@article{Grasso2016, abstract = {Abstract Background The heterogeneity and tumourigenicity of metastatic melanoma is attributed to a cancer stem cell model, with CD133 considered to be a cancer stem cell marker in melanoma as well as other tumours, but its role has remained controversial. Methods We iteratively sorted CD133+ and CD133- cells from 3 metastatic melanoma cell lines, and observed tumourigenicity and phenotypic characteristics over 7 generations of serial xeno-transplantation in NOD/SCID mice. Results We demonstrate that iterative sorting is required to make highly pure populations of CD133+ and CD133- cells from metastatic melanoma, and that these two populations have distinct characteristics not related to the cancer stem cell phenotype. In vitro, gene set enrichment analysis indicated CD133+ cells were related to a proliferative phenotype, whereas CD133- cells were of an invasive phenotype. However, in vivo, serial transplantation of CD133+ and CD133- tumours over 7 generations showed that both populations were equally able to initiate and propagate tumours. Despite this, both populations remained phenotypically distinct, with CD133- cells only able to express CD133 in vivo and not in vitro. Loss of CD133 from the surface of a CD133+ cell was observed in vitro and in vivo, however CD133- cells derived from CD133+ retained the CD133+ phenotype, even in the presence of signals from the tumour microenvironment. Conclusion We show for the first time the necessity of iterative sorting to isolate pure marker-positive and marker-negative populations for comparative studies, and present evidence that despite CD133+ and CD133- cells being equally tumourigenic, they display distinct phenotypic differences, suggesting CD133 may define a distinct lineage in melanoma.}, author = {Grasso, Carole and Anaka, Matthew and Hofmann, Oliver and Sompallae, Ramakrishna and Broadley, Kate and Hide, Winston and Berridge, Michael V. and Cebon, Jonathan and Behren, Andreas and McConnell, Melanie J.}, doi = {10.6084/m9.figshare.c.3640292}, journal = {BMC Cancer}, month = {jan}, title = {Iterative sorting reveals CD133+ and CD133- melanoma cells as phenotypically distinct populations}, url = {http://dx.doi.org/10.1186/s12885-016-2759-2}, volume = {16}, year = {2016} }