A Comparative Study on MIB-1, AgNORs and PCNA Expressions in Astrocytic Tumors

ABSTRACT

Cell cycle associated nuclear proteins such as proliferating cell nuclear antigen(PCNA), argyrophilic nucleolar organizer regions(AgNORs) and the family of nuclear proteins identified by the Ki-67 epitope, have been primarily utilized for estimating of growth potential of neoplasms. Although PCNA and AgNORs staining are possible in the paraffin-embedded tissue, Ki-67 staining had been only possible on frozen sections. Recently monoclonal antibody MIB-1 is available, and reacts with the Ki-67 epitope in paraffin-embedded tissue. Twenty eight astrocytic tumors in paraffin-embedded, archival materials were stained by immunohistochemical technique for the MIB-1, PCNA, and by silver colloid stain for AgNORs. The MIB-1 labeling indicies(LI) ranged from 2 to 25%(10+/-7.58) for 10 glioblastomas; from 2 to 15%(7+/-3.74) for 11 anaplastic astrocytomas; and from 1 to 5%(3+/-1.91) for low grade astrocytomas. Glioblastomas and anaplastic astrocytomas exhibited significantly higher MIB-1 LI than their benign counterparts(p<0.05). The AgNORs count per cell ranged from 1.3 to 3.1(1.96+/-0.57) for 10 glioblastomas from 1.2 to 3.1(1.9+/-0.64) for 11 anaplastic astrocytomas and from 0.8 to 1.5(1.2+/-0.26) for low grade astrocytomas. Glioblastomas and anaplastic astrocytomas exhibited significantly higher AgNORs count than their benign counterparts(p<0.05). The PCNA LI ranged from 10 to 40%(24.5+/-10.39) for 10 glioblastomas; from 5 to 20%(11.6+/-5.24) for 11 anaplastic astrocytomas; and from 5 to 10%(7.1+/-2.67) for low grade astrocytomas. The differences of PCNA LI between glioblastomas and anaplastic astrocytomas(p<0.01), and between glioblastomas and low grade astrocytomas(p<0. 001) were statistically significant. Linear regression analysis showed correlations between MIB-1 LI and AgNORs count(Spearmans r=0.4306, p<0.05), between PCNA LI and AgNORs count(Spearman's r=0.586, p<0.05) and between PCNA and MIB-1 LI(Spearman's r=0.4523, p<0.05). These findings suggest that LI of MIB-1, PCNA and AgNORs count are correlated each other, and can be used as helpful markers for differentiating astrocytic tumors in addition to conventional staining methods.