Somatic DNA alterations in breast carcinomas of different lymph-node status by DNA fingerprint analyses

The purpose of this study was to screen for somatic changes in invasive breast tumors by multilocus DNA fingerprints comparing normal (blood) and malignant tissue samples from 34 patients. The comparison of lymph node-positive and node-negative breast carcinomas was of primary interest. After restriction enzyme digestion with HinfI and HaeIII, altered banding patterns were detected by using the oligonucleotide probe (GTG)5 in 7 of 34 (20.5%) and in 3 of 34 (8.8%) tumors after hybridization with (GACA)4. The overall frequency of changes thus amounted to 29.4%. Because long (GACA)n repeat motifs, generating predominant DNA fingerprint bands, are localized on the short arms of the human acrocentric chromosomes, sequences that are important in breast carcinogenesis may be present in these regions. The overall methylation status of the DNA does not appear to be responsible for DNA fingerprint differences, as can be demonstrated with the restriction endonuclease HaeIII. DNA fingerprint differences did not correlate with tumor grade, stage, and hormone receptor status. Tumors with lymph-node metastases expressed DNA fingerprint differences more frequently.