Abstract
Hirsuteine is extracted from Uncaria rhynchophylla, the bark of which has traditionally been used to treat hypertension, cancer, convulsions, hemorrhage, auto-immune disorders, and other ailments. The anticancer properties of hirsuteine are of significant importance to the research community; however, its underlying mechanism of action is not well understood. The aim of the present study was to examine the antiproliferative ability of hirsuteine using human breast cancer MDA-MB-453 cells and to determine the underlying molecular mechanism involved in its therapeutic efficacy. The effects of hirsuteine on cell viability were determined using CCK-8 and colony formation assays, while apoptosis was assessed using flow cytometry. Cell cycle distribution was assessed using flow cytometry, and apoptotic cell quantification was performed using via Annexin V-FITC/PI staining and flow cytometry. Reverse transcription-quantitative PCR and western blotting were used to assess the expression of cell cycle progression and apoptosis associated genes and proteins. MDA-MB-453 cell proliferation was significantly reduced by hirsuteine in a concentration and time-dependent manner. Hirsuteine-treated cells exhibited G2/M phase arrest, as evidenced by the increase in G2/M phase cells and a decrease in the G0/G1 phase cells, and this was related to cyclin B1 and CDK1 downregulation. Furthermore, hirsuteine accelerated MDA-MB-453 cell apoptosis by downregulating Bcl-2 while upregulating cytoplasmic cytochrome c, Bax, Apaf1, cleaved caspase-3, and cleaved caspase-9 levels, which together drove apoptotic cell death. Thus, hirsuteine suppressed MDA-MB-453 cancer cell proliferation by inducing cell cycle arrest and promoting apoptosis.