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At least 19 recordsLinked to original sources
PubMed1994

Increased mdr1 gene transcript levels in high-grade carcinoma of the bladder determined by quantitative PCR-based assay.

Overexpression of the multidrug resistance (mdr1) gene has been implicated in resistance to a number of the chemotherapeutic agents currently used in the treatment of bladder cancer (doxorubicin, vincristine and epirubicin). We report the development and validation of a quantitative assay for the determination of mdr1 gene transcript levels based on reverse transcription and the polymerase chain reaction (PCR), sensitive to less than 2-fold variations in transcript levels. Using these techniques, mdr1 mRNA levels were investigated in 32 primary untreated transitional cell carcinomas of the bladder. mdr1 mRNA was detected in all samples, with levels varying between individual tumours over a 63-fold range. These variations were not associated with the proliferative status of the tumour. mdr1 mRNA levels were significantly higher in poorly differentiated high-grade (G3) tumours than in well- and moderately differentiated low-grade (G1 and G2) tumours (P = 0.0057). The results suggest that this relationship may extend to mdr1 mRNA levels being an indicator of poor prognosis, as anticipated on the basis of the observed relationship to tumour stage and grade. No evidence was found to implicate mdr1 mRNA levels as a predictor of tumour recurrence or progression. Given that mdr1 mRNA levels are increased in a proportion of high-grade bladder tumours that are routinely subjected to chemotherapy, we discuss the possibility that mdr1 mRNA levels may be clinically significant as determinants of chemotherapeutic response and outcome in bladder cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Comparison of cathepsin D determinations in human carcinomas by enzyme immunoassay and immunoradiometric assay.

Overexpression of cathepsin D in several types of carcinoma in women appears to be associated with a poor clinical course. In this prospective investigation, cathepsin D levels in 170 specimens of normal and neoplastic human tissues were determined simultaneously by enzyme immunoassay (EIA) and immunoradiometric assay (IRMA) to allow comparisons in multicentric studies, such as cooperative clinical trials. Nonmalignant uteri and specially prepared reference powders were also evaluated. Linear regression analysis between the two assays for all specimens [EIA = 0.87(IRMA)-3.18] demonstrated a correlation coefficient (r) of 0.99 (P < 0.001). When malignancies were categorized by the tissue origin (i.e., breast, uterus, ovary, lymph node, and colon), highly significant correlations were also observed (regressions slopes ranged from 0.58 to 1.02). Intra- and interassay controls conducted for the new EIA procedure gave CV% ranging from 4.4 to 10.2, which was similar to the IRMA test for cathepsin D. The results of both assays correlated well and were highly reproducible. Either assay may be used with confidence that comparable cathepsin D values will be obtained in a wide range of tissue biopsies.

Breast Neoplasms↗
PubMed2003

An in vitro assay using overexpressed yeast SRP demonstrates that cotranslational translocation is dependent upon the J-domain of Sec63p.

The signal recognition particle (SRP) is required for co-translational targeting of polypeptides to the endoplasmic reticulum (ER). Once at the membrane, the precursor interacts with a complex proteinaceous machinery that mediates its translocation across the bilayer. Genetic studies in yeast have identified a number of genes whose products are involved in this complex process. These mutants offer a potentially valuable resource with which to analyze the biochemical role played by each component in the pathway. However, such analyses have been hampered by the failure to reconstitute an efficient in vitro assay for SRP-dependent translocation. We report the construction of two multicopy vectors that allow overexpression of all seven gene products required to make SRP in the yeast Saccharomyces cerevisiae. The overexpressed subunits assemble into intact and functional SRP particles, and we further demonstrate that in vitro reconstitution of co-translational translocation is greatly enhanced using cytosol from the overexpression strain. We use this assay to demonstrate that Sec63p is required for co-translational translocation in vitro and specifically identify the "J-domain" of Sec63p as crucial for this pathway.

Base Sequence↗
PubMed2004

Identification of a ZU5 and death domain-containing inhibitor of NF-kappaB.

