Results of a preliminary "blind" study on the presence of the human tumor nucleolar antigen in breast carcinomas, benign breast tumors, and normal breast tissues

A study was made on the presence in benign and malignant breast tumors of a common nucleolar antigen previously found in a broad range of human malignant tumors (Busch et al., Cancer Res. 39, 3024, 1979). The specimens were treated first with rabbit antibodies to "nucleolar preparations" or the nuclear 0.01 M Tris-HCl extracts of HeLa S3 cells and then with fluorescein-conjugated goat anti-rabbit antibodies. With this procedure, bright nucleolar immunofluorescence was observed in 19 20 (95%) of known breast cancer specimens. In the group of 80 unknown samples in the "blind" study, 75 (94%) were correctly identified as malignant or benign on the basis of the presence and distribution of the nucleolar fluorescence. In a group of 67 samples in which the nucleolar fluorescence was either readily observed or virtually absent, 47 48 (98%) of the malignant tumors were correctly identified. Of the benign lesions or normal breast specimens, 18 19 (95%) were correctly identified as negative for nucleolar fluorescence. These studies extend the results previously reported of a common nucleolar antigen in a broad range of human cancers to a larger series of malignancies of a particular organ. The tumor nucleolar antigen(s) were partially characterized by isoelectric focusing on 4% polyacrylamide gels. One major band had a pI of 6.3 and a minor band had a pI of 6.1. These antigens were not found in the normal human liver nucleoli.