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)

In order to better understand the molecular events in murine hepatocarcinogenesis, the frequency and types of mutations in the murine H-ras proto-oncogene isolated from 184 independent, spontaneously occurring hepatic lesions were determined. Hepatocellular foci, hyperplasias, adenomas and carcinomas were obtained from archival samples of control male (134 samples) and female (50 samples) B6C3F1 mice used in oncogenicity studies that were conducted at Lilly Research Laboratories from 1979 to 1986. The 61st codon region of the H-ras oncogene from these sections was amplified using the polymerase chain reaction. Mutation frequencies were determined by restriction fragment length polymorphism analysis. The types of mutations were characterized by allele-specific oligonucleotide hybridization and confirmed by DNA sequencing. Forty-two per cent of the carcinomas, 44% of the adenomas, 42% of the hyperplasias and 29% of the foci contained mutations at the 61 codon. The mutation spectra for the carcinomas, adenomas and hyperplasias consisted of mostly CAA-AAA transversions, followed by CAA-CGA transitions, followed by CAA-CTA transversions. These results demonstrate that: (i) the frequency of spontaneous mutations in the H-ras 61st codon is equivalent in murine hyperplasias, adenomas and carcinomas, and (ii) sex was not a determining factor in either the mutation frequency or mutation spectrum for the spontaneous lesions. If these lesions represent successive stages in the carcinogenic process, then these results suggest that mutations in the 61st codon of H-ras are early events in spontaneous murine hepatocarcinogenesis.
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PMID:Genetic alterations in the 61st codon of the H-ras oncogene isolated from archival sections of hepatic hyperplasias, adenomas and carcinomas in control groups of B6C3F1 mouse bioassay studies conducted from 1979 to 1986. 135 Sep 49

The efficiency of detection of H- and K-ras mutations in 27 CD-1 mouse liver tumors by direct sequencing of polymerase chain reaction (PCR)-amplified DNA isolated from formalin-fixed and paraffin-embedded tissues was compared with that after assay by both NIH 3T3 transfection (followed by sequencing of amplified transformant DNA) and direct sequencing of PCR-amplified DNA isolated from frozen tumors. Some tumor samples were chosen for comparison because they contained ras mutations that were detected by either NIH 3T3 transfection or sequencing of PCR-amplified DNA derived from frozen tumors, but were not detected by both techniques. The efficiency of detecting K-ras mutations was similar for sequencing of amplified fragments derived from both paraffin-embedded tissues and from frozen tumors. However, these two techniques differed in their efficacy for detection of H-ras codon 61 mutations. Furthermore, this difference appeared to be mutation-specific: the sequencing of amplified products from paraffin-embedded tumor tissues allowed increased detection of CAA to AAA mutations but decreased detection of CAA to CTA mutations relative to sequencing of amplified fragments derived from frozen tumor DNA. Direct sequencing of PCR products from paraffin-embedded sections was more sensitive than NIH 3T3 transfection for detection of activated K-ras genes containing codon 13 mutations but less sensitive for detection of activated H-ras genes containing codon 61 mutations. In summary, direct sequencing of amplified DNA from either frozen tumors or formalin-fixed, paraffin-embedded tissues can be more sensitive than NIH 3T3 transfection for detection of codon 13-activated K-ras genes. However, it appears to be less sensitive than NIH 3T3 transfection for detection of certain activating H-ras mutations. Depending upon the questions being asked of the data, each of the methods can provide useful information about ras gene mutations in tumor samples. The apparent differences in sensitivities between the methods is not yet understood, but such differences should be considered in the analysis of data obtained when only one method is used.
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PMID:Polymerase chain reaction/sequencing analysis of ras mutations in paraffin-embedded tissues as compared with 3T3 transfection and polymerase chain reaction/sequencing of frozen tumor deoxyribonucleic acids. 158 89

