Tumor hypersensitive DNA is enriched in c-myc sequences and reacts differentially with normal and malignant genomic DNA.
We now show that exposure of B16 melanoma cells to bromodeoxyuridine increases cell-substratum interactions concurrent with an increase in genome susceptibility to nucleases. Hypersensitive DNA was isolated after mild nicking of nuclei with DNase I followed by repair with DNA polymerase I in the presence of biotin-19-SS-dUTP and affinity chromatography on streptavidin-agarose. Dot blot studies showed that the hypersensitive DNA is enriched in c-myc sequences compared to total tumor genomic DNA, and hybridizes preferentially to the latter, compared to normal genomic DNA, particularly when prepared from BrdU-treated cells. Since hypersensitive DNA can hybridize with multiple Alu sequences in the genome, we postulate that one of the mechanisms for its differential reactivity may be by recognition of an unequal number of Alu repeats in normal and tumor genomic DNA.
Rieber
M
M
Centre of Microbiology and Cell Biology, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela.
Rieber
M S
MS
D000818:Animals; D015139:Blotting, Southern; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002460:Cell Line; D004256:DNA Polymerase I / Q000378:metabolism; D004260:DNA Repair; D004273:DNA, Neoplasm / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D003850:Deoxyribonuclease I; D008546:Melanoma, Experimental / Q000235:genetics; D051379:Mice; D009693:Nucleic Acid Hybridization; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016271:Proto-Oncogene Proteins c-myc; D011519:Proto-Oncogenes / Q000187:drug effects
D004273:DNA, Neoplasm; D011518:Proto-Oncogene Proteins; D016271:Proto-Oncogene Proteins c-myc; D011505:Protein-Tyrosine Kinases; D004256:DNA Polymerase I; D003850:Deoxyribonuclease I; D001973:Bromodeoxyuridine