EARLY PROGRESSION STAGE OF MALIGNANCY AS REVEALED BY IMMUNOHISTOCHEMICAL DEMONSTRATION OF DNA INSTABILITY .1. HUMAN GASTRIC ADENOMAS

The degree of DNA-instability as revealed by the immunohistochemical s taining with monoclonal anti-single-stranded DNA antibody after acid h ydrolysis (DNA-instability test) was used as the marker of malignancy. This was applied to human gastric regenerative epithelium in chronic peptic ulcer (5 cases), adenoma (35 cases), and well differentiated tu bular adenocarcinoma (5 cases). Proliferative activity was evaluated b y proliferating cell nuclear antigen (PCNA) immunohistochemistry, and the quantitative analyses of the mean number and mean area of silver-s tained nucleolar organizer regions (AgNORs) per one nucleus were perfo rmed for all these cases. All cancers and adenomas were positively sta ined by the DNA-instability test diffusely, indicating the malignant c haracter of the latter from the view point of DNA-instability, in cont rast to the negative stainability of all regenerative epithelium. The percent number of PCNA-positive cells and mean number and mean area of AgNORs tended to be larger in adenoma and cancer than in regenerative epithelium, although the differences were not usually statistically s ignificant. Supporting the malignant character of adenoma, single cell necroses and abnormal mitoses were almost always present in the lesio n. In conclusion, all adenoma lesions were regarded as malignant in na ture, namely, in-situ carcinoma,existing at an early stage of progress ion of malignancy.