Heavy-ion irradiation induced alteration in histopathology and cancer stem cell markers

The purpose of this study was to investigate whether carbon ion irradiation (IR) had beneficial effects by targeting putative human colon cancer stem cells, cancer stem-like cells sorted from HCT116 were treated with or without carbon ion or X-ray IR and then colony formation assay, spheroid formation assay, fluorescence-activated cell sorter (FACS) analysis, as well as xenograft tumor growth control analyses were performed. CD133+, CD44+/ESA+ cells significantly have higher number of colony, spheroid compared to CD133-, CD44-/ESA-cells. CD133+, CD44+/ESA+ cells were showed radioresistance to both X-ray and carbon ion IR, but the relative biological effectiveness (RBE) values calculated at the D10 level for cancer stem-like cells were 2.05 to 2.09. CD133+, CD44+/ESA+ cells have shown more potential to form tumors in severe combined immunodeficiency (SCID) mice than CD133-, CD44-/ESA-cells, and carbon ion IR has more effectively eradicate xenograft tumors compared to X-rays. In conclusion, heavy ion IR has a great potential to effectively target radioresistant putative human colon cancer stem cells. (author)