Abstract
The total amount of nm23 protein, the relative ratios of H1 and H2 isoforms (H2/H1) and the localization of these proteins in human normal tissues were studied by a semiquantitative immunoblot technique followed by densitometry and immunohistochemistry with monoclonal antibody against nm23 protein (Pan-242). All tissues contained both isoforms recognized as the 20.5kD H1 protein and 18.5kD H2 protein by immunoblotting. Nm23 protein was abundant in liver, kidney and adrenal gland tissue, and scarce in heart and muscle. H2 levels were always higher than H1, but the isoform ratios (H2/H1) were variable from tissue to tissue. Immunostaining revealed that nm23 protein was predominantly present in cytoplasm and the pattern of staining was homogeneous in parenchymal cells of the liver, pancreas and colonic mucosa and heterogeneous in gastric mucosa and kidney. These results demonstrated that the levels of nm23 protein and the H2/H1 ratios and distribution of isoforms were different in each tissue, and suggests that, when the alterations of nm23 gene expression in tumor tissues are examined, the levels and ratios in non-tumorous tissues surrounding the tumor nest should be considered.
