INCREASED PROSOMAL PROTEINS IN BREAST-CANCER CELLS AND IN NEIGHBORINGNORMAL-CELLS IN PARSI AND NON-PARSI POPULATIONS

Monoclonal antibodies were raised against the prosomal proteins p27K, p29K and the prosome-like protein p21K (PLP) from normal breast glandu lar cells and from benign and malignant tumors. They were used to clar ify the involvement of prosomes in tumorigenesis of human breast cells . Immunostaining showed the distribution of prosomes in the cytoplasm and nuclei of cells from European normal women (EN) and Parsi (P) and non-Parsi (NP) benign (B) and malignant (M) tissues. The flow-cytometr y studies showed an increased mean percentage of labeled cells, partic ularly with anti-p27K prosomal protein mAb, in malignant tissue from N P compared to EN. The p21K data indicated an increase in the number of cells labeled by flow-cytometry studies in all groups compared to EN, while p29K-expressing cells were more abundand in NPN, PB, PM and NPM . Intergroup comparison showed that the mean percentage of cells label ed with anti-p27K and anti-p29K was significantly higher in PB than in NPB, as seen by flow cytometry, whereas there was a higher production or accumulation of the p21K (PLP) prosomal protein in NPM than in PM, as seen by immunostaining. By comparison with EN, there were also sig nificantly more normal cells containing the three antigens in the appa rently normal tissue in the neighborhood of the tumor in NPM, and more cells containing p21K in PM patients than in EN. As prosomes are invo lved in the cell differentiation and in the cell cycle control, the ch anges observed in breast tissues may be related to oncogenic processes . Furthermore, the modified subunit pattern of prosomes in cancer and, possibly, pre-cancer tissue may be of interest for diagnosis purposes .