Tumor endothelial marker 1–specific DNA vaccination targets tumor vasculature
John G. Facciponte, … , George Coukos, Andrea Facciabene
John G. Facciponte, … , George Coukos, Andrea Facciabene
Published March 18, 2014
Citation Information: J Clin Invest. 2014;124(4):1497-1511. https://doi.org/10.1172/JCI67382.
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Research Article Oncology

Tumor endothelial marker 1–specific DNA vaccination targets tumor vasculature

Abstract

Tumor endothelial marker 1 (TEM1; also known as endosialin or CD248) is a protein found on tumor vasculature and in tumor stroma. Here, we tested whether TEM1 has potential as a therapeutic target for cancer immunotherapy by immunizing immunocompetent mice with Tem1 cDNA fused to the minimal domain of the C fragment of tetanus toxoid (referred to herein as Tem1-TT vaccine). Tem1-TT vaccination elicited CD8+ and/or CD4+ T cell responses against immunodominant TEM1 protein sequences. Prophylactic immunization of animals with Tem1-TT prevented or delayed tumor formation in several murine tumor models. Therapeutic vaccination of tumor-bearing mice reduced tumor vascularity, increased infiltration of CD3+ T cells into the tumor, and controlled progression of established tumors. Tem1-TT vaccination also elicited CD8+ cytotoxic T cell responses against murine tumor-specific antigens. Effective Tem1-TT vaccination did not affect angiogenesis-dependent physiological processes, including wound healing and reproduction. Based on these data and the widespread expression of TEM1 on the vasculature of different tumor types, we conclude that targeting TEM1 has therapeutic potential in cancer immunotherapy.

Authors

John G. Facciponte, Stefano Ugel, Francesco De Sanctis, Chunsheng Li, Liping Wang, Gautham Nair, Sandy Sehgal, Arjun Raj, Efthymia Matthaiou, George Coukos, Andrea Facciabene

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Figure 1

Physiological and plasmid DNA-induced TEM1 expression.

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Physiological and plasmid DNA-induced TEM1 expression. (A) Tem1 was expr...
(A) Tem1 was expressed in tumors in vivo. qRT-PCR was performed with a Tem1 probe. An 18S probe was used as an endogenous control, and samples were normalized with mouse liver. Post–qRT-PCR calculations to analyze relative gene expression were performed by the 2–ΔΔCt method. Error bars denote SD (n = 5). (B) Tem1 RNA colocalized with CD31+ cells. CT26 tumor sections were subjected to immunofluorescence with a CD31 antibody (red) and single-molecule RNA FISH for Tem1 (yellow) or CD31 (cyan). Bright spots in the RNA FISH channels correspond to individual transcript molecules. DAPI staining (purple) shows cell nuclei. Original magnification, ×100. Images shown are 85 μm wide. (C) Expression of the Tem1-TT DNA plasmid. A fusion Tem1-TT construct was generated by fusing codon-optimized Tem1 cDNA (nt 1–2,297; aa 1–765) with the cDNA of the amino terminal domain of the fragment C of TT (819 bp, 273 aa). Expression of Tem1 or TT after transfection of the Tem1-TT construct was tested with CHO cells and assessed by qRT-PCR. Error bars denote SD (n = 3).