The expression profiles of microRNAs in Kaposi’s sarcoma

MicroRNAs (miRNAs) are non-protein-coding small RNAs in the size range 19–25 nucleotides (nt) that are cleaved from 70-100 nt hairpin pre-miRNA precursors.MiRNAs bind to complementary sequences in the 3′-untranslated regions of their target mRNAs and induce mRNA degradation or translational repression. Recent intensive studies have revealed that miRNAs play important roles in a large number of biological processes, including cellular differentiation, proliferation and death. These wide-ranging biological roles suggest that miRNAs may be involved in cancer development. MiRNAs regulate a variety of biological processes, including developmental timing, signal transduction, cell growth, and cell death.Kaposi’s sarcoma (KS) is a multicentric angioproliferative tumor of mesenchymal origin.8, 9 In 1872, the disease was first described by Moritz Kaposi, and it mostly affects elderly men of Italian, Jewish, or Mediterranean origin. In China, more than 90% of KS cases occur in Xinjiang,12-14 which is a multiethnic gathering place where Uyghur (45.7%) and Han (39.7%) are the main ethnic groups; other groups include the Kazakh (7%) and Hui(4.5%). The specific geographical environment and ethnic specificity may characterize some of the specific features of KS in this area, which might also be reflected in the miRNA expression profile in KS tissues. MicroRNAs (miRNAs) are non-protein-coding small RNAs in the size range 19–25 nucleotides (nt) that are cleaved from 70-100 nt hairpin pre-miRNA precursors.MiRNAs bind to complementary sequences in the 3′-untranslated regions of their target mRNAs and induce mRNA degradation or translational repression. Recent intensive studies have revealed that miRNAs play important roles in a large number of biological processes, including cellular differentiation, proliferation and death. These wide-ranging biological roles suggest that miRNAs may be involved in cancer development. MiRNAs regulate a variety of biological processes, including developmental timing, signal transduction, cell growth, and cell death.Kaposi’s sarcoma (KS) is a multicentric angioproliferative tumor of mesenchymal origin.8, 9 In 1872, the disease was first described by Moritz Kaposi, and it mostly affects elderly men of Italian, Jewish, or Mediterranean origin. In China, more than 90% of KS cases occur in Xinjiang,12-14 which is a multiethnic gathering place where Uyghur (45.7%) and Han (39.7%) are the main ethnic groups; other groups include the Kazakh (7%) and Hui(4.5%). The specific geographical environment and ethnic specificity may characterize some of the specific features of KS in this area, which might also be reflected in the miRNA expression profile in KS tissues. KS tissues and matched normal tissues were obtained from surgical specimens immediately after resection from Jan 2012 to Sep 2013 in the Department of Dermatology, People’s Hospital of the Xinjiang Uyghur Autonomous Region, China.The samples were flash frozen in liquid nitrogen and stored at -180℃until RNA extraction. RNA labeling and hybridization were completed by KangChen Bio-tech Inc. (Shanghai, China) according to the manufacturer's instructions. Briefly,Total RNA was harvested using TRIzol (Invitrogen) and miRNeasy mini kit (QIAGEN) according to manufacturer’s instructions. After having passed RNA quantity measurement using the NanoDrop 1000, the samples were labeled using the miRCURY™ Hy3™/Hy5™ Power labeling kit and hybridized on the miRCURY™ LNA Array (v.18.0) which contains probes for 3100 mature miRNA.Following the washing steps the slides were scanned using the Axon GenePix 4000B microarray scanner.Scanned images were then imported into GenePix Pro 6.0 software (Axon) for grid alignment and data extraction. Replicated miRNAs were averaged and miRNAs that intensities>=30 in all samples were chosen for calculating normalization factor. Expressed data were normalized using the Median normalization. After normalization, significant differentially expressed miRNAs were identified through Volcano Plot filtering. Finally, hierarchical clustering was performed to show distinguishable miRNA expression profiling among samples.