Regulation of the Coxsackie and adenovirus receptor expression is dependent on cystic fibrosis transmembrane regulator in airway epithelial cells.

The coxsackievirus and adenovirus receptor (CAR), in addition to serving as viral receptor, is a component of tight junctions and plays an important role in tissue homeostasis. Defects in the cystic fibrosis transmembrane regulator (CFTR) in lung epithelial cells are linked to inflammation and susceptibility for respiratory tract infections. Here, we demonstrate that CAR expression and infectivity with adenovirus (Ad) are increased in cystic fibrosis airway epithelial cells. Inhibition of CFTR or histone deacetylase (HDAC) enhanced CAR expression while CFTR overexpression or restoration of the diminished HDAC activity in cystic fibrosis cells reduced CAR expression. This connects the CFTR to CAR expression and infectivity with adenovirus through HDAC.

Coxsackievirus and adenovirus receptor-positive cells compose the putative stem/progenitor cell niches in the marginal cell layer and parenchyma of the rat anterior pituitary.

The pituitary gland is a slow generative tissue but actively responds to demands by changing homeostasis. The marginal cell layer (MCL) facing the residual lumen has long been indicated as a stem/progenitor cell niche of the pituitary. On the other hand, the coxsackievirus and adenovirus receptor (CAR), which localizes at the tight-junction of the polarized epithelium, is known to participate in the development, differentiation and regeneration of specified tissues. The present study attempts to characterize the cells lining the MCL during pituitary development by immunohistochemistry of CAR. Consequently, we found that CAR localizes in an apical surface of the single cell layer facing the oral cavity in the invaginating oral epithelium on rat embryonic day (E) 11.5. On E13.5, when this single layer constructs the MCL in the pituitary primordium Rathke's pouch, CAR-positive cells occupied the MCL and this localization pattern of CAR was persistently maintained throughout life. Moreover, clusters of CAR-positive cells were also found in the parenchyma. CAR-positive cells were positive for stem/progenitor cell markers sex-determining region Y-box 2 (SOX2) and epithelial calcium-dependent adhesion (E-cadherin). However, prior to the postnatal growth wave, cells positive for CAR in the basolateral surface constructed multiple cell layers beneath the MCL and cell-type transition to a putative migratory cell phenotype by fading of SOX2 and E-cadherin occurred, suggesting the composition of new putative niches in the parenchyma. These data, together with our previous reports, suggest that CAR-positive cells are pituitary stem/progenitor cells and compose putative stem/progenitor cell niches in the MCL and parenchyma.

Expression of coxsackievirus and adenovirus receptor (CAR)-Fc fusion protein in Pichia pastoris and characterization of its anti-coxsackievirus activity.

Coxsackievirus and adenovirus receptors (CARs) are the common cellular receptors which mediate coxsackievirus or adenovirus infection. Receptor trap therapy, which uses soluble viral receptors to block the attachment and internalization of virus, has been developed for the inhibition of virus infection. In this study, we have constructed a pPIC3.5K/CAR-Fc expression plasmid for the economical and scale-up production of CAR-Fc fusion protein in Pichia pastoris. The coding sequence of the fusion protein was optimized according to the host codon usage bias. The amount of the CAR-Fc protein to total cell protein was up to 10% by 1% methanol induction for 96h and the purity was up to 96% after protein purification. Next, the virus pull-down assay demonstrated the binding activity of the CAR-Fc to coxsackievirus. The analyses of MTT assay, immunofluorescence staining and quantitative real-time PCR after virus neutralization assay revealed that CAR-Fc could significantly block coxsackievirus B3 infection in vitro. In coxsackievirus B3 infected mouse models, CAR-Fc treatment reduced mortality, myocardial edema, viral loads and inflammation, suggesting the significant virus blocking effect in vivo. Our results indicated that the P. pastoris expression system could be used to produce large quantities of bioactive CAR-Fc for further clinical purpose.

Expression of the coxsackie adenovirus receptor in neuroendocrine lung cancers and its implications for oncolytic adenoviral infection.

