Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.25.1 (proteasome)
28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

PA28-gamma is the activator of 20S proteasome, the ATP-dependent proteolytic system that plays an important role in cell cycle progression in various cell types. In this paper, we show the abnormally high expression of PA28-gamma in various thyroid neoplasms. Thyroid samples were obtained from patients with normal thyroid (4 cases) and with the following diseases: papillary adenocarcinoma (13 cases), multinodular goiter (4 cases), and anaplastic carcinoma (1 case). PA28-gamma expression was estimated by immunohistochemical staining and Western blotting. In all of the papillary adenocarcinoma samples, PA28-gamma was abnormally overexpressed, especially in cancer cells existing at the peripheral region of the cancer mass or in cancer cells invading the capsular region surrounding the cancer mass. In cancer cells of these areas, PA28-gamma was predominantly distributed in nucleus rather than in the cytoplasm of cancer cells. On the other hand, no obvious PA28-gamma expression was observed in the adjacent normal thyroid follicular cells. In multinodular goiter, the expression of PA28-gamma was relatively low compared with papillary adenocarcinoma. In anaplastic carcinoma, PA28-gamma was expressed at the highest level, especially in poorly differentiated regions such as squamous metaplasia of anaplastic cancer tissue. Therefore, the PA28-gamma expression seems to be restricted to thyroid cancer cells, especially in the region where the growth rate of cancer cells is accelerated. This result is further confirmed by the fact that C2, alpha-subunit of 20S proteasome, and proliferating cell nuclear antigen are similarly overexpressed in this region. Thus, PA28-gamma might be involved in the regulatory system for the cell cycle. Moreover, the growth of thyroid cancer cell lines was affected by the proteasome inhibitor, clasto-lactacystin beta-lactone. These results demonstrate that PA28-gamma is overexpressed in thyroid cancer, especially in its growth-accelerated cells.
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PMID:Abnormally high expression of proteasome activator-gamma in thyroid neoplasm. 1262 32

We show that treatment of a panel of thyroid carcinoma cell lines naturally harboring the RET/PTC1 oncogene, with the RET kinase inhibitors PP1 and ZD6474, results in reversible G(1) arrest. This is accompanied by interruption of Shc and mitogen-activated protein kinase (MAPK) phosphorylation, reduced levels of G(1) cyclins, and increased levels of the cyclin-dependent kinase inhibitor p27Kip1 because of a reduced protein turnover. MAP/extracellular signal-regulated kinase 1/2 inhibition by U0126 caused G(1) cyclins down-regulation and p27Kip1 up-regulation as well. Forced expression of RET/PTC in normal thyroid follicular cells caused a MAPK- and proteasome-dependent down-regulation of p27Kip1. Reduction of p27Kip1 protein levels by antisense oligonucleotides abrogated the G(1) arrest induced by RET/PTC blockade. Therefore, in thyroid cancer, RET/PTC-mediated MAPK activation contributes to p27Kip1 deregulation. This pathway is implicated in cell cycle progression and in response to small molecule kinase inhibitors.
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PMID:Regulation of p27Kip1 protein levels contributes to mitogenic effects of the RET/PTC kinase in thyroid carcinoma cells. 1517 89

Overexpression of pituitary tumor-transforming 1 (PTTG1) is associated with thyroid cancer. We found elevated PTTG1 levels in the thyroid tumors of a mouse model of follicular thyroid carcinoma (TRbeta(PV/PV) mice). Here we examined the molecular mechanisms underlying elevated PTTG1 levels and the contribution of increased PTTG1 to thyroid carcinogenesis. We showed that PTTG1 was physically associated with thyroid hormone beta receptor (TRbeta) as well as its mutant, designated PV. Concomitant with thyroid hormone-induced (T3-induced) degradation of TRbeta, PTTG1 proteins were degraded by the proteasomal machinery, but no such degradation occurred when PTTG1 was associated with PV. The degradation of PTTG1/TRbeta was activated by the direct interaction of the liganded TRbeta with steroid receptor coactivator 3 (SRC-3), which recruits proteasome activator PA28gamma. PV, which does not bind T3, could not interact directly with SRC-3/PA28gamma to activate proteasome degradation, resulting in elevated PTTG1 levels. The accumulated PTTG1 impeded mitotic progression in cells expressing PV. Our results unveil what we believe to be a novel mechanism by which PTTG1, an oncogene, is regulated by the liganded TRbeta. The loss of this regulatory function in PV led to an aberrant accumulation of PTTG1 disrupting mitotic progression that could contribute to thyroid carcinogenesis.
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PMID:Aberrant accumulation of PTTG1 induced by a mutated thyroid hormone beta receptor inhibits mitotic progression. 1703 56

