Identification Of Differently Expressioned MicroRNAs And Prilimary Exploration Of The Associated MicroRNAs' Functions In Papillay Thyroid Carcinoma

ObjectiveMicroRNAs (miRNAs) are non-encoding small RNAs existing extensively in plants, animals, and viruses, at an approximate length of 21-23nt and highly conserved. They bind to specific mRNA 3'-UTR and regulates gene transcription, mature miRNAs form with other proteins into RNA induced silencing complex, resulting in the degradation or translation suppression of target mRNA if binding to target mRNA 3'-UTR miRNAs are involved in the regulation of multiple critical biological activities, and play a critical role in tumorigenesis.Papillary thyroid carcinoma (PTC) is the most common type of endocrine system malignant tumor, accounts for about 80% of thyroid cancer cases. Incidence rate of PTC increases year and year, has been the eighth in females tumor incidence. PTC is seriously threatening human health and life, has recently become one of research focuses in endocrine system tumors. However, the pathogenesis of PTC is not clear, so, further exploring the molecular pathogenesis of PTC has a very vital significance to improve diagnosis and treatment.We aimed to select differentially expressed miRNAs by using microarray chip in PTC and adjacent tissues, discovery the related miRNAs with PTC, and discuss occurrence and development of PTC with them. It provides a theory and research basis for further miRNAs studies on the molecular mechanism of occurrence and development in PTC. MethodsSurgical specimens of PTC were harvested from PTC patients(n=3)undergoing surgery at Department of Thyroid Surgery in the First Affiliated Hospital of Zhengzhou University in June 2010. RNAs of PTC and adjacent tissues were extracted respectively. UsingμParafloTM microarray chip select differentially expressed miRNAs in PTC and adjacent tissues, and differently expressioned miRNAs were analysised. We used real-time quantitative polymerase chain reaction (PCR) with TaqMan MicroRNA Assays to verify the microarray results and examined the expression profiles of miR-21 and miR-181c in PTC and adjacent tissues. Regulating target genes of significant differential expression miR-146b-5p and miR-7 in PTC were forecasted by using function prediction softwares, including their preliminary biological functions.Results1 Thirty-eight upregulated expression miRNAs were identified in PTC, significantly upregulated miRNAs(log2≥1) including miR-146b-5p, miR-221, miR-222, miR-34a, miR-375, miR-31, miR-181a-2*, miR-21, miR-181c, miR-146b-3p, miR-181a, miR-1260b, miR-182, miR-1281, miR-22*, relative to adjacent tissues. Twenty-six downregulated expression miRNAs were identified, significantly downregulated miRNAs(log2≤-1) including miR-7, miR-204, miR-486-5p, miR-7-2*, miR-335, miR-3149, miR-374b, miR-126, miR-130a, miR-99a, miR-150, miR-338-5p, miR-100, miR-3115(p<0.05).2 We used real-time quantitative PCR with TaqMan MicroRNA Assays to verify the microarray results and examined the expression profiles of miR-21 and miR-181c in PTC and adjacent tissues. RNU48 was used as an internal control. In contrast to those in adjacent tissues, miR-21 and miR-181c were upregulated by 3.81-and 1.34-fold in PTC, respectively.3 we predicted target genes of miR-146b-5p and miR-7 with most significant differential expression profiling by using function prediction softwares, including 80 target genes for miR-146b-5p and 129 for miR-7. 4 The analysis of biological activities showed that many target genes were involved in cell proliferation, differentiation, apoptosis, cycle, signaling transduction pathway, angiogenesis, et al, some target genes was responsible for multiple biological activities.Conclusion1 In the present study,15 miRNAs are significantly expressed upregulated in PTC,14 miRNAs are significantly expressed downregulated, respectively. The results indicates that the abnormal expression of these miRNAs may correlate with patho genesis of PTC.2 The comparison of fluorescence quantitative PCR with microarray results showed a generally consistent tendency, Which indicates accuracy of real-time quantitative PCR for verification of miRNA expression.3 Target prediction with softwares shows that various target genes was responsible for cell biological activities, which indicates that the abnormal expression of these miRNAs may play important roles in pathogenesis of PTC by inducing regulation of target genes.