Expression Of ABCG2 In Human Malignant Glioma And Reversion Of Drug Resistance By Targeting ABCG2

Part one: Stem cell marker: Investigate the expression of ABCG2 inmicroarray chip containing glioma tissue specimens withdifferent malignant degrees【Objective】The ATP-binding cassette transporter protein ABCG2 is a marker originatedfrom haematopoietic stem cells. However, the role of ABCG2 in tumorigenesis andmalignant progression of glioma is unclear. This study was to investigate the expression ofABCG2 in different malignant grades, implanted xenografts of nude mice, cell linesspheroids and stem cellular spheroids of glioma in vitro.【Methods】A microarray chip containing glioma tissue specimens with differentmalignant degrees, implanted xenografts of nude mice, cell lines spheroids and stemcellular spheroids of glioma in vitro was prepared. The expression of ABCG2 was detectedby immunohitochemical staining.【Result】The positive rate of ABCG2 was 26.8％in the 71 specimens of humanglioma tissues, with 11.1％in gradeⅠglioma tissues, 8％in gradeⅡglioma tissues,43.5％in gradeⅢglioma tissues, and 42.9％in gradeⅣglioma tissues;the expression ofABCG2 in gradeⅢ-Ⅳglioma tissue was significantly higher than in gradeⅠ-Ⅱgliomatissue. (X2=10.710, P=0.001). The positive rates of ABCG2 was 100％in neural stemcells, implanted xenografts of nude mice and brain tumor stem cells. It was also expressedin some normal tissue. The positive cells was observed surround and involve vessels inglioma tissues.【Conclusion】ABCG2 is overexpressed in glioma stem cell, glioma tissues of highergrades and implanted xenografts tissues. It is interesting that the positive cells was observed surround and involve vessels in glioma tissues.Therefore, ABCG2 can be usedfor further researches as a angiogenesis molecule associated with the tumorigenesis andmalignant progression of the brain gliomas.Part two: Reversion of drug resistance in brain tumor stem cell bynicardipine in vitro【Objective】To isolate and cultivate tumor stem cells from glioma tissues,and study itsdrug resistance.【Methods】1,Neural stem cell marker CD133 were used to isolated tumor stem cells bymagnetic cell sorting. Glioma samples collected shortly after operation, cell suspensionswere made and cultured into tumor spheres. By magnetic sorting, CD133+ cells wereacquired and cultured. 2,Detect the expression of ABCG2 in CD133+ cells by RT-PCR.3,Contribution of nicardipine in reversing drug resistance of brain tumor stem cell byMTT. 4,Flow cytometry detect the rate of apoptosis.【Result】1,Using magnetic cell sorting, CD133 positive cells were acquired. Evencultured in vitro for a long time, CD133+ cells still maintain the capacity to grow intospheres and self-renew and proliferate in certain condition. 2,Overexpression of ABCG2in CD133+ cells. 3,Nicardipine can reverse drug resistance of mitoxantrone in brain tumorstem cell. 4,Nicardipine can increase apoptosis of brain tumor stem cell by Mitoxantrone.【Conclusion】Human glioma tissuecontain tumor stem cells, which could be effectivedly,isolated by magnetic cell sorting. They could be kept and passed on for long term, whichprovids a powerful tool for research of origin cell of glioma.Nicardipine can reverse drug resistance in brain tumor stem cell, it maybe used as a newchemotherapeutics.