The transcription factor NF-kappaB plays important roles in inflammation and cell survival. NF-kappaB is composed of homodimeric and heterodimeric complexes of Rel/NF-kappaB family members, including p65 (RelA), c-Rel (Rel), RelB, NF-kappaB1/p50, and NF-kappaB2/p52. Here we report the identification and characterization of a novel ZU5 and death domain-containing protein designated ZUD. In reporter gene assays, overexpression of ZUD inhibited NF-kappaB-dependent transcription induced by both tumor necrosis factor (TNF) and interleukin-1 and their downstream signaling proteins. Gel shift assays indicated that the overexpression of ZUD inhibited binding of NF-kappaB to its target sequence. ZUD is a cytoplasmic protein, and coimmunoprecipitation assays indicated that ZUD interacted with the NF-kappaB subunit p105 and transactivator p65. Consistent with its role in inhibition of NF-kappaB-dependent transcription, ZUD sensitized cells to apoptosis induced by TNF and the TNF-related apoptosis-inducing ligand (TRAIL). Our findings suggest that ZUD is an inhibitor of NF-kappaB activation and that this protein may provide an alternative regulatory mechanism for NF-kappaB-mediated transcription.

Apoptosis↗
PubMed2003

Identification of a novel serine/threonine kinase that inhibits TNF-induced NF-kappaB activation and p53-induced transcription.

SINK is a p65-interacting protein that inhibits PKAc-induced phosphorylation of p65 and NF-kappaB transcriptional competence. We identified a SINK-homologous serine/threonine kinase SHIK. SHIK is ubiquitously expressed and is localized in the cytoplasm. Overexpression of SHIK inhibits TNF-triggered NF-kappaB activation in reporter gene assays. Overexpression of SHIK also inhibits p53-mediated transcription in reporter gene assays, while a point mutant (D197-->I) of SHIK potentiates p53-mediated transcription. Our findings suggest that SHIK is a negative regulator of NF-kappaB- and p53-mediated gene transcription.

Amino Acid Sequence↗
PubMed1996

Mutated Atf4 suppresses c-Ha-ras oncogene transcript levels and cellular transformation in NIH3T3 fibroblasts.

A frameshift mutation is present in one allele of the Atf4 gene in genomic DNA from F9 embryonal carcinoma stem cells. The mutation results in the fusion of a short 5' open reading frame to the coding sequence of Atf4, replacing the first 18 N-terminal amino acids with 50 amino acids encoded by the upstream open reading frame. The ability of both normal and mutated Atf4 gene products to influence cell growth was tested using an NIH3T3 cell transformation assay. Overexpression of mutant Atf4 suppresses ras-induced transformation in this assay. In G418r cell lines derived from parallel co-transfections, expression of transfected mutant Atf4 mRNA correlates with a loss of transformed morphology and a reduction in ras mRNA levels. Transient cotransfection assays in NIH3T3 cells demonstrate that wild type Atf4 is able to inhibit transcription directed by the human c-Ha-ras1 promoter and that this effect is increased by the mutation.

3T3 Cells↗
PubMed2004

CEACAM6 is a determinant of pancreatic adenocarcinoma cellular invasiveness.

Pancreatic adenocarcinoma is among the most aggressively invasive malignancies. The immunoglobulin superfamily member carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is emerging as an important determinant of the malignant phenotype in a range of cancers. We sought to define the role of CEACAM6 in pancreatic adenocarcinoma cellular invasiveness. CEACAM6 was stably overexpressed in Capan2 cells, which inherently express low levels of CEACAM6. Retrovirally mediated RNA interference was used to silence CEACAM6 expression in BxPC3 cells, which inherently overexpress CEACAM6. Cellular invasiveness was quantified using a modified Boyden chamber assay. Overexpression of CEACAM6 increased Capan2 cellular invasiveness, whereas CEACAM6 knockdown attenuated BxPC3 invasiveness. A role for the c-Src tyrosine kinase in mediating CEACAM6-dependent invasiveness was defined using constitutively active and dominant-negative c-Src expression constructs. c-Src-dependent modulation of matrix metalloproteinase-9 activity contributes significantly to the increased cellular invasiveness induced by CEACAM6 overexpression. Levels of CEACAM6 expression can modulate pancreatic adenocarcinoma cellular invasiveness in a c-Src-dependent manner. This pathway warrants further investigation as a target for therapy.

