Minichromosome maintenance (MCM) and AgNOR proteins expression in desmoid tumours: a tissue microarray analysis

Abstract

In the present study, nuclear proliferative proteins: MCM2, MCM5, MCM7, Ki-67 and AgNORs expression wasassessed in paraffin sections from sporadic desmoid tumours using a tissue microarray (TMA)-based immuno- and histochemistry,respectively. Nuclear expression of MCM7, where the percentage of positive cells was 0.87% (±1.64) (range0-5%), was found in 4/20 (20.0%) cases. In 32/32 (100%) of the examined desmoid cases no expression of nuclear proteinsMCM2 and MCM5 was detected. Nuclear expression of Ki-67 was observed in 4/21 (19%) cases. Paraffin sections from30 cases of desmoid tumours were silver-stained to visualize AgNORs. The following AgNOR parameters were calculated:mean AgNOR number per nucleus (N), mean AgNOR area per nucleus, mean AgNOR dot area per nucleus (A), and meanAgNOR content (C = N/A). In the investigated group the mean values of AgNOR parameters were the following number:4.34 (±0.11); area: 0.74 μm2 (±0.19); dot area: 0.18 m2 (±0.01), and AgNOR content: 23.73 (±1.85). The mean AgNOR numberper nucleus and mean AgNOR content in desmoid tumours were statistically significantly higher as compared to the controls(tonsil tissue) (p<0.001). This study observed low level of MCM7 and Ki-67 and lack of MCM2, MCM5 proteinsexpression which may explain commonly known low mitotic activity of desmoid tumour cells. The morphology of dotsrelated to AgNORs (number, area) and their morphometric parameters point to elevated transcriptional activity of desmoidcells.

Keywords

• MCM proteins
• AgNOR proteins
• desmoid tumours