Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P00492 (hypoxanthine-guanine phosphoribosyltransferase)
 2,385 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have determined the frequency and spectrum of spontaneous mutations at the hprt locus in LoVo, HCT116, LS180 and DLD-1 colon carcinoma cell lines exhibiting microsatellite genetic instability. Each cell line has a different mutator gene. LoVo and HCT116 cells have mutated hMSH2 and hMLH1 genes, respectively, which account for the majority of hereditary non-polyposis colorectal cancer (HNPCC). LS180 cells are wild type for these genes and also for hPMS1 and hPMS2 mismatch repair genes. DLD-1 cells harbor a mutated GTBP mismatch binding factor and a mutated DNA Polymerase delta. The mutation rate at the hprt locus was several hundred fold higher in these cell lines relative to control cell lines without microsatellite instability. The mutations were frameshifts (deletions and insertions of a single nucleotide in short repeats) and single base substitutions (transversions and transitions). Some mutations were shared by these four cell lines. However, every cell line also exhibited a distinctive spectrum of mutations suggesting that each mutator gene induces a particular mutator phenotype. These results also suggest that the frequency and spectrum of somatic mutations in tumor cells of the microsatellite mutator phenotype may have diagnostic applications to discriminate among the diverse underlying mutator genes.
 ...
PMID:Differences in the spectrum of spontaneous mutations in the hprt gene between tumor cells of the microsatellite mutator phenotype. 864 58

Results from the analysis of human tumor cell lines with mutations in DNA mismatch repair genes have contributed to the understanding of the functions of these gene products in DNA mismatch repair, microsatellite instability, cell cycle checkpoint control, transcription-coupled nucleotide excision repair, and resistance to cytotoxic agents. However, complementation of human DNA mismatch repair defects by introduction of a single cloned gene or cDNA, which would serve to directly prove or disprove their involvement in these processes, has not been accomplished. Here, we introduce a wild-type copy of the hPMS2 cDNA by stable transfection into the PMS2 mutant HEC-1-A cell line. HEC-1-A cells expressing wild-type hPMS2 exhibit increased microsatellite stability, have a reduced mutation rate at the endogenous hypoxanthine phosphoribosyltransferase locus and extracts from these cells are able to perform strand-specific mismatch repair. These results demonstrate that the hPMS2 gene is integral to the maintenance of genome stability.
 ...
PMID:Single gene complementation of the hPMS2 defect in HEC-1-A endometrial carcinoma cells. 967 58

The spectrum of mutations was determined at the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus in the human uterine tumor cell line HEC-1-A which is defective in the mismatch repair gene hPMS2. The mutation frequency at the hprt locus in HEC-1-A was about two orders higher than that in wild type repair-proficient cells. The fifty-eight mutations detected were exclusively point mutations, with frameshifts of one base deletion/addition predominating (66%) the remaining were base substitutions. All the frameshift mutations occurred at sites of monotonous repeating sequences, including six consecutive guanine bases site which was the hot spot for the addition of one G that contributed 60% of the total mutations. Although the observed specificity of mutations in HEC-1-A apparently resembled that of the hMLH1-deficient cell line HCT116 [Ohzeki, S., Tachibana, A., Tatsumi, T., Kato, T., 1997. Spectra of spontaneous mutations at the hprt locus in colorectal carcinoma cell lines defective in mismatch repair. Carcinogenesis, 18, 1127-1133.], the pronounced increase of +/-1 bp frameshifts and the reduced incidence of C-->T transitions at the CpG site suggest that the hPMS2 gene product may have an additional function in the mismatch repair process independent of it's role in the hMutLalpha heterodimer.
 ...
PMID:Specificity of mutations in the PMS2-deficient human tumor cell line HEC-1-A. 983 64