Glioma stem-like cells are less susceptible than glioma cells to sonodynamic therapy with photofrin.

Despite remarkable progress in diagnosis and treatment, malignant glioma, a highly lethal cancer of the central nervous system, remains incurable. Although glioma stem-like cells (GSCs) represent a relatively small fraction of the cells in malignant glioma, they can proliferate and self renew extensively, being crucial for tumor recurrence. Cancer treatment by sonodynamic therapy (SDT) chiefly depends on antitumor effects of reactive oxygen species (ROS) generated from a sonosensitizer activated by ultrasound.

The ABCG2 transporter is a key molecular determinant of the efficacy of sonodynamic therapy with Photofrin in glioma stem-like cells.

We aimed to investigate the role of the ABCG2 transporter in the efficacy of sonodynamic therapy (SDT) with Photofrin in the glioma stem-like cells (GSCs) isolated and cultured from U251 glioma cells. Immunocytochemistry and flow cytometry analyses showed that ABCG2 was overexpressed in GSCs, and the percentage of ABCG2-positive GSCs was approximately 100%. The effect of ABCG2 on Photofrin extrusion in the absence or presence of a specific inhibitor of ABCG2 (fumitremorgin C; FTC) was investigated by determining the intracellular concentration of Photofrin in GSCs incubated with 20μg/ml Photofrin.