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 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.
Cancer Res 1990 Mar 01
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.
Cancer Res 1990 Sep 01
PMID:Aristolochic acid activates ras genes in rat tumors at deoxyadenosine residues. 220 37

We examined the incidence of point mutation in codons 12, 13 and 61 of c-Ki-ras and N-ras genes in human hepatocellular carcinoma (HCC) using the polymerase chain reaction and oligonucleotide hybridization techniques. Among 34 tissues specimens surgically resected from 30 patients and 5 cell lines of human HCC, only two had ras point mutations; in one case, codon 12 of c-Ki-ras was altered from GGT, coding glycine, to GTT, coding valine; in the other case, codon 61 of N-ras was altered from CAA, coding glutamine, to AAA, coding lysine. Thus, point-mutational activation of ras oncogenes is an uncommon event in human HCC.
Jpn J Cancer Res 1989 Mar
PMID:Low incidence of point mutation of c-Ki-ras and N-ras oncogenes in human hepatocellular carcinoma. 254 5

Lung and liver tumors were induced in female A/J mice after treatment for 7 weeks (3 times/week, i.p.) with either 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) (50 mg/kg) or nitrosodimethylamine (NDMA) (3 mg/kg). Both compounds can be activated via alpha-hydroxylation to methylating agents, while NNK may also undergo hydroxylation at the N-methyl carbon to form a pyridyloxobutylated adduct. The purpose of these studies was to identify and characterize the activated oncogenes present in tumors induced by NDMA and NNK. Following transfection of high molecular weight DNA onto NIH/3T3 mouse fibroblasts, transforming genes were detected in 90% of both NNK- (10 of 11) and NDMA- (9 of 10) induced lung tumors. In contrast, transformation of NIH/3T3 fibroblasts was observed only in 40% (2 of 5) and 13% (1 of 8) of the liver tumors from NNK- and NDMA-treated mice, respectively. Southern blot analysis indicated that the transforming gene present in all lung tumors was an activated K-ras oncogene. Both rearranged bands and amplified signals were detected in the transfectants. The one transformant from the NDMA-induced liver tumor contained an activated K-ras gene. In contrast, the two liver transformants from NNK-induced tumors did not contain an activated ras or raf gene. Hybridization with oligonucleotide probes that were centered around either codon 12 or 61 of the K-ras gene were utilized to localize the mutations. Activation of this gene appeared to occur largely via a mutation in codon 12 (15 of 20 transformants) and was observed with a similar frequency in pulmonary tumors induced by either compound. The remaining mutations were found in codon 61. The specific mutation within these two codons was determined by amplifying the exon containing the base change, followed by direct sequencing. With one exception the mutation observed in codon 12 was a GC to AT transition (GGT to GAT). One transformant contained a GC to TA transversion. The activating mutation detected in codon 61 was always an AT to GC transition of the middle A (CAA to CGA). The GC to AT mutation observed in codon 12 is consistent with the formation of the O6-methylguanine adduct. Similar concentrations (23 to 32 pmol/mumol deoxyguanosine) of this promutagenic adduct were detected in lungs during treatment with either NNK or NDMA.(ABSTRACT TRUNCATED AT 400 WORDS)
Cancer Res 1989 Oct 01
PMID:Relationship between the formation of promutagenic adducts and the activation of the K-ras protooncogene in lung tumors from A/J mice treated with nitrosamines. 267 Feb 1

The purpose of this study was to determine if a panel of monoclonal antibodies could define phenotypic markers that could be used in risk assessment of a spectrum of colonic polyps and colon cancers. Using the ABC immunoperoxidase technique on formalin-fixed sections of surgical specimens, the following results were obtained: 1) Mab B72.3 demonstrated increased reactivity in villous lesions and cancers compared with hyperplastic polyps and tubular adenomas; 2) Mab anti-CAA demonstrated increased reactivity in polyps compared with colon cancers; and 3) using the two antibodies (Mab B72.3 and Mab anti-CAA), a malignancy ratio was obtained that determined malignancy risk for individual polyps. No hyperplastic polyp gave a positive ratio, but about 30 percent of villous lesions were positive. Over 50 percent of villous lesions greater than 2 cm in size had a positive ratio. The malignancy potential ratio may be a valuable marker in assessing risk of malignancy in an individual case.
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PMID:Phenotypic markers for a spectrum of colonic polyps and cancers. The malignancy potential ratio. 284 48

A transforming N-ras allele was molecularly cloned from the RD human rhabdomyosarcoma cell line, and the nature of its activation studied. Construction of chimeric recombinants between the RD-transforming allele and a normal human allele enabled us to localize the alteration responsible for the activation to the second exon of the N-ras gene. The nucleotide sequence of this exon, when compared to that of the normal allele, revealed a single difference at the 61st amino acid position of the encoded protein; the CAA codon for glutamine in the normal allele was mutated to a CAT codon for histidine in the RD-transforming allele. This result is the first description of a histidine replacing glutamine in the 61st position and provides further evidence that the 61st amino acid is one of the preferential sites for N-ras activation.
Int J Cancer 1985 May 15
PMID:N-ras gene activation in the RD human rhabdomyosarcoma cell line. 315 13

