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

Abstract

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.