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)

We looked for MDM2 gene amplification and over-expression by Southern and Northern blot analysis in 135 and 66 cases of haematological malignancies, including ALL, AML, CML in chronic phase, CLL, MDS, PLL, non-Hodgkin's lymphoma (NHL) and myeloma. No amplification of the gene was found. An over-expression of MDM2 RNA was seen in 9/66 (14%) patients tested, including 3/9 ALL, 3/24 AML, 2/4 myelomas, 1/1 PLL, but 0/2 CML, 0/2 NHL and 0/21 MDS. None of the patients over-expressing MDM2 had modifications of P53 gene transcript or p53 mutations. Most of the patients over-expressing MDM2 gene had poor prognostic features (including 'unfavourable' cytogenetic abnormalities), poor response to chemotherapy and short survival. Our findings suggest that over-expression of MDM2 is seen in a relatively small number of haematological malignancies, and is associated with poor prognosis.
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PMID:Over-expression of the MDM2 gene is found in some cases of haematological malignancies. 780 95

A group of 20 CLL patients selected for advanced clinical stage p53 mutations were analysed by single-strand conformational polymorphism (SSCP) following PCR amplification of exons 5-9. In two patients abnormal SSCP of either exon 5 or exon 8 was found and PCR products were analysed by direct sequencing. A hemizygous or homozygous 12bp deletion at codon 135 and 3bp heterozygous deletion at codon 264 were detected; also, in the latter sample a heterozygous mutation at codon 282 (Arg to Gln) was found. To our knowledge, this is the first report of p53 deletions in B-CLL. The two patients were elderly, and both had a rapidly progressive disease in the absence of unfavourable cytogenic abnormalities. These findings support a role for p53 alterations in the clinical course of some B-CLL patients.
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PMID:Novel small deletions of the p53 gene in late-stage B-cell chronic lymphocytic leukaemia. 781 13

Chemosensitivity of B lymphocytes, obtained from 65 patients with B-cell chronic lymphocytic leukemia (B-CLL), Rai stages 0 through IV, was determined using the MTT assay. The results were expressed by the drug concentration required for 50% inhibition of cell viability (IC50). The cytotoxicity of chlorambucil (CLB) was compared with that of fludarabine and the DNA topoisomerase I inhibitors, camptothecin, 9-aminocamptothecin, 10,11-methylenedioxy-20(S)-camptothecin (10,11-MDC) and 9-amino-10,11-methylenedioxy-20(S)-campthothecin (9-A-10,11-MDC), and topotecan. Considerable heterogeneity in sensitivity to CLB was observed, with a median IC50 of 40.5 mumol/L in untreated patients. B-CLL cells from patients treated with CLB had a significantly higher median IC50 of 86.0 mumol/L (P < .01). Untreated as well as CLB-treated patients were divided into two subsets. For the purpose of this study, B-CLL lymphocytes with an IC50 CLB of less than 61.0 mumol/L were designated as "sensitive" and those with an IC50 CLB of > or = 61.0 mumol/L were designated as "resistant." After baseline assays, 15 untreated patients received CLB; after treatment, the IC50 increased in B-CLL lymphocytes from 13 of 15 patients. The response to CLB treatment, determined by its effect on the absolute lymphocyte count and by the Eastern Cooperative Oncology Group clinical criteria, was significantly better in patients whose lymphocytes had an IC50 CLB of less than 61.0 mumol/L before therapy (P < .01). B-CLL lymphocytes also had a variable degree of sensitivity in vitro to each of the other drugs. There was significant cross-resistance between CLB and fludarabine (P < 0.01). Whereas only 29% of CLB-resistant B-lymphocyte specimens obtained from individual patients were sensitive to fludarabine in vitro, 52% and 67% of CLB-resistant lymphocyte samples were sensitive to 10,11-MDC and 9-A-10,11-MDC, respectively. We have previously reported that p53 gene mutations were associated with aggressive B-CLL and a poor prognosis. B lymphocytes from seven patients with these mutations were resistant to CLB, and five of six were resistant to fludarabine. Lymphocytes from four of seven were resistant to 10,11-MDC, and three of four were resistant to 9-A-10,11-MDC. This study implies that the MTT assay may be useful in identifying subsets of CLL patients resistant to conventional chemotherapy. However, definitive conclusions can not be drawn in view of the small number of patients studied prospectively. In addition, these results suggest the potential of camptothecin-based therapy for patients unresponsive to standard treatment.
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PMID:Chemosensitivity of lymphocytes from patients with B-cell chronic lymphocytic leukemia to chlorambucil, fludarabine, and camptothecin analogs. 794 99