DNA isolated from blood or bone-marrow samples from 18 patients with acute non-lymphocytic leukemia (ANLL) and 14 patients with acute lymphocytic leukemia (ALL) was analyzed for the presence of mutations in the N-ras gene. Using synthetic oligonucleotide probes we detected mutations in 5 cases of ANLL; 4 GGT----GAT transitions in codon 12 and one CAA----AAA transversion in codon 61. One case exhibited homozygosity for the mutation. No mutations could be detected at these codons in the DNA of the 14 ALL patients. In a follow-up study with 3 of the above 5 patients, the mutation could no longer be detected in 2 cases following successful induction of clinical remission by chemotherapy. However, the mutated N-ras persisted in one patient who did not achieve remission. We show that oligonucleotide hybridization is a sensitive assay for the detection of N-ras point mutations, which in ANLL could be used to follow the fate of the leukemic clone during (and after) therapy.
Int J Cancer 1988 Jan 15
PMID:Mutation analysis of the N-ras proto-oncogene in active and remission phase of human acute leukemias. 327 90

We have generated a monoclonal antibody (MAb), designated anti-CAA (colon-associated antigen), using as immunogen a membrane-enriched fraction of a biopsy from a moderately-differentiated human colonic adenocarcinoma. The molecular weight of this reactive antigen was determined by Western blotting to be greater than 200 kDa. When immunohistochemical techniques were used, MAb anti-CAA reacted with epithelium in the majority of normal, dysplastic and malignant colon specimens tested (greater reactivity was observed in normal colon than in benign or malignant lesions). Cell sorter analyses demonstrated a heterogeneous distribution of CAA on the cell surface of the well-differentiated LS-174T cell line. Antigen positive and antigen-negative cells were separated by means of flow cytometric techniques. These two subpopulations were then inoculated into immunosuppressed rats, resulting in xenograft tumors which differed significantly in their degree of histologic differentiation. Antigen-positive cells developed into well-differentiated adenocarcinomas, while antigen-negative cells developed into poorly differentiated adenocarcinomas. These results, along with immunohistochemical studies, indicate that the antigen detected by MAb anti-CAA has characteristics of a colon-associated antigen whose expression correlates with cellular differentiation. Moreover, differences in molecular weight as well as tissue distribution indicate that CAA may be a novel antigen different from those previously described.
Int J Cancer 1987 Jan 15
PMID:Immunological characterization of a novel human colon-associated antigen (CAA) by a monoclonal antibody. 379 69

Enhanced nitrogen utilization occurs when adults with gastrointestinal disease are fed partially hydrolyzed proteins instead of isonitrogenous, isocaloric crystalline amino acids. A controlled trial was conducted to determine if this difference was also seen in malnourished stressed cancer patients and to gain an understanding of the underlying mechanism. Sixteen malnourished patients with head and neck cancer were prospectively randomized to either crystalline amino acid-glucose (CAA-G) or partially hydrolyzed protein-glucose (PHP-G) diets. Patients were fed via an enteral tube for 10 days starting on the second postoperative day. Blood SMA-6 and amino acid levels were measured on Days 1 and 10. Daily calorie counts and fluid balance were obtained. Daily 24-hr urine and stools were analyzed for total N during the last 5 days of the study period. The daily positive N balance with both diets was the same (CAA-G = +7.8 +/- 0.8 vs PHP-G = +8.2 +/- 1.0 g; mean +/- SE) and 3-methylhistidine:creatinine ratio did not differ. Patients on PHP-G diet gained significantly more weight (+0.5 vs - 1.5 kg; P less than 0.01) and had significantly higher serum albumin (3.2 +/- 0.2 vs 2.8 +/- 0.1 g/dl; P = 0.5) by the end of the 10th study day. Weight changes were not due to fluid retention: serum Na+, K+, creatinine and mean fluid intake for the two groups remained the same during the study period. A significantly greater rise in BUN occurred on the CAA-G diet (from 9.2 +/- 1.7 to 15.4 +/- 1.4 mg/dl; P less than 0.05) while BUN remained unchanged on the PHP-G diet.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of elemental diet on albumin and urea synthesis: comparison with partially hydrolyzed protein diet. 637 51

Ornithine decarboxylase (ODC) plays an important role in cell growth, and its activity is regulated by many mechanisms. The biochemical characteristics of ODC in malignant cells differ from those of ODC in normal cells. To determine whether novel changes occur in ODC in neoplastic tissue, we compared the nucleotide sequence of ODC cDNA obtained from human hepatoma tissue as determined by reverse transcriptase-PCR with that of ODC cDNA obtained from nontumorous tissue in the same patients. There were three point mutations accompanied by replacements of amino acids in hepatoma tissue with other amino acids or a stop codon. In one poorly differentiated hepatoma, codon 415, CAA was converted to TAA, resulting in replacement of Gln-415 by a stop codon. The mutated ODC protein produced by translation in a reticulocyte-lysate protein synthesizing system was truncated and stabilized in an ATP antizyme-dependent degradation system. These findings suggest that formation of a truncated and stabilized ODC protein due to point mutation is one reason why ODC activity is high in human hepatoma tissue.
Cancer Res 1995 Aug 15
PMID:Point mutation of ornithine decarboxylase gene in human hepatocellular carcinoma. 762 54


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