Endosialin expression in side populations in human sarcoma cell lines.

The Hoechst 33342 exclusion side population (SP) assay is a validated method used to identify cells with stem cell-like properties. When isolated from tumors, SP cells have been shown to have high malignant potential. SPs have been found in both carcinomas and sarcomas. The molecular profile of sarcoma SP is poorly understood. The purpose of the present study was to determine whether endosialin is a suitable therapeutic target for sarcomas. Six cell lines (HT-1080 fibrosarcoma, SJSA-1 and HOS osteosarcoma, A-673 and SK-ES-1 Ewing sarcoma) were used for the SP analysis. Flow cytometry was used to count and examine the cells. Results showed for the first time that endosialin (CD248), which was previously identified as a sarcoma marker, is expressed in sarcoma SP cells. This observation supports the hypothesis that endosialin is a promising therapeutic target for sarcomas.