Adenocarcinoma↗
PubMed1995

ras and p53 in the prediction of survival in Dukes' stage B colorectal carcinoma.

Aims-To determine possible associations between p53 allelic deletion, c-Ki-ras mutational activation, immunohistochemical detection of p53 and ras proteins, various clinicopathological variables, and patient outcome in 168 Dukes' stage B colorectal carcinomas.Methods-Allelic deletion at the p53 tumour suppressor gene locus was detected using polymerase chain reaction (PCR) based loss of heterozygosity (LOH) assays. Overexpressed proteins were detected using the CM1 polyclonal antibody. A PCR based assay was used to detect the presence of activating mutations at codon 12 of c-Ki-ras. Immunostaining was carried out using a monoclonal antibody to p21(ras).Results-p53 LOH, CM1 immunostaining, c-Ki-ras mutational activation, and p21(ras) immunostaining were not predictive of survival by logrank analysis. Multivariate analysis using Cox regression did not predict survival in this group of tumours.Conclusions-Aberrations in ras and p53 are unlikely to play an important role in the subdivision of patients with Dukes' stage B colorectal carcinoma into more accurate prognostic strata. It is possible that later genetic events are more important in conferring a specific phenotype on the resultant Dukes' stage B tumour.

Journal Article↗
PubMed2004

Targeted therapy in breast cancer: the HER-2/neu gene and protein.

The HER-2/neu oncogene, a member of the epidermal growth factor receptor or erb gene family, encodes a transmembrane tyrosine kinase receptor that has been linked to prognosis and response to therapy with the anti-HER-2-humanized monoclonal antibody, trastuzumab (Herceptin, Genentech, South San Francisco, CA) in patients with advanced metastatic breast cancer. HER-2/neu status has also been tested for its ability to predict the response of breast cancer to other therapies including hormonal therapies, topoisomerase inhibitors, and anthracyclines. This review includes an analysis of 80 published studies encompassing more than 25,000 patients designed to consider the relative advantages and disadvantages of the various methods of measuring HER-2/neu in clinical breast cancer specimens. Southern blotting, PCR amplification detection, and fluorescence in situ hybridization assays designed to detect HER-2/neu gene amplification are compared with HER-2/neu protein overexpression assays performed by immunohistochemical techniques applied to frozen and paraffin-embedded tissues and enzyme immunoassays performed on tumor cytosols. The significance of HER-2/neu overexpression in ductal carcinoma in situ and the HER-2/neu status in uncommon female breast conditions and male breast cancer are also considered. The role of HER-2/neu testing for the prediction of response to trastuzumab therapy in breast cancer is reviewed along with the current studies designed to test whether HER-2/neu status can predict the response to standard and newer hormonal therapies, cytotoxic chemotherapy, and radiation. The review will also evaluate the status of serum-based testing for circulating HER-2/neu receptor protein and its ability to predict disease outcome and therapy response.

Antineoplastic Agents↗
PubMed2003

The Her-2/neu gene and protein in breast cancer 2003: biomarker and target of therapy.

The HER-2/neu oncogene encodes a transmembrane tyrosine kinase receptor with extensive homology to the epidermal growth factor receptor. In this review, the association of HER-2/neu gene and protein abnormalities with prognosis and response to therapy with trastuzumab and to other therapies in breast cancer is presented. By considering a series of 80 published studies encompassing more than 25,000 patients, the relative advantages and disadvantages of Southern blotting, polymerase chain reaction amplification, and fluorescence in situ hybridization assays designed to detect HER-2/neu gene amplification are compared with HER-2/neu protein overexpression assays performed by immunohistochemical techniques applied to frozen and paraffin-embedded tissues and enzyme immunoassays performed on tumor cytosols. The significance of HER-2/neu overexpression in ductal carcinoma in situ and the HER-2/neu status in uncommon female breast conditions and male breast cancer are also considered. The role of HER-2/neu testing for the prediction of response to trastuzumab therapy in breast cancer is presented as well as its potential impact on responses to standard and newer hormonal therapies, cytotoxic chemotherapy, and radiation. The review also evaluates the status of serum-based testing for circulating HER-2/neu receptor protein and its ability to predict disease outcome and therapy response.

