Hypericum perforatum L. extracts exert cytotoxic effects and show different miRNA signatures in PC-3 and DU 145 prostate cancer cells

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.