Savinska L. Differential expression of alpha and beta isoforms of ribosomal protein S6 kinase during malignant transformation in human mammary gland tissues

The work is devoted to studying the S6K alpha and S6К beta expression profile in tumor and normal human mammary gland tissues. As a result of this study, several polyclonal and monoclonal antibodies against recombinant peptides of S6K and against full-length S6К beta have been generated. Using Western-blotting techniques, comparative analysis of expression of S6K alpha and S6К beta has been conducted at the protein level in human breast cancer cell lines, normal mammary gland tissues and mammary gland tumors (both non-malignant and malignant). Elevated level of S6K expression has been detected both in cell lines and in malignant tumors (adenocarcinomas) of human mammary gland. Intracellular localization of S6K in normal tissues and tumors has been analyzed by immunohistochemical methods. Accumulation of S6K in cytoplasm and nuclei of malignant cells has been demonstrated. Clear tendency of translocation of the kinase from cytoplasm to nuclei was evident for S6K beta isoform. Potential application of these differences of S6K expression for the diagnostics of oncological pathologies of human mammary gland has been discussed.