Detection of CD133 expression in U87 glioblastoma cells using a novel anti-CD133 monoclonal antibody.

In glioblastomas, the surface glycoprotein CD133 (prominin-1) indicates the presence of cancer stem cells (CSCs), which are able to initiate tumor growth and are highly resistant to conventional chemo/radiotherapy. However, a number of studies have reported that certain CD133- glioma cells are able to self-renew and retain tumorigenic potential. In addition, the reliability of CD133 as a CSC marker is controversial due to inconsistent findings with regard to the prognostic values and distribution of CD133. Such controversies may be due to the detection limits using currently available anti-CD133 antibodies. In the present study, novel anti-human CD133 monoclonal antibodies (mAbs) were generated using two recombinant extracellular domains of human CD133: CD133 ectodomain 1 (amino acids 171-420) and CD133 ectodomain 2 (amino acids 507-716). One of the antibodies produced against CD133 ectodomain 2, C2E1, detected high expression levels of CD133 protein in glioblastoma U87 cells, in contrast to previous studies which did not detect CD133 expression in these cells. The cells exhibited a cytoplasmic distribution pattern of CD133 and produced a 95 kDa band following western blot analysis. In addition, C2E1 was able to bind the full-length glycosylated CD133 on the cell surface and inhibit the proliferation of tumor cells. Therefore, this antibody may be a valuable tool to study CD133 as a CSC marker and may be significant in future cancer treatments.