Marking characteristics of anti‐nuclear matrix protein NM200.4 in human breast carcinomas and normal human tissues

Nuclear matrix proteins are a group of recently described proteins that are thought to be cell‐type specific. Using a monoclonal antibody (NM 200.4; Matritech, Cambridge, MA) generated against nuclear matrix proteins isolated from a human breast carcinoma cell line, we examined frozen tissue sections from 30 breast carcinomas, and a variety of normal tissues to determine the antibody specificity, and to assess the relationship with the staining pattern and tumor type and hormone receptor status. Most breast carcinomas marked with the antibody, but stromal and vascular endothelial cells in the tissues surrounding these lesions also marked focally. Marking of vascular endothelium in a variety of benign tissues, renal tubular epithelium, and occasionally uterine smooth muscle cells was also observed. Normal breast tissue from 4 patients without breast cancer did not react. Studies on breast tumors revealed that 15/20 invasive ductal, 3/4 in situ ductal, 3/3 medullary, 2/2 invasive lobular, and 1/1 colloid carcinomas marked with this antibody. Image analysis revealed that the staining intensity of medullary carcinoma was twice that found in invasive ductal carcinoma (avg pixel density 76.6 vs. 30.1; P <0.05). Invasive lobular and in situ ductal carcinoma also expressed higher staining intensities than invasive ductal carcinoma, but these differences were not significant. Invasive ductal carcinomas had heterogeneity in staining intensity (avg. pixel intensity range: 0‐94 units). Tumors with multiple aneuploid populations had significantly higher stain intensity values than either diploid lesions or lesions containing a single aneuploid population (P <0.05). Nuclear grade did not correlate with staining intensity. No significant correlation was found between the image analysis values and either the estrogen or progesterone receptor content of the lesions as determined by charcoal‐ligand binding bioassay. Our studies indicate that a monoclonal antibody to such a protein may be useful in defining a subset of breast carcinomas. © 1993 Wiley‐Liss, Inc.