Coxsackie adenovirus receptor (CAR) is the primary receptor to which oncolytic adenoviruses have to bind for internalization and viral replication. A total of 171 neuroendocrine lung tumors in form of multitissue arrays have been analyzed resulting in a positivity of 112 cases (65.5%). Immunostaining correlated statistically significant with histopathology and development of recurrence. The subtype small cell lung cancer (SCLC) showed the highest CAR expression (77.6%), moreover the CAR level was correlated to the disease-free survival. Further, high CAR expression level in SCLC cell lines was found in vitro and in vivo when cell lines had been transplanted into immunodeficient mice. A correlation between CAR expression in the primary tumors and metastases development in the tumor model underlined the clinical relevance. Cell lines with high CAR level showed a high infectivity when infected with a replication-deficient adenovirus. Low levels of CAR expression in SCLC could be upregulated with Trichostatin A, a histone deacetylase inhibitor. As a result of the unaltered poor prognosis of SCLC and its high CAR expression it seems to be the perfect candidate for oncolytic therapy. With our clinically relevant tumor model, we show that xenograft experiments are warrant to test the efficiency of oncolytic adenoviral therapy.

Aptamer modification improves the adenoviral transduction of malignant glioma cells.

Adenovirus has shown increasing promise in the gene-viral therapy for glioblastoma, a treatment strategy that relies on the delivery of viruses or transgenes into tumor cells. However, targeting of adenovirus to human glioblastoma remains a challenge due to the low expression level of coxsackie and adenovirus receptor (CAR) in glioma cells. Aptamers are small and highly structured single-stranded oligonucleotides that bind at high affinity to a target molecule, and are good candidates for targeted imaging and therapy. In this study, to construct an aptamer-modified Ad5, we first genetically modified the HVR5 of Ad hexon by biotin acceptor peptide (BAP), which would be metabolically biotinylated during production in HEK293 cells, and then attached the biotin labeled aptamer to the modified Ad through avidin­biotin binding. The aptamers used in this study includes AS1411 and GBI-10. The former is a DNA aptamer that can bind to nucleolin, a nuclear matrix protein found on the surface of cancer cells. The latter is a DNA aptamer that can recognize the extracellular matrix protein tenascin-C on the surface of human glioblastoma cells. To examine if aptamer-modification of the hexon protein could improve the adenoviral transduction efficiency, a glioblastoma cell line, U251, was transduced with aptamer-modified Ads. The transduction efficiency of AS1411- or GBI-10-modified Ad was approximately 4.1-fold or 5.2-fold higher than that of the control. The data indicated that aptamer modified adenovirus would be a useful tool for cancer gene therapy.

Gene therapy using adenovirus against malignant mesothelioma.

BACKGROUND: Adenovirus vectors have been utilized for cancer gene therapies. The present study examined the oncolytic effects of adenovirus type 5 (Ad5) and fiber-substituted conditionally replicating adenovirus (CRAD) Ad5/F35 vectors on the human malignant mesothelioma cells MSTO-211H, NCI-H28, NCI-H2052, and NCI-H2452 cells. MATERIALS AND METHOD: For the adenovirus, the first mRNA/protein to be made (~1 h after infection) is E1A. Ad5F35 and Ad5 CRAD vectors containing the E1 gene controlled by the human midkine promoter (Ad5F35/MKp-E1 and Ad5/MKp-E1, respectively) were constructed. Western blotting and cell viability assays were carried out in cells transfected with Ad5/MKp-E1 and Ad5F35/MKp-E1. RESULTS: Coxsackie and adenovirus receptor (CAR), a cell surface target of Ad5, and CD46, a cell surface target of Ad35, were expressed in all the malignant mesothelioma cell lines examined here, as much as in HEK293 cells, with no significant differences in the expression levels among cells. Both Ad5/MKp-E1 and Ad5F35/MKp-E1 induced oncolysis of malignant mesothelioma cells in a viral particle-dependent manner, with similar efficacy. CONCLUSION: The results of the present study suggest that both Ad5/MKp-E1 and Ad5F35/MKp-E1 are useful for the gene therapy of human malignant mesothelioma.