Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mantle cell lymphoma (MCL) is a distinct type of B-cell non-Hodgkin's lymphoma characterized by the t(11;14)(q13;q32) and cyclin D1 overexpression. Defects in apoptosis may contribute to pathogenesis. This study evaluated the expression of the anti-apoptotic protein Mcl-1 in two MCL cell lines and five frozen MCL tumours (four small-cell, one blastoid/large-cell) using western blot analysis. Mcl-1 expression was also assessed in 36 formalin-fixed, paraffin wax-embedded MCL tumours (24 small-cell, 12 blastoid/large-cell) by immunohistochemistry. Western blot analysis revealed the expected 37 kD protein product in both MCL cell lines and in five frozen tumours, with the blastoid case having the highest expression level. Using a cut-off of >10% immunolabelled cells for Mcl-1, it was found that 12 of 36 MCL tumours were positive. Mcl-1-positive tumours had a higher frequency of blastoid/large-cell morphology (8/12 versus 4/24, p = 0.009), p53 overexpression (3/10 versus 1/23, p = 0.04), and higher Ki67 immuno-labelling (p = 0.002). It is concluded that expression of Mcl-1 in MCL is heterogeneous. A relatively high level of Mcl-1 expression correlates with high-grade morphology, a high proliferative state, and p53 overexpression.
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PMID:Expression of Mcl-1 in mantle cell lymphoma is associated with high-grade morphology, a high proliferative state, and p53 overexpression. 1247 31

This study explores whether the presence of somatic mutations or a biased use of IgV(H) genes were associated with the clinical features in a series of 96 patients with mantle cell lymphoma (MCL). The cases were studied by seminested polymerase chain reaction using primers from the FR1 and J(H) regions. There was an unexpectedly high frequency of somatic mutations, with 29 of 103 sequences showing more than 2% of mutations. Biased usage of specific V(H) segments was also found; the most widely used genes in this series were V(H)3-21 (10 cases), V(H)3-23 (9 cases), V(H)4-34 (11 cases), and V(H)4-59 (9 cases). V(H) mutation frequency, taking into account different thresholds, did not distinguish different overall survival probabilities. Nevertheless, a more frequent use of V(H)3-21 or V(H)4-59 (8 of 18) was observed in the group of long-term survivors (18 cases > 5 years; P <.01). None of these long-term survivors presented the V(H)3-23 gene rearrangement. As in other lymphoproliferative disorders, the expression of CD38 or p53 or both was associated with a poorer survival probability. This nonrandom usage of IgV(H) segments suggests that specific antigens may play a pathogenically relevant role in the genesis or progression of subsets of MCL cases and may help in distinguishing a significant group of MCL long-term survivors.
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PMID:Molecular heterogeneity in MCL defined by the use of specific VH genes and the frequency of somatic mutations. 1251 5

Mantle cell lymphoma (MCL) is a distinctive non-Hodgkin's lymphoma subtype, characterized by overexpression of cyclin D1 as a consequence of the chromosomal translocation t(11;14)(q13;q32). MCL remains an incurable disease, combining the unfavourable clinical features of aggressive and indolent lymphomas. The blastic variant of MCL, which is often associated with additional cytogenetic alterations, has an even worse prognosis and new treatment options are clearly needed. The present study investigated the effect of a specific proteasome inhibitor, lactacystin, on cell cycle progression and apoptosis in two lymphoma cell lines harbouring the t(11;14)(q13;q32) and additional cytogenetic alterations, including p53 mutation (NCEB) and p16 deletion (Granta 519). Granta cells were more susceptible to inhibition of the proteasome with respect to inhibition of proliferation and apoptosis induction. No changes were observed in the expression levels of the G1 regulatory molecules cyclin D1 and cdk4, but cell cycle arrest and apoptosis induction was accompanied by accumulation of the cdk inhibitor p21 in both cell lines. Increased p53 expression was only observed in Granta cells with wild-type p53. Cleavage of procaspase-3 and -9 was observed but cleavage of procaspase-8 was not involved in apoptosis induction. The proapoptotic effect of lactacystin was reversed by pretreatment with the pancaspase inhibitor zVAD.fmk. Lactacystin was also effective in inducing apoptosis in lymphoma cells from MCL patients. We conclude that inhibition of the proteasome might be a promising therapeutic approach for this incurable disease.
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PMID:Inhibition of the proteasome induces cell cycle arrest and apoptosis in mantle cell lymphoma cells. 1284 95