Adult↗
PubMedDate not supplied

Targeted therapy for cancer: the HER-2/neu and Herceptin story.

The HER-2/neu oncogene encodes a transmembrane tyrosine kinase receptor with extensive homology to the epidermal growth factor receptor. In this article, the association of HER-2/neu gene and protein abnormalities with prognosis and response to therapy with Herceptin and other therapies in breast cancer is presented. By considering a series of 80 published studies encompassing more than 25,000 patients, the relative advantages and disadvantages of Southern blotting, polymerase chain reaction amplification, and fluorescence in situ hybridization assays designed to detect HER-2/neu gene amplification are compared with HER-2/neu protein overexpression assays performed by immunohistochemical techniques applied to frozen and paraffin-embedded tissues and enzyme immunoassays performed on tumor cytosols. The significance of HER-2/neu overexpression in ductal carcinoma in situ and the HER-2/neu status in uncommon female breast conditions and male breast cancer also are considered. The role of HER-2/neu testing for the prediction of response to Herceptin therapy in breast cancer is presented as well as its potential impact on responses to standard and newer hormonal therapies, cytotoxic chemotherapy, and radiation. The review also will evaluate the status of serum-based testing for circulating HER-2/neu receptor protein and its ability to predict disease outcome and therapy response.

Antibodies, Monoclonal↗
PubMed1999

HER-2/neu (c-erb-B2) gene and protein in breast cancer.

The HER-2/neu oncogene encodes a transmembrane tyrosine kinase receptor with extensive homology to the epidermal growth factor receptor. The association of HER-2/neu gene and protein abnormalities with prognosis in breast cancer is presented by considering a series of 52 published studies including more than 16,000 patients. The relative advantages and disadvantages of Southern blot testing, polymerase chain reaction amplification, and fluorescence in situ hybridization assays designed to detect HER-2/neu gene amplification are compared with HER-2/neu protein overexpression assays performed with immunohistochemical techniques applied to frozen and paraffin-embedded tissues and enzyme immunoassays performed on tumor cytosols. The importance of HER-2/neu protein overexpression in ductal carcinoma in situ, and HER-2/neu protein status in uncommon breast diseases in female patients and breast cancer in male patients are also considered. The potential value of HER-2/neu protein status for the prediction of response to therapy in breast cancer is presented for standard hormonal therapy, cytotoxic chemotherapy, and radiation therapy. Also evaluated is the status of serum-based testing for circulating HER-2/neu receptor protein and its ability to predict disease outcome and therapy response. Finally, preliminary data concerning use of antibody-based therapies directed against HER-2/neu protein and their potential use in breast cancer treatment are considered.

Breast Neoplasms↗
PubMed2006

Repression of human GSTA1 by interleukin-1beta is mediated by variant hepatic nuclear factor-1C.

Down-regulation of glutathione transferase A1 (GSTA1) expression has profound implications in cytoprotection against toxic by-products of lipid peroxidation produced during inflammation. We investigated the role of hepatic nuclear factor 1 (HNF-1) in repression of human GSTA1 expression by interleukin (IL)-1beta in Caco-2 cells. In luciferase reporter assays, overexpression of HNF-1alpha increased GSTA1 transcriptional activity via an HNF-1 response element (HRE) in the proximal promoter. In addition, constitutive mRNA levels of GSTA1 and HNF-1alpha rose concurrently in Caco-2 cells with increasing stage of confluence. IL-1beta reduced GSTA1 mRNA levels at all stages of confluence; however, HNF-1alpha mRNA levels were not altered. IL-1beta repressed GSTA1 transcriptional activity, an effect that was abolished by mutating the HRE. Similar results were observed in HT-29 and HepG2 cells. Overexpression of HNF-1alpha did not counteract IL-1beta-mediated repression of GSTA1 transcription either in reporter assays or at the mRNA level. Involvement of the transdominant repressor C isoform of variant HNF-1 (vHNF-1C) in GSTA1 repression was demonstrated, because vHNF-1C overexpression significantly reduced GSTA1 transcriptional activity. Finally, IL-1beta caused concentration-related up-regulation of vHNF-1C mRNA levels and increased binding of vHNF-1C protein to the HRE, whereas HNF-1alpha-HRE complex formation was reduced. These findings indicate that IL-1beta represses GSTA1 transcription via a mechanism involving overexpression of vHNF-1C.

