TOP2A, HELLS, ATAD2, and TET3 Are Novel Prognostic Markers in Renal Cell Carcinoma

Abstract

To identify and validate novel prognostic marker genes in clear cell renal cell carcinoma (RCC) that are increasingly expressed during tumor progression. Total RNA was isolated from normal renal tissue, primary G1 and G3 tumors, 14 samples each, and 32 metastases from RCC patients. Expression profiles were created using oligonucleotide microarrays. Significant gene expression differences (P < .05) were identified among normal kidney, primary tumor, and metastases. For all filtered genes, univariate survival analysis was carried out. Genes for which lower expression was significantly associated with longer survival were further analyzed using multivariate analysis. Expression of the best candidate markers was further validated in an independent cohort of 55 primary tumors using quantitative real-time polymerase chain reaction. Fifty-nine genes exhibited increased expression in primary RCC compared with normal kidney, and in metastases compared with primary tumors. In univariate or multivariate survival analysis, upregulation of 15 genes was significant. Expression of 8 genes was validated by quantitative real-time polymerase chain reaction. Survival analysis in an independent cohort of 55 RCC patients based on expression in primary RCC showed that TOP2A (hazard ratio [HR] = 4.3, P = .005), HELLS (HR = 3.7, P = .007), ATAD2 (HR = 3.7, P = .019), and TET3 (HR = 2.8, P = .035) represent independent predictors for cancer-specific survival. The proteins encoded by these genes function as topoisomerase, helicase, chromatin modifier, and methyl cytosine dioxygenase, respectively. They are involved in proliferation, transcription, and epigenetic modification. High mRNA levels of TOP2A, HELLS, ATAD2, and TET3 are independent predictors of poor outcome in RCC patients and may be used for individual risk-adapted therapy in the future.