Hepatocellular tumors were induced in 15 day old male B6C3F1 mice following a single exposure to N-nitrosodiethylamine (DEN; 5 mg/kg, i.p.). Tumors were collected at 38 and 65 weeks to compare the frequencies and types of mutations in the 61st codon of the H-ras oncogene. The 61st codon was amplified using the polymerase chain reaction (PCR). Allele-specific oligonucleotide (ASO) probes were used to determine the frequency and types of mutations present in these tumors. Forty-nine nodular hepatic lesions were obtained from seven animals at the 38 week timepoint. Five of these samples (10%) had mutations at the 61st codon with one CAA-AAA, one CAA-CGA and three CAA-CTA. Thirty-six nodular hepatic lesions were obtained from six animals at the 65 week timepoint. Ten of these samples (28%) had mutations at the 61st codon with one CAA-AAA, five CAA-CGA and four CAA-CTA. These data indicate that DEN-induced mutations at the 61st codon of the mouse H-ras oncogene (i) are an infrequent event, (ii) have different frequencies at the 38 and 65 week timepoints and (iii) are different from the types of mutations seen in spontaneous lesions.
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PMID:Temporal changes in the mutant frequency and mutation spectra of the 61st codon of the H-ras oncogene following exposure of B6C3F1 mice to N-nitrosodiethylamine (DEN). 163 98

Okadaic acid, dinophysistoxin-1 (35-methylokadaic acid), and calyculin A are the okadaic acid class of non-12-O-tetradecanoylphorbol-13-acetate (TPA)-type tumor promoters, which do not bind to the phorbol ester receptors in cell membranes or activate protein kinase C in vitro. They have potent tumor-promoting activities on mouse skin, as strong as TPA-type tumor promoters, such as TPA, teleocidin, and aplysiatoxin. DNA samples isolated from tumors induced by dimethylbenz[alpha]anthracene and each of the okadaic acid class tumor promoters had the same mutation at the second nucleotide of codon 61 (CAA to CTA) in the c-H-ras gene. Okadaic acid receptors, protein phosphatases 1 and 2A, are present in the particulate as well as cytosolic fractions of various mouse tissues. The apparent "activation" of protein kinases by the okadaic acid class tumor promoters, after their incubation with 32P-ATP, protein kinases, and protein phosphatases, was observed. This activation was caused by inhibition of protein phosphatases 1 and 2A by the okadaic acid class tumor promoters. Treatment of primary human fibroblasts and human keratinocytes with the okadaic acid class tumor promoters induced the hyperphosphorylation of a 60-kDa protein in nuclear and cytosolic fractions, due to the inhibition of protein phosphatases. The 60-kDa protein is a proteolytic fragment of nucleolin, a major nonhistone protein and is designated as "N-60." The mechanisms of action of the okadaic acid class tumor promoters are discussed with emphasis on the inhibition of protein phosphatase activity.
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PMID:Mechanisms of action of okadaic acid class tumor promoters on mouse skin. 166 50

10 derivations of rat tracheal epithelial (RTE) cells, including normal cells, normal primary cultures, 7 tumorigenic cell lines and 1 nontumorigenic cell line transformed in vitro by treatment with 7,12-dimethylbenz[a]anthracene (DMBA), benzo[a]pyrene (BP) and/or 12-O-tetradecanoylphorbol-13-acetate (TPA) were examined for oncogene alterations. No abnormalities of Ha-ras or Ki-ras were seen that were suggestive of amplification, rearrangement or the presence of RFLPs. Analysis of specific-point mutations in Ha-ras using Pst I digestion (codon 12, GGA to GCA) or Ha-ras and Ki-ras using Xba I (codon 61, CAA to CTA) were negative. In one cell line derived by DMBA treatment, changes in the c-myc restriction digest pattern were seen after incubation with Bam HI and Hind III. Northern analysis revealed consistent differences between normal and transformed cells when probed with Ha-ras; c-myc expression was of low intensity, and the expression of Ki-ras could not be detected. Transfection of RTE cell DNAs into NIH/3T3 cells did not result in the appearance of morphologic transformants. The studies suggest that Ha-ras or Ki-ras codon 61 A to T transversions (CAA to CTA) are not associated with the immortal/tumorigenic phenotype in RTE cells transformed by DMBA or TPA, and are in contrast to results reported in some other biological systems.
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PMID:Oncogene alterations in in vitro transformed rat tracheal epithelial cells. 169 45

