Differential expression of S100 calcium-binding proteins characterizes distinct clinical entities in both WHO grade II and III astrocytic tumours

The computer-assisted microscopic analysis of Feulgen-stained nuclei enable d us to identify two subgroups of astrocytomas (WHO grade II) and two subgr oups of anaplastic astrocytomas (WHO grade III) with significantly distinct clinical outcomes (Decaestecker et al. Brain Pathol 1998; 8: 29-38). The a strocytomas labelled in the present study as typical (TYP-ASTs) behaved cli nically like real astrocytomas while atypical astrocytomas (ATYP-ASTs) beha ved similarly to anaplastic astrocytomas. The anaplastic astrocytomas that we labelled as typical (TYP-ANAs) behaved clinically like anaplastic astroc ytomas while atypical ones (ATYP-ANAs) behaved like glioblastomas. In the p resent study, we investigate whether some biological characteristics could be evidenced across these four groups of TYP- and ATYP-ASTs and TYP- and AT YP-ANAs. The data show that the levels of expression (immunohistochemically assayed and quantitatively determined by means of computer-assisted micros copy) of vimentin, the glial fibrillary acidic protein and the platelet-der ived growth factor-alpha did not differ significantly across these four gro ups of astrocytic tumours. The level of cell proliferation (determined by m eans of both the anti-proliferating cell nuclear antigen and the anti-MIB-1 antibodies; P < 0.001 to P < 0.0001) differed very significantly between t he astrocytomas and anaplastic astrocytomas, but not between the typical an d atypical variants identified in each group. In sharp contrast, the levels of expression of the S100A3 and S100A5 proteins differed markedly in the s olid tumour tissue in relation to the astrocytic tumour types and grades. I n addition, while the levels of expression of S100A6 did not change in the astrocytic tumour tissue in relation to histopathological grade, the levels of expression of this S100 protein (but not those of S100A3 and S100A5) di ffered markedly in the blood vessel walls according to whether these vessel s originated from low- or high-grade astrocytic tumours.