Cyclin Dl amplification and expression in human breast carcinoma: Correlation with histological prognostic markers and oestrogen receptor expression

Abstract

Aims-To study the amplification of the Cyclin Dl gene (CCND1) in human breast carcinoma; to relate this to Cyclin Dl protein expression; to relate these parameters to recognised pathological prognostic factors, including oestrogen receptor (ER) status. Methods-DNA extracted from frozen sections of breast tumours (n = 36) was used for Southern blotting. Probes for CCND1, c-myc and the immunoglobulin heavy chain locus (IgH) were hybridised to tumour DNA. Immunocytochemical expression of Cyclin Dl protein and ER was studied in paraffin wax sections from the same tumours. Results-Amplification of CCND1 was observed in 11% (four of 36) of tumours studied. Over expression of Cyclin Dl protein was observed in 73% (30/41) of tumours. There was no correlation between recognised histological prognostic markers and either gene amplification or expression. However, a weak association was seen between Cyclin Dl expression and ER status. Conclusions-A disparity exists between locus amplification and over expression of Cyclin Dl, suggesting the existence of another mechanism for raised protein expression. No significant correlation was detected between either Cyclin Dl amplification or over expression and established prognostic markers.