Dual endothelin-1/VEGFsp receptor (DEspR): Common target on tumor vascular endothelial cells (TVECs), tumor cells (TCs), and cancer stem cells (CSCs) in glioblastoma and pancreatic cancer.

Abstract

e13574 Background: New therapies are needed for glioblastoma (GBM) and pancreatic adenocarcinoma (PCa), given their low survival rates. To address this mandate, we tested the hypothesis that inhibition of DEspR, as a common target on TVECs, TCs, and CSCs, can affect multiple key steps in metastasis: angiogenesis, invasiveness, anoikis resistance. Methods: Various analyses were performed: co-immunostaining of tumor tissue and cancer cell lines from PCa and GBM using anti-CD133 and anti-DEspR mAbs; in vitro anti-DEspR mAb inhibition of angiogenesis and TC invasiveness; isolation, functional validation, and DEspR immunostaining of CSCs from PCa (Panc1) and GBM (U87) cell lines; DEspR inhibition of Panc1- and U87-derived CSC tumorsphere formation and CSC-enriched xenograft tumor growth in nude rats respectively; and phosphoproteome analysis of DEspR signaling. Results: In PCa and GBM, we detected DEspR+ TVECs, TCs, and CD133+ putative CSCs in contrast to respective normal tissues. DEspR expression on TCs and TVECs were confirmed in PCa (Panc1) and GBM (U87) cell lines, and HUVECs undergoing angiogenesis, respectively. Dose-dependent anti-DEspR mAb inhibition decreased HUVEC angiogenesis and Panc1 invasiveness compared to isotype controls. DEspR+ expression was detected in functionally validated Panc1 and U87 CSCs exhibiting tumorsphere formation, increased tumorigenicity in nude rat xenograft models, and self-renewal from xenograft tumors. DEspR inhibition decreased tumorsphere formation and increased dead cell numbers, suggesting decreased anoikis resistance for both U87 and Panc1 CSCs. Phosphoproteome analysis detected DEspR signaling through phosphoproteins implicated in TVEC-TC crosstalk, angiogenesis, and anoikis resistance. DEspR inhibition decreased tumor growth of Panc1 and U87 CSC-enriched subcutaneous xenograft tumors in nude rat models. Conclusions: Data demonstrate DEspR as a common target on TVECs, TCs, and CSCs in PCa and GBM, whose inhibition provides a potential therapeutic strategy for simultaneous inhibition of multiple pro-malignancy steps: angiogenesis, invasiveness, and anoikis resistance.