Base Sequence↗
PubMed2004

Overexpression of human peroxiredoxin 5 in subcellular compartments of Chinese hamster ovary cells: effects on cytotoxicity and DNA damage caused by peroxides.

Peroxiredoxin 5 is a mammalian thioredoxin peroxidase ubiquitously expressed in tissues. Peroxiredoxin 5 can be intracellularly localized to mitochondria, peroxisomes, the cytosol, and, to a lesser extent, the nucleus. This remarkably wide subcellular distribution compared with the five other mammalian peroxiredoxins prompted us to further investigate the antioxidant protective function of peroxiredoxin 5 in mammalian cells according to its subcellular localization. Chinese hamster ovary cells overexpressing human peroxiredoxin 5 in the cytosol, in mitochondria, or in the nucleus were established by stable transfection. Cells overexpressing peroxiredoxin 5 were exposed for 1 h to low or acute oxidative stress with exogenously added hydrogen peroxide or tert-butylhydroperoxide. Cell protection conferred by peroxiredoxin 5 was evaluated by clonogenicity and lactate dehydrogenase assays. Overexpressing peroxiredoxin 5 in either the cytosolic, mitochondrial, or nuclear compartment significantly reduced cell death, with more effective protection with overexpression of peroxiredoxin 5 in mitochondria, confirming that this organelle is a major target of peroxides. Moreover, we evaluated, with the comet assay, nuclear DNA damage induced by hydrogen peroxide or tert-butylhydroperoxide. Overexpression of peroxiredoxin 5 in the nucleus significantly decreased DNA damage induced by both peroxides. In conclusion, the present study suggests that multiple subcellular targeting of peroxiredoxin 5 in mammalian cells can be implicated in antioxidant protective mechanisms under nonpathological conditions but also during acute oxidative stress caused by peroxides occurring in pathophysiological situations.

Animals↗
PubMed2005

Overexpression of SR proteins and splice variants modulates chondrogenesis.

Fibronectin alternative exon EIIIA is largely included in undifferentiated mesenchymal cells of the developing limb bud, whereas the exon is excluded in differentiated chondrocytes. Inclusion of exon EIIIA in chondrocytic cells is increased by overexpression of SRp40, and, to a lesser extent, SRp75, but not SRp55. RT-PCR analysis using real-time PCR revealed that the levels of the mRNAs for these three proteins did not vary significantly in chick chondrocytes versus mesenchymal cells of the developing limb bud. However, a variant spliced form of SRp40, termed, SRp40LF, is detected preferentially in chondrocytes and in chondrifying mesenchymal cells. Forced overexpression of SRp40 or SRp75, but not SRp55, enhanced chondrogenic differentiation of chick limb mesenchymal cells in a high-density micromass assay. Overexpression of SRp40LF, which produces a truncated form of SRp40, also was strongly pro-chondrogenic. In a HeLa cell-based assay, SRp40LF fails to substitute for SRp40 in mediating an increase in exon EIIIA inclusion, suggesting that the latter event is not essential for the pro-chondrogenic effect. These results demonstrate the ability of these highly conserved splicing factors to modulate chondrogenesis and are consistent with earlier results that implicated exon EIIIA-containing isoforms of fibronectin in formation of chondrogenic condensations.

Alternative Splicing↗
PubMed1998

[Clinical and pathological significance of p53 gene mutation in human cerebral glioblastoma multiforme].