Study of molecular actions of thyroid hormone receptor beta (TRbeta) mutants in vivo has been facilitated by creation of a mouse model (TRbetaPV mouse) that harbors a knockin mutant of TRbeta (denoted PV). PV, which was identified in a patient with resistance to thyroid hormone, has lost T3 binding activity and transcription capacity. The striking phenotype of thyroid cancer exhibited by TRbeta(PV/PV) mice has allowed the elucidation of novel oncogenic activity of a TRbeta mutant (PV) [PAS1] beyond nucleus-initiated transcription. PV was found to physically interact with the regulatory p85alpha subunit of phosphatidylinositol 3-kinase (PI3K) in both the nuclear and cytoplasmic compartments. This protein-protein interaction activates the PI3K signaling by increasing phosphorylation of AKT, mammalian target of rapamycin (mTOR), and p70(S6K). PV, via interaction with p85alpha, also activates the PI3K-integrin-linked kinase-matrix metalloproteinase-2 signaling pathway in the extra-nuclear compartment. The PV-mediated PI3K activation results in increased cell proliferation, motility, migration, and metastasis. In addition to affecting these membrane-initiated signaling events, PV affects the stability of the pituitary tumor-transforming gene (PTTG) product. PTTG (also known as securin), a critical mitotic checkpoint protein, is physically associated with TRbeta or PV in vivo. Concomitant with T3-induced degradation of TRbeta, PTTG is degraded by the proteasome machinery, but no such degradation occurs when PTTG is associated with PV. The degradation of PTTG/TRbeta is activated by the direct interaction of the T3-bound TRbeta with the steroid receptor coactivator-3 (SRC-3) that recruits a proteasome activator (PA28gamma). PV that does not bind T3 cannot interact directly with SRC-3/PA28gamma to activate proteasome degradation, and the absence of degradation results in an aberrant accumulation of PTTG. The PV-induced failure of timely degradation of PTTG results in mitotic abnormalities. PV, via novel protein-protein interaction and transcription regulation, acts to antagonize the functions of wild-type TRs and contributes to the oncogenic functions of this mutation.
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PMID:Novel functions of thyroid hormone receptor mutants: beyond nucleus-initiated transcription. 1716 89

Proteasome inhibitors represent a novel class of antitumor agents with preclinical and clinical evidence of activity against hematological malignancies and solid tumors. Emerging lines of evidence suggest that the unfolded protein response is implicated in proteasome inhibitors-induced apoptosis. Glucose-regulated protein 78 kDa (GRP78) and CCAAT/enhancer-binding protein homologous protein (CHOP) as part of the unfolded protein response play critical roles in cell survival or death. Here we demonstrate that induction of GRP78 and CHOP are differently regulated upon proteasome inhibition in different thyroid cancer cell lines, and GRP78 levels as well as preferential induction of GRP78 or CHOP appears to be involved in the responsiveness. Insensitive ARO, 8305C, and 8505C cell lines inherently express relatively high levels of GRP78 compared with sensitive cell lines, and its levels are further up-regulated upon treatment with proteasome inhibitors. CHOP levels are dramatically induced in sensitive cell lines until 24 h after proteasome inhibition. On the other hand, only a slight increase is observed at 4 h in insensitive cell lines, and this increase is unable to be detected after 8 h. Insensitive cells are sensitized to proteasome inhibition by suppression of GRP78. Furthermore, suppression of CHOP induction or overexpression of GRP78 partially prevents proteasome inhibition-mediated cell death. Our study indicates a molecular mechanism by which the sensitivity of thyroid cancer cells is regulated by the level of GRP78 as well as preferential induction of GRP78 or CHOP upon treatment with proteasome inhibitors. Our experiments therefore suggest a novel approach toward sensitization of thyroid cancer cells to proteasome inhibitors.
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PMID:Different induction of GRP78 and CHOP as a predictor of sensitivity to proteasome inhibitors in thyroid cancer cells. 1743 Oct 3