Rat hepatoma McA-RH7777 cell lines transfected with full-length human apolipoprotein (apo) B constructs produce mostly human apoB48 and only small amounts of apoB100, as a result of mRNA editing at codon 2153 (C to U conversion at nucleotide 6666). To abolish the formation of apoB48 and increase the yield of apoB100 and other forms of apoB longer than apoB48, site-specific mutations were introduced at or near the site of apoB mRNA editing. Among four mutations examined, only that in which codon 2153 was converted from CAA (Gln) to CTA (Leu) effectively precluded the formation of apoB48. In this mutant, a stop codon would not be generated even if the C to U conversion occurred. The three other mutations were introduced to disrupt the proposed stem-loop structure encompassing the editing site. Changes made in the third positions of five codons on the 5' side of the edited base or of four codons 3' of the edited base failed to eliminate the production of a protein with the approximate size of apoB48. A construct in which codon 2153 was changed from CAA to GAT (Asp) also failed to eliminate the production of a protein the size of apoB48. Analysis of the region between nucleotides 6200 and 6900 of the cDNA did not detect any prevalent alternate editing sites. Immunoblot analysis using polyclonal antibodies raised against synthetic peptides of human apoB100 indicated that the carboxyl terminus of the apoB48-like proteins probably resides between amino acid residues 2068 and 2129 of apoB100. These results provide some insight into the mechanism of apoB mRNA editing and will facilitate further studies on apoB-containing lipoproteins.
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PMID:Elimination of apolipoprotein B48 formation in rat hepatoma cell lines transfected with mutant human apolipoprotein B cDNA constructs. 173 Jun 41

Male F344 rats were fed 0.2% N-[4-(5-nitro-2-furyl)-2-thiazoly]formamide for 6 weeks and then fed 3% or 5% sodium saccharin, 5% sodium ascorbate, 3.12% calcium saccharin, 1.34% sodium chloride, 5.2% calcium saccharin plus 1.34% sodium chloride, or basal diet alone for 72 weeks. Protein and DNA were extracted from 89 bladder tumors [87 transitional cell carcinomas (TCC), 1 papilloma, and 1 sarcoma] from 86 rats p21 expression was examined by Western blotting using a monoclonal antibody against p21 (NCC-RAS-004). H-ras mutations in exons 1 and 2 were examined by direct sequencing of DNA amplified by polymerase chain reaction. Sequencing results demonstrated mutations at codon 61 (CAA to CGA in 15 TCCs; CAA to CTA in 2 TCCs), at codon 12 (GGA to TGG in 1 TCC), and at codon 13 (GGC to GTC in 3 TCCs). Mutations at codon 61 were confirmed by faster mobility of the p21 band in Western blots. The level of p21 expression varied among samples, but many TCCs appeared to express more p21 than controls. The overall incidence of H-ras mutations was 24.4% (21 of 86 rats). The type of chemical used for the promoting phase had essentially no effect on H-ras mutation, suggesting that the effects observed were related to FANFT administration. The frequency of H-ras mutation in each group was negatively related to the incidence of carcinoma (r = -0.85; P less than 0.01). Two groups of tumors (with or without the mutated ras gene) were compared for tumor size (reflected by the bladder weight), histological grading, and the presence of invasion. The size of tumors with mutated ras was significantly smaller than those without mutated ras. There was no difference in the histological grading between the two groups. Although not statistically significant, histological invasion was more frequently observed in tumors with mutated ras (14.3%) than in tumors without mutation (3.1%).
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PMID:H-ras mutations in rat urinary bladder carcinomas induced by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide and sodium saccharin, sodium ascorbate, or related salts. 205 86

The expression of the c-myc gene has previously been shown to be elevated and deregulated in the human hepatoma cell line Hep G2 (B. E. Huber and S. S. Thorgeirsson, Cancer Res., 47: 3414-3420, 1987). We now report that the Hep G2 N-ras gene is activated to a dominant-acting, transforming gene by a missense mutation in codon 61. Hep G2 DNA produced transformed foci when transfected into NIH 3T3 cells. Subsequent to a secondary round of transfection, Southern blot analysis of tumorigenic NIH 3T3 foci demonstrated the presence of human N-ras sequences. Nucleotide sequence analysis of one Hep G2 N-ras allele demonstrated that codons 12, 13, and 59 were normal and that codon 61 had a missense mutation (CAA to CTA). This mutation results in the incorporation of leucine instead of glutamine at residue 61 of the N-ras gene product, p21. N-ras sequences were amplified by the polymerase chain reaction from both Hep G2 genomic DNA and Hep G2 complementary DNA. Analysis of the amplified sequences demonstrated that only one Hep G2 N-ras allele exhibited the codon 61 mutation and that both the mutant and normal alleles were transcribed. Northern blot analysis demonstrated equivalent steady-state levels of N-ras transcripts in Hep G2 cells and normal human liver. The steady-state levels of N-ras and ornithine decarboxylase transcripts were positively correlated suggesting a positive relationship between N-ras expression and the replication rate of Hep G2 cells. c-Ki-ras and c-Ha-ras transcripts were not detected in either Hep G2 cells or normal human liver. Immunoprecipitation experiments using the monoclonal antibody Y13-259 demonstrated the presence of p21 in Hep G2 cells. Expression of a dominant-acting, transforming N-ras gene, in conjunction with the altered regulation of the c-myc gene, documents two important genetic lesions that could be responsible for the transformed phenotype of Hep G2 cells.
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PMID:Characterization of a transforming N-ras gene in the human hepatoma cell line Hep G2: additional evidence for the importance of c-myc and ras cooperation in hepatocarcinogenesis. 215 25

