Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01034 (cystatin C)
 3,397 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The presence of activated transforming genes was investigated in four patients with therapy-related leukemia and in three with therapy-related myelodysplastic syndrome. DNA of bone marrow cells from six of the patients exhibited transforming activity in the tumorigenicity assay. Five of the six patients who were positive in the tumorigenicity assay contained activated N-ras oncogenes, and three contained activated K-ras oncogenes. Thus, concurrent activation of N-ras and K-ras oncogenes was observed in two patients. In vitro DNA amplification followed by oligonucleotide dot-blot analysis was used to investigate mutations in codons 12, 13, and 61 of the N-ras and K-ras oncogenes. Two patients exhibited an N-ras mutation, substituting aspartic acid (GAT) for glycine (GGT), and three patients exhibited an N-ras codon 13 mutation, substituting valine (GTT) for glycine. Two patients exhibited K-ras codon 12 mutations, substituting aspartic acid (GAT) or cysteine (TGT) for glycine (GGT), respectively, and one case exhibited a K-ras codon 61 mutation, substituting lysine (AAA) for glutamic acid (CAA). Cytogenetic analysis revealed that loss of chromosome 7 was frequent (four patients: 57%). Our data indicate that activation of N-ras and K-ras genes, as well as loss of heterozygosity for specific alleles on chromosome 7, plays a more important role in the leukemogenesis of both therapy-related leukemia and myelodysplastic syndrome.
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PMID:Transforming genes and chromosome aberrations in therapy-related leukemia and myelodysplastic syndrome. 185 83

N-ras mutations were examined in DNA samples extracted from the spleen of CBA/Ca mice that developed myeloid leukemia (ML) following exposure to radiations of different qualities. A total of 17 ML cases, i.e. 5 cases of neutron-induced and 12 cases of photon- (3 gamma-ray and 9 x-ray) induced ML were included in the study along with 12 DNA samples from the bone marrow cells of control mice. Polymerase chain reaction-single strand conformational polymorphisms (PCR-SSCP) and the direct sequencing of PCR products were used to analyze three regions of the N-ras gene: (i) a 120 base-pair (bp) long portion of exon I (codons 2-37); (ii) a 103 bp long portion of exon II (codons 48-82); and (iii) a 107 bp long portion of exon III (codons 118-150). PCR-SSCP mobility shifts indicated mutations within only exon II of the N-ras gene. Such mutations were more prevalent in samples from mice exposed to fast neutrons. The exact type and location of these mutations were then determined by direct DNA sequencing. Silent point mutations, i.e. base transitions at the third base of codons 57 (GAC-->GAT), 62 (CAA-->CAC), or 70 (CAG-->CAA) were present only in mice that developed ML after exposure to fast neutrons. A base transversion at the third base of codon 61 (CAA-->CAC) was also observed in some ML cases. DNA sequencing demonstrated that ML samples contained normal as well as mutated DNA sequences. The higher frequency of N-ras mutations in neutron-induced ML suggested that fast neutrons are more effective in inducing genomic instability at the N-ras region of the genome. More importantly, N-ras mutations are not the initiating event in radiation leukemogenesis. This conclusion was supported by the finding that N-ras mutations were detected only in mice with an overt leukemic phenotype but not in mice with minimal tissue infiltration of leukemic cells, suggesting that the disease may be present prior to the presence of N-ras mutations. Alternatively, N-ras may be present in these mice but a large number of normal spleen cells in these mice interferes with the detection of mutation in a small population of leukemic cells.
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PMID:N-ras mutations in radiation-induced murine leukemic cells. 907 79

Leukemia, a form of haematological malignancy, is a multi-stage disease and a wide range of diverse genes has been speculated to correlate with its initiation and development. Ras has been speculated to be an initiating gene for haematological malignancy, but more investigation will be needed to determine the genes associated with the progression of the disease. 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat leukemia provides a good tool for research into various stages of the disease. The entire coding regions of p53 and ras genes were examined for mutations in the present study. In this experiment, we used fluorescence-labeled polymerase chain reaction single-stranded conformation polymorphism analysis (PCR-SSCP) and direct sequencing to detect mutations of both genes on rat erythroleukemia. Fifteen out of 18 (83.3%) rat leukemias were found to have N-ras codon 61 mutation, consistent with previous results. The result of direct sequencing showed a single base substitution (CAA to CTA), resulting in an amino-acid change from Gln to Leu. No mutations were found in H-ras, K-ras or codon 12 of N-ras. The incidence of p53 gene mutation was 16.6% (3/18) in rat leukemia at late-stage. In the present study, mutation of the p53 gene was detected in three DMBA-induced leukemias as follows: a single-base substitution (CAT to CGT) at codon 177 (exon 5), resulting in an amino-acid change from Arg to Leu, a CGG to CTG/CGG changed at codon 211 (exon 6) resulting in an amino-acid change from His to Arg/His, and a GGG to TGG at codon 242 (exon 6) resulting in an amino-acid change from Gly to Trp, respectively. Thus, mutations of p53 gene do not seem to respond to the carcinogenesis of the DMBA-induced leukemia, in contrast to mutation of the N-ras oncogene, and may possibly be involved in the progress of multi-stage leukemogenesis.
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PMID:Incidence of p53 and ras gene mutations in DMBA-induced rat leukemias. 1238 83