Phytochemicals and bioactive substances derived from a wide range of plant
extracts have been reported to exert various anticancer effects. Prostate
cancer is one of the leading causes of cancer-related deaths within the male
population. Prostate cancer-specific miRNA signatures were associated with
cancer formation and progression, with various subtypes, and response to
therapy. MicroRNA levels of expression were shown to change after the
treatment of various compounds and substances extracted from natural
products. Natural herbal compounds were shown to induce variations in miRNA
expression levels in cancer cells. The aims of this study were to
investigate the cytotoxic effects of methanol, ethyl-acetate, and hexane
extracts obtained from branch-body part and flowers of Hypericum perforatum
L. against humane PC-3 and DU 145 and to test potential
miRNA-128/133b/155/193a/206/21/335 signature changes and differences between
the two prostate cancer cell lines. Cytotoxic activity of H. perforatum
extracts, their effects on cell cycle distribution, and miRNA expression
levels were examined in humane PC-3 and DU 145 prostate cancer cells by MTT
cell survival assay, flow cytometry, and quantitative real-time PCR. Hexane
extract of flowers showed the strongest intensity of cytotoxic activity
against PC-3 and DU 145 cells. The highest increase in the percentage of
PC-3 cells in the subG1 phase was observed in cell samples treated with
hexane extract of flowers and branch-body part. Significant differences in
miRNA-128/133b/155/193a/206/21/335 levels were observed between PC-3 and DU
145 cell lines, especially in samples treated with flower extracts compared
with the branch-body part. Conclusions: Investigated extracts have
significant anticancer potential not only from the aspects of cytotoxicity
and cell cycle effects but also from the aspect of lowering oncogenic or
increasing tumor-suppressive miRNAs. The best effect might be the increase
of tumor-suppressive miR-128 (accompanied by miR-193a) induced by the hexane
extract of the flowers, which also exerted the highest cytotoxic activity.
Hexane extract of flowers may be the candidate for further investigation for
improving the efficiency of standard therapies for PCa. A miRNA signature
might be cell-type specific after the treatment with H. perforatum extracts.