Immunohistochemical detection of cell-cycle associated markers on paraffin embedded and formalin fixed needle biopsies of prostate cancer: correlation of p120 protein expression with AgNOR, PCNA/Cyclin, KI-67/MIB1 proliferation-scores and Gleason gradings.

Paraffin embedded and formalin fixed needle biopsies of prostate cancer (PC) were used to immunocytochemically detect the p120 nucleolar protein in relation to the Gleason histological gradings (GHG), the labelling indices of proliferating nuclear immunocytochemical markers (PCNA/Cyclin, Ki-67/MIB1) and the argyrophilic nucleolar region (AgNOR) rate. The twenty-six cases of PC (6 from large histological samples and 20 from needle biopsies) were equally distributed into low (less than or equal to 6) or high (greater than or equal to 7) GHG groups. The p120 nucleolar protein immunocytochemical reaction was randomly expressed in large histological sections but uniformly distributed without gaps in needle biopsy sections. Only on the latter were quantitative values of PCNA/Cyclin (23.2 in low and 45.3 in high GHG), Ki-67/MIB1 (13.8 in low and 43.3 in high GHG) and AgNOR (5.0 in low and 7.5 in high GHG) related to those of p120 nucleolar protein (0.8 in low and 3.8 in high GHG). The values of all these cell cycle markers increased from low to high GHG of PC, all four reaching high statistical significance between the two groups (ANOVA - two tailed p < 0.0001). The PCNA/Cyclin index showed a higher positivity than the Ki-67/MIB1 index in PC with low GHG but not in PC with high GHG. In conclusion, paraffin embedded and formalin fixed PC needle biopsies exhibit a higher diagnostic PCNA/Cyclin than Ki-67/MIB1 index for cases presenting differentiated features, whereas p120 nucleolar protein detection seems to be a suitable marker of poorer outcome of PC.