(Authors 1, 8): Enviromental Dept., Sector of Biological and Toxicological Sciences, ENEA-Casaccia
(Authors 2, 3, 6, 7, ): I Dept. of Surgery, Univ. of Rome "La Sapienza"
(Author 4): Dep. of Histology and Medical Embryology, Univ. of Rome"La Sapienza"
(Author 5): Inst. for Chemistry, High School Lagrange
With the aim of establishing an experimental model allowing the identification of cellular clones in the primary tumors responsable of proliferation invasion and metastasis in breast cancer, four different clonal cell lines representing tumor heterogeneity were isolated from a ductal infiltrating mammary rat tumor induced by 7,12-dimethylbenz(a)anthracene. The primary culture was characterized by 3 aneuploid subpopulations with DNA index of 1.16, 1.30, and 1.45. The cell line at 1.30 was build up of two subpopulations based on the dual parameter DNA/protein analysis. We attempted to isolate cell lines with corresponding DNA index by the use of flow cytometry.The selected 4 lines were characterized by a DI of 1.16, 1.25, 1.30 and 1.45, by a mean chromosome number of 45, 46, 47, and 88, respectively, by different morphology, proliferative features and different growth promoting activity in culture medium that stimulated proliferation of Swiss 3T3 cells. Cytoskeletal protein espression showed myeblastic type. Nude mice tumorogenesis experiments showed a strong tumor induction for line with DI at 1.16 lower tumor induction for line at 1.45 both showed the highest proliferative activity. The detection of cytoskeleton protein indicates that vimentin was highly exspressed in these two lines while its presence was low in line with DI at I.25 and 1.30 also showing very low and no tumorigenic potential respectively. In conclusion, selection of cell clones from primary tumor by flow cytometry demonstrated itself to be a useful method to develop a model for studying malignant characteristics in vivo and in vitro.