An Adenovirus Vector Incorporating Carbohydrate Binding Domains Utilizes Glycans for Gene Transfer

Julius W Kim,Hideyo Ugai,Joel N Glasgow,Ferhat Ak,David T Curiel,Masaharu Nakayama

doi:10.1371/journal.pone.0055533

Abstract

BackgroundVectors based on human adenovirus serotype 5 (HAdV-5) continue to show promise as delivery vehicles for cancer gene therapy. Nevertheless, it has become clear that therapeutic benefit is directly linked to tumor-specific vector localization, highlighting the need for tumor-targeted gene delivery. Aberrant glycosylation of cell surface glycoproteins and glycolipids is a central feature of malignant transformation, and tumor-associated glycoforms are recognized as cancer biomarkers. On this basis, we hypothesized that cancer-specific cell-surface glycans could be the basis of a novel paradigm in HAdV-5-based vector targeting.Methodology/Principal FindingsAs a first step toward this goal, we constructed a novel HAdV-5 vector encoding a unique chimeric fiber protein that contains the tandem carbohydrate binding domains of the fiber protein of the NADC-1 strain of porcine adenovirus type 4 (PAdV-4). This glycan-targeted vector displays augmented CAR-independent gene transfer in cells with low CAR expression. Further, we show that gene transfer is markedly decreased in cells with genetic glycosylation defects and by inhibitors of glycosylation in normal cells.Conclusions/SignificanceThese data provide the initial proof-of-concept for HAdV-5 vector-mediated gene delivery based on the presence of cell-surface carbohydrates. Further development of this new targeting paradigm could provide targeted gene delivery based on vector recognition of disease-specific glycan biomarkers.

Highlights

Vectors based on human adenovirus type 5 (HAdV-5) have shown considerable utility as gene delivery vectors, in the contexts of vaccination and cancer gene therapy
Altered glycosylation appears to be a universal hallmark of cancer, and unlike many other cellular dysfunctions that occur throughout tumorogenesis, aberrant glycoconjugates are present on the cell surface and available for direct analysis
While the family Adenoviridae contains over 100 known serotypes, the presence of carbohydrate binding domains is unique to porcine adenovirus type 4 (PAdV-4) and is presumed to have evolved from insertion of a vertebrate gene [51]

Summary

Introduction

Vectors based on human adenovirus type 5 (HAdV-5) have shown considerable utility as gene delivery vectors, in the contexts of vaccination and cancer gene therapy. HAdV-5 tropism is determined by distinct virus-cell interactions: binding of the virus capsid protein, fiber, to the primary high-affinity HAdV-5 receptor CAR, followed by internalization of the virion via secondary interactions with a variety of cell-surface integrins including avb, avb and others [6,7,8] This CAR-dependent tropism hinders HAdV-5based cancer gene therapy approaches, as decreases in CAR expression appears to coincide with tumor progression [9]. Aberrant glycosylation of cell surface glycoproteins and glycolipids is a central feature of malignant transformation, and tumor-associated glycoforms are recognized as cancer biomarkers On this basis, we hypothesized that cancer-specific cell-surface glycans could be the basis of a novel paradigm in HAdV-5-based vector targeting

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Conclusion