Expression of dystroglycan correlates with tumor grade and predicts survival in renal cell carcinoma

The dystroglycan (DG) complex is a transmembrane glycoprotein that forms a continuous link from the extracellular matrix to the actin cytoskeleton. Deregulated expression of DG has been reported in a variety of human malignancies and related to tumor aggressiveness. In this study expression of the DG subunit was evaluated by immunostaining in a series of renal epithelial cancers and its relation with traditional prognostic indicators and with the clinical outcome of the patients was evaluated. alphaDG expression was undetectable in a significant fraction of tumors (54%). In renal cell carcinomas (RCC) loss of alpha-DG staining correlated with higher tumor grade (p = 0.02) but not with tumor stage nor tumor size. In clear cell RCC patients loss of alphaDG staining correlated with an increased risk of recurrence (p = 0.002 by log-rank test) and death (p = 0.004) also when patients with lower grade or stage tumors were analyzed separately. In a multivariate analysis loss of DG staining confirmed to be and independent predictor of shorter disease-free (p = 0.001; RR = 4.9) and overall (p = 0.009; RR = 4.9) survival stronger than tumor grade and size. These findings demonstrate that loss of alphaDG expression, which correspond to loss of a functional DG complex, is a frequent event in human renal tumorigenesis and is an independent predictor of early recurrence and death for patients with clear cell RCC.