Background & objective: ATP-binding cassette transporter protein ABCG2 is a marker derived from hematopoietic stem cells. However, its role in tumorigenesis and malignant progression of glioma is unclear. This study was to investigate the expression and significance of ABCG2 in gliomas of different malignant grades.
Methods: A microarray chip containing glioma tissues of different malignant grades, implanted glioma xenografts in nude mice, spheroids of glioma cell lines and glioma stem cells was prepared and examined for the expression of ABCG2 with immunohistochemical staining.
Results: The positive rate of ABCG2 was 26.8% in the 71 specimens of human glioma tissues, with 11.1% in grade I gliomas, 8% in grade II gliomas, 43.5% in grade III gliomas, and 42.9% in grade IV gliomas; it was significantly higher in grade III-IV gliomas than in grade I-II gliomas (chi2=10.710, P=0.001). The positive rate of ABCG2 was 100% in implanted glioma xenografts in nude mice, gliomas stem cells, and neural stem cells. It was also expressed in some normal tissues. The positive cells surrounded and invaded into vessels in glioma tissues.
Conclusions: ABCG2 is overexpressed in glioma stem cells, glioma tissues of higher grades, and implanted glioma xenografts. The positive cells distribute around vessels in glioma tissues.