ABSTRACT
Proceeding from their early data showing that some portion of DNA originating from apoptotic cells can enter the blood stream and pass through the renal barrier by preserving its template capabilities, the authors analyzed urine DNA from 29 patients with colorectal cancer. PCR was used to compare DNA samples from the normal mucosa surrounding the tumor and from the urine collected just prior to surgery. Six microsatellite loci were studied with oligonucleotide primers. The following results were obtained: i) 3 cases showed differences in one of the studied loci in normal and tissue DNA; ii) some patients displayed changes in urine DNA microsatellite loci, namely: disappearance of some alleles (loss of heterozygocity) and appearance of new ones; iii) there were no differences in microsatellite patterns of lymphocytic DNA (taken as a control) and urine DNA in healthy donors. The findings are discussed in view of current concepts of tumor clonal heterogeneity and interpreted as a promising approach to diagnosing and monitoring tumor growth.
Subject(s)
Adenocarcinoma/urine , Colorectal Neoplasms/urine , DNA, Neoplasm/urine , Intestinal Mucosa/metabolism , Adenocarcinoma/pathology , Adult , Aged , Biomarkers, Tumor/analysis , Colorectal Neoplasms/pathology , DNA Primers/chemistry , Disease Progression , Female , Humans , Male , Microsatellite Repeats/genetics , Middle Aged , Polymerase Chain Reaction , UrinalysisSubject(s)
DNA, Recombinant/analysis , Electrophoresis, Gel, Pulsed-Field/methods , Animals , Base Sequence , Cloning, Molecular , DNA Primers , DNA, Recombinant/chemistry , DNA, Recombinant/isolation & purification , DNA, Recombinant/ultrastructure , Escherichia coli/genetics , Humans , Mice , Microscopy, Electron , Molecular Weight , Polymerase Chain Reaction , Tumor Cells, CulturedABSTRACT
Discrete bands of free DNAs of approximately 25 kbp were detected in human cell cultures. According to electrophoretic shifts induced by single and double strand breaks, they from topological isoforms (supercoiled, open, and linear). Long-term labeling (24 h) of growing and quiescent cultured cells by [3H]thymidine indicates differences of free versus chromosomal DNAs including (i) significantly lower specific radioactivity in growing cells, (ii) higher specific radioactivity in quiescent cells, and (iii) resistance to fluorodeoxyuridine labeling. During apoptosis of cultured Namalwa cells, heterogeneous fragments are formed which differ from free DNAs. Crosslinking of nascent RNA with DNA template by 8-methoxypsoralen indicated slight transcriptional activity of free DNAs.
