Figure 1.

Angiogenic factor apelin (APLN) expression in glioblastoma (GBM) cells and the tumor neo-vasculature. (A) Expression analysis of APLN RNA was performed by qPCR on the human cells U87MG and U251, the murine GL261 cells and on APLN^WT or APLN^KO mouse brain tissue. APLN RNA expression was not detectable (n.d.) in GL261 cells but high in U87MG cells. (B) In situ hybridization against mouse APLN showed no expression in implanted mouse GL261 tumor cells but an upregulation of APLN in the tumor vessels of GL261 or U87MG gliomas (arrowheads). The right panel is the magnifications within the tumor that is depicted in the overview panel on the left. Note that vascular APLN RNA expression is highest in hypoxic regions marked by human vascular endothelial growth factor (VEGFA) RNA expression (arrows) in the U87MG xenografts. (C) Lentiviral transduction of U87MG parental cells caused shRNAmir-mediated stable APLN knock-down (AKD) by 90% (as analyzed by qPCR) compared to the non-silencing shRNA control (NSC) transduced cells. (D) Cell viability, as well as in vitro proliferation (E), was unchanged in U87^AKD cells compared to U87^NSC control or untransduced U87MG cells. In contrast, U87 cells transduced with the shRNA against the kinesin EG5 significantly reduced viability and proliferation of U87^E5KD cells compared to U87^NSC control. Data are obtained from more than 3 independent experiments each and reported as mean +/-SEM; statistical significance (one-way ANOVA plus Bonferroni’s post hoc test) is indicated ** p < 0.005, *** p < 0.0005. WT = wildtype; KO = knockout.