Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The dioxin receptor is a gene regulatory protein which exhibits many structural and functional similarities to steroid hormone receptors. In this study we compare the subunit composition of two forms of the dioxin receptor, sedimenting at approximately 9S and approximately 6S respectively, which are present in nuclear extract from wild-type Hepa 1c1c7 mouse hepatoma cells following treatment in vivo with dioxin. The nuclear approximately 9S receptor form contained the 90 kd heat shock protein, hsp90. As assessed by a gel mobility shift assay, this receptor form did not bind to the xenobiotic response element (XRE) of the target gene cytochrome P-450 IA1. In contrast, the smaller approximately 6S receptor form did not contain any immunochemically detectable hsp90. Moreover, this receptor form specifically bound to the XRE recognition sequence. Thus, the specific DNA binding activity of the dioxin receptor was inhibited by association with hsp90, and the approximately 9S dioxin receptor species could be regarded as a nonactive receptor form. Neither the approximately 9S nor the approximately 6S receptor forms were detected in nuclear extract from a dioxin treated mutant clone of Hepa 1 that expresses a nuclear translocation deficient receptor phenotype. We conclude that activation of the dioxin receptor is, at least, a two step process involving binding of the ligand and dissociation of hsp90 from the ligand-binding receptor protein. Inhibition of the DNA binding activity of transcription factors by protein--protein interaction has also been described for several steroid hormone receptors and for the NF kappa B factor.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:The specific DNA binding activity of the dioxin receptor is modulated by the 90 kd heat shock protein. 215 80

Effects of various stresses were examined on the accumulation of mRNA for microsomal heme oxygenase and a heat shock protein, hsp70, in three human hepatoma cell lines. By heat shock, hsp70 mRNA was induced in all three hepatoma lines, Hep G2, Hep 3B and Hep G2f, while heme oxygenase mRNA was increased only in Hep 3B. Time-courses of the heat shock induction of both mRNAs in Hep 3B were similar. Arsenite caused induction of both mRNAs in all three cell lines, while cadmium increased them in Hep G2 and Hep 3B, but not in Hep G2f cells. These findings suggest that, although both hsp70 and heme oxygenase are heat shock proteins, the mode of induction of mRNAs for these proteins is different.
 ...
PMID:Activation of heme oxygenase and heat shock protein 70 genes by stress in human hepatoma cells. 215 80

Heat shock-induced alterations in protein synthesis and the cytoskeleton of two mammalian cell types have been investigated. A hyperthermic treatment of 30 min at 43 degrees C causes an accumulation of heat shock proteins (HSPs). The apparent molecular weights of HSPs of Reuber H35 hepatoma cells and of N2A neuroblastoma cells are 28 000, 65 000, 68 000, 70 000, 84 000, 100 000 D and 68 000, 70 000, 84 000 and 100 000 D respectively. Hyperthermia induces the disruption of microfilaments in hepatoma cells. Microtubules and intermediate filaments (vimentin and cytokeratin) remain intact. In neuroblastoma cells microfilaments remain intact whereas microtubules become disorganized after heat shock. As a result vimentin is found as a perinuclear aggregate. These cells were still able to synthesize heat shock proteins after pretreatment with cytoskeleton disrupting drugs such as dihydroxycytochalasin B and colchicine. Therefore it is concluded that the alterations in the cytoskeleton observed after the heat treatment are unlikely to be the cause of heat shock protein synthesis. Our results suggest that these heat shock-induced alterations in the cytoskeleton can be considered as a part of the heat shock response.
 ...
PMID:Studies on a possible relationship between alterations in the cytoskeleton and induction of heat shock protein synthesis in mammalian cells. 242 73

