Analysis of the progression of intraductal proliferative lesions in the breast by PCR-based clonal assay

Abstract

To analyze the progression in patients with a morphological diagnosis of intraductal proliferative lesions by PCR-based clonal assay. An X-chromosome inactivation assay was applied to explore clonal relationships in human intraductal proliferative lesions of the breast. Four groups samples, including 40 cases of usual ductal hyperplasia (UDH), 40 cases of atypical ductal hyperplasia (ADH), 29 cases of flat epithelia atypia (FEA), and 40 cases of ductal carcinoma in situ (DCIS) were selected for analysis. Thirty specimens of normal breast tissue were used as a control group. Microdissection was performed to collect the tissue samples for extraction of genomic DNA from paraffin-embedded tissues. The DNA was subjected to PCR amplification of the CAG repeats in androgen receptor (AR) gene exon I with and without prior digestion of methylation-sensitive restriction enzyme HhaI. Gel electrophoresis was used to detect the clonal nature of these four groups samples. The clonal analysis confirmed monoclonality in all informative samples of DCIS cells. Normal tissues and the majority (97.1%) of UDH were shown to be polyclonal. Monoclonality was revealed in 20/39 (51.3%) cases of ADH. Among 26 cases of FEA, 20 were shown to be polyclonal, while six displayed monoclonal alterations which accounted for 23.1%. These findings reinforce recent suggestions that clonal analysis with AR gene polymerase chain reaction may be used to define the genetic relationships among the human tumor and the breast intraductal proliferative lesions. Furthermore, our observations demonstrate nearly a half ADH and the smaller part of FEA have clonal alterations, which may be neoplastic lesions. This method would shed light on genetic abnormalities that play a role in early tumorigenesis of the breast, and thus might be an adjunct in predicting the probability of breast tumor occurrence and in guiding the management of these cases.