Abstract
linc-ROR is reported to be a potential biomarker of breast cancer, but the detailed mechanism of linc-ROR-mediated breast cancer regulation has not been fully studied. We aimed to explore how linc-ROR affects proliferation, metastasis, and drug sensitivity in breast cancer. Cell lines in which linc-ROR was overexpressed or knocked down were constructed, and the cell proliferation, colony formation, cell migration, and invasion abilities of these lines were explored. A CCK-8 assay was performed to determine the sensitivity of the breast cancer cells to rapamycin. Next-generation sequencing was conducted to explore the detailed regulatory mechanism of linc-ROR; differentially expressed RNAs in the linc-ROR-overexpressing cell line compared with the negative control were screened out, and their target genes were chosen to perform Gene Ontology analysis, Kyoto Encyclopedia of Genes and Genomes analysis, protein-protein interaction network analysis, and competing endogenous RNA (ceRNA) network analysis. The ceRNA mechanism of linc-ROR for miR-194-3p, which targets MECP2, was determined through dual-luciferase reporter assay, RT-qPCR, western blot, and rescue experiments. Finally, we found that linc-ROR was upregulated in breast tumor tissues. linc-ROR promoted the cell proliferation, colony formation, cell migration, and invasion of breast cancer and decreased the sensitivity of breast cancer cells to rapamycin. The overexpression of linc-ROR triggered changes in the whole transcriptome of breast cancer cells, and a total of 85 lncRNAs, 414 microRNAs, 490 mRNAs, and 92 circRNAs were differentially expressed in the linc-ROR-overexpressing cell line compared with the negative control. Through a series of bioinformatic analyses, the 'linc-ROR/miR-194-3p/MECP2' ceRNA regulatory axis was confirmed to be involved in the linc-ROR-mediated progression and drug sensitivity of breast cancer. In conclusion, linc-ROR serves as an onco-lncRNA in breast cancer and promotes the survival of breast cancer cells during rapamycin treatment by functioning as a ceRNA sponge for miR-194-3p, which targets MECP2.