Triplet repeat instability correlates with dinucleotide instability in primary breast cancer.

The expansion of triplet repeat microsatellite sequences is the molecular correlate of anticipation in a number of rare Mendelian neurodegenerative disorders. This finding prompted us to study these sequences in primary breast cancer in which there is evidence of genetic anticipation. We used a PCR/silver stain method to determine whether triplet-repeat instability (TRI) was present in DNA from malignant breast tumors, and analyzed microsatellite instability (MSI) in triplets SCA1, SCA2, SCA3, SCA6, HD, DRPLA and X25-GAA.

Loss of hMSH2 expression in primary breast cancer with p53 alterations.

Inactivation of DNA mismatch repair genes (MRG) is a recently described pathway of cancer development and progression resulting in genetic instability. Germline mutations in MRG have been studied predominantly in patients with hereditary non-polyposis colorectal cancer (HNPCC) where it is associated with microsatellite instability (MSI). The expression of MRG in primary breast cancer is still largely unexplored.

p53 expression is decreased in primary breast carcinomas with microsatellite instability.

p53 and p185 expression in primary breast cancer with microsatellite instability (MSI) is still largely unexplored. To investigate the relationship between these oncoproteins and the pathways of genomic instability, we examined 52 primary invasive breast cancers stratified by the presence and absence of MSI. We determined the status of eight microsatellite loci using radioactive and silver staining methods, and evaluated the immunohistochemical expression of p53 and p185 in a consecutive series of Italian cancer patients characterized by clinical-pathological and biological parameters.