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.