The expression of the murine double minute-2 (MDM2) gene, the product of which binds to and inactivates p53, was studied in 60 patients with B-cell chronic lymphocytic leukemia (B-CLL) or non-Hodgkin's lymphoma (B-NHL). Northern blot analysis showed that the level of MDM2 gene expression was low in normal human B-cells, whereas 17 of the patients (28.3%) with B-CLL or NHL had more than 10-fold higher levels of MDM2 gene expression than that observed in normal B cells. Immunohistochemical analysis confirmed MDM2 overexpression at the cellular protein level. MDM2 gene overexpression was found more frequently in patients with the low-grade type of lymphoma (56.5%) than in those with intermediate-/high-grade types (10.8%) (P = .001). Moreover, MDM2 overexpression was found significantly more frequently in patients at advanced clinical stages. Simultaneous analysis of p53 gene mutation showed that three patients had both MDM2 gene overexpression and p53 gene mutation. The results of the present study suggest that MDM2 gene overexpression may play an important role in the tumorigenicity and/or disease progression of CLL and low-grade lymphomas of B-cell origin.
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PMID:The MDM2 oncogene overexpression in chronic lymphocytic leukemia and low-grade lymphoma of B-cell origin. 794 88

We have analysed the p53 status in non-progressive and progressive chronic B-cell leukemia (B-CLL) by ELISA, immunoprecipitation, FACS and cDNA sequencing in relation to in vitro proliferation in response to Staphylococcus aureus strain Cowan I (SAC) and IL-2. In FACS, cells from progressive leukaemia were found to over-express p53 with a conformation recognized by PAB240. In a PAb240-based ELISA, 60% of progressive B-CLL were positive. DNA sequencing of p53 exons 5 to 9 revealed a codon 179 His to Gln change in one of the ELISA-positive, progressive B-CLL but failed to reveal any mutations in 4 other ELISA-positive, progressive B-CLL. Among progressive B-CLL populations, 10/14 responded by proliferation in vitro to SAC/IL-2. In non-progressive cells, low levels of p53 were found by FACS, none was positive in the PAb240 ELISA and only one case showed a weak proliferative response to SAC/IL-2. Low p53 expression was also seen in different types of normal B cells, resting and activated, and in EBV-transformed B-cell lines, in contrast to the high expression observed in Burkitt lymphoma cell lines with verified p53 mutations. We conclude that progressive B-CLL is characterized by aberrant p53 expression which may be a significant prognostic factor.
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PMID:Progressive B-cell chronic lymphocytic leukaemia frequently exhibits aberrant p53 expression. 805 42

Clinicobiological, histological, cytogenetic and molecular genetic studies were performed in a case of atypical B-cell chronic lymphocytic leukaemia (B-CLL) with the t(11;14)(q13;q32) evolving into Richter's syndrome (RS) in order (a) to determine the clonal relationship between the cell of origin for B-CLL and RS, and (b) to analyse genetic events underlying the disease progression in this patient. After 4 years following diagnosis, a rapid deterioration of the clinical picture occurred, concomitant with the appearance of large lymphoid blasts in peripheral blood (PB), bone marrow (BM) and ascites samples. A diagnosis of RS was made and cytogenetic analysis revealed karyotype evolution with trisomy 7 and del(17p) in addition to t(11;14). Fluorescence in situ hybridization showed 78% lymphoid blast cells obtained from ascites sample to be trisomic using a chromosome-7-specific pericentromeric probe. Whereas no rearrangement of the c-myc proto-oncogene was detected at disease progression, direct sequencing of p53 gene exon 5-9 revealed an exon 7 missense point mutation. This abnormality was not present in the CLL phase. Immunological staining with the monoclonal antibody PAb-1801, detecting the p53 protein product, revealed a negative pattern in the CLL phase, whereas 24% positivity was documented in representative samples obtained at RS. It is concluded that RS was cytogenetically related with B-CLL in this patient, suggesting the occurrence of a bona fide transformation and that the mutation of p53 exon 7, in association with the development of 17p deletion, possibly played a role in the development of RS.
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PMID:Richter's syndrome in a case of atypical chronic lymphocytic leukaemia with the t(11;14)(q13;q32): role for a p53 exon 7 gene mutation. 860 3

