Nevertheless, there exists a certain intersection between

groups of miRNAs identified in individual studies, and several interesting mechanistic studies have revealed the functions of some miRNAs in vitro [21]. The aim of our study was to validate expression changes of selected miRNAs identified in previous microarray studies (miR-155 [16], miR-106a [19], miR-106b [19], miR-200b [16, 19], miR-200c [15, 16, 19], miR-141 [15, 16], miR-182 [13] and miR-210 [16, 19]) by the standardized and more quantitative Selleck 4EGI-1 method that is real-time polymerase chain reaction (PCR). For the first time, we have correlated miRNAs with the relapse-free survival of RCC patients in order to evaluate them as potential predictive biomarkers of early metastasis after nephrectomy. Patients and methods Study population SRT2104 in vitro Thirty-eight patients (24 men, 14 women) diagnosed for clear cell renal cell carcinoma at Masaryk Memorial Cancer Institute (Brno, Czech Republic) between 2003 and 2009 were included AZD8931 mw in this study. The study has been approved by the local Ethical Committee. Patients’ ages ranged between 41 and 89 years, with a median of 68. Histological diagnosis was established

according to the guidelines of the World Health Organization. Cases were selected according to tissue availability and were not stratified for any known preoperative or pathological prognostic factor. Clinical follow-up data in the form of annually assessed survival time was

available for all patients. The median follow-up time for all cases was 40 months and ranged from 3 to 105 months. Clinical characteristics of the patients are summarized in Table 1. Table 1 Patient characteristics Factor Number Age   mean 68 range 41-89 Sex   male 24 PI-1840 female 14 Stage   T1+T2 19 T3 19 Fuhrman grade   G1 6 G2 25 G3 7 Early recurrence   Yes* 15 No** 23 * Recurrence-free survival = 11.5 (5-36) months ** Follow-up = 50 (41-62) months Medians and 25th and 75th percentiles in parentheses. Tissue sample preparation and miRNA purification Under the supervision of an experienced pathologist, 48 tissue samples were collected (before any treatment was started) from surgically resected tissues – 38 samples from primary tumors and 10 from adjacent non-tumoral renal parenchyma. All samples were immediately stored in liquid nitrogen until RNA extraction. Samples were homogenized (Retch MM301) in sterile conditions before total RNA isolation. Total RNA isolation and small RNA enrichment procedures were performed using the mirVana miRNA Isolation Kit (Ambion, USA) according to the manufacturer’s instructions. DNA was extracted using the Qiagen DNA Mini Kit (Qiagen, Germany), again following the manufacturer’s instructions. Nucleic acid concentration and purity were controlled by UV spectrophotometry (A260:A280 > 2.0; A260:A230 > 1.8) using a Nanodrop ND-1000 (Thermo Scientific, USA).