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

During a search for trans-acting factors associating with insulin-like growth factor II (IGF-II) mRNAs, we recently identified a family of three IGF-II mRNA-binding Proteins (IMP1, IMP2 and IMP3) that exhibit multiple attachments to IGF-II leader 3 mRNA and the reciprocally imprinted H19 RNA. IMPs contain the unique combination of two RNA recognition motifs (RRMs) and four hnRNP K homology (KH) domains. IMP1 is orthologous to the chicken zipcode-binding protein (ZBP-1), and the mouse c-myc coding region determinant-binding protein (CRD-BP) that associates with beta-actin and c-myc mRNA, respectively. Moreover, the p62 protein identified in hepatocellular carcinoma represents a splice variant of IMP2, and IMP3 is orthologous to the Xenopus Vegetal 1 RNA-binding protein (Vgl-RBP/Vera). IMPs are produced in a biphasic fashion--initially during the early stages of embryogenesis and subsequently later in development. IMPs and their orthologues are predominantly cytoplasmic and are implicated in the transport of their RNA targets towards the leading edge in somatic cells and to the vegetal pole in Xenopus oocytes, respectively. RNA localization is a conserved mechanism of polarizing genetic information in the establishment of asymmetries during both embryogenesis and adult life, enabling local protein synthesis at final destinations within the cell. The identification of developmentally expressed zipcode-binding proteins indicates that RNA trafficking participates in processes such as cell-growth and migration during embryogenesis.
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PMID:A family of IGF-II mRNA binding proteins (IMP) involved in RNA trafficking. 1171 86

Exposure of cells to stress, particularly oxidative stress, leads to misfolding of proteins and, if they are not refolded or degraded, to cytoplasmic protein aggregates. Protein aggregates are characteristic features of a variety of chronic toxic and degenerative diseases, such as Mallory bodies (MBs) in hepatocytes in alcoholic and non-alcoholic steatohepatitis, neurofibrillary tangles in neurons in Alzheimer's, and Lewy bodies in Parkinson's disease. Using 2D gel electrophoresis and mass spectrometry, we identified p62 as a novel MB component. p62 and cytokeratins (CKs) are major MB constituents; HSP 70, HSP 25, and ubiquitinated CKs are also present. These proteins characterize MBs as a prototype of disease-associated cytoplasmic inclusions generated by stress-induced protein misfolding. As revealed by transfection of tissue culture cells overexpressed p62 did not induce aggregation of regular CK filaments but selectively bound to misfolded and ubiquitinated CKs. The general role of p62 in the cellular response to misfolded proteins was substantiated by detection of p62 in other cytoplasmic inclusions, such as neurofibrillary tangles, Lewy bodies, Rosenthal fibers, intracytoplasmic hyaline bodies in hepatocellular carcinoma, and alpha1-antitrypsin aggregates. The presence of p62 along with other stress proteins and ubiquitin in cytoplasmic inclusions indicates deposition as aggregates as a third line of defense against misfolded proteins in addition to refolding and degradation.
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PMID:p62 Is a common component of cytoplasmic inclusions in protein aggregation diseases. 1178 19

Recently our laboratory identified a cytoplasmic RNA-binding protein p62 which binds to and regulates the expression of IGF II mRNA. p62 was initially shown to be recognized by auto-antibodies in hepatocellular carcinoma (HCC) but now anti-p62 has been described in diverse malignancies. p62 is uniformly expressed in fetal liver and prominently in 33% of HCC nodules, but not detectable in adult liver or normal tissue adjacent to HCC nodules. In this study, a 90 kDa protein (p90), auto-antibodies to which were found associated with anti-p62 responses in the same HCC patient group, was identified by cDNA expression cloning. Indirect immunofluorescence showed that, like p62, p90 localized to the cytoplasm in cultured cells and mouse fetal, but not adult liver. Among 11 human gastric cancer tissues examined, p90 was overexpressed in six (55%). Together with other cancer associated auto-antibodies such as anti-p53, anti-p62, anti-Koc, and anti-CENP-F, auto-antibodies to p90 represent a new marker for tumors such as HCC and gastric cancer. Our data support the working hypothesis that auto-antibody production in cancer may be directly linked to aberrant auto-antigen expression.
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PMID:Cloning and characterization of a novel 90 kDa 'companion' auto-antigen of p62 overexpressed in cancer. 1211 81

