UMLS:C1140680 - FACTA Search

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Query: UMLS:C1140680 (ovarian cancer)
28,141 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ovarian adenocarcinoma cell line HEY was used as an in vitro model to study the influence of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on epithelial tumours such as ovarian cancer. Serum-starved cells were treated with rhG-CSF in a time- and dose-dependent manner. Cell proliferation, measured as cell division and DNA synthesis, was stimulated about 40% by rhG-CSF. After harvesting, cells were examined for the presence of G-CSF receptor (FACS analysis and RT-PCR), as well as for expression of genes involved in mitogen signalling (ERKs, JNKs) and early gene expression (c-jun). rhG-CSF affected mitogen-activated pathways and was receptor-mediated if the G-CSF receptor was present. After rhG-CSF induction, Janus N-terminal kinases (JNK 1 and 2) were simultaneously increased in the cytosol, up to 30-fold as measured by Western blotting), whereas ERK 1 and 2 accumulated maximally by 2.5-fold 1 hr after rhG-CSF induction. c-Jun was up-regulated strongly by this cytokine at the translational level. Our data suggest that rhG-CSF affects genes involved in mitogen signalling and early gene expression in solid tumours. We also noted the presence of G-CSF receptor on ovarian cancer cell lines.
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PMID:rhG-CSF affects genes involved in mitogen signalling and early gene expression in the ovarian cancer cell line HEY. 950 29

The urokinase-type plasminogen activator receptor (u-PAR) has been implicated in tumor progression, and previous studies have shown that the expression of this gene is strongly up-regulated by PMA. Although the signaling mechanism by which PMA modulates u-PAR expression is not known, the effect of this phorbol ester on the expression of other genes has been ascribed to activation of the c-Raf-1-ERK signaling pathway. However, in the current study we examined an alternate possibility that the inductive effect of PMA on u-PAR expression also required a JNK1-dependent signaling cascade usually associated with stress-inducing stimuli. PMA treatment of the u-PAR-deficient OVCAR-3 ovarian cancer cells, which contain low JNK activities, resulted in a rapid (5 min) increase in JNK activity. Maximal JNK activity (12-fold induction) occurred after 30 min; this preceding the earliest detected rise in u-PAR protein (2 h). Dose-response studies with PMA also indicated that the increased JNK activity was tightly correlated with elevated u-PAR protein levels. The stimulation of u-PAR promoter activity by PMA required an intact upstream AP-1 motif (-184) and in PMA-treated cells this motif was bound with c-Jun as indicated from mobility shift assays. PMA up-regulated the c-Jun trans acting activity as indicated by the higher activity of a GAL4-regulated luciferase reporter in phorbol-ester-treated cells co-transfected with an expression vector encoding the c-Jun transactivation domain fused to the GAL4 DNA-binding domain. The ability of PMA to stimulate u-PAR promoter activity was effectively titrated out by the co-expression of either a kinase-defective JNK1 or a dominant negative MEKK1 the latter being an upstream activator of JNK1. Conversely, u-PAR promoter activity was stimulated by the co-expression of a constitutively active MEKK1 and this induction was antagonized by the inclusion of the kinase-defective JNK1 plasmid. We also determined the biological significance of the JNK1-dependent signaling cascade in regulating u-PAR promoter activity by c-Ha-ras since this oncogene is activated and/or overexpressed in a variety of tumors including ovarian cancer. Transfection of an activated c-Ha-ras into OVCAR-3 cells stimulated u-PAR promoter activity over 20-fold and this could be countered by the individual expression of dominant negative expression constructs to Rac-1, MEKK1 or JNK1. Taken together, these data suggest that the PMA- or c-Ha-Ras-dependent stimulation of u-PAR gene expression requires a JNK1-dependent signaling module and that, at least for PMA, the concurrent stimulation of a JNK1-independent signaling module is also required. Thus, caution should be exercised in invoking linear signaling modules to account for the regulation of inducible gene expression.
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PMID:Stimulation of urokinase-type plasminogen activator receptor expression by PMA requires JNK1-dependent and -independent signaling modules. 967 6

