Amplifications of oncogene erbB-2 and chromosome 20q in breast cancer determined by differentially competitive polymerase chain reaction.
A new method of measuring gene copy number in small samples of DNA was used to measure amplification of the erbB-2 gene and of chromosome 20q in breast cancer. This method, termed 'differentially competitive polymerase chain reaction' (DC-PCR) combines the advantages of two other techniques for measuring amplification by PCR, namely differential PCR and competitive PCR. The DC-PCR methodology was evaluated for sensitivity and specificity by comparing amplification of erbB-2 measured by DC-PCR with that obtained by fluorescence in situ hybridization (FISH) for 42 cases or Southern blotting and/or slot blot analysis for 34 cases. There was over 90 percent concordance with both FISH and Southern blotting and/or slot blot analysis. DC-PCR was used to further characterize the newly described amplicon at chromosome 20q. By analyzing DNA from 10 breast cancer cell lines at 7 different loci, we identified a potential common region of amplification of approximately 5 centimorgans at chromosome 20q13 bordered by loci D20S52 and RMC20C100-S1. One hundred and seventeen cases of primary breast cancer were evaluated for amplification at these two loci. Amplification at one or more loci, defined as > 1.5 fold higher copy number than that of normal DNA, was found in 25 cases (21%). Sixteen cases were amplified at only one of the two probes (12 cases for RMC20C001-S1 and 4 cases for D20S52), suggesting that the target gene lies between the two markers or that there are two independent target genes within a small chromosome region.
Deng
G
G
Geraldine Brush Cancer Research Institute at California Pacific Medical Center, San Francisco 94115, USA.
Yu
M
M
Chen
L C
LC
Moore
D
D
Kurisu
W
W
Kallioniemi
A
A
Waldman
F M
FM
Collins
C
C
Smith
H S
HS
D015139:Blotting, Southern; D001943:Breast Neoplasms / Q000235:genetics*; D002890:Chromosomes, Human, Pair 20; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D005784:Gene Amplification; D018734:Genes, erbB-2; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D016133:Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D004273:DNA, Neoplasm