Nucleolar organizer region-associated proteins in cancer cells. Quantitative investigations on gliomas, meningiomas, urinary bladder carcinomas and pleural lesions.

Using a modified silver staining technique, we investigated nucleolar organizer region-associated proteins (AgNORs) in paraffin sections of 156 neoplastic tissues and other lesions, including gliomas (n = 41), meningiomas (n = 20), urinary bladder carcinomas (n = 58), and neoplastic and reactive lesions of the mesothelium of the pleural cavity (n = 37). We found significant differences in the mean number and area of AgNORs per nucleus between nonanaplastic and anaplastic astrocytomas. In meningiomas AgNOR analysis may be useful to distinguish between mostly benign tumors (grade 1 tumors) and atypical ones. Urinary bladder carcinomas exhibited a statistically significant increase in both AgNOR number and area as the grade of malignancy increased. Diagnostically useful differences in the AgNOR configuration between inflammatory and neoplastic processes were found for mesothelial lesions. In general, a higher grade of malignancy correlated with an increase in the AgNOR number. This was accompanied by an increase in the total AgNOR area per nucleus, irrespective of whether the size of the individual AgNORs had changed.