Studies of autoantibodies in systemic rheumatic diseases have provided abundant evidence suggesting that autoimmune responses are antigen-driven and that autoantibodies often can be viewed as reporters of the immune system revealing the identity of antigens which might be playing roles in the pathophysiology of the disease process. Recent data from our laboratory suggest a similar mechanistic process may be involved in humoral immune responses in certain cancers such as hepatocellular carcinoma (HCC). HCC is unique in that one can follow a cohort of patients with chronic liver disease who will likely progress to develop malignancy over a period of 10 or more years. It has been observed that during transition from chronic liver disease to HCC, novel autoantibodies can appear which are not detected prior to pre-malignant conditions. The hypothesis is that these novel antibody responses may be stimulated by cellular proteins which are involved in carcinogenesis. By immunoscreening an expression library to isolate cDNA clones of autoantigens, a RNA-binding autoantigen p62 has been identified in HCC recently and autoantibodies to p62 were found in 21% of a cohort of HCC patients. p62 is a cytoplasmic protein which binds to mRNA encoding insulin-like growth factor II (IGF-II), a growth factor which is known to be overexpressed in HCC and is tumorigenic in transgenic animals. The expression of p62 is developmentally regulated, and expressed in fetal, but not in adult liver. Our recent observations showing that p62 was aberrantly expressed in 30% of unselected HCC suggest that it could play a role in HCC and other tumors by upregulating expression of growth factor IGF-II in the milieu of other oncogenic factors.
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PMID:Autoantibodies to IGF-II mRNA binding protein p62 and overexpression of p62 in human hepatocellular carcinoma. 1284 8

p62 is a cancer-associated antigen binding to mRNA encoding insulin-like growth factor II that was isolated by immunoscreening a cDNA expression library with autoantibodies from patients with hepatocellular carcinoma (HCC). In the present study, multiple methods including flow cytometry, confocal laser-scanning microscope, electron microscope were used to characterize the effect of ATRA on BGC-823 cells, which presented two phenotypes of differentiation and apoptosis in cells treated with 1.0 and 50 microM ATRA, respectively. Interestingly, we found that p62 was cytoplasmic in location, but it significantly decreased in cytoplasm and appeared in nucleus of cells when the cells were treated with 50 microM all-trans retinoic acid (ATRA) for 5 days. Furthermore, proteomics approach on differential nucleus proteins showed that the up-regulation and/or down-regulation of cell cycle proteins and IGF binding proteins were involved in the apoptosis of BGC-823 cells induced by ATRA. These results suggest that there is a significant association between expression and distribution of p62 and the growth arrest of tumor cells, in which p62 is associated with cell apoptosis induced by ATRA.
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PMID:Effect of all-trans-retinoic acid on mRNA binding protein p62 in human gastric cancer cells. 1561 18

The expression of p62 autoantigen and the frequency of p62 autoantibody have been reported in hepatocellular carcinoma (HCC) and many types of malignant tumors, respectively, but information regarding to the expression of p62 in other cancer tissues and the association of autoantibody to p62 with tumor behaviors is not available. In the current study, the expression of p62 in tissues and the appearance of p62 autoantibody in sera were detected by immunohistochemical staining and ELISA in four clinical types of digestive system cancers including gastric cancer, esophageal cancer, large intestine cancer and HCC, respectively. Interestingly, the immunohistochemistry staining of p62 has been shown in all of digestive canal tissues (stomach, esophagus, large intestine) including tissues with cancers, beside cancers and from non-malignant patients, whereas the frequencies were 62.5% and 0% in tissues with cancer and beside cancer in patients with HCC, respectively. Importantly, we found that the p62 expression and the frequency of autoantibody to p62 were associated to cell differentiation and tumor metastasis, respectively. These results suggest that the expression of p62 in tissues and the appearance of autoantibody to p62 in sera might be related to cell malignant manifestations. Moreover, p62 autoantibody is a significant marker for the prognosis of cancers and the evaluation of clinical treatments.
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PMID:The diversity expression of p62 in digestive system cancers. 1588 58

