Identification of CD24 as a marker for tumorigenesis of melanoma.

Objective: Cutaneous melanoma (CM) is a common skin cancer. Surgery is still the primary treatment for CM, as melanoma is resistant to chemotherapy. In the recent years, it has been found that cancer stem-like cells (CSCs) are responsible for this drug resistance. CD24 is a widely used marker to isolate CSCs. In this study, we aimed to analyze the properties of CD24(+) and CD24(-) subpopulation of melanoma cells. Materials and methods: We isolated CD24(-) cells CSCs using magnetic-activated cell sorting system. We extracted total RNA and carried out reverse transcription polymerase chain reaction analysis. We counted the cell colonies using soft agar assay and assessed the cell invasion using cell migration assay. We implanted CD24(+) or CD24(-) cells into the flank of non-obese diabetic severe combined immunodeficiency mice, and measured the tumor volumes every 5 days until the end of the experiment. We carried out immunohistochemical analysis to study the tissue sections. Results: We demonstrated that the CD24(+) subpopulation has self-renewal properties in vitro and in vivo by using soft agar assay and xenograft tumor model. Furthermore, we confirmed that CD24 expression is accompanied by activation of Notch 1 signaling pathway. Conclusion: This study provides new knowledge on the role of CD24 in the tumorigenic ability of melanoma.