Despite recent advances in the treatment of metastatic
prostate cancer (PCa), resistance development after
taxane treatments is inevitable, necessitating effective options to combat drug resistance. Previous studies indicated antitumoral properties of the natural compound
amygdalin. However, whether
amygdalin acts on drug-resistant
tumor cells remains questionable. An in vitro study was performed to investigate the influence of
amygdalin (10 mg/mL) on the growth of a panel of
therapy-naïve and
docetaxel- or
cabazitaxel-resistant PCa cell lines (PC3, DU145, and LNCaP cells).
Tumor growth, proliferation, clonal growth, and cell cycle progression were investigated. The cell cycle regulating
proteins (phospho)cdk1, (phospho)cdk2,
cyclin A,
cyclin B, p21, and p27 and the
mammalian target of rapamycin (mTOR) pathway
proteins (phospho)Akt, (phospho)Raptor, and (phospho)Rictor as well as
integrin β1 and the
cytoskeletal proteins vimentin,
ezrin,
talin, and
cytokeratin 8/18 were assessed. Furthermore, chemotactic activity and adhesion to extracellular matrix components were analyzed.
Amygdalin dose-dependently inhibited
tumor growth and reduced
tumor clones in all (parental and resistant) PCa cell lines, accompanied by a G0/G1 phase accumulation. Cell cycle regulating
proteins were significantly altered by
amygdalin. A moderate influence of
amygdalin on
tumor cell adhesion and chemotaxis was observed as well, paralleled by modifications of
cytoskeletal proteins and the
integrin β1 expression level.
Amygdalin may, therefore, block
tumor growth and disseminative characteristics of
taxane-resistant PCa cells. Further studies are warranted to determine
amygdalin's value as an
antitumor drug.