Mantle cell lymphomas (MCL) are characterized by their aggressive behavior and poor response to chemotherapy regimens. We report here evidence of increased in vitro radiation sensitivity in two cell lines that we have generated from two MCL patients (UPN1 and UPN2). However, despite their increased radiation sensitivity, UPN2 cells were totally resistant to apoptotic cell death, whereas UPN1 cells underwent massive apoptosis 6 h after irradiation. The frequency of induced chromosomal abnormalities was higher in UPN1 as compared to UPN2. Distinct mechanisms have been found to contribute to this phenotype: a major telomere shortening (UPN1 and UPN2), deletion of one ATM allele and a point mutation in the remaining allele in UPN2, mutation of p53 gene (UPN1 and UPN2) with absence of functional p53 as revealed by functional yeast assays. After irradiation, Ku70 levels in UPN1 increased and decreased in UPN2, whereas in the same conditions, DNA-PKcs protein levels decreased in UPN1 and remained unchanged in UPN2. Thus, irradiation-induced apoptotic cell death can occur despite the nonfunctional status of p53 (UPN1), suggesting activation of a unique pathway in MCL cells for the induction of this event. Overall, our study demonstrates that MCL cells show increased radiation sensitivity, which can be the result of distinct molecular events. These findings could clinically be exploited to increase the dismal response rates of MCL patients to the current chemotherapy regimens.
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PMID:Multiple molecular mechanisms contribute to radiation sensitivity in mantle cell lymphoma. 1297 Jul 38

A 76-year-old man presented with leukostasis syndrome, including oculodynia, blurred vision, and visual field defects, due to mantle cell lymphoma, prolymphocytoid variant, with marked leukocytosis, 1227 x 10(9)/l. He had splenomegaly but no lymphadenopathy or hepatomegaly. The tumor cells were CD5+, CD19+, CD20+, FMC-7+, and kappa light chain restricted. Immunohistochemistry showed expression of p53 and of cyclin D1. Fluorescent in situ hybridization demonstrated t(11;14) with translocation between CYCLIN D1 and the immunoglobulin heavy-chain genes. The patient received leukapheresis and aggressive chemotherapy, but the leukocyte count remained above 100 x 10(9)/l. The patient's condition rapidly deteriorated with lymphomatous infiltration of his lungs and soft tissues, and he expired 6 months after diagnosis. While it is known that mantle cell lymphoma may have a leukemic phase, the degree of leukocytosis in this case exceeds that previously reported in the literature and resulted in a clinical syndrome of leukostasis.
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PMID:Case report: mantle cell lymphoma, prolymphocytoid variant, with leukostasis syndrome. 1519 1

We describe a progressive mantle cell lymphoma (MCL) in which multicolor fluorescence in situ hybridization (M-FISH) on metaphases did not detect the characteristic t(11;14)(q13;q32), although translocations of chromosomes 11 with 15, and 14 with 15 were observed. When CCND1/IGH probes were hybridized to metaphases, however, cryptic fusion signals were detected on the der(11) and der(14) sites of CCND1 (11q13) and IGH (14q32), revealing a complex translocation involving chromosomes 11, 14, and 15. Interphase FISH with CCND1/IGH probes revealed varying patterns with one or two fusion signals, and some with no clear evidence of fusion. Loss of 17p and gain of 3q, known to be associated with disease progression in MCL, were detected with M-FISH and confirmed with the use of p53 and BCL6 probes together with comparative genomic hybridization, which detected also an interstitial deletion on 7p21. This case further illustrates the value of M-FISH in combination with fusion probes in elucidating complex cytogenetic abnormalities.
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PMID:Molecular cytogenetic study of a mantle cell lymphoma with a complex translocation involving the CCND1 (11q13) region. 1538 76

Mantle cell lymphoma (MCL) is a mature B-cell proliferation characterized by the presence of translocation t(11;14)(q13;q32), an aggressive clinical course, and poor response to chemotherapy. The majority of drugs currently used in the treatment of lymphoproliferative disorders induce cell death by triggering apoptosis, but few data concerning drug-induced apoptosis in MCL have been reported. We have analysed the mechanisms of drug-induced cell death in four cell lines with the t(11;14) and in primary cells from 10 patients with MCL. Mitoxantrone, a topoisomerase II inhibitor, induced a strong cytotoxic effect in three cell lines (JVM-2, REC-1, and Granta 519), and in primary MCL cells. This cytotoxic effect due to apoptosis induction was observed despite the presence of either p53 or ATM abnormalities. However, no cytotoxic effect was detected after incubation with DNA-damaging agents in the NCEB-1 cell line, carrying p53 and ATM alterations, despite the presence of functional mitochondrial machinery. These results support that mitoxantrone can be effective in the treatment of MCL but that this activity requires the integrity of functional DNA-damage response genes.
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PMID:Activation of mitochondrial apoptotic pathway in mantle cell lymphoma: high sensitivity to mitoxantrone in cases with functional DNA-damage response genes. 1548 Apr 31

