METALLOTHIONEIN AS AN EPITHELIAL PROLIFERATIVE COMPARTMENT MARKER FORDNA FLOW-CYTOMETRY

The antibody to the metal-binding low molecular weight protein metallo thionein (MT) stains preferentially the proliferative edge of epitheli al tumors in paraffin sections. The present report demonstrates its us efulness as an epithelial cell marker in DNA flow cytometry of archiva l specimens. Nine control breast (mammoplasty) specimens, 10 control c olonic specimens (resection edges), 12 adenocarcinomas of breast, and 13 adenocarcinomas of colon were analyzed by DNA flow cytometry after MT and DNA staining. The average percentage of cells stained by MT ran ged from 12% to 27% in these groups of specimens, which contain epithe lial as well as stromal and inflammatory cells. Comparing cell turnove r, measured as S-phase fraction (SPF) in unstained and MT-stained prep arations, it was 10% and 20%, respectively, in control tissues and 10% and 30%, respectively, in adenocarcinomas. The SPP is lower in unstai ned preparations because of dilution by noncycling inflammatory and st romal cells. Immunohistochemical staining of various tissues for MT sh owed specific staining of epithelial cells. Evaluation of aneuploid ma lignant epithelial cells detected in six breast and eight colonic aden ocarcinomas showed that on average, 47% of cells were stained with MT and that their SPF increased by about 50% when MT staining was compare d with the unstained preparations. The results suggest that MT stains epithelial cells adequately for ploidy and cell cycle evaluation and t hat it may stain preferentially the proliferating cell compartment, wh ich is considered to be an index of malignancy.