Exposure of cultured rat hepatoma (HTC) cells to a 43 degrees C heat shock transiently accelerates the degradation of the long-lived fraction of cellular proteins. The rapid phase of proteolysis which lasts approximately 2 h after temperature step-up is followed by a slower phase of proteolysis. During the first 2 h after temperature step-up there is a wave of ubiquitin conjugation to cellular proteins which is accompanied by a fall in ubiquitin and ubiquitinated histone 2A (uH2A) levels. Upon continued incubation at 43 degrees C the levels of ubiquitin conjugates fall with a corresponding increase of ubiquitin and uH2A to initial levels. The burst of protein degradation and ubiquitin conjugation after temperature step-up is not affected by the inhibition of heat shock protein synthesis. Cells of the FM3A ts85 mutant, which have a thermolabile ubiquitin activating enzyme (E1), do not accelerate protein degradation in response to a 43 degrees C heat shock, whereas wild-type FM3A mouse cells do. This observation indicates that the ubiquitin system is involved in the degradation of heat-denatured proteins. Sequential temperature jump experiments show that the extent of proteolysis at temperatures up to 43 degrees C is related to the final temperature and not to the number of steps taken to attain it. Temperature step-up to 45 degrees C causes the inhibition of intracellular proteolysis. We propose the following explanation of the above observations. Heat shock causes the conformational change or denaturation of a subset of proteins stable at normal temperatures.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Effect of heat shock on protein degradation in mammalian cells: involvement of the ubiquitin system. 303 79

It has been established that the 90-kilodalton murine heat shock protein, hsp90, is associated with the untransformed, non-DNA-binding form of the glucocorticoid receptor in L cell cytosol. In this work, we show that incubation of L cell cytosol with Affi-Gel-coupled monoclonal antibodies directed against either alpha-tubulin alone or both alpha- and beta-tubulin results in the immune-specific adsorption of hsp90 identified by Western blotting with the AC88 monoclonal antibody. Similarly, the AC88 antibody, which is specific for hsp90, causes the immune-specific isolation of both alpha- and beta-tubulin from hypotonic cytosol. The distribution of hsp90 in cultured Potorous tridactylis kidney cells was examined by indirect immunofluorescence using the AC88 monoclonal as primary antibody. In interphase cells, AC88-dependent fluorescence was distributed like antitubulin antibody-dependent fluorescence in a fibrillar array located in the cytoplasm and around the periphery of the nucleus. In cells undergoing mitosis, AC88 fluorescence was located in the mitotic spindle. These observations suggest that a significant portion of hsp90 is associated with a tubulin-containing complex both in a hypotonic cytosol preparation from mouse fibroblasts and in intact marsupial kidney epithelial cells. The distribution of AC88 fluorescence in interphase Potorous tridactylis kidney cells is similar to the distribution of glucocorticoid receptor demonstrated by Wikstrom, A. C., Bakke, O., Okret, S., Bronnegard, M., and Gustafsson, J. A in rat hepatoma and human uterine cells.
 ...
PMID:Evidence that the 90-kilodalton heat shock protein is associated with tubulin-containing complexes in L cell cytosol and in intact PtK cells. 306 85

A conditioning treatment of 30 min at 42 degrees C or 43 degrees C, followed by a 4-h recovery period at 37 degrees C, induces thermotolerance state in the cytoskeleton of Reuber H35 hepatoma cells and N2A neuroblastoma cells. Evidence for the involvement of heat shock proteins in the development of thermotolerance in the cytoskeleton has been obtained from the following observations: only those conditioning treatments inducing the enhanced synthesis of heat shock proteins (HSPs) are able to induce the heat-resistant state of the cytoskeleton; prevention of HSP synthesis by actinomycin D or cycloheximide also prevents the acquisition of thermotolerance in the cytoskeleton; an alternative inducer of HSP synthesis, sodium arsenite, is also able to induce the cytoskeletal thermotolerance; the kinetics of development and disappearance of thermotolerance in the cytoskeleton is parallel to the kinetics of accumulation and decay of HSPs. The possible function of HSPs in the heat-resistant cytoskeleton of H35 hepatoma and N2A neuroblastoma cells is discussed.
 ...
PMID:Stress-induced thermotolerance of the cytoskeleton of mouse neuroblastoma N2A cells and rat Reuber H35 hepatoma cells. 381 63

Rat hepatoma cells become refractory to the induction of heat shock proteins and highly resistant to severe hyperthermia when incubated in Ca2+-free medium. The Ca2+-depleted cells synthesize polypeptides identified as the glucose-regulated proteins, but these proteins do not appear to be directly involved in the inhibition of the heat shock response. The results suggest that a Ca2+-dependent metabolic process is involved in the generation of the heat shock signal and/or mediates a step in the subsequent cascade of events that leads to the induction of heat shock protein synthesis and cell death.
 ...
PMID:Inhibition of the heat shock response and synthesis of glucose-regulated proteins in Ca2+-deprived rat hepatoma cells. 393 41

