Linked Life Data

8112887

Source:http://linkedlifedata.com/resource/pubmed/id/8112887

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1994-3-30
pubmed:abstractText
Cytogenetic studies performed on human colorectal tumors have revealed 2 specific patterns of chromosomal anomalies. The major pattern, known as the monosomic type (MT), is characterized by the loss or deletion of chromosomes 18, 17 (short arm 17p) and, less frequently, 1p, 4, 15, 5 (long arm 5q) and 21. The other one, known as the trisomic type (TT), is characterized by the gain of several chromosomes: 7, 12, X, 5 and 8. Losses of chromosome 18 and of the 17p arm never coexist in TT tumors. It was observed that many chromosome losses or deletions involved genes encoding for enzymes of the de novo pathways of nucleotide synthesis. In contrast, gains involved genes encoding for enzymes of the salvage pathways of the same metabolism. This led to the hypothesis that chromosome imbalances corresponded to those of nucleotide synthesis in tumor cells. Such an interrelation was confirmed by the dosage of thymidylate synthase (TS) and thymidine kinase (TK) activities in a series of colorectal grafted tumors. This study has been expanded to a larger series of xenografted tumors (23 cases) in which both TS and TK activities were studied, in parallel with an analysis of mRNA, by Northern blotting. The amount of mRNA was found to correlate with the number of gene copies calculated from cytogenetic data, indicating a direct gene-dosage effect. It also correlated with enzyme activities, but less strongly. This suggests the existence of an efficient post-transcriptional regulation, in particular for TS, whose level of expression varies over a wide range. Such variations may explain the diversity of responses to chemotherapy.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0020-7136
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
56
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
506-11
pubmed:dateRevised
2007-7-24
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Gene dosage and expression, and enzyme activity of thymidine kinase and thymidylate synthase in xenografted colorectal adenocarcinomas.
pubmed:affiliation
CEA/DSV/DPTE/LCG, Fontenay aux Roses, France.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't