The expression profiles of microRNAs in Kaposi's sarcoma

Kaposi's sarcoma (KS) is a multicentric angioproliferative tumor of mesenchymal origin. The molecular and biologic aspects of KS are not fully understood. MicroRNAs are non-protein-coding small RNAs in the size range 19-25 nucleotides (nt) that play important roles in biological processes, including cellular differentiation, proliferation, and death. We performed a miRNA microarray analysis by detecting six paired KS and matched adjacent healthy tissues using the 7th generation of miRCURY(TM) LNA Array (v.18.0) (Exiqon) containing 3100 capture probes. We selected 10 significant differentially expressed miRNAs, which were confirmed by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) in 18 paired KS and matched adjacent healthy tissue specimens. We also investigated the associations between clinical features and miRNA expression. Among the 3100 human miRNA probes in the microarrays, we identified 170 differentially expressed miRNAs (69 upregulated and 101 downregulated miRNAs) in KS versus adjacent healthy tissues. Among the most significantly upregulated miRNAs were miR-126-3p, miR-199a-3p, miR-16-5p, and the 13 KSHV-related miRNAs. The most significantly downregulated miRNAs included miR-125b-1-3p and miR-1183. Eight upregulated miRNAs, miR-181b-5p, miR-199a-3p, miR-15a-5p, miR-126-3p, miR-1297, kshv-miR-k12-12-3p, kshv-miR-k12-1-5p, and miR-16-5p, and two downregulated miRNAs, miR-125b-1-3p and miR-1183, were confirmed by qRT-PCR in 18 paired KS samples. The qRT-PCR results for 10 miRNAs were consistent with our microarray results. The miR-125b-1-3p and miR-16-5p had statistically significant associations with HHV-8 and HIV infections in KS. The results of miRNA profiling showed that KS appears to have unique expression patterns when compared with paired adjacent healthy tissues, suggesting that deregulation of miRNAs plays an important role in the progression of KS. These differentially expressed miRNAs may provide novel diagnostic and prognostic tools.