Abstract
Proliferating cell nuclear antigen (PCNA/cyclin), a non-histone, acidic nuclear protein commonly believed to be strictly confined to proliferating cells, was successfully demonstrated exclusively in the nuclei of human glioma cells both in vitro and in situ by an indirect immunoperoxidase method. Speckled nucleoplasmic staining for PCNA, with variable nucleolar staining, was observed in approximately 37% of cultured human glioma (KY) cells in exponential growth, whereas only 14% of subcutaneous KY tumor cells from inoculated nude mice stained unequivocally positive for nuclear PCNA. A direct comparison of this method and autoradiography would be valuable. However, immunocytochemical demonstration of PCNA appears to be a simple method of estimating the proliferative activity of glioma cells, since the number of PCNA-positive KY cells closely corresponds to the number of S phase cells that exhibit nuclear uptake of bromodeoxyuridine.