Proteasome inhibitors are emerging as effective drugs for the treatment of relapsed/refractory multiple myeloma and possibly some solid tumors. Bcl-2-associated athanogene 3 (BAG3) is a survival protein that has been shown to be stimulated during cell response to stressful conditions, such as exposure to high temperature, heavy metals. We have recently demonstrated that BAG3 is also induced by proteasome inhibitors at the transcriptional level and the induction of BAG3 by proteasome inhibition is antiapoptotic. Here, we demonstrated that although proteasome inhibitors triggered similar upregulation of BAG3 transcript in sensitive and insensitive thyroid cancer cells, persistent increase of BAG3 protein was detected in insensitive cells, whereas less increase or even decrease was observed in sensitive cells. Notably, decrease of BAG3 protein was associated with the appearance of a BAG3 fragment of approximately 40kDa, which appeared to be caspase-dependent. Therefore, caspase-dependent cleavage of BAG3 might facilitate apoptosis in sensitive cells.
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PMID:Caspase-dependent cleavage of BAG3 in proteasome inhibitors-induced apoptosis in thyroid cancer cells. 1832 27

Anaplastic thyroid carcinoma (ATC) is among the most aggressive human malignancies, being responsible for the majority of thyroid cancer-related deaths. Despite multimodal therapy including surgery, chemotherapy, and radiotherapy, the outcome of ATC is poor. The human ATC cell line MB1, derived from tumor tissue of a 57-year-old man with thyroid cancer and pronounced neutrophilia, was established from surgically excised tumor tissue. The karyotype of the cell line shows many chromosomal abnormalities. Preclinical investigations have shown antitumor activity and effectiveness of the BRAF kinase inhibitor Sorafenib and the proteasome inhibitor Bortezomib. After establishment of the MB1 cell line these agents were applied in vitro and, showing activity in a cell culture model, were also used for in vivo treatment. Sorafenib had some clinical effect, namely normalization of leucocytosis, but had no sustained impact on subsequent tumor growth and development of distant metastasis. Molecular diagnostics of the tumor demonstrated no BRAF mutations in exons 11 and 15 concordant with a rather modest effect of Sorafenib on MB1 cell growth. Clinical benefit was seen with subsequent bortezomib therapy inducing a temporary halt to lymph node growth and a progression-free interval of 7 weeks. Our observations together with previous data from preclinical models could serve as a rationale for selecting those patients suffering from ATC most likely to benefit from targeted therapy. A prospective controlled randomized trial integrating kinase and proteasome inhibitors into a therapeutic regime for ATC is warranted.
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PMID:Targeted therapeutic approach for an anaplastic thyroid cancer in vitro and in vivo. 1861 78

