Expression and Function of Long-Noncoding RNA in Breast Cancer Cell Lines and Tissues.

miR-29b2 and miR-29c play a suppressive role in breast cancer progression. (also named ) is the host gene for generating both microRNAs. However, the region also expresses longer transcripts with unknown functions. We employed bioinformatics and experimental approaches to decipher expression and function in breast cancer tissues. We also used the CRISPR/Cas9 technique to excise a predicted distal promoter and followed the behavior of the edited cells by real-time PCR, flow cytometry, migration assay, and RNA-seq techniques. We observed that long transcript is significantly downregulated in triple-negative breast cancer. We also identified a promoter for the longer transcripts of whose functionality was demonstrated by transfecting MCF7 cells with a promoter-GFP construct. Knocking-out the promoter by means of CRISPR/Cas9 revealed no alterations in the expression of the neighboring genes and , while the expression of miR-29c was reduced by half. Furthermore, the promoter knockout elevated the migration ability of the edited cells. RNA sequencing revealed many up- and downregulated genes involved in various cellular pathways, including epithelial to mesenchymal transition and mammary gland development pathways. Altogether, we are reporting here the existence of an additional/distal promoter with an enhancer effect on miR-29 generation and an inhibitory effect on cell migration.