CD24 expression and stem-associated features define tumor cell heterogeneity and tumorigenic capacities in a model of carcinogenesis.

Background: Most carcinomas are composed of heterogeneous populations of tumor cells with distinct and apparently stable phenotypic characteristics. Methods: Using an in vitro model of carcinogenesis we aimed at experimentally elucidating the significance of heterogeneity in the expression of CD24, a marker frequently overexpressed in various cancers and correlated with poor prognosis. Results: We show that CD24(Neg) and CD24(Pos) cells issued from the same tumorigenic cell line display striking differences in stern-related properties, expression of epithelial-mesenchymal transition/mesenchymal-epithelial transition markers, and tumorigenic capacity. Indeed, while CD24(N)(eg) cells were as tumorigenic as the parental cell line, CD24( )(Pos)cells, although unable to form tumors, were unexpectedly more mesenchymal, displayed enhanced sternness-related properties, and expressed a proinflammatory signature. Conclusion: Our findings support the view that acquisition of stem-like cell, CD24-associated, attributes like migration, invasion, and plasticity by a tumor subpopulation is not necessarily related to local tumor growth but may be required for escaping the niche and colonizing distant sites.