CD24 flags anastasis in melanoma cells.

Anastasis is a phenomenon observed in cancer cells, where cells that have initiated apoptosis are able to recover and survive. This molecular event is increasingly recognized as a potential contributor to cancer metastasis, facilitating the survival and migration of tumor cells. Nevertheless, the identification of a specific surface marker for detecting cancer cells in anastasis remained elusive. Here we report our observation that the cell surface expression of CD24 is preferentially enriched in a non-adherent FSC^lowSSC^high melanoma subpopulation, which is generally considered a non-viable population in cultivated melanoma cell lines. More than 90% of non-adherent FSC^lowSSC^highCD24^+ve metastatic melanoma cells exhibited bonafide features of apoptosis on the cell surface and in the nucleus, marking apoptotic or seemingly apoptotic subpopulations of the in vitro cultivated metastatic melanoma cell lines. Unexpectedly, however, the CD24^+ve subpopulation, despite being apoptotic, showed evidence of metabolic activity and exhibited proliferative capacities, including anchorage-independent growth, when inoculated in soft agarose growth medium. These findings indicate that apoptotic FSC^lowSSC^highCD24^+ve melanoma subpopulations are capable of reversing the progression of apoptosis. We report CD24 as the first novel cell surface marker for anastasis in melanoma cells.