ATP5A1 and ATP5B are highly expressed in glioblastoma tumor cells and endothelial cells of microvascular proliferation

Glioblastoma (GBM) is the most common primary malignant brain tumor. Microvascular proliferation is one of the characteristic pathologic features of GBM. Mitochondrial dysfunction plays an important role in the pathogenesis of GBM. In this study, microvascular proliferation from GBM and normal brain blood vessels were laser microdissected and total RNA was isolated from these microvasculatures. The difference of mRNA expression profiles among GBM microvasculature, normal brain blood vessels and GBM tumor cells was evaluated by mitochondria and metabolism PCR gene arrays. It was found that the mRNA levels of ATP5A1 and ATP5B in GBM tumor cells as well as microvascular proliferation were significantly higher compared with normal brain blood vessels. Immunohistochemical stains with anti-ATP5A1 antibody or anti-ATP5B antibody were performed on tissue microarray, which demonstrated strongly positive expression of ATP5A1 and ATP5B in GBM tumor cells and GBM microvascular proliferation while normal blood vessels were negative. By analyzing The Cancer Genome Atlas data sets for GBM and other cancers, genomic DNA alterations (mutation, amplification or deletion) were less likely the reason for the high expression of ATP5A1 and ATP5B in GBM. Our miRNA microarray data showed that miRNAs that target ATP5A1 or ATP5B were down-regulated, which might be the most likely reason for the high expression of ATP5A1 and ATP5B in GBM tumor cells and microvascular proliferation. These findings help us better understand the pathogenesis of GBM, and agents against ATP5A1 and/or ATP5B might effectively kill both tumor cells and microvascular proliferation in GBM. MiRNAs, such as Let-7f, miR-16, miR-23, miR-100 and miR-101, that target ATP5A1 or ATP5B, might be potential therapeutic agents for GBM.