Aristolochic acid I (AAI), a nitrophenanthrene derivative, is the major component of the carcinogenic plant extract aristolochic acid, which has been used as a medicine since antiquity. Long term oral administration of AAI to male Wistar rats induces multiple tumors, mainly in the forestomach, ear duct, and small intestine. The presence of activated transforming genes was investigated in various tumors of 18 AAI treated rats, namely in 14 squamous cell carcinomas of the forestomach, 7 squamous cell carcinomas of the ear duct, 8 tumors of the small intestine, 3 tumors of the pancreas, 1 adenocarcinoma of the kidney, 1 lymphoma, and 2 metastases in the lung and the pancreas. By utilizing the tumorigenicity assay and Southern blot analysis, we have detected an activated c-Ha-ras gene in the DNAs of 5 of 5 squamous cell carcinomas of the forestomach. Direct sequencing of amplified material revealed an AT----TA transversion mutation at the second position of codon 61 of the c-Ha-ras gene (CAA to CTA) in all transfectants as well as in the 5 original rat tumors. Enzymatic amplification of ras sequences followed by selective oligonucleotide hybridization detected identical mutations in 93% (13 of 14) of forestomach tumors, in 100% (7 of 7) of ear duct tumors, and in the lung metastasis. Among those tumors tested, we had 4 cases in which the forestomach tumors and the ear duct tumors originated from the same rat, showing the same mutation in both tissues. Moreover, similar mutations were demonstrated at c-Ki-ras codon 61 in 1 of 7 ear duct tumors (CAA to CAT) and in 1 of 8 tumors of the small intestine (CAA to CTA) as well as at c-N-ras 61 (CAA to CTA) in a pancreatic metastasis. Additional transfection experiments of some tumors scoring negative for ras gene mutations in dot blot analyses revealed a CAA to CTA transversion at codon 61 of the c-Ha-ras gene in 1 forestomach tumor as well as at codon 61 of the c-N-ras in 1 hyperplasia of the pancreas and in 1 lymphoma. The apparent selectivity for mutations at adenine residues in AAI induced tumors is consistent with the identification of an N6-deoxyadenosine-AAI adduct formed by reaction of AAI with DNA in vitro, suggesting that carcinogen-deoxyadenosine adducts are the critical lesions in the tumor initiation by aristolochic acid.
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PMID:Aristolochic acid activates ras genes in rat tumors at deoxyadenosine residues. 220 37

Male F344 rats were fed N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) for up to 4 wk, then were given the basal diets (Prolab 3200 or AIN-76A) with or without 5% sodium saccharin for up to 100 wk. Eleven transitional cell carcinomas (TCCs), one undifferentiated carcinoma, and two sarcomas of the urinary bladder were examined for the expression of ras gene product, p21, by immunohistochemical staining and western blot analysis. Point mutation in codons 12 or 61 of the Ha-ras genes amplified by polymerase chain reaction was examined by a slot-blot screening procedure using allele-specific oligonucleotide probes. Immunohistochemical staining showed enhanced immunoreactivity with the antibody to ras p21 in seven TCCs and one undifferentiated carcinoma. Western blot analysis showed faster migration of the p21 band in 6 of 11 TCCs. Oligonucleotide hybridization revealed the point mutation in codon 12 of Ha-ras gene (GGA----GTA in 1 TCC) and in codon 61 (CAA----CGA in 5 TCCs and CAA----CTA in 1 TCC). Two mutations in codons 12 and 61 coexisted in one tumor, which were found to be present in different Ha-ras alleles. The incidence of Ha-ras gene mutations were similar in groups treated with (3 of 6) or without (3 of 8) sodium saccharin. These results suggest the involvement of activated Ha-ras gene in rat urinary bladder carcinogenesis induced by FANFT.
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PMID:Point mutation in codons 12 and 61 of the Ha-ras gene in rat urinary bladder carcinomas induced by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide. 220 84


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