Human microrna microarray v2

microRNA expression profiles were performed using the human microRNA microarray V2 (Agilent Technologies, Santa Clara, California, USA) which contains 723 human microRNAs (Sanger database V.10.1) and 76 human viral microRNAs. Three biological replicate samples for each experimental condition (normoxia, 16 h hypoxia, 32 h hypoxia and 48 h hypoxia) were analysed. Samples were prepared with the Mirna Labelling Reagent and Hybridization kit (Agilent Technologies, Santa Clara, California, USA) following the instructions supplied by the manufacturer. The microarray hybridization was performed at 55°C for 20 h and at a constant speed rotation of 20 rpm. The hybridization signals were detected by the Agilent Microarray scanner G2565BA and quantified using the Agilent Feature extraction software version 9.5.1 (both from Agilent Technologies, Santa Clara, California, USA). A GeneView file including the Total Gene Signal (raw data) and the Total Gene Error for each of the microRNAs interrogated on the microarray was generated for all the samples and used for further analysis. One sample corresponding to MCF-7 cells exposed to hypoxia for 16 h was affected by a random technical problem and had to be removed due to the bad quality of the scan.