T11TS Treatment Augments Apoptosis of Glioma Associated Brain Endothelial Cells, Hint Toward Anti‐Angiogenic Action in Glioma

Malignant glioma continues to be a clinical challenge with an urgent need for developing curative therapeutic intervention. Apoptosis induction in tumor‐associated endothelial cells represent a central mechanism that counteracts angiogenesis in glioma and other solid tumors. We previously demonstrated that intraperitoneal administration of sheep erythrocyte membrane glycopeptide T11‐target structure (T11TS) in rodent glioma model inhibits PI3K/Akt pathway and Raf/MEK/ERK signaling in glioma‐associated brain endothelial cells. In the present study, we investigated whether T11TS treatment influence apoptosis signaling in vivo in glioma‐associated brain endothelial cells. Annexin‐V/PI staining showed that T11TS treatment in glioma‐induced rats increases apoptosis of glioma‐associated endothelial cells within glioma milieu compared to brain endothelial cells in glioma induced and control groups. Flowcytometric JC‐1 assay revealed that T11TS administration triggers loss of mitochondrial membrane potential in glioma‐associated brain endothelial cells. Flowcytometry, immunoblotting, and in situ immunofluoresecnt imaging were employed to investigate the effect of T11TS on apoptotic regulatory proteins in brain endothelial cells. T11TS treatment‐upmodulated expression of p53, Bax, Fas, FasL, and FADD in glioma associated endothelial cells and downregulated Bcl‐2 protein. T11TS therapy induced cytochrome‐c release into cytosol, activated caspase −9, 8, 3, and cleaved Bid in glioma associated brain endothelial cells. The study demonstrates that T11TS induces apoptosis in glioma‐associated brain endothelial cells via p53 accumulation and activation of intrinsic as well as Fas‐dependent extrinsic pathway. The pro‐apoptotic action of T11TS on glioma‐associated endothelial cells provides crucial insight into how T11TS exerts its anti‐angiogenic function in glioma. J. Cell. Physiol. 232: 526–539, 2017. © 2016 Wiley Periodicals, Inc. T11TS induced apoptosis of glioma‐associated brain endothelial cells and its effect on glioma angiogenesis.