Genome-wide identification and expression analysis of microRNA involved in small cell lung cancer via deep sequencing

Small cell lung cancer is a major cause of mortality worldwide. microRNAs (miRNAs) are involved in various biological processes through regulating gene expression. In the present study, to identify the miRNAs involved in human small cell lung cancer at the genome-wide level, Solexa sequencing was employed to sequence two small RNA (sRNA) libraries from small cell lung cancer tissues (LC sRNA library) and the corresponding normal tissues (NT sRNA library). Deep sequencing of the two sRNA libraries identified a number of conserved miRNAs and differential expression analysis of these miRNAs revealed 81 miRNAs differentially expressed in small cell lung cancer, of which more than half were downregulated. The expression trends determined by sequencing were validated by reverse transcription-quantitative polymerase chain reaction analysis. The annotations for the targets of these miRNAs were predicted. This study provides valuable information for understanding the regulatory mechanisms of miRNAs involved in human small cell lung cancer.