Determination of Dysregulated miRNA Expression Levels by qRT-PCR after the Application of Usnic Acid to Breast Cancer

Background and Purpose: Breast cancer still remains to be one of the most threatening cancer types in women. Recent studies have allowed scientists to better investigate the potential use of natural compounds in the treatment of breast cancers. Usnic acid is a secondary metabolite extracted from lichen species and has many biological activities. The response of microRNAs regulated by drug molecules may provide useful diagnostic and prognostic biomarkers, as well as potential therapeutics for breast cancers. Although the aberrant expression of microRNAs was observed after drug treatment, the regulatory mechanisms remain partially known. Micro RNAs (miRNAs) play an important role in gene regulation at the post-transcriptional level. Methods: In this study, we used quantitative Real-Time PCR (qRT-PCR) technology to demonstrate that usnic acid significantly changes the expression profile of miRNAs. Results: Eleven miRNAs were significantly and differentially expressed in breast cancer cells after treatment with usnic acid. Three miRNAs were up-regulated, while eight were down-regulated in usnic acid treated cells. Target prediction and GO analysis revealed many target genes and their related pathways that are potentially regulated by usnic acid regulated differentially expressed miRNAs. We found that usnic acid treatment caused significant changes in the expression of hsa-miR-5006-5p, hsa-miR-892c-3p, hsa-miR-4430, hsa-miR-5194, hsa-miR-3198, hsa-miR-3171, hsa-miR-933 and hsa-miR-185-3p in breast cancer cells. Conclusion: Usnic acid response miRNAs might play important regulatory roles in the tumorigenesis and development of breast cancer, and they could serve as prognostic predictors for breast cancer patients.