Mutant-type IkBα gene inhibits expression of Epo and EpoR in glioma and suppresses tumor growth

Abstract

Objective To investigate the regulation of mutant-type IkBα （IkBαM） to Erythropoietin （Epo） and its receptor （EpoR） in human glioblastoma multiform （GBM） cells, and the correlation to tumor angiogenesis. Methods Human GBM cell line which steadily express IkBαM protein was established, and then subcutaneously injected into nude mice. The expression of Epo, EpoR and FactorⅧ was detected by immunohistochemistry method, the microvasculer density （MVD） analyzed, and the apoptosis rate tested by using flow cytometry （FCM）. Results The positive expression rate of Epo was （54.8 ± 12.4） % （ G36△ group）, （65.7±15.6） % （ G36△-W group）, （6.1 ±10.1 ） % （ G36△-M group） and （68.3 ± 11.4） % （ G36△-P group）, while that of EpoR （ 33.6± 16.4） % （ G36A group）, （ 37.3 ± 13.9）% （G36△-W group）, （2. 5 ± 17.5）% （G36△-M group）,and （37.2± 14.4）% （G36A-P group）, respectively. The expression of Epo and EpoR was decreased significantly in G36△-M group in vivo,but the remaining three groups （G36△-W,G36A-P and G36△） almost had the same tread. The apoptosis rate was （8.31±1.85）% （G36△ group） ,（8.06 ±2.08）% （G36△-W group） ,（28.35 ±3.26）% （ G36△-M group） , and （7.40 ± 2.35 ） % （ G36△-P group） respectively. The apoptosis rate was increased obviously in G36△-M group. The MVD was decreased obviously in G36△-M group. Conclusion IkBαM gene could down-regulate the expression of Epo and EpoR proteins in the human GBM cell line, reduce the ability of tumor angiogenesis and promote apoptosis of tumor cells, and suppresse tumor growth. Key words: Glioma; IkBαM ; Eerythropoietin receptor; Flow cytometry