Paclitaxel (Taxol) is a novel anti-cancer drug that has shown efficacy toward several malignant tumors, particularly ovarian tumors. We reported previously that paclitaxel can induce interleukin (IL)-8 promoter activation in subgroups of ovarian cancer through the activation of both AP-1 and nuclear factor kappaB. Further analysis of paclitaxel analogs indicates that the degree of IL-8 induction by analysis correlates with the extent of cell death; however, IL-8 itself is not the cause of cell death. This suggests that pathways that lead to IL-8 and cell death may overlap, although IL-8 per se does not kill tumor cells. To decipher the upstream signals for paclitaxel-induced transcriptional activation and cell death, we studied the involvement of protein kinases that lead to the activation of AP-1, specifically the c-Jun NH2-terminal kinase (JNK1), p38, and the extracellular signal-regulated kinase 1 (ERK1). The role of IkappaB in paclitaxel-induced cell death was also analyzed. Paclitaxel activated JNK, and to a lesser degree p38, but not ERK1. Paclitaxel-induced IL-8 promoter activation was inhibited by dominant-inhibitory mutants of JNK, p38, and the super-repressor form of IkappaBalpha, but not by dominant-inhibitory forms of ERK1. Dominant-inhibitory mutants of JNK1 also greatly reduced paclitaxel-induced cell death, and the kinetics of JNK induction was closely followed by DNA fragmentation. These results indicate (i) that paclitaxel activates the JNK signaling pathway and (ii) that JNK activation is a common point of paclitaxel-induced gene induction and cell death.
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PMID:Paclitaxel (Taxol)-induced gene expression and cell death are both mediated by the activation of c-Jun NH2-terminal kinase (JNK/SAPK). 977 47

The antineoplastic agent paclitaxel (TaxolTM), a microtubule stabilizing agent, is known to arrest cells at the G2/M phase of the cell cycle and induce apoptosis. We and others have recently demonstrated that paclitaxel also activates the c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) signal transduction pathway in various human cell types, however, no clear role has been established for JNK/SAPK in paclitaxel-induced apoptosis. To further examine the role of JNK/SAPK signaling cascades in apoptosis resulting from microtubular dysfunction induced by paclitaxel, we have coexpressed dominant negative (dn) mutants of signaling proteins of the JNK/SAPK pathway (Ras, ASK1, Rac, JNKK, and JNK) in human ovarian cancer cells with a selectable marker to analyze the apoptotic characteristics of cells expressing dn vectors following exposure to paclitaxel. Expression of these dn signaling proteins had no effect on Bcl-2 phosphorylation, yet inhibited apoptotic changes induced by paclitaxel up to 16 h after treatment. Coexpression of these dn signaling proteins had no protective effect after 48 h of paclitaxel treatment. Our data indicate that: (i) activated JNK/SAPK acts upstream of membrane changes and caspase-3 activation in paclitaxel-initiated apoptotic pathways, independently of cell cycle stage, (ii) activated JNK/SAPK is not responsible for paclitaxel-induced phosphorylation of Bcl-2, and (iii) apoptosis resulting from microtubule damage may comprise multiple mechanisms, including a JNK/SAPK-dependent early phase and a JNK/SAPK-independent late phase.
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PMID:Microtubule dysfunction induced by paclitaxel initiates apoptosis through both c-Jun N-terminal kinase (JNK)-dependent and -independent pathways in ovarian cancer cells. 1007 25

Disabled-2 (Dab2) is a putative tumor suppressor in breast and ovarian cancers. Its expression is lost in a majority of tumors, and homozygous deletions have been identified in a small percentage of tumors. Dab2 expression is absent or very low in the majority of breast and ovarian cancer cell lines, including MCF-7 and SK-Br-3 breast cancer cells. Transfection and expression of Dab2 in MCF-7 and SK-Br-3 cells suppress tumorigenicity. The cells reach a much lower saturation density and have reduced ability to form colonies on agar plates. In examining the signal transduction pathway of Dab2-transfected cells, we found that serum-stimulated c-Fos expression was greatly suppressed; however, the effects of Dab2 on MAPK family kinases were not as consistent. In MCF-7 and SK-Br-3 cells, although c-Fos expression was suppressed, the Erk1/2, JNK, and p38(MAPK) activities were unchanged or even increased. Serum-stimulated c-Fos expression is dependent on MAPK/Erk activity because the MEK inhibitor PD98059 suppresses Erk activity and c-Fos expression. Therefore, Dab2 appears to uncouple MAPK activation and c-fos transcription. Thus, we conclude that Dab2 re-expression suppresses tumorigenicity by reducing c-Fos expression at a site downstream of the activation of MAPK family kinases. Because Dab2 is frequently lost in cancer, the uncoupling of MAPK activation and c-Fos expression may be a favored target for inactivation in tumorigenicity.
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PMID:Disabled-2 exerts its tumor suppressor activity by uncoupling c-Fos expression and MAP kinase activation. 1135 72