Cerebral glioblastomas multiforme (GMs), the most malignant human primary brain tumor, molecular genetically comprise two subsets characterized by p53 tumor suppressor gene status. One is characterized by p53 mutation and another is with wild-type p53 and overexpression of epidermal growth factor receptor (EGFR). We analyzed the p53 status by a highly reliable yeast-based assay, overexpression of EGFR by immunohistochemistry, and their relations to clinical outcome along with other several clinical parameters, in a total of 42 patients with GMs. We found p53 mutations in 18 cases (43%) of 42 GMs and overexpression of EGFR in 16 cases (43%) of 37 GMs. The tumors with p53 mutation were associated with younger onset ages and longer survival. We also analyzed their survival and radiation sensitivity relative to p53 status, EGFR and other prognostic factors, including onset age, extent of surgery, post-operative Karnofsky performance score (KPS), and location of tumor. Log-rank tests showed that younger onset ages (below 50 years; p < 0.0111), p53 mutation (p < 0.0005), superficial tumor location (p < 0.0026) and post operatives KPS (over 80%; p < 0.0147) correlated with longer survival. Multivariate Cox regression analysis identified the absence of p53 mutation (p < 0.0335) and the deep tumor location (p < 0.0297) as the independent, adverse prognostic factors. Tumor response to radiation was assessed by progression-free period (time to progression; TTP). A significant correlation was found between TTP and survival (p < 0.0001). Log-rank tests and multivariate Cox regression analysis showed that younger onset ages (below 50 years; p < 0.0145), p53 mutation (p < 0.0001), radical resection (p < 0.0198) and post operative KPS (over 80%; p < 0.0001) correlated with radiation sensitivity, and identified the absence of p53 mutation (p < 0.0146) as the sole independent hazard for radiation response. In conclusion, p53 mutation confers radiation sensitivity in GMs, which results in patients' longer survival.

Adolescent↗
PubMed1998

E1A represses apolipoprotein AI enhancer activity in liver cells through a pRb- and CBP-independent pathway.

The apolipoprotein AI (apoAI) promoter/enhancer contains multiple cis -acting elements on which a variety of hepatocyte-enriched and ubiquitous transcription factors function synergistically to regulate liver-specific transcription. Adenovirus E1A proteins repress tissue-specific gene expression and disrupt the differentiated state in a variety of cell types. In this study expression of E1A 12Sor 13S in hepatoblastoma HepG2 cells repressed apoAI enhancer activity 8-fold. Deletion mapping analysis showed that inhibition by E1A was mediated by the apoAI promoter site B. E1A selectively inhibited the ability of HNF3beta and HNF3alpha to transactivate reporter genes controlled by the apoAI site B and the HNF3 binding site from the transthyretin promoter. The E1A-mediated repression of HNF3 activity was not reversed by overexpression of HNF3beta nor did E1A alter nuclear HNF3beta protein levels or inhibit HNF3 binding to DNA in mobility shift assays. Overexpression of two cofactors known to interact with E1A, pRb and CBP failed to overcome inhibition of HNF3 activity. Similarly, mutations in E1A that disrupt its interaction with pRb or CBP did not compromise its ability to repress HNF3beta transcriptional activity. These data suggest that E1A inhibits HNF3 activity by inactivating a limiting cofactor(s) distinct from pRb or CBP.

Adenovirus E1A Proteins↗
PubMed2003

Zebrafish prickle, a modulator of noncanonical Wnt/Fz signaling, regulates gastrulation movements.

In addition to the canonical Wnt/beta-catenin signaling pathway, at least two noncanonical Wnt/Fz pathways have been described: the planar cell polarity (PCP) pathway in Drosophila [1] and the Wnt/calcium pathway in vertebrate embryos [2]. Recent work suggests that a vertebrate pathway homologous to the PCP pathway acts to regulate the convergent extension movements of gastrulation [3-7]. To further test this hypothesis, we have identified two zebrafish homologs of the Drosophila PCP gene prickle (pk) [8], both of which show discrete and dynamic expression patterns during gastrulation. Both gain and loss of pk1 function cause defects in convergent extension. Pk1 localizes to both the cytoplasm and the cell membrane, and its normal localization is partially dependent on its C-terminal prenylation motif. At the cell membrane, Pk1 is frequently localized asymmetrically around the cell and can colocalize with the signaling molecule Dishevelled (Dsh). In overexpression assays, Pk1 is able to activate AP-1-mediated transcription and inhibit activation of Wnt/beta-catenin signaling. Like noncanonical Wnts [9-10], overexpression of Pk1 increases the frequency of calcium transients in zebrafish blastulae. Our results support the idea that a vertebrate PCP pathway regulates gastrulation movements and suggest that there is overlap between the PCP and Wnt/calcium pathways.

Adaptor Proteins, Signal Transducing↗