Expression of proline-directed protein kinase, (p34cdc2/p58cyclin A), a novel cell proliferation marker in childhood brain tumors.

The presence of two proteins of the proline-directed protein kinase (PDPK), the catalytic subunit p34cdc2 and the regulatory subunit p58cyclin A was determined in seven primitive neuroectodermal tumors (PNETs), three choroid plexus neoplasms and eleven astroglial tumors. The highest expression was registered in the cellularly undifferentiated PNETs and glioblastoma multiforme from the astroglial malignant group. Rabbit immunoantiserum against the two subunits of PDPK, a cell proliferation marker, was employed to detect proliferation activity in childhood brain tumors. The PDPK activity was present from Gl- to M-phases in 21 childhood brain tumors with different central nervous system (CNS) localization and cellular atypia. Immunocytochemical analysis employed an indirect, alkaline phosphatase conjugated biotin-streptavidin antigen detection technique on frozen and routine, formalin-fixed and paraffin-wax-embedded tissue sections of brain tumors. We compared the proliferation activity in the cells of normal, morphologically changed and neoplastically transformed choroid plexus. The average proliferation activity was low in comparison with other tissues. The results in normal and neoplastically transformed choroid plexus were very similar. The lowest proliferation activity in the astroglial group belonged to pilocytic ASTRs. The use of cell differentiation as a prognostic factor in primary brain tumors has already been established and is strongly suggested by our research group. Further systematic neoplasm studies and regular employment of these two polyclonal antibodies for immunocytochemical screening experiments are necessary to determine their true diagnostic and prognostic significance.