The Different Effects Of MicroRNA On The Same Target Gene In Normal And Hypoxia Condition Of CNE

MicroRNAs (miRNA) are a set of short non-coding RNA with 20-24 nucleotied length. They can bind to the 3' untranslated regions (3'UTR) of target gene and regulate the post-transcriptional progress of mRNA. The mechanism of miRNA regulating the post-transcritional progress by specific binding to the target gene with the RNA-Induced Silencing Complex has been fully studied. However, the studies of miRNA are confined in one target gene-one miRNA or one target gene-one miRNA family. Here we used the pRL-TK Lusifer Reporter Vector as our basic tool to build a set of full length 3'UTR Lusifer Reporter Vectors. The vectors can detect the lusifer inhibition rate of target gene's 3'UTR interfered by the regulation of the endogenous miRNA. We used the normal and hypoxia-induced human nasopharyngeal carcinoma cell Line (CNE) to study the differences between their miRNA expression profiles and the miRNA-directed regulation of the same target gene. We found that the alteration of the miRNA expression profile tended to increase the inhibition rate of the target gene's (for example, the angiogenesis factor VEGF and PTN) translation. At the same time, the change of the miRNA expression profile can inhibit the cell proliferation by increasing the inhibition rate of the CCND1's translation. Thus the CNE can adapt itself to the change of energy metabolism under hypoxia environment. We also proved that the translating inhibition rate was co-related with the total numbers of miRNA target sites. The target sites are predicted by the bioinformatic software. When the total numbers of miRNA target sites in a full length 3'UTR was up to 50, the inhibition efficiency of the miRNA to mRNA seemed saturated and the inhibition rate did not increase. Our results revealed the integrated regulation mechanism of endogenous miRNAs to the target gene and pointed out the change of the miRNA expression profile enhanced the stress resistance of the CNE cell under the hypoxia condition.