PHENOTYPIC PROFILING OF OSTEOTROPIC BREAST CANCER CELLS

One of the preferred locations of metastases from breast cancer is the bone tissue. On the other hand, it should be recalled that mammary tumors with equal clinical diagnosis have a different course, and also different metastatic progression. Therefore, it would be helpful to have appropriate markers of osteotropism to test on the surgical cancer tissues, in order to predict the possible propensity of the breast cancer to generate bone metastases and to adequate the therapeutic plan. We previously reported1,2 on the setting-up of an in vitro model for the study of the osteotropic propensity of breast cancer cells and the influences exerted by the bone microenvironment on the cancer cells phenotype. Viable bone fragments, deriving from surgery on traumatic lesions of young subjects were washed from bio-contaminants under sterile conditions and placed into cell culture capsules with the proper culture medium supplemented with foetal bovine serum, L-glutamine, L-ascorbic acid and antibiotics. The explants were kept for controlled timing in the humidified incubator in order to promote the release of resident cells, and then co-cultured with under-confluent breast cancer cells (SKBR3), until confluence. The bone fragments were then recovered, washed, placed again in culture dishes and monitored daily. The cells released from the bone fragments were then collected and processed for immunological characterization and proteomic profiling. The proteomic profiles of the cells seeded into the bone fragments were compared with the original cell culture, revealing an interesting differential proteomic pattern. The collection of identified proteins on the maps has reached up today the number of 373. Differentially expressed proteins between boneseeded cells and wild type cells were about 30%. Among the differentially expressed proteins were several proteins belonging to the cytoskeleton remodelling and proteins of the class of calcium- binding cluster. The relevance of these protein clusters is discussed.