Astragaloside attenuates the progression of prostate cancer cells through endoplasmic reticulum stress pathways

Astragaloside (As) has been demonstrated extensively to serve roles in a variety of tumor types, including glioma, lung cancer, colorectal cancer, breast cancer and cervical cancer, and has therefore been widely used in Traditional Chinese Medicine. To the best of our knowledge, the present study was the first to investigate the efficacy of the Traditional Chinese Medicine astragaloside on tumor growth and the apoptosis of prostate cancer cells. In addition, further investigation into the underlying molecular mechanisms via the endoplasmic reticulum (ER) stress pathway was also performed. In the present study, the human prostate cancer DU-145 cell line was employed as an experimental model in vitro and cells were divided into five treatment groups: Dimethyl sulfoxide (DMSO) group (control), low-dose astragaloside group (L-As; 20 nmol/l), moderate-dose astragaloside group (M-As; 50 nmol/l), high-dose astragaloside group (H-As, 100 nmol/l) and ER stress suppressor group (tauroursodeoxycholic acid; TUDCA). The proliferative ability and apoptosis rate of the DU-145 cells were detected via Cell Counting kit-8 methods and flow cytometry, respectively. Furthermore, the ER stress factors [binding immunoglobulin protein (BiP), C/EBP homologous protein (CHOP) and caspase-12] were assessed through reverse transcription polymerase chain reaction. Additionally, the protein expression levels of inositol-requiring enzyme 1 (IRE1), phosphorylated protein kinase R-like ER kinase (p-PERK), iron-regulated transcriptional activator Aft (AFT)4 and AFT6 were measured detected by western blot analysis. Administration of As significantly reduced the cell viability and promoted apoptosis (P<0.05) in a dose-dependent manner. Expression of ER-stressed genes BiP, CHOP and caspase-12 mRNA was increased by As administration, while TUDCA treatment led to a lower mRNA expression of these genes, compared with the control group. Results of western blot analysis indicated that the protein expression of IRE1, AFT4 and AFT6 was upregulated in the H-As group, and that the ratio of p-PERK/PERK was also higher than in the other groups. The administration of As demonstrated significant therapeutic effects on the proliferation of prostate cancer cells, as well as the expression of related proteins and genes. The results of the present study suggested future clinical potential of As for the treatment of prostate cancer.