Mallory bodies (MBs) and intracellular hyaline bodies (IHBs) are cytoplasmic hepatocellular inclusions that consist of aggregated proteins. MBs are characteristically associated with alcoholic and non-alcoholic steatohepatitis, but may also be found in chronic cholestatic and metabolic (eg copper intoxication) diseases and hepatocellular neoplasms, particularly hepatocellular carcinomas. IHBs have hitherto only been described in hepatocellular carcinoma cells. In the present study hepatocellular carcinomas (HCCs) and a case of idiopathic copper toxicosis were evaluated with respect to the presence and mutual relationship of MBs and IHBs. IHBs alone were present in 8.6%, MBs alone in 16.1% and both types of inclusion in 7.5% of HCCs. It is shown that IHBs may also occur in non-neoplastic hepatocytes in association with idiopathic copper toxicosis, together with MBs. In HCCs and idiopathic copper toxicosis, MBs and IHBs may be present within the same cell. Moreover, hybrid inclusions holding an intermediate position between MBs and IHBs regarding light microscopy, ultrastructure and composition exist. MBs and IHBs contain p62, a stress-inducible adapter protein, as the major constituent. In MBs p62 is associated with keratins, whereas classical IHBs lack keratins. Light microscopic, electron microscopic and immunohistochemical data suggest a close pathogenetic relationship between MBs and IHBs. Both types of inclusion are the result of over-expression and accumulation of the stress protein p62. If p62 is induced alone, or at least prevails, IHBs may arise by aggregation. However, if abnormal keratins are present in addition to p62, p62 associates and co-aggregates with keratins, finally leading to classical MBs.
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PMID:Are the Mallory bodies and intracellular hyaline bodies in neoplastic and non-neoplastic hepatocytes related? 1647 90

The peroxisome proliferator-activated receptor alpha (PPARalpha) belongs to the nuclear receptor family and plays a central role in the regulation of lipid metabolism, glucose homeostasis and inflammatory processes. In addition to its ligand-induced activation, PPARalpha is regulated by phosphorylation via ERK-MAPK, PKA and PKC. In this study we examined the effect of p38-MAPK on PPARalpha transcriptional activity. In COS-7 cells, anisomycin, a p38 activator, induced a dose-dependent phosphorylation of PPARalpha and a 50% inhibition of its transcriptional activity. In H4IIE hepatoma cells, anisomycin-induced p38 phosphorylation decreased both endogenous and PPARalpha ligand-enhanced L-CPTI and ACO gene expression. Interestingly, PPARalpha/p38 interaction required the molecular adapter ZIP/p62. Reducing ZIP/p62 expression by siRNA, partially reversed the inhibitory effect of anisomycin on L-CPTI gene expression. In conclusion, we showed that p38 activation induced PPARalpha phosphorylation and inhibition of its transcriptional activity through a trimeric interaction between p38-MAPK, ZIP/p62 and PPARalpha.
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PMID:Involvement of ZIP/p62 in the regulation of PPARalpha transcriptional activity by p38-MAPK. 1837 65

Impaired selective turnover of p62 by autophagy causes severe liver injury accompanied by the formation of p62-positive inclusions and upregulation of detoxifying enzymes. These phenotypes correspond closely to the pathological conditions seen in human liver diseases, including alcoholic hepatitis and hepatocellular carcinoma. However, the molecular mechanisms and pathophysiological processes in these events are still unknown. Here we report the identification of a novel regulatory mechanism by p62 of the transcription factor Nrf2, whose target genes include antioxidant proteins and detoxification enzymes. p62 interacts with the Nrf2-binding site on Keap1, a component of Cullin-3-type ubiquitin ligase for Nrf2. Thus, an overproduction of p62 or a deficiency in autophagy competes with the interaction between Nrf2 and Keap1, resulting in stabilization of Nrf2 and transcriptional activation of Nrf2 target genes. Our findings indicate that the pathological process associated with p62 accumulation results in hyperactivation of Nrf2 and delineates unexpected roles of selective autophagy in controlling the transcription of cellular defence enzyme genes.
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PMID:The selective autophagy substrate p62 activates the stress responsive transcription factor Nrf2 through inactivation of Keap1. 2019 Aug 29

Suppression of autophagy is always accompanied by marked accumulation of p62, a selective autophagy substrate. Because p62 interacts with the Nrf2-binding site on Keap1, which is a Cullin 3-based ubiquitin ligase adapter protein, autophagy deficiency causes competitive inhibition of the Nrf2-Keap1 interaction, resulting in stabilization of Nrf2 followed by transcriptional activation of Nrf2 target genes. Herein, we show that liver-specific autophagy-deficient mice harbor adenomas linked to both the formation of p62- and Keap1-positive cellular aggregates and induction of Nrf2 targets. Importantly, similar aggregates were identified in more than 25% of human hepatocellular carcinomas (HCC), and induction of Nrf2 target genes was recognized in most of these tumors. Gene targeting of p62 in an HCC cell line markedly abrogates the anchorage-independent growth, whereas forced expression of p62, but not a Keap1 interaction-defective mutant, resulted in recovery of the growth defect. These results indicate the involvement of persistent activation of Nrf2 through the accumulation of p62 in hepatoma development.
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PMID:Persistent activation of Nrf2 through p62 in hepatocellular carcinoma cells. 2148 15


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