At present, the clinical and pathological analysis used in the diagnosis of papillary thyroid cancer (PTC) are insufficient to discern tumor behavior, and new diagnostic and prognostic markers need to be identified. In this study, we performed a comparative proteome analysis to examine the global changes of fine needle aspiration fluid (FNA) protein patterns of two variants of malignant PTC (classical variant PTC (cPTC) and tall cell variant PTC (TCV)) with respect to the controls. Changes in protein expression were identified using two-dimensional electrophoresis (2DE) and peptide mass fingerprinting via MALDI-TOF mass spectrometry (MS), as well as Western blot analysis. A statistical significant up-regulation of 17 protein spots in cPTC and/or TCV with respect to controls was demonstrated. These proteins included transthyretin precursor (TTR), ferritin light chain (FLC), proteasome activator complex subunit 1 and 2, alpha-1-antitrypsin precursor, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), lactate dehydrogenase chain B (LDH-B), apolipoprotein A1 precursor (Apo-A1), annexin A1, DJ-1 protein and cofilin-1. In addition, 12 protein spots were found exclusively in cPTC and three exclusively in TCV. These latter proteins (ferritin heavy chain (FHC), peroxiredoxin 1 (PRX1) and 6-phosphogluconate dehydrogenase (6-PDGH)) correspond to stress response proteins and, until now, had not been described in thyroid tumors. These findings illustrate the potential use of FNA proteomics to identify protein changes associated with thyroid cancer and to advance potential protein biomarkers in the diagnostic classification of the disease.
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PMID:Fine-needle aspiration of thyroid nodules: proteomic analysis to identify cancer biomarkers. 1866 25

Advanced thyroid cancer refers to thyroid tumors which are resistant to conventional therapies and do not respond to radioiodine and comprises metastatic or recurrent differentiated cancers, poorly differentiated and anaplastic tumors. Progress in the knowledge of genetic/epigenetic alterations in thyroid cancer cells is rapidly offering several opportunities to develop new drugs directed to specific targets. Drugs currently proposed for molecular therapy include: (a) monoclonal antibodies; (b) kinase inhibitors; (c) anti-angiogenetic drugs; (d) proteasome inhibitors; (e) retinoic acid and PPAR-gamma ligands; (f) radionuclide therapy; (g) epigenetic drugs (deacetylase inhibitors and demethylating agents). The results of several phase II trials using molecular drugs look promising. None of the treated patients, however, had a complete response, and only a minority of them had a partial response. The review will focus especially on epigenetic therapy, whose goal is to target the chromatin in rapidly dividing tumor cells and potentially restore normal cell functions. Deacetylases inhibitors modulate both epigenetic and multiple non-epigenetic mechanisms; they are, thus, viewed as a promising class of anticancer drugs. Experimental data show that deacetylase inhibitors are effective against advanced thyroid cancer. However, since multiple pathways need to be inhibited in order to substantially affect thyroid cancer growth, it is likely that a significant increase in the response rate to treatment of advanced thyroid cancer will be achieved through combinatorial drug therapies. Actually, many pre-clinical and clinical studies evaluate the combination of either two epigenetic drugs or a non-epigenetic chemotherapeutic and an epigenetic drug, in the effort to increase response rates.
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PMID:Emerging molecular therapies of advanced thyroid cancer. 2017 50

Proteasome inhibitors represent a novel class of antitumor agents with pre-clinical and clinical evidence of activity against hematologic malignancies and solid tumors. However, emerging evidence indicates that antiapoptotic factors may also accumulate as a consequence of exposure to these drugs, thus it seems plausible that the activation of survival signaling cascades might compromise their antitumoral effects. Peroxiredoxins (PRDXs) are a family of thiol-containing peroxidases identified primarily by their ability to remove cellular hydroperoxides. The function of PRDX1 in particular has been implicated in regulating cell proliferation, differentiation, and apoptosis. Another important finding is that aberrant upregulation of PRDX1 has been discovered in various cancers. Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein kinase (MAPK) kinase kinase that is regulated under conditions of cellular stress. ASK1 phosphorylates c-Jun N-terminal kinase and p38 MAPK, and elicits an apoptotic response. ASK1 activity is regulated at multiple levels, one of which is through interaction with PRDX1. In this study, for the first time we report that upregulation of PRDX1 expression was found in thyroid cancer cells treated with proteasome inhibitors, and PRDX1 knockdown resulted in accelerated proteasome inhibitor-induced cell death. In addition, we demonstrated that ASK1 activity was implicated in the PRDX1-dependent response of thyroid cancer cells to proteasome inhibitor-mediated cell death.
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PMID:Suppression of MG132-mediated cell death by peroxiredoxin 1 through influence on ASK1 activation in human thyroid cancer cells. 2041 Jan 61


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