Analysis of molecular profiling of renal cell carcinoma: Identification of a 4-microRNA signature as a prognostic value in patients with stage I-II disease.

Abstract

395 Background: Renal-cell carcinoma (RCC) accounts for 3% of all cancers and produces over 12,000 deaths every year in the EE.UU. Currently, there is a need to identify stage I/II RCC patients with high risk of relapse following nephrectomy, given that these patients do not receive adjuvant treatment and ≈ 25% of them relapse. MicroRNAs (miRNAs) are a class of small noncoding RNAs that control gene expression by targeting mRNA and playing an important role as regulators of gene expression during tumorigenesis. Our willing is to define a miRNA expression profile associated with a high risk of relapse in early RCC. Methods: We analyzed 113 pts. with RCC stage I-II of a local data-base who had undergone nephrectomy from 2000 to 2008. RNA was extracted from FFPE samples using RecoverAll (Ambion). RNA samples were hybridized to Human miRNA Microarray Release 14.0, 8x15K (Agilent Technologies. Data were normalized using Quantile Normalization. Only 396 miRNAs with detectable signal in at least 10% of the hybridized samples were considered for further analysis. Identification of miRNAs related with recurrence risk and subsequent developing and validation of miRNA expression-based prediction models of recurrence risk were performed in BRB-ArrayTools v4.2.1. Results: We identified a 4-miRNA expression signature that distinguishes early stage RCC patients with low and high recurrence risk (p value = 0.0013; HR = 4.68 [1.82-12.0]). Distant recurrence free survival rate at five years was 97.4 and 81.2 for the low and high recurrence risk groups respectively. High levels of miR-424 were related with a high recurrence risk (p = 0.023). Conclusions: The TNM staging system lacks accuracy to identify prognostic markers of survival in early RCC. Our results suggest that specific miRNAs are involved in the recurrence of early disease. We have found a miRNA expression signature that identifies patients with high risk of developing distant metastasis using the FFPE sample of primary tumors. High expression levels of miR-424 were related with a high recurrence risk. MiR-424 is a hypoxia induced miRNA whose expression has been related with HIF-1α and HIF-2α stabilization and angiogenesis induction.