Distinctive microRNA expression in early stage nasopharyngeal carcinoma patients

The goal of this study was to investigate microRNAs (miRs) expression at different stages of nasopharyngeal carcinoma (NPC). MiR expression profiling at various stages of NPC was performed by miR array and further verified using quantitative real-time RT-PCR. Pathway enrichment analysis was carried out to identify the functional pathways regulated by the miRs. The expression of a selected group of identified miRs was verified in stage I NPC by in situ hybridization (ISH). A total of 449 miRs were identified with significantly different expressions between NPC tissues and normal pharyngeal tissues. Eighty-four miRs were dysregulated only in stage I NPC, among which 45 miRs were up-regulated and the other 39 were down-regulated. Pathway enrichment assay revleaed that three significantly down-regulated and three significantly up-regulated miRs involved in 12 pathways associating with tumour formation and progression. Quantitative RT-PCR confirmed the miR array result. In addition, the low expression levels of hsa-miR-4324, hsa-miR-203a and hsa-miR-199b-5p were further validated in stage I NPC by ISH. This present study identifed the miR signature in stage I NPC, providing the basis for early detection and treatment of NPC.