpression of STAT3 reproduced the effects of tumor-derived factors. Thus, this is a first demonstration that tumor-derived factors may affect myeloid cell differentiation in cancer via constitutive activation of Jak2/STAT3.
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PMID:Hyperactivation of STAT3 is involved in abnormal differentiation of dendritic cells in cancer. 1468 56

Patients with multiple myeloma (MM) with mutated RAS are less likely to respond to chemotherapy and have a shortened survival. Therefore, targeting RAS farnesylation may be a novel approach to treatment of MM. We evaluated the activity and tolerability of the farnesyltransferase (FTase) inhibitor tipifarnib (Zarnestra) in a phase 2 trial as well as its ability to inhibit protein farnesylation and oncogenic pathways in patients with relapsed MM. Forty-three patients (median age, 62 years [range, 33-82 years]) with a median of 4 (range, 1-6) chemotherapy regimens entered the study. Tipifarnib, 300 mg orally twice daily, was administered for 3 weeks every 4 weeks. The most common toxicity was fatigue occurring in 66% of patients. Other toxicities included diarrhea, nausea, neuropathy, anemia, and thrombocytopenia. Sixty-four percent of the patients had disease stabilization. Treatment with tipifarnib suppressed FTase (but not geranylgeranyltransferase I) in bone marrow and peripheral blood mononuclear cells and also inhibited the farnesylation of HDJ-2 in unfractionated mononuclear cells and purified myeloma cells. Inhibition of farnesylation did not correlate with disease stabilization. Finally, tipifarnib decreased the levels of phosphorylated Akt and STAT3 (signal transducer and activator of transcription 3) but not Erk1/2 (extracellular signal regulated kinase 1 and 2) in bone marrow cells. We conclude that tipifarnib is tolerable, can induce disease stabilization, and can inhibit farnesylation and oncogenic/tumor survival pathways.
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PMID:Farnesyltransferase inhibitor tipifarnib is well tolerated, induces stabilization of disease, and inhibits farnesylation and oncogenic/tumor survival pathways in patients with advanced multiple myeloma. 1472 2

Crk-associated substrate (Cas) is highly phosphorylated by v-Src and plays a critical role in v-Src-induced cell transformation. In this study, we found that the Src homology (SH) 3 domain of Cas blocked v-Src-stimulated anchorage-independent cell growth, Matrigel invasion, and tumor growth in nude mice. Biochemical analysis revealed that the Cas SH3 domain selectively inhibited v-Src-stimulated activations of AKT and JNK, but not ERK and STAT3. Attenuation of the AKT pathway by the Cas SH3 domain rendered v-Src-transformed cells susceptible to apoptosis. Inhibition of the JNK pathway by the Cas SH3 domain led to suppression of v-Src-stimulated invasion. Taken together, our results indicate that the Cas SH3 domain has an anti-tumor function, which severely impairs the transforming potential of v-Src.
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PMID:Blockade of v-Src-stimulated tumor formation by the Src homology 3 domain of Crk-associated substrate (Cas). 1474 71

Deficient T cell immune function and intracellular signaling in cancer patients may result from effects of tumors or their products on lymphocytes. Recently, it was demonstrated that several ovarian carcinoma cell lines could produce soluble factors that inhibited T cell proliferation. The aim of this study is to assess the effect of supernatants from 3 ovarian carcinoma cell lines (OVCAR3, CAOV3, SKOV3) on signal transduction elements that are linked to the IL-2R and its JAK-STAT pathway. A profound inhibition of proliferation, lower level of IFN-gamma and higher level of IL-10 gene expression were observed when CD8+ T cells were co-cultured with supernatants from 3 ovarian carcinoma cell lines. Cell cycle studies on inhibited CD8+ T cells showed most of them were growth arrested in G0/G1 phase. Western blot analysis showed that tumor supernatants suppressed expression of JAK3 and tyrosine phosphorylation of STAT5. JAK1 was not altered and the inhibition of STAT3 only appeared in OVCAR3 cells. Tumor supernatants also partially blocked induction of IL-2R beta and gamma chains expression. These findings suggest that ovarian carcinoma cells may suppress T cell proliferation through inhibition IL-2 dependent signaling pathways, which may be a mechanism of ovarian carcinoma induced immunosuppression.
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PMID:Ovarian carcinoma cells inhibit T cell proliferation: suppression of IL-2 receptor beta and gamma expression and their JAK-STAT signaling pathway. 1474 32

To search for the signaling events in lung carcinoma relevant to its tumorigenesis, we investigated the phosphorylation of MAPK and STAT3 in human lung carcinoma tissues and their paired normal tissues. Although relative amounts of MAPK levels differed among the cases examined, no clear difference in MAPK levels was observed between tumor tissues and their paired normal tissues. Of 79 cases examined, only 7 cases (8.9%) showed tumor-specific phosphorylation of MAPK, whereas 41 cases (52%) showed more than 2-fold lower levels of MAPK phosphorylation in tumor tissues. In contrast to MAPK, 42 cases (53%) showed tumor-specific increase in STAT3 expression. In addition, 15 cases (19%) showed tumor-specific increase of STAT3 phosphorylation and 51 cases (65%) had STAT3 phosphorylation proportional to its expression. Moreover, exogenous expression of either JAB or dominant negative STAT3 in lung carcinoma cell lines led to the suppression of STAT3 phosphorylation and the drastic reduction of anchorage- independent growth of the cells. Taken together, our results suggest that JAK-STAT3 signaling has a pivotal role for oncogenic growth of lung carcinoma cells.
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PMID:STAT3 and MAPK in human lung cancer tissues and suppression of oncogenic growth by JAB and dominant negative STAT3. 1501 Aug 32


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