Assessment of proliferative index in different grades of breast cancers using AgNOR (Agyrophilic Nuclear Organizer Region) expression

Abstract

Nucleolar organiser regions (NORs) are loops of DNA which are responsible for ribosomal RNA (rRNA) transcription in the nucleus of cells. NORs can be selectively stained by silver methods. The NORs agyrophilia is due to a group of nucleolar proteins, which have affinity for silver (Agyrophilic Nucleolar Organizer Regions, AgNOR proteins). The aim of the present study is to assess proliferative index in different grades of invasive ductal carcinoma (IDC) by using AgNOR as a marker. A total of 18 formalin fixed paraffin-embedded breast tissue blocks were retrieved from the archives of the histopathology department of the Komfo Anokye Teaching Hospital, Ghana. The tissue blocks included 17 IDC, (with 8 as grade 2 IDC, 9 as grade 3 IDC) and 1 normal breast tissues. Tissue sections were diagnosed and graded following haematoxylin and eosin (H&E) staining. Silver staining was used to demonstrate the presence of AgNOR. The AgNOR dots were manually counted in 50 and 100 cells. The mean AgNOR count (mAgNOR) and proliferative index, (pAgNOR, percentage of cells with ≥5 AgNOR dots per nucleus), significantly increased with increasing grade of IDC. The mAgNOR and pAgNOR were low in normal breast, (at p-value less than 0.05). There was no significant difference in the mAgNOR and pAgNOR score for counting 50 and 100 cells (at a p-value of 0.01). mAgNOR and pAgOR increases with increase in grade of IDC and hence can be used to assess proliferative index of IDC.