title: Association between tumorigenic potential and the fate of cancer cells in a syngeneic melanoma model.
abstract: The self-renewal potential of a cancer cell can be estimated by using particular assays, which include xenotransplantation in immunocompromised animals or culturing in non-adherent serum-free stem-cells media (SCM). However, whether cells with self-renewal potential actually contribute to disease is unknown. Here we investigated the tumorigenic potential and fate of cancer cells in an in-vivo melanoma model. We examined cell lines which were derived from the same parental line: a non-metastatic cell line (K1735/16), a metastatic cell line (K1735/M4) and a cell line which was selected in non-adherent conditions (K1735/16S). All cell lines exhibited similar proliferation kinetics when grown on culture plates. K1735/16 cells grown in soft agar or in suspension non-adherent conditions failed to form colonies or spheroids, whereas the other cell lines showed prominent colonogenicity and spheroid formation capacity. By using sphere limiting dilution analysis (SLDA) in serum-free media, K1735/16S and K1735/M4 cells grown in suspension were capable of forming spheroids even in low frequencies of concentrations, as opposed to K1735/16 cells. The tumorigenic potential of the cell lines was determined in SCID mice using intra footpad injections. Palpable tumors were evident in all mice. In agreement with the in-vitro studies, the K1735/M4 cell line exhibited the highest growth kinetics, followed by the K1735/16S cell line, whereas the K1735/16 cell line had the lowest tumor growth potential (P<0.001). In contrast, when we repeated the experiments in syngeneic C3H/HeN mice, the K1735/16 cell line produced macroscopic tumors 30-100 days after injection, whereas K1735/M4 and K1735/16S derived tumors regressed spontaneously in 90-100% of mice. TUNEL analysis revealed significantly higher number of apoptotic cells in K1735/16S and K1735/M4 cell line-derived tumors compared to K1735/16 tumors (P<0.001). The models we have examined here raised the possibility, that cells with high-tumorigenic activity may be more immunogenic and hence are more susceptible to immune-regulation.
authors.affiliation: The Laboratory for Applied Cancer Research, Tel Aviv Sourasky Medical Center, Sackler Faculty of Health, Tel Aviv University, Tel Aviv, Israel. kreliny@gmail.com
authors.forename: Yakov
authors.initials: Y
authors.lastname: Krelin
authors.forename: Liron
authors.initials: L
authors.lastname: Berkovich
authors.forename: Moran
authors.initials: M
authors.lastname: Amit
authors.forename: Ziv
authors.initials: Z
authors.lastname: Gil
mesh_terms: D000818:Animals; D017209:Apoptosis; D015415:Biomarkers / Q000378:metabolism; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D005260:Female; D015870:Gene Expression; D016130:Immunophenotyping; D008545:Melanoma / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D016513:Mice, SCID; D009365:Neoplasm Regression, Spontaneous; D009368:Neoplasm Transplantation; D014411:Neoplastic Stem Cells / Q000378:metabolism*; D018874:Spheroids, Cellular; D014185:Transplantation, Isogeneic; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay
chemical_list: D015415:Biomarkers