Acid-Extractable Nuclear Proteins of Cancer Cells. I. Staining With Ammoniacal Silver

Abstract

Studies of lymph-node responses disclosed that antigenic stimulation was associated with a change in ammoniacal-silver (A-S) staining of paraffin sections of lymph nodes. Sections of control lymph nodes lacked A-S staining of cell nuclei, but sections of lymph nodes responding to antigenic stimulation had A-S staining of the nuclei. Parallel changes were also seen in the nuclei of parenchymal cells. However, the nuclei of malignant lymphoid and parenchymal cells showed minimal or no A-S staining, regardless of the staining of the control homologous cells. These observations prompted a more detailed study of A-S staining of control and cancer cells. Smears of fresh tissues from human beings and mice were used. Under the conditions of study, A-S stained cell nuclei precisely. The chromatin structures of noncancerous cells were distinctly stained by A-S. In contrast, cancer cells had fine, silver-staining granules scattered with minimal structural orientation throughout the nuclei. Differential extraction studies indicated that A-S stained acid-extractable nuclear protein (AENP) whose physical characteristics and staining with alkaline Fast Green corresponded to that of a histone. Apparently, cancer cells are characterized by well-defined alterations in their AENP. However, further studies are needed to define the detailed physicochemical nature and biological significance of the observed changes in AENP.