Breast cancer is among the most common tumors affecting women. It is characterized by a number of genetic aberrations. Some 5-10% of cases are thought to be inherited. The hereditary breast and ovarian cancer syndrome includes genetic alterations of various susceptibility genes, particularly BRCA1 and BRCA2. Breast tumors of patients with germ-line mutations in the BRCA1 and BRCA2 genes have more genetic defects than sporadic breast tumors. Here we review new findings in the function of BRCA1 gene function. Accumulation of somatic genetic changes during tumor progression map follows a specific and more aggressive pathway of chromosome damage in these individuals. A major BRCA1 downstream target gene is the DNA damage-responsive gene GADD45. Induction of BRCA1 triggers apoptosis by activation of c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK). BRCA1 interacts with SWI/SNF, a chromatin remodeling complex important in gene expression. Recent advances in genomics and bioinformatics, particularly in DNA-sequencing approaches and DNA-chip technology are expected to improve identification of small molecules, which might be drugable targets. New knowledge about the genetic portrait of breast tumor is coming from differential gene expression profiling using microarrays. Human genome studies, as well as development of "DNA chips," provide a window for observing patterns of gene activity in cells, which will contribute to more accurate cancer classification. However, substantial work connected with analytical and statistical tools must still be carried out to confirm the function of differentially expressed genes. Knowledge of the molecular characteristics of breast tumor has already started to make possible the identification of breast cancer patients who could benefit from therapies that target those features. Progress in basic research into signaling provides the opportunity to attack at least some signal-transduction targets involved in proliferation, survival, invasion, angiogenesis, metastasis, and resistance. Exciting knowledge in breast cancer biology is rapidly accumulating in parallel with recent developments in rational selection and validation of relevant targets that provide unique opportunities for development of "intelligent" therapeutics.
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PMID:Recent advances in molecular genetics of breast cancer. 1169 53

The multidrug resistant protein MDR-1 has been associated with the resistance to a wide range of anti-cancer drugs. Taxol is a substrate for this transporter system and is used in the treatment of a wide range of human malignancies including lung, breast and ovarian cancer. We have generated a series of ovarian cell lines resistant to this compound, all of which overexpress MDR-1 through gene amplification. We present novel evidence that a constitutive activation of the ERK1/2 MAP kinase pathway was also observed although the level of active JNK and p38 remained unchanged. Inhibition of the ERK1/2 MAP kinase pathway using UO126 or PD098059 re-sensitised the Taxol resistant cells at least 20-fold. Importantly, when Mdr-1 cDNA was stably expressed in the wild-type cell line to generate a highly Taxol-resistant sub-line, 1847/MDR5, ERK1/2 MAP kinases again became activated. This result demonstrated that the increased activity of the signalling pathway in the Taxol-resistant lines was directly attributable to MDR-1 overexpression and was not due to the effects of Taxol itself. Additionally, we demonstrated that inhibition of the P13K pathway with LY294002 sensitised the MDR-1-expressing 1847/TX0.5 cells and 1847/MDR5 cells at least 10-fold but had no effect in the wild-type cells. This finding suggests a possible role for this pathway, also, in the generation of resistance to Taxol.
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PMID:Cross-talk between signalling pathways and the multidrug resistant protein MDR-1. 1171 Aug 32

Mutation in the BRCA1 gene is associated with an increased risk of breast and ovarian cancer. Recent studies have shown that the BRCA1 gene product may be important in mediating responses to DNA damage and genomic instability. Previous studies have indicated that overexpression of BRCA1 can induce apoptosis or cell cycle arrest at the G(2)/M border in various cell types. Although the activation of JNK kinase has been implicated in BRCA1-induced apoptosis, the role of other members of the mitogen-activated protein kinase family in mediating the cellular response to BRCA1 has not yet been examined. In this study, we monitored the activities of three members of the MAPK family (ERK1/2, JNK, p38) in MCF-7 breast cancer cells and U2OS osteosarcoma cells after their exposure to a recombinant adenovirus expressing wild type BRCA1 (Ad.BRCA1). Overexpression of BRCA1 in MCF-7 cells resulted in arrest at the G(2)/M border; however, BRCA1 expression in U2OS cells induced apoptosis. Although BRCA1 induced JNK activation in both cell lines, there were marked differences in ERK1/2 activation in response to BRCA1 expression in these two cell lines. BRCA1-induced apoptosis in U2OS cells was associated with no activation of ERK1/2. In contrast, BRCA1 expression in MCF-7 cells resulted in the activation of both ERK1/2 and JNK. To directly assess the role of ERK1/2 in determining the cellular response to BRCA1, we used dominant negative mutants of MEK1 as well as MEK1/2 inhibitor PD98059. Our results indicate that inhibition of ERK1/2 activation resulted in increased apoptosis after BRCA1 expression in MCF-7 cells. Furthermore, BRCA1-induced apoptosis involved activation of JNK, induction of Fas-L/Fas interaction, and activation of caspases 8 and 9. The studies presented in this report indicate that the response to BRCA1 expression is determined by the regulation of both the JNK and ERK1/2 signaling pathways in cells.
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PMID:BRCA1-induced apoptosis involves inactivation of ERK1/2 activities. 3110 59

