1525

CXADR

coxsackie virus and adenovirus receptor;CXADR;coxsackie virus and adenovirus receptor

46 kD coxsackievirus and adenovirus receptor (CAR) protein|CVB3-binding protein|HCVADR|coxsackievirus B-adenovirus receptor|coxsackievirus and adenovirus receptor

21q21.1

protein-coding

The coxsackie and adenovirus receptor (CAR) is involved in the epithelial cell tight junction, the downregulated expression of which is observed in different cancer types. In the present study, we examined CAR's role in tumor metastasis using a B16 melanoma and CT26 colon adenocarcinoma model of experimental metastasis. In lung metastasis, the colony number of B16 cells stably expressing CAR (B16CAR) was significantly lower than that of the control CAR-negative B16 cells. B16 and CT26 cells transiently expressing CAR, which were transduced with adenovirus (Ad) vector expressing CAR, also reduced lung metastasis, suggesting that CAR plays a role in the early stage of metastasis. CAR expression significantly decreased the accumulation of B16 cells in the lung after i.v. injection and the migration in vitro. CAR expression reduced expression of alpha(v), alpha(4), beta(3) and beta(1) integrin, which play important roles in attachment to cells or basement membrane. Thus, CAR expression likely acts as a metastatic suppressor.

AIMS: Coxsackie and adenovirus receptor (CAR) is a tumor suppressor and a primary receptor for adenovirus type 5 (Ad5). Our study aims to examine the influence of forced expression of CAR in rhabdomyosarcoma cells (RD) on expression levels of integrins implicated in Ad5 entry, and the effect of CAR on cell-extracellular matrix adhesion and migration. MAIN METHODS: CAR expressing clones were established from RD cells by stable transfection. Flow cytometry was used to evaluate the expression of CAR and integrins. Adhesion was measured in plates previously coated with vitronectin or fibronectin. Boyden chambers were used to investigate migration. Transfection of cells with siRNA was used to achieve integrin silencing. Ad5-mediated transgene expression was measured by beta-gal staining. KEY FINDINGS: Increased expression of CAR in RD cells reduces the expression of alphavbeta3 and alphavbeta5 integrins. Cells overexpressing CAR exhibit significantly reduced adhesion to vitronectin and fibronectin, and reduced cell migration. Specifically silencing alphavbeta3 integrin in RD cells reduced cell migration indicating that reduced migration could be the consequence of alphavbeta3 integrin downregulation. This study also demonstrates the negative effect of reduced levels of alphavbeta3 and alphavbeta5 integrins on Ad5-mediated transgene expression with Ad5 retargeted to alphav integrins. SIGNIFICANCE: The pharmacological upregulation of CAR aimed to increase Ad5-mediated transgene expression may actually downregulate alphavbeta3 and alphavbeta5 integrins and thus alter Ad5-mediated gene transfer. The mechanism of decreased cell migration, a prerequisite for metastasis and invasion, due to increased CAR expression may be explained by reduced alphavbeta3 integrin expression.

AIMS: Coxsackie and adenovirus receptor (CAR) is a tumor suppressor and a primary receptor for adenovirus type 5 (Ad5). Our study aims to examine the influence of forced expression of CAR in rhabdomyosarcoma cells (RD) on expression levels of integrins implicated in Ad5 entry, and the effect of CAR on cell-extracellular matrix adhesion and migration. MAIN METHODS: CAR expressing clones were established from RD cells by stable transfection. Flow cytometry was used to evaluate the expression of CAR and integrins. Adhesion was measured in plates previously coated with vitronectin or fibronectin. Boyden chambers were used to investigate migration. Transfection of cells with siRNA was used to achieve integrin silencing. Ad5-mediated transgene expression was measured by beta-gal staining. KEY FINDINGS: Increased expression of CAR in RD cells reduces the expression of alphavbeta3 and alphavbeta5 integrins. Cells overexpressing CAR exhibit significantly reduced adhesion to vitronectin and fibronectin, and reduced cell migration. Specifically silencing alphavbeta3 integrin in RD cells reduced cell migration indicating that reduced migration could be the consequence of alphavbeta3 integrin downregulation. This study also demonstrates the negative effect of reduced levels of alphavbeta3 and alphavbeta5 integrins on Ad5-mediated transgene expression with Ad5 retargeted to alphav integrins. SIGNIFICANCE: The pharmacological upregulation of CAR aimed to increase Ad5-mediated transgene expression may actually downregulate alphavbeta3 and alphavbeta5 integrins and thus alter Ad5-mediated gene transfer. The mechanism of decreased cell migration, a prerequisite for metastasis and invasion, due to increased CAR expression may be explained by reduced alphavbeta3 integrin expression.