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Abstract

ABSTRACT:The complex history of consensus sequence in microRNA family appears to be closely linked to the early evolution of primates. Each miRNA is predicted to target several hundred genes and the expression pattern of conserved miRNA among species through evolutionary time is an important phenomenon in cancer.Since miRNAs are major post-transcriptional negative regulators of target gene transcript; their origins and functional evolution in primates still remains unclear and controversial. Sixteen miRNAs from seven different types of cancers were analyzed to identify the conserved miRNAs in human and to assess their expression patterns. Evolutionarily conserved sequences were identified among primates for 16 miRNAs by ClustalV algorithm. The expression patterns of 16 miRNAs were confirmed by RT-qPCR. The consensus sequence match was observed in cancer with GU-rich region among globally expressed miRNAs. However, there was an AU-rich region was observed in all sixteen matured miRNAs. Moreover, GU-rich region was observed in stem-loop structured miRNAs. This result indicated that CU-region does not or less evolutionary conserved in cancer and it was replaced by other regions during evolution. The result reveals that these 16 miRNAs showed similar sequence conservation among primates and differentially expressed in seven different types of human cancer cell lines. The present research work reports the sequence conservation of globally expressed miRNA through evolution among primates located on the top branch of the phylogenetic tree and the conserved miRNAs are the major regulators in cancer.