Microarray data analysis.

The slides were scanned using an Axon GenePix 4000B microarray scanner (Axon Instruments, Foster City, CA). Scanned images then were imported into GenePix Pro 6.0 software (Axon) for grid alignment and data extraction. Signal intensities for each spot were scanned and calculated by subtracting background levels. miRNAs with intensities of >50 were chosen for calculating the median normalization factor. Expressed miRNA data were normalized using median normalization. After normalization, obtained average values for each miRNA spot were used for statistics. Finally, hierarchical clustering was performed to show distinguishable miRNAs using MEV software (v4.6; TIGR [The institute for Genomic Research]).