CD133+ subpopulation of the HT1080 human fibrosarcoma cell line exhibits cancer stem-like characteristics

The cancer stem cell (CSC) theory holds that a minority population within tumors possesses stem cell properties of self-renewal and multilineage differentiation capacity and provides the initiating cells from which tumors are derived and sustained. However, verifying the existence of these CSCs has been a significant challenge. The CD133 antigen is a pentaspan membrane glycoprotein proposed to be a CSC marker for cancer-initiating subpopulations in the brain, colon and various other tissues. Here, CD133(+) cells were obtained and characterized from the HT1080 cell line to determine the utility of this marker for isolating CSCs from human fibrosarcoma cells. In this study, CD133(+) cells were separated from HT1080 cells using magnetic beads and characterized for their proliferation rate and resistance to chemotherapeutic drugs, cisplatin and doxorubicin, by MTS assay. Relative expression of tumor-associated genes Sox2, Oct3/4, Nanog, c-Myc, Bmi-1 and ABCG2 was measured by real-time polymerase chain reaction (PCR). Clonal sphere formation and the ability of CD133(+) cells to initiate tumors in BALB/c nude mice was also evaluated. We found that CD133(+) cells showed a high proliferation rate, increased resistance to chemotherapy drugs and overexpression of tumor-associated genes compared with these features in CD133(-) cells. Additionally, CD133(+) cells were able to form spherical clusters in serum-free medium with high clonogenic efficiency, indicating a significantly greater tumor-initiating potential when compared with CD133(-) cells. These findings indicate that CD133(+) cells identified within the HT1080 human fibrosarcoma cell line possess many CSC properties and may facilitate the development of improved therapies for fibrosarcoma.