Glioblastoma multiforme cells: expression of erythropoietin receptor and response to erythropoietin.

Erythropoietin (EPO) is a glycoprotein hormone that is a primary regulator of erythropoiesis. In erythroid cells, EPO binds to its receptor (EPOR) to stimulate growth, prevent apoptosis, and promote differentiation. Both EPO and EPOR have been found in many normal and tumor nonerythroid cell types. EPO has been reported to stimulate proliferation and inhibit apoptosis of cancer cells. In this study, we found that EPOR is expressed in brain tumors, glioma cell lines and explants, as well as, normal brain. EPO slightly stimulated the growth of serum-starved glioma cells. Furthermore, EPO increased the phosphorylation of AKT through the PI3K pathway in the glioma cells. It also increased the phosphorylation of ERK, c-jun, JNK, as well as, the expression of BCL-2 and BCL-xl in these cells. These results suggest that the EPO-EPOR pathway may promote glioma cell survival and could become a therapeutic target in brain tumors.