Immunohistochemical analysis of the distribution of the human ATPase (hASNA-I) in normal tissues and its overexpression in breast adenomas and carcinomas.

Human ATPase (hASNA-I) is a novel human gene recently cloned on the basis of homology to the arsA gene of bacteria. Its protein product is an ATPase that is free in the cytoplasm and bound in the perinuclear area and nucleolus in human cells. We prepared the hASNA-I-specific 5G8 monoclonal antibody and used it to investigate the expression of hASNA-I in normal human tissues and breast cancers. hASNA-I was detected immunohistochemically only in the epithelial cells of the liver, kidney, and stomach wall, in the adrenal medulla, in the islet cells of the pancreas, in the red pulp of the spleen, and in cardiac and skeletal muscle. No staining was observed in the uterus, testis, lung, thyroid, cerebellum, and large intestine. Although no staining was also observed in normal breast tissue, all four cases of breast fibroadenomas and all 15 cases of either primary or metastatic breast carcinoma demonstrated increased staining. No embryological or functional common denominator is readily apparent. However, the increased expression in malignant breast cells is of particular interest with respect to the use of this antibody for screening of cytological specimens.