p27/kip1 expression in oligodendrogliomas and its possible prognostic role

p27/kip1 regulates the G1-S transition of the cell cycle by inhibiting cycl inD-CDK4, cyclinE-CDK2 and cyclinA-CDK2 complexes. Regulation of p27 levels occurs mainly post-translationally by ubiquitin-mediated proteasomal prote olysis. Although genetic changes of p27/kip1 are extremely rare, in many hu man carcinomas p27 levels are reduced, correlate with histological malignan cy, and are associated with poor prognosis. In astrocytic gliomas, p27 decr eases with anaplasia and is almost absent in glioblastomas. p27/kip1 was im munohistochemically studied in 37 oligodendrogliomas, categorized according to WHO classification. In this series, the immunohistochemical reaction fo r p27 was confined to nuclei. p27 score showed a tendency to decrease with malignancy. When the p27 score was considered as high versus low expression (cut-off of p27 labeling index, LI, at 25%), it represented an independent prognostic factor in univariate (P = 0.02) and in multivariate analysis (P = 0.04). The risk ratio suggested that the p27 low expression group had a threefold increased possibility to show a reduced survival. Moreover, p27 l evels did not correlate with MIB-1 LI, suggesting that p27 is not merely as sociated with the control of proliferation.