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Simultaneous analyses of p(185/Her2) and pS2 protein expression in breast cancer is discussed to add information about prognosis and response to endocrine treatment. In a retrospective study, expression of p(185/Her2) and pS2 protein were detected by immunohistochemistry in paraffinembedded, formalin-fixed sections of 219 primary breast cancers. Median age was 56.6 years, median follow-up 168 months. Results were correlated with clinical parameters and steroid receptor status. ER was positive in 55%, PgR in 54% of the tumors. ER correlated inversely with tumor size, and with tumor grade. pS2 was detected in 54% of the tumors, but showed no correlations with other parameters. p(185/Her2) was present in 24% of the tumors and correlated positively with tumor size. pS2 and ER or PgR status correlated (p<0.001). In the sub-group of negative steroid receptors and positive pS2 a qualitative significant difference for p(185/Her2) expression was seen. ER, pS2 and p(185/Her2) status had no prognostic impact on disease-free or overall survival; PgR status correlated with clinical outcome.

Two monoclonal antibodies (mAb), MEC 7.46 (IgG1) and MEC 13.3 (IgG2a) that specifically recognize mouse endothelial cells (EC) of blood vessels, were produced immunizing a Lewis rat with a polyoma middle T transformed EC line. Antibodies were screened by enzyme-linked immunosorbent assay (ELISA) and by immunofluorescence on different cultured cell lines and by immunoperoxidase staining on frozen sections of various mouse normal and inflammatory tissues. Both mAbs reacted with eight transformed endothelial lines tested in vitro, but were consistently negative on various cell lines of different histological origin. Reactivity was not altered by preexposure of the cell lines to IL-1. Microscopic immunofluorescence analysis showed that the MEC mAbs localized at the cell-cell contacts in EC. Immunohistochemical staining of various mouse tissue was always restricted to the EC of all blood vessels of the organ considered. Staining of the endothelial lining of blood vessels was greater at cell-to-cell contacts. Weak reactivity was detected in bone marrow and spleen megakaryocytes. This picture was not altered in inflamed and tumor tissues. In the developing mouse embryo, MEC 13.3 specifically stained proliferating and sprouting endothelium in all organs and tissues examined. Both MEC 7.46 and MEC 13.3 mAbs were able to precipitate a molecule with an apparent molecular mass of 130 kDa from endothelioma lysates. The protein was synthesized by the cells and exposed on the cell surface. Immunodepletion analysis indicated that MEC 13.3 recognized a molecule related to the murine from of PECAM or CD31. We believe that these mAbs are promising tools for the identification of murine EC and for studying their ontogenesis and functions.

Analyses of the level of expression of the epidermal growth factor receptor (EGF-R) of breast cancer tumors may add independent information about the prognosis of individual patients. Furthermore, the use of monoclonal antibodies directed against EGF-R as therapeutic tools (e.g., Mab 425) requires a reliable evaluation of the individual EGF-R content. Various analytical methods have been published, including (Scarff RW and Torloni H: World Health Organization, Geneva, 1968), biochemical detection of EGF-R by a radiolabeled physiologic ligand [I-125]EGF, (Early Breast Cancer Trialists' Collaborative Group: Lancet 329: 1-15, 1992) biochemical analyses of EGF-R content with a monoclonal antibody, and (McGuire WL and Clark GM: N Engl J Med 326: 1756-1761, 1992) immunohistochemical EGF-R detection. We measured the EGF-R content in membrane pellets derived from routine processing for evaluation of estrogen (ER, ER-EIA) and progesterone receptor (PgR; PgR-EIA) in 185 breast cancers and 18 benign breast samples, using a single-point saturation assay (RBA). Simultaneously, ER (ER-ICA), PgR (PgR-ICA), and EGF-R immunohistochemistry was performed on frozen sections of the same tumors. Various cell lines and normal skin tissue samples served as EGF-R positive or negative controls. The results of the two different EGF-R analyzing methods were compared with other biological characteristics of the tumors. 37% of the tumors were EGF-R positive. There was an inverse correlation between the ER or PgR and the EGF-R content. EGF-R overexpression correlated with high tumor grade. Analyses of EGF-R content in membrane pellets of breast cancer samples by single point saturation assay as well as the evaluation of tumor sections by immunohistochemistry can be performed routinely. The results obtained with both analytical methods did not differ significantly. but the immunohistochemistry proved to be more difficult to perform and to interpret. Thus, we prefer to perform both analytical methods simultaneously to provide information potentially useful for clinical management of individual cancer patients.