Fibronectin 1 mRNA expression correlates with advanced disease in renal cancer

Background: Fibronectin 1 (FN1) is a glycoprotein involved in cellular adhesion and migration processes. The aim of this study was to elucidate the role of FN1 in development of renal cell cancer (RCC) and to determine a prognostic relevance for optimal clinical management. Methods: 212 renal tissue samples (109 RCC, 86 corresponding tissues from adjacent normal renal tissue and 17 oncocytomas) were collected from patients undergoing surgery for renal tumors and subjected to total RNA extraction. Detection of FN1 mRNA expression was performed using quantitative real time PCR, three endogenous controls, renal proximal tubular epithelial cells (RPTEC) as biological control and the Delta Delta Ct method for calculation of relative quantities. Results: Mean tissue specific FN1 mRNA expression was found to be increased approximately seven fold comparing RCC and corresponding kidney control tissues (p < 0.001; ANOVA). Furthermore, tissue specific mean FN1 expression was increased approx. 11 fold in clear cell compared to papillary RCC (p = 9x10(-5); Wilcoxon rank sum test). Patients with advanced disease had higher FN1 expression when compared to organ-confined disease (p < 0.001; Wilcoxon rank sum test). Applying subgroup analysis we found a significantly higher FN1 mRNA expression between organ-confined and advanced disease in the papillary and not in the clear cell RCC group (p = 0.02 vs. p = 0.2; Wilcoxon rank sum test). There was an increased expression in RCC compared to oncocytoma (p = 0.016; ANOVA). Conclusions: To our knowledge, this is the first study to show that FN1 mRNA expression is higher in RCC compared to normal renal tissue. FN1 mRNA expression might serve as a marker for RCC aggressiveness, indicating early systemic progression particularly for patients with papillary RCC.