Abstract: Objective To screen novel miRNAs targeting EZH2 3’ untranslated region (UTR) in recombinational MCF-7 breast
cancer cells over-expressing EZH2 3’ UTR and quantitative analyze the expressions of the screened miRNA in breast cancer
cells and tissues. Methods A lentiviral library was transfected into the recombinant cell line MCF-7. The cells were screened
with cytotoxic agents before extraction of the genome for amplification of the miRNA precursors using PCR. The screened
miRNAs were identified with sequence analysis and their expressions were analyzed quantitatively with real-time PCR in
breast cancer cells and tissues. Results Seven miRNAs were screened from the recombinant MCF-7 cells, namely miR-15b,
miR-16-2, miR-181b2, miR-217, miR-224, miR-329-1, and miR-487b, all of which failed to be predicted by bioinformatics
software. Real-time PCR showed that miR-217, miR-329-1, and miR-487b were over-expressed in MCF-7 cells, and the
expression of miR-15b and miR-16-2 was significantly increased in cancer tissues compared with the adjacent tissues (P<0.05).
Conclusions Novel targeted miRNAs that can not be predicted by bioinformatics software were successfully screened from
MCF-7 breast cancer cells over-expressing EZH2 3’ UTR. These miRNAs are expressed differentially between normal breast
cells and breast cancer tissues.