Miller C R, Buchsbaum D J, Reynolds P N, Douglas J T, Gillespie G Y, Mayo M S, Raben D, Curiel D T
Gene Therapy Program, University of Alabama at Birmingham, 35294, USA.
Cancer Res. 1998 Dec 15;58(24):5738-48.
Adenovirus (Ad) vectors are promising for gene therapy of glioma due to their ability to achieve efficient gene transfer upon intratumoral administration. Yet in this context, Ad mediates widespread gene transfer to both tumor and surrounding parenchyma. Ad entry is dependent upon the expression of fiber receptors, such as coxsackie/adenovirus receptor, and alpha(v) integrins on the target cells for binding and internalization, respectively. We hypothesized that the susceptibility of human gliomas to Ad would likely be heterogeneous due to variable expression of these receptors. It was found that established human glioma cell lines exhibited differential susceptibility to Ad-mediated gene transfer, which correlated directly with the level of radiolabeled Ad binding and with the expression of coxsackie/adenovirus receptor but not with the expression of alpha(v) integrins. To circumvent the lack of fiber receptors and to target Ad gene transfer specifically to tumor cells, we used a bispecific antibody conjugate to ablate Ad binding to fiber receptors and retarget binding to the epidermal growth factor receptor (EGFR), a tumor-associated marker negligibly expressed in normal, mitotically quiescent neural tissues. The results demonstrate that EGFR-targeted Ad gene transfer was EGFR specific and independent of fiber-fiber receptor interactions. Furthermore, EGFR targeting significantly enhanced Ad gene delivery to 7 of 12 established glioma cell lines and to 6 of 8 cultured primary gliomas. Interestingly, EGFR-targeted Ad gene transfer did not correlate with EGFR expression across cell lines, suggesting the importance of other factors. This study establishes that fiber receptor expression limits the utility of Ad vectors for gene transfer to glioma cells and suggests that targeting Ad via EGFR may prove valuable for tumor-specific gene transfer to high-grade gliomas. These findings have key relevance in the context of Ad vector-based approaches for glioma gene therapy.
腺病毒（Ad）载体因其在瘤内给药后能够实现高效基因转移，在胶质瘤基因治疗方面具有广阔前景。然而在此情况下，Ad介导基因广泛转移至肿瘤及周围实质组织。Ad的进入依赖于纤维受体的表达，如柯萨奇病毒/腺病毒受体，以及靶细胞上的α(v)整合素，分别用于结合和内化。我们推测，由于这些受体表达的差异，人类胶质瘤对Ad的易感性可能存在异质性。研究发现，已建立的人类胶质瘤细胞系对Ad介导的基因转移表现出不同的易感性，这与放射性标记的Ad结合水平以及柯萨奇病毒/腺病毒受体的表达直接相关，但与α(v)整合素的表达无关。为了规避纤维受体的缺乏，并将Ad基因转移特异性靶向肿瘤细胞，我们使用了一种双特异性抗体偶联物来消除Ad与纤维受体的结合，并将结合重新靶向至表皮生长因子受体（EGFR），EGFR是一种在正常的、有丝分裂静止的神经组织中表达极低的肿瘤相关标志物。结果表明，靶向EGFR的Ad基因转移具有EGFR特异性，且独立于纤维-纤维受体相互作用。此外，EGFR靶向显著增强了Ad基因向12个已建立的胶质瘤细胞系中的7个以及8个培养的原发性胶质瘤中的6个的递送。有趣的是，靶向EGFR的Ad基因转移与跨细胞系的EGFR表达无关，这表明其他因素的重要性。本研究证实，纤维受体的表达限制了Ad载体用于向胶质瘤细胞进行基因转移的效用，并表明通过EGFR靶向Ad可能对向高级别胶质瘤进行肿瘤特异性基因转移具有重要价值。这些发现在基于Ad载体的胶质瘤基因治疗方法中具有关键意义。
