Cyclin D₁in breast cancer is not associated with Ki67 but with ER

Excerpt

D-type cyclins are implicated in cell cycle regulation. The cyclin D₁ gene is amplified in 15-20% of breast cancers while the protein is overexpressed in 50% of these cancers (see Additional information [1]). Overexpression of cyclin D₁ has been linked with oestrogen receptor (ER)a, because it can stimulate transcriptional functions in the absence of oestrogen (see Additional information [2]). A negative association in normal breast has been reported for ERa and Ki67 (a proliferation marker), although this relationship changes in many precancerous and ER-positive cancers. Therefore, the aim of the study was to investigate the interaction between cyclin D₁, ER and Ki67 in normal and malignant breast material. …