Effect of Ribonuclease A and Deoxyribonuclease I on Immunostaining of Ki-67 in Cultured Melanoma Cells.

Immunostaining of the cell cycle-associated Ki-67 antigen was studied, using the Ki-67-specific MIB-1 monoclonal antibody on slides prepared by cytocentrifugation of cultured A375 melanoma cells. Immunomorphological analysis of the Ki-67 immunostaining pattern of both nuclear and nucleolar locations was carried out following pre-treatment of the slides including ribonuclease and deoxyribonuclease pre-digestion of the cells. Immunostaining of nucleolar Ki-67 was reduced by ribonuclease pre-digestion, but was not altered by deoxyribonuclease pre-treatment. Ribonuclease did not reduce the staining intensity of Ki-67 in the nuclear matrix, but the intensity decreased after deoxyribonuclease pre-digestion. We suggest that the Ki-67 molecule may play an important role in ensuring contact between nuclear DNA and nucleolar RNA during transcriptional processes in cell proliferation.