title: Cell-cycle inhibitor p27/Kip-1 expression in non-astrocytic and non-oligodendrocytic human nervous system tumors.
abstract: p27/kip-1 is a 'universal inhibitor' which inhibits cyclin complexes with cyclin-dependent kinases (CDKs), preventing cell cycle from the G1-S progression. It is expressed in normal oligodendrocytes and in differentiated glial tumors, decreasing with anaplasia and malignancy. In non-astrocytic and non-oligodendrocytic tumors of the nervous system, such as meningiomas, schwannomas, medulloblastomas, neuroblastomas and malignant lymphomas, p27/kip-1 is inconstantly and sometimes poorly expressed. This can be due to the lacking of p27 expression in the normal counterpart of tumor cells. In some tumors, p27/kip-1 expression can be attributed to a differentiation process, as in the pale islands of desmoplastic medulloblastoma and in neuroblastomas. A correlation of p27/kip-1 expression with histology was not found, with the exception of apoptosis in medulloblastomas. p27/kip-1 is in feed-back with cyclins and CDKs for the control of cell proliferation and its expression may occur where requested by the interplay with cyclins and other inhibitors.
mesh_terms: D017209:Apoptosis / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins; D002454:Cell Differentiation / Q000502:physiology; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004806:Ependymoma / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008527:Medulloblastoma / Q000378:metabolism / Q000473:pathology; D008579:Meningioma / Q000378:metabolism / Q000473:pathology; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009423:Nervous System Neoplasms / Q000378:metabolism* / Q000473:pathology; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology; D025521:Tumor Suppressor Proteins