We tested the effects of theophylline, a phosphodiesterase inhibitor inducing intracellular accumulation of cyclic adenosine monophosphate (cAMP), on malignant B cells from 15 patients with B-chronic lymphocytic leukemia (B-CLL). We observed a large increase in apoptotic cell numbers (mean, 90% v 20% in medium alone) in the presence of theophylline (100 micrograms/mL) or chlorambucil (10 mumol/L) after 72 hours of incubation. Maximal apoptosis (90%) was reached after 36 hours when the two drugs were used together at fourfold lower concentrations, indicating a synergistic effect; no effect was observed with normal B cells, suggesting that the combination might have therapeutic interest. Chlorambucil induced intracellular Ca+2 influx, pointing to the involvement of two signaling pathways that might explain its synergy with theophylline through their effects on oncogenes. The expression of bcl-2 protein, a proto-oncogene inhibiting apoptosis, decreased after incubation with the drugs, while c-myc, recently described as having a potent role in apoptosis, was overexpressed. For p53 we observed an overexpression in the presence of chlorambucil or both theophylline-chlorambucil and a decrease after theophylline incubation. Chlorambucil- and theophylline-induced apoptosis was partially inhibited by interleukin-4 (IL-4), which also abrogated the effects on oncogene expression. These results provide insight into the mechanisms underlying B-CLL apoptosis and suggest that the theophylline-chlorambucil combination may be of therapeutic value in this setting.
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PMID:Theophylline synergizes with chlorambucil in inducing apoptosis of B-chronic lymphocytic leukemia cells. 882 37

We describe a new nonrandom rearrangement, dic(4;17)(p11;p11), which was identified in three patients with small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL). All three cases had in common atypical morphological features with a significant component of prolymphocytes, an unusual clinical outcome, and were refractory to chemotherapy. To further define the cytogenetic breakpoints, we investigated the cases by whole chromosome painting and fluorescence in situ hybridization (FISH) with centromeric probes. FISH analysis detected the same cytogenetic rearrangement in all patients, suggesting that the dic(4;17)(p11;p11) is a recurrent translocation in SLL/CLL. Moreover, FISH analysis showed a monoallelic deletion of the TP53 gene in all cases, suggesting a correlation with the aggressive course of the disease and the clinical outcome observed in these patients.
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PMID:dic(4;17)(p11;p11): a new recurrent chromosomal abnormality in chronic B-lymphoid disorders. 894 98

Cytogenetic analysis of patients with chronic B-cell leukemia (B-CLL) indicates that 50% have chromosome abnormalities, while fluorescence in situ hybridization (FISH) and molecular techniques reveal an even higher incidence. Trisomy 12 and deletions or translocation of chromosome 13q14 are the most common abnormalities, but in neither case has the gene or genes involved in the abnormalities been identified. Combined FISH and immunophenotyping studies suggest that both abnormalities are secondary events in B-CLL. Other recurring chromosome abnormalities include 6q-, 11q- and 12p-, but the genes involved in these abnormalities have not been identified. Involvement of the BCL1, BCL2, and BCL3 genes has been reported, but the numbers are low and the cases tend to be atypical. Trisomy 12 in association with complex karyotypic abnormalities is associated with a poor prognosis, and FISH studies show a strong correlation between trisomy 12, atypical morphology, and advanced disease. Ten to 15% of patients have mutations of p53 which is associated with advanced disease, resistance to treatment, and poor survival.
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PMID:Genes and chromosomes in chronic B-cell leukemia. 907 90

Several genes have been implicated in the regulation of apoptosis including bcl-2, bax, bcl-X and p53. These genes may be important in the development of nitrogen mustard (NM) drug resistance in B-cell chronic lymphocytic leukemia (B-CLL). Using Western blot analysis, we examined the levels of Bcl-2, Bax, Bcl-X and p53 protein expression and determined whether the levels of these proteins correlated with in vitro drug resistance in CLL patients' lymphocyte samples. Our investigations suggest that in CLL, NM drug resistance develops without any detectable alteration of Bcl-2, Bax or Bcl-X. In addition, we determined the presence of p53 mutations in 14 samples in order to assess if there is an association between in vitro drug resistance and the presence of p53 mutations. Using single-stranded conformational polymorphism (SSCP) and sequencing analysis, we observed a p53 mutation in two out of seven resistant samples. The mutation occurring in both cases was a G:C --> A:T transition at codon 273 (exon 8). One of these cases was de novo resistant to the nitrogen mustards. Only one of six samples with acquired resistance to the nitrogen mustards had a p53 mutation suggesting that p53 mutations are not a prominent feature of acquired NM resistance in CLL.
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PMID:Relationship between nitrogen mustard drug resistance in B-cell chronic lymphocytic leukemia (B-CLL) and protein expression of Bcl-2, Bax, Bcl-X and p53. 945 75


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