Synergistic antitumor effect of brusatol combined with cisplatin on colorectal cancer cells

Colorectal cancer (CRC) is a common and life-threatening type of malignant cancer, which is associated with a high mortality rate. Cisplatin (CDDP) is a commonly used chemotherapy drug with significant side effects. Brusatol (BR) is one of the principal chemical compounds isolated from the Chinese herb Bruceae Fructus, which has been reported to markedly inhibit the proliferation of numerous cancer cell lines. The present study aimed to investigate the possible synergistic anticancer effects of CDDP combined with BR on CT-26 cells, and to evaluate the underlying mechanisms of action. The growth inhibitory effects of BR, CDDP, and BR and CDDP cotreatment on CT-26 cells were assessed by MTT assay. Cell apoptosis were determined by flow cytometry and western blot analysis. The results indicated that compared with single-agent treatment, cotreatment of CT-26 cells with CDDP and BR synergistically inhibited cell proliferation and increased cellular apoptosis. Furthermore, treatment of CT-26 cells with CDDP and BR resulted in a marked increase in the release of cytosolic cytochrome c, decreased expression of procaspase-3 and procaspase-9, and upregulation of the B-cell lymphoma 2 (Bcl-2)-associated X protein/Bcl-2 ratio compared with treatment with BR or CDDP alone. These results strongly suggested that the combination of CDDP and BR was able to produce a synergistic antitumor effect in CRC cells, thus providing a solid foundation for further development of this combination regimen into an effective therapeutic method for CRC.