Morris hepatoma 7777 cells, heat conditioned at 43 degrees for 0.5 hr, become gradually thermoresistant during an incubation at 37 degrees as judged by their ability to form colonies following a second heat challenge. Pulse incorporation of [35S]methionine into proteins at various times after the conditioning treatment and subsequent fractionation of the proteins by polyacrylamide gel electrophoresis indicate that the gradual putative modifications occurring at the cellular level and leading to the thermotolerance state are accompanied by an elevated synthesis above the normal level of a small set of polypeptides with apparent molecular weights of 27,000, 65,000, 68,000, 70,000, 89,000, and 107,000. Both thermotolerance development and protein induction are completed after a 6- to 8-hr period. At the end of this period, thermotolerance is at its maximum level and heat shock protein synthesis is returned to normal. This acquired thermal resistance eventually disappears between 60 and 80 hr following conditioning treatment. In a parallel manner, the heat shock-induced proteins synthesized during the first 4 hr following the conditioning treatment are maintained in the cells at a high level for several hr but become undetectable by 82 hr. The results provide strong circumstantial evidence that heat shock proteins are involved in the acquisition, maintenance, and decay of thermotolerance.
 ...
PMID:Synthesis and degradation of heat shock proteins during development and decay of thermotolerance. 707 23

Responses of Reuber H35 hepatoma cells exposed to increasing doses of heat, arsenite ions, or cadmium ions were investigated. Doses which are capable of activating the heat shock transcription factor (HSF) were determined. The activity of this factor in the poststress period was correlated to the recovery of total protein synthesis in this same period. Subsequently, increases of mRNA levels and rates of synthesis of heat shock protein (HSP)60, HSP68, and HSP84 after exposure to the stressors were determined. We generally found that the rate of HSP synthesis correlated well with HSP mRNA levels, supporting the idea that the stress response is regulated mainly at the transcriptional level. A stressor-specific pattern of HSP mRNA induction can be observed. The most striking example is cadmium chloride which does not induce HSP60 nor its mRNA. Interestingly, under these conditions maximal activation of HSF is observed. Therefore, we conclude that more processes than just HSF activations are involved in the induction of heat shock genes.
 ...
PMID:Stressor-specific activation of heat shock genes in H35 rat hepatoma cells. 748 29

Human liver carcinoma cells (BEL-7404) and human KB adenocarcinoma cells were selected by stepwise increases in cisplatin. Drug sensitivity assays indicated that the IC50 value for 7404-CP7.5 cells was 49 micrograms ml-1 cisplatin, 111-fold higher than for the parental hepatoma cells. The IC50 value for KB-CP10 cells was 38 micrograms ml-1 cisplatin, which is 1152-fold higher than for the parental KB cells. The 7404-CP7.5 cells were cross-resistant to methotrexate (39 x), 5-fluorouracil (23 x) and 6-mercaptopurine (13 x), but were sensitive to drugs which are known substrates for the multidrug transporter (P-glycoprotein), including colchicine, vinblastine and actinomycin D. Similar cross-resistance patterns were observed for KB-CP10 cells. No evidence of DNA amplification or expression of the MDR1 gene was found. One-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed increases in 52 kDa protein(s) in both the soluble cytosolic and crude membrane fractions in 7404-CP(r) cells and in KB-CP(r) cells. The amount of 52 kDa protein was proportional to the degree of resistance of the 7404-CP(r) cells to cisplatin. Two-dimensional gel analysis demonstrated that two polypeptides of molecular mass 52 and 50 kDa were overexpressed in the membrane fractions in both 7404-CP20 and KB-CP20 cells. Using amino acid microsequencing and Western blotting, major 52 kDa protein was identified as the mitochondrial heat shock protein hsp60. Two-dimensional gels of [35S]methionine-labelled polypeptides showed many other changes, including reduction in soluble proteins of approximately 57 kDa molecular weight in KB-CP20 cells, and of 35 kDa in both 7404-CP20 and KB-CP20 cells. These results suggest that alterations of certain proteins occur commonly in cisplatin-resistant cells, particularly proteins of molecular weight 52 and 50 kDa.
 ...
PMID:Characterisation of high-level cisplatin-resistant cell lines established from a human hepatoma cell line and human KB adenocarcinoma cells: cross-resistance and protein changes. 771 Sep 28


1 2 3 4 5 6 7 8 9 Next >>