Synucleins are a family of highly conserved small proteins predominantly expressed in neurons. Recently we and others have found that gamma-synuclein is dramatically up-regulated in the vast majority of late-stage breast and ovarian cancers and that gamma-synuclein over-expression can enhance tumorigenicity. In the current study, we have found that gamma-synuclein is associated with two major mitogen-activated kinases (MAPKs), i.e. extracellular signal-regulated protein kinases (ERK1/2) and c-Jun N-terminal kinase 1 (JNK1), and have shown that over-expression of gamma-synuclein leads to constitutive activation of ERK1/2 and down-regulation of JNK1 in response to a host of environmental stress signals, including UV, arsenate, and heat shock. We also tested the effects of gamma-synuclein on apoptosis and activation of JNK and ERK in response to several chemotherapy drugs. We have found that gamma-synuclein-expressing cells are significantly more resistant to the chemotherapeutic drugs paclitaxel and vinblastine as compared with the parental cells. The resistance to paclitaxel can be partially obliterated when ERK activity is inhibited using a MEK1/2 inhibitor. Activation of JNK and its downstream caspase-3 by paclitaxel or vinblastine is significantly down-regulated in gamma-synuclein-expressing cells, indicating that the paclitaxel- or vinblastine-activated apoptosis pathway is blocked by gamma-synuclein. In contrast to paclitaxel and vinblastine, etoposide does not activate JNK, and gamma-synuclein over-expression has no apparent effect on this drug-induced apoptosis. Taken together, our data indicate that oncogenic activation of gamma-synuclein contributes to the development of breast and ovarian cancer by promoting tumor cell survival under adverse conditions and by providing resistance to certain chemotherapeutic drugs.
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PMID:Gamma-synuclein promotes cancer cell survival and inhibits stress- and chemotherapy drug-induced apoptosis by modulating MAPK pathways. 1212 74

The 70 kDa ribosomal S6 kinase (p70S6K) is important for cell growth and survival. Activation of p70S6K requires sequential phosphorylation of multiple serine and threonine sites often triggered by growth factors and hormones. Here, we report that paclitaxel, a microtubule-damaging agent, induces phosphorylation of p70S6K at threonine 421 and serine 424 (T421/S424) in a concentration- and time-dependent manner in multiple breast and ovarian cancer cell lines demonstrated by a T421/S424 phospho-p70S6K antibody. Phosphoamino-acid analysis and Western blot analysis by serine-/threonine-specific antibodies further confirms that both serine and threonine residues are phosphorylated in p70S6K following treatment with paclitaxel. Paclitaxel-induced p70S6K(T421/S424) phosphorylation requires both de novo RNA and protein synthesis via multiple signaling pathways including ERK1/2 MAP kinase, JNK, PKC, Ca(++), PI3K, and mammalian target of rapamycin (mTOR). Despite phosphorylation of p70S6K(T421/S424), paclitaxel inactivates this kinase in a concentration- and time-dependent manner as illustrated by in vitro kinase assay. Inhibitors of mTOR, PI3K, and Ca(++) impair p70S6K activity, whereas inhibitors of JNK and PKC stimulate p70S6K activity. Inhibition of PKC and JNK prevents paclitaxel-induced p70S6K inactivation. Moreover, the paclitaxel-induced phosphorylation and low activity of p70S6K mainly occurs during mitosis. In summary, paclitaxel is able to induce p70S6K(T421/S424) phosphorylation and decrease its activity in mitotic cells via multiple signaling pathways. Our data suggest that paclitaxel-induced p70S6K(T421/S424) phosphorylation and kinase inactivation are differentially regulated. Our data also indicate that paclitaxel may exert its antitumor effect, at least in part, via inhibition of p70S6K.
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PMID:Paclitaxel induces inactivation of p70 S6 kinase and phosphorylation of Thr421 and Ser424 via multiple signaling pathways in mitosis. 1255 62

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