CHK1: gene encodes for a serine/threonine kinase involved in the regulation of cell cycle progression and DNA damage checkpoints. To determine the role of CHK1 in the pathogenesis of lymphoid neoplasms and its relationship to other DNA damage response genes, we have analyzed the gene status, protein, and mRNA expression in a series of tumors and nonneoplastic lymphoid tissues. CHK1 protein and mRNA expression levels were very low in both reactive tissues and resting lymphoid cells, whereas tumor samples showed a variable pattern of expression related to their proliferative activity. However, seven aggressive tumors showed a dissociate pattern of extremely low or negative protein expression in spite of a high proliferative activity. Four of these tumors were diffuse large B-cell lymphomas (DLCLs) with concordant reduced levels of mRNA, whereas one blastoid mantle cell lymphoma (B-MCL) and two DLCLs had relatively normal levels of mRNA. No gene mutations, deletions, or hypermethylation of the promoter region were detected in any of these cases. In all these tumors ATM, CHK2, and p53 genes were wild type. These findings suggest that CHK1 inactivation in NHLs occurs by loss of protein expression in a subset of aggressive variants alternatively to ATM, CHK2, and p53 alterations.
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PMID:Checkpoint kinase 1 (CHK1) protein and mRNA expression is downregulated in aggressive variants of human lymphoid neoplasms. 1552 25

The heterocyclic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), formed during the cooking of meat, induces tumors of the prostate, colon, and mammary gland when fed to rats. PhIP is readily absorbed and efficiently metabolized to a genotoxic derivative by CYP1 enzymes. Although metabolism and mutational potential of PhIP have previously been well characterized, the intervening cellular and genomic responses to the chemical are not fully understood. We have examined the cellular response to PhIP exposure in human mammary epithelial MCF10A cells, which retain characteristics of normal breast epithelial cells. Because these cells fail to activate PhIP, they were cocultured with a human lymphoblastoid cell line MCL-5, which constitutively expresses CYP1A1, and have been transfected to express human CYPs1A2, 2A6, 3A4, and 2E1. The MCL-5 cells were irradiated (2,000 rads) prior to coculture, rendering them unable to replicate yet still retaining metabolic competency. MCF10A cells were treated (in the presence of MCL-5 cells) with PhIP (1-100 microM) and harvested at various time-points. Compared to DMSO control, treatment (24 or 48 h) with PhIP resulted in a significant dose-dependent fall in cell number. Cells treated for 48 h then cultured in the absence of PhIP (and MCL-5 cells) for a further 6 days showed a much greater dose-dependent reduction in cell number. Flow cytometric analysis indicated that PhIP treatment (48 h) resulted in a dose-dependent accumulation of cells in the G1 population. Western blotting revealed elevated expression of p53 and the cyclin dependent kinase inhibitor p21WAF1/CIP1 after PhIP treatment. Levels of MDM2, a negative regulator of p53, and the hypophosphorylated form of RB were also elevated, consistent with the triggering of G1 cell cycle checkpoint. These cell cycle effects are critical, as they enable cells to effect genome repair, accept mutation, or eliminate excessively damaged cells.
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PMID:A mechanistic basis for the role of cycle arrest in the genetic toxicology of the dietary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). 1563 49

The proteasome is the main extralysosomal system involved in intracellular proteolysis. A number of proteasome substrates, including cyclins, IkappaB, and p53, are critical to cell cycle progression and apoptosis. Interruption of the degradation of these substrates through proteasome inhibition is a novel and unique approach to the treatment of malignancies. First-generation proteasome inhibitors lacked usefulness because of broad specificity and irreversible binding to the proteasome. However, the later synthesis of the peptide boronic acid proteasome inhibitor bortezomib allowed for selective, reversible binding. Basic investigations have reported the antitumor activity of bortezomib in a variety of hematologic and solid tumor models and have demonstrated the ability of bortezomib to enhance chemosensitivity and overcome cellular mechanisms of drug resistance attributable, in part, to abrogation of NF-kappaB induction. In patients with relapsed, refractory multiple myeloma who had received a median of six prior regimens, treatment with bortezomib resulted in a 35% response rate (complete plus partial plus minimal response) using criteria of the European Group for Blood and Marrow Transplantation. Encouraging activity has been demonstrated with bortezomib in the first-line treatment of myeloma and in patients with mantle cell lymphoma. Investigations of its utility in the treatment of patients with solid tumors are ongoing.
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PMID:Proteasome inhibition in the treatment of cancer. 1565 70


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