The coxsackievirus and adenovirus receptor acts as a tumour suppressor in malignant glioma cells

The coxsackievirus and adenovirus receptor (CAR) is a membrane glycoprotein with a cytoplasmic domain, a transmembrane domain and an extracellular region consisting of two immunoglobulin-like domains, an amino-terminal immunoglobulin variable (IgV)-related domain (D1), which is distal to the cell surface, and a proximal IgC2 domain (D2). The coxsackievirus and adenovirus receptor has been shown to exhibit tumour suppression activity in human bladder and prostate cancer cells. In the current paper, we demonstrate that CAR is a tumour suppressor in glioma cells and that the extracellular D2 domain is not required for this inhibitory effect. This finding provides a biological basis for the observation that expression of CAR is downregulated in malignant glioma cells. This suggests that strategies to redirect adenoviruses to achieve CAR-independent infection will be necessary to realise the full potential of